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© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.1
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.1
Introduction to
QUALITY OF SERVICE and TRAFFIC LOAD
MONITORING
BSS release B8
B8
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.2
1.2
PROGRAM
1 INTRODUCTION2 GLOBAL INDICATORS3 DETAILED INDICATORS4 HANDOVER INDICATORS5 DIRECTED RETRY INDICATORS6 RADIO MEASUREMENT STATISTICS INDICATORS7 TRAFFIC INDICATORS
B8
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.3
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.3
1 INTRODUCTION
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.4
1.4
1 IntroductionSession presentation
Objective: to be able to explain what is QoS and Traffic Load monitoring of the BSS and what are the information sources available for that purpose
Program: 1.1 Monitoring the QoS of the BSS 1.2 Monitoring the Traffic Load of the BSS1.3 Information sources available1.4 Introduction to K1205 PC emulation
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.5
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.5
1 INTRODUCTION
1.1 Monitoring the QoS of the BSS
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.6
1.6
1.1 Monitoring the QoS of the BSSDefinition
”Monitor" "network" "quality"monitor = measure or ensure? network = BSS? BSS+NSS? BSS+NSS+PSTN …quality = service (end-user) and/or system (technical)
But also detect, localize, diagnose outagesdetect (decide according to thresholds)localize (which cell, BSC, etc.)diagnose: radio, BSS, TC problems
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.7
1.7
1.1 Monitoring the QoS of the BSSUsage
QoS ResultsQoS Results
Management•network monitoring•comparison with competitor•comparison of manufacturers•contractual requirement: licence•quality responsible
Management•network monitoring•comparison with competitor•comparison of manufacturers•contractual requirement: licence•quality responsible
Radio optimization•cell radio quality survey•HO quality monitoring•assessment of tuning efficiency
Radio optimization•cell radio quality survey•HO quality monitoring•assessment of tuning efficiency
BSS maintenance•cell/BSC/TC problem detection
BSS maintenance•cell/BSC/TC problem detection
3 usages of QoS data ⇒ 3 levels of QoS reports: 1. Management team: has to compare Network QoS with competitors' one and to plan Network evolutions.
⇒ needs to have a general view of the Network QoS on a monthly (and sometimes weekly) basis.2. Radio Optimization team: has to detect bad QoS areas in the network and to implement and assess modifications for QoSimprovement.
⇒ needs to have a detailed status and evolution of the QoS at BSS and cell (and sometimes TRX) levels on a weekly, daily (and sometimes hourly) basis.
3. Supervision and Maintenance team: has to detect dramatic QoS degradations and identify the responsible Network Element (and if possible component).
⇒ needs to have the most detailed status of QoS at cell and TRX levels on an hourly basis.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.8
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.8
1 INTRODUCTION
1.2 Monitoring the Traffic Load of the BSS
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.9
1.9
1.2 Monitoring the Traffic Load of the BSS Definition
Measure the "quantity" of traffic handled by:the networkthe BSCsthe cells
Analyze traffic characteristicscall, handover, location update, etc.
As input for dimensioning/architecture team
Traffic characteristics used as a "call mix" to dimension or re-dimension the network will be developed in the section Monitoring the Traffic Load of the BSS.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.10
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.10
1 INTRODUCTION
1.3 Information sources available
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.11
1.11
1.3 Information sources available Observation means
DIFFERENT WAYS TO OBSERVE/MEASURE the GSM network
External Interface AnalysisA interface: MSC/TC-BSCAbis interface: BSC/BTSAir MS/BTS
Counter browser
OMC CountersBSC(NSS)
Tektronix K1205
Gnnettest MPAW&G NPA
QoS data can be built-up from different and complementary kinds of information sources.Usually post-processing applications will build up QoS indicators from:
OMC-R counters provided by the BSS system itself.Signaling messages provided by a protocol acquisition tool on the different interfaces handled by the BSS: Air, Abis, A (or Ater).
Abis
A
MSC/VLR
AbisBSC TCBTS
Ater
Air
SACCH RSL N7 N7
drive test tool protocol analyzer
MS
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.12
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1.3 Information sources available A interface trace
INFORMATION SOURCE: EXTERNAL INTERFACE "A"
Capture/decode signaling between MSC and BSC-TC (A or AterMUX)with "protocol analyzer" (Wandel, Tektronix, Gnnettest, etc.)
+ GSM standard, can be used for arbitrage between manufacturers+ Complete information (message contents, time-stamp)+ Possible detection of User/MS/BSS/TC/NSS problems- High cost of equipment- Time consuming, "post mortem" (installation of tool, file analysis)- Important expertise needed for analysis- Low coverage (K1103/MA10: 8 COCs, K1205/MPA: 32 COCs maximum!) - Large amount of data (>> 10 Mbytes /hour/BSC)
The main advantage of the A interface is to allow the detection of Call Setup failures either due to the User or to the NSS (or PSTN).Some typical user failure causes are: Some typical NSS failure causes are:
IMSI Unknown in VLR Temporary FailureIMSI Unknown in HLR Resource UnavailableIMEI Not Accepted Switching Equipment CongestionPLMN Not Allowed Normal UnspecifiedService Option Not Supported Recovery on Timer ExpiryRequested Service Not Supported Call Reject Unassigned Number InterworkingOperator Determined Barring Protocol ErrorUser Alerting Network FailureFacility Not Subscribed CongestionNo Route to DestinationNormal Call ClearingUser BusyInvalid Number FormatCall RejectInterworkingNormal Unspecified
CAUTION: In order to assess the QoS of a BSS or some cells of a BSS, all N7 links between this BSC and the MSC must be traced. Indeed, as the N7 signaling load is spread over all N7 links, signaling messages relating to one call can be conveyed onany of the active N7 links.
K1103 protocol analyzer can trace up to 8 COCs at the same time but on maximum 4 PCM physical links.K1205 protocol analyzer can trace up to 32 COCs at the same time but on maximum 16 PCM physical links.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.13
1.13
1.3 Information sources available Abis interface trace
INFORMATION SOURCE: EXTERNAL INTERFACE "Abis"Capture/decode signaling between BSC and BTS with "protocol analyzer" (Wandel, Tektronix, Gnnettest, etc.)
Complete information (message contents, time-stamp)Possible detection of User/MS/BSS/TC/NSS problemsComplete radio information thanks to measurement messagesDownlink and uplink
– High cost of equipment– Time consuming, "post mortem" (installation of tool, file analysis)– Important expertise needed for analysis– Very low coverage (A few RSLs, a few cell(s))– Very large amount of data (>> 10 Mbytes/hour/BTS)
The main advantage of the Abis trace is to allow a detailed and precise assessment of the radio quality of a cell at TRX level. Both DownLink and UpLink paths can be observed and compared.BUT from B7 release, the Radio Measurement Statistics (RMS) feature implemented in the BSS provides a good level of information allowing to reduce the number of Abis traces to be done for radio network optimization.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.14
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1.3 Information sources available Air interface trace
INFORMATION SOURCE: EXTERNAL INTERFACE "Air"
Use trace MS to capture signaling and signal characteristics
Give precise location (x,y) of problemsGive downlink radio informationOnly way to localize a lack of coverageOnly way to monitor competitor
– High cost of equipment– Very time-consuming– Difficulty to perform a lot of calls
number of samples insufficient only a few streets
– No uplink
The main advantage of the Air trace is to associate a radio quality measurement to a given geographical area of the network. Even if in release B7 the RMS feature will allow to assess the radio quality as perceived by the end user, no location of the radio problems is provided through the RMS.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.15
1.15
1.3 Information sources available Performance Measurement counters
SUB-SYSTEM COUNTERS
Counts events seen by sub-system, value reported periodically (1 hour)
Low cost: collected directly at OMCCompact data: possibility to store counters for a complete network
– Raw information, having to be consolidated to be understandable– Manufacturer's dependent: questionable/difficult to compare– Weak to analyze other sub-systems
The main advantage of the BSS counters is to provide easily QoS data for permanent QoS monitoring.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.16
1.16
1.3 Information sources available Exercise
Training exerciseDraw the BSS PM counters flow on the chartIn which sub-system are the BSS QoS indicators computed and stored?
BSC
BSC
BSC
OMC-R
OMC-R OMC-R
NPA
NPA is the Alcatel product for the Network Performance Analysis of the Alcatel BSS.RNO is the Alcatel product for the Radio Network Optimization of the Alcatel BSS.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.17
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1.3 Information sources available BSS counters
BSS COUNTERS
Combined into significant formulae: indicatorsUsed to monitor BSS network qualityOver a complete network, with breakdown per cell/BSC
SPECIFIC DRAWBACKNSS/PSTN/MS/USER problems not seen
As BSS PM counters are defined in order to provide information to assess the QoS of the BSS and help to detect BSS misbehavior, there is no way to identify QoS problems due to NSS, PSTN or User.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.18
1.18
1.3 Information sources available NSS counters
NSS COUNTERS
Combined into significant formulas: indicatorsUsed to monitor NSS network qualityOver a complete network, with breakdown per BSC (maximum)
SPECIFIC DRAWBACKSBSS problems usually not precisely identifiedNo breakdown per cell
The NSS QoS is provided through NSS PM counters and indicators. It is out of the scope ot this training course.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.19
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1.3 Information sources available ALCATEL BSS counters
INFORMATION SOURCES: BSS CountersIn order to provide the operators with an easy and cost-effective way to monitor their network and carried traffic, BSS manufacturers have implemented specific software features, called performance management.
The principle is to count for a given duration called granularity period (typically 1 hour) pre-defined events occurring on the Abis or A interface, or internally. These counters are stored for each duration, with breakdown per network component (i.e. cell).
In BSS B8, about 970 counters are available (without GPRS).
In Alcatel BSS (except GPRS), counters are computed by BSC, based mainly on Abis messages.Every reporting period, counters values are sent to the OMC-R for storage.In B7 159 ALCATEL counters are reported to the OMC-R permanently every PM granularity period:
3 per cell adjacency 20 per TRX127 per cell4 per N7 link5 per BSC
⇒ millions of counters are collected every day
Alcatel has chosen to implement PM counters in the BSC and to increment them mostly on Abis interface signaling messages. Other suppliers may have chosen to increment them on A interface signaling messages or to implement them in the BTS. Therefore caution should be taken when interpreting QoS indicators value since some discrepancies may be observed due to these possible choices.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.20
1.20
1.3 Information sources available Example of BSS counter
MC718: counter numberNB_TCH_NOR_ASS_SUCC_TRX: counter nameCumulative: method of computationType 110: Overview measurements: BSS PM measurement type to which the counter belongs Measured object: minimum object level for which the counter is provided: TRX or CELL or BSC or N7 LINK or X25 LINK etc.
Counter Example
All counters are described in the "PM counters and indicators" document whose B7 reference is xxxxxxxxx.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.21
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1.3 Information sources available BSS counter characteristics
Collection mechanism
CumulativeThe counter is incremented at the occurence of a specific eventAbis or A message, or internal eventAt the end of a collection period, the result is the sum of the events
InspectionEvery 20 or 10 seconds, a task quantifies an internal resource status (usually a table)At the end of a collection period, the result is the mean value
ObservationSet of recorded information about a telecom procedure (handover,channel release, UL & DL measurements reporting)
Main counters are of cumulative type. Inspection counters are of gauge type.Observation counters are grouped in a Performance Measurement record associated to a particular GSM BSS telecom procedure: SDCCH channel seizure, TCH channel seizure, internal handover, etc.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.22
1.22
BSS Performance Measurement types
1.3 Information sources available BSS PM types
N° Type Name Type definition1 Traffic Measurement Set of counters related to the traffic evaluation per telecom procedure2 Resource Availability Measurement Set of counters related to the availability of the CCCH, SDCCH, or TCH channels3 CCCH channel resource usage measurements Set of counters related to the usage of CCCH channel (PCH, AGCH, RACH)4 SDCCH channel resource usage measurements Set of counters related to the usage of SDCCH channel5 TCH channel resource usage measurements Set of counters related to the usage of TCH channel6 TCH Handover Measurements Set of counters related to the TCH handover procedure7 LAPD Measurement Set of counters related to the LapD logical links8 X.25 Measurement Set of counters related to the X25 links OMC-BSC9 N7 Measurement Set of counters related to the N7 Signaling Links
10 SDCCH Observations Observation counters on SDCCH channels allocated11 TCH measurements observations Observation counters on 08.58 MEASUREMENT REPORT for a TCH12 Internal Handover Observations Observation counters on internal intra-cell or inter-cell SDCCH or TCH handover13 Incoming External Handover Observations Observation counters on incoming external SDCCH or TCH handover14 Outgoing External Handover Observations Observation counters on outgoing external SDCCH or TCH handover15 TCH Observation Observation counters on TCH channel allocated18 A Interface measurements different causes of 08.08 CLEAR REQUEST and 08.08 ASSIGNMENT FAILURE19 SMS PP Measurements Set of counters related to Short Message Service Point to Point25 SCCP Measurements Set of counters related to SCCP Layer of the N7 signaling Links26 TCH outgoing Handover per adjency Set of counters related to outgoing TCH handover provided per adjency27 TCH incoming Handover per adjency Set of counters related to incoming TCH handover provided per adjency28 SDCCH Handover Set of counter related to the SDCCH handover procedure29 Directed Retry measurements Set of counter related to the directed retry handover procedure30 SMS CB Measurements Set of counters related to Short Message Service Cell Broadcast31 Radio Measurement Statistics Set of counters providing radio quality measurements for TRX/Cell32 Change of frequency band measurements Set of counters related to handovers including a change of TCH Frequency band
110 Overview measurements Set of key counters allowing to access Quality of Service of a given Cell/BSC/Network180 Traffic Flow measurements Set of counters related to incoming inter-cell SDCCH/TCH handover performed
per (servin a cell, target cell) adjency
B8
NewB8
BSS Performance Measurement types (PM types) are split into two categories: standard types (7, 8, 9, 18, 19, 25, 28, 29, 30, 31, 32,110, 180)detailed types (1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, 15, 26, 27)
The most important types for QoS monitoring and Radio Network Optimization are in bold.A standard PM type can be activated for the whole network. It means that the related counters are reported for all the Network Elements they are implemented on (TRX, CELL, N7 link, X25 link, LAPD link, Adjacency).A detailed PM type can be activated only on a sub-set of the network. It means that the related counters are reported only for a limited number of Network Elements:
40 cells per BSS for PM types 1, 2, 3, 4, 5, 6, 26, 2915 cells per BSS for PM types 10, 12, 13, 14, 151 cell per BSS for PM types 11, 27
Counter numbering rules: Cyz: cumulative or inspection counters in PM types 1, 2, 3, 4, 5, 6, 18, 19, 25, 26, 27, 28, 29, 30, 32, 180Ly.z: cumulative counters in PM type 7 (L stands for LAPD link)Xy.z: cumulative counters in PM type 8 (X stands for X25 link)Ny.z: cumulative counters in PM type 9 (N stands for N7 link)Syz: observation counters in PM type 10 (S stands for SDCCH)Ryz:: observation counters in PM type 11 (R stands for Radio measurements)HOyz: observation counters in PM type 12, 13, 14 (HO stands for HandOver)Tyz: observation counters in PM type 15 (T stands for TCH)RMSyz: cumulative counters in PM type 31 (RMS stands for Radio Measurement Statistics)MCyz or MNy.z: cumulative counters in PM type 110 (M stands for Major)
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.23
1.23
1.3 Information sources available Observation means
Training exercise: find the best source of information
Observation to be done : best source why
overall radio quality of 1 cell Counters Type 31 : RMS
monitor user failures
get average network quality
localise precise location of a radio pb
identify abnormal cells in a network
history of network quality for several weeks
compare networks quality
discriminate problems between BSS/NSS. BSSand NSS coming from different providersmake statistics about complete network
In a building, one is thinking that an elevator isinducing PCM trouble, how to confirm ?Identify potential interfering cells of 1 cell
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.24
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.24
2 GLOBAL INDICATORS
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.25
1.25
2 Global indicatorsSession presentation
Objective: to be able to explain what is a Global indicator and what are the main BSS indicators regarding GSM services provided by the Alcatel BSS
Program: 2.1 Indicators definition2.2 Methodological precautions2.3 Typical call failures2.4 Description of global indicators2.5 Traps and restrictions of global indicators2.6 Global indicators interpretation
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.26
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.26
2 GLOBAL INDICATORS
2.1 Indicators definition
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.27
1.27
2.1 Indicators definitionGlobal / detailed
BSS INDICATORS DEFINITION (Alcatel)
Numerical data providing information about network performance regarding:
The complete network: GLOBAL indicatorAn element of the network: DETAILED indicator
TS/TRX/CELL/BTS/BSC/TCA formulae of several counter(s)Counters vs. Indicators
Counters: provided by the BSS equipmentsIndicators: computed by BSS Monitoring equipments
The indicators computation can be performed from several counters or by a simple counter mapping.Example:
call drop rate = Call Drop nb / Call nb = f(counters)call drop = Call drop nb = 1 counter
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.28
1.28
2.1 Indicators definitionGlobal
GLOBAL INDICATORS
Measure the performance of the complete network
Analyzed according their trend and valuesUsually every day (week, month)
Compared with:Competitor results if availableContractual requirementsInternal quality requirements
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.29
1.29
2.1 Indicators definitionThresholds
EXAMPLE: Thresholds on Call Drop Rate indicator
Weekly CDR "GSM"
0,00%
0,50%
1,00%
1,50%
2,00%
2,50%
3,00%
3,50%
1 5 9 13 17 21 25 29 33 37 41 45
week number
CD
R
weekly call drop ratecontractual call drop ratequality CDR
Weekly CDR "GSM"
0,00%
0,50%
1,00%
1,50%
2,00%
2,50%
3,00%
3,50%
1 5 9 13 17 21 25 29 33 37 41 45
week number
CD
R
weekly call drop ratecontractual call drop ratequality CDR
The Call Drop rate at network level has to compared to: Contractual threshold: can be requested by the operator management to the operational radio team, can be requested by the operator to the provider on swap or network installationQuality threshold: fixed internally by radio team management.
Quality thresholds are usually more tight than contractual ones.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.30
1.30
2.1 Indicators definitionExercise
TRAINING EXERCISE: GLOBAL OR NOT
INDICATOR DESCRIPTION G ?average of call setup success rate for the network Yesrate of call lost due to radio pb on cell CI=14, LAC=234 Nocall drop rate in your capitalcall drop rate of the cell covering a specific buidling% of HO with the cause better cell (among other causes) for the networkaverage rate of TCHs dropped for all TRXs of the network carrying 1 SDCCH8rate of SDCCHs dropped on TRX1 of cell 12,24call success of 1 PLMN% of cells being congested today
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.31
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.31
2 GLOBAL INDICATORS
2.2 Methodological precautions
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.32
1.32
2.2 Methodological precautions Objective
METHODOLOGICAL PRECAUTIONS
Avoid typical errors regarding indicators interpretation
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.33
1.33
A good value for a global indicator
⇓All network components are OK regarding this indicator
ExampleA global call drop rate of 1%Can hide some cells with 10 % of call drop rate
2.2 Methodological precautions Global indicator value
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.34
1.34
2.2 Methodological precautions Network Element aggregation
THE AVERAGE VALUE OF AN INDICATOR FOR A NETWORKIS NOT THE AVERAGE OF CELL RESULTS (or any sub-part of it)BUT THE AVERAGE WEIGHTED BY THE TRAFFIC
number of calls number of call drop call drop ratecell 1 390 8 2,10%cell 2 546 29 5,25%cell 3 637 20 3,10%cell 4 1029 12 1,14%cell 5 536 3 0,50%cell 6 2 1 50,00%cell 7 3 1 33,00%cell 8 210 4 2,11%cell 9 432 5 1,20%cell 10 321 4 1,11%
average of cell results 9,95%total nb of drop/total number of calls 2,10%
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.35
1.35
2.2 Methodological precautions Time period aggregation
Take care of data consolidation
Example: Mean cell congestion rate during busy hourWeighted average of cell congestion at the busy hour of the network? Weighted average of cell congestion rate for its specific busy hour? (definition of busy hour?)
Usually: Cell Busy Hour = hour of the day where max TCH traffic (in erlang) is observed.BSC Busy Hour = hour of the day where max TCH traffic (as the sum of the TCH traffic of all cells of the BSS) is observed.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.36
1.36
2.2 Methodological precautions Exercise
METHODOLOGICAL PRECAUTION: Training exercise
INDICATOR Sample(calls)
conclusion OK ?
call drop = 0.9% in your country 2456435 all the cells have a good call drop NOK
call setup success for cell 15, 145 = 99,5% 2315 there is a good call setup success rate for15,145
In Paris : 2500 cells with 95% of call setupsuccessIn the rest of France : 5000 cells with98%
3267872for France
In France, call setup success = 97 %
call drop for BSS « BSS_1 » = 1% 4500 the call drop for BSS_1 is good
call drop for cell 156;13 = 5% 215 cell 156;13 has certainly a trouble
for BSS 1, call drop of 2,0%for BSS 2, call drop of 3,0%
40002000
LA = BSS1 + BSS2 has a call drop of 2,3 %
MSC « Stadium » has a call setup success of95 %
15346 BSS1 belonging to MSC Stadium has a call setupsuccess of 95¨%
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.37
© Alcatel University - 8AS 90200 1424 VT ZZA Ed.021.37
2 GLOBAL INDICATORS
2.3 Typical call failures
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.38
1.38
2.3 Typical call failures Objective
Description of the main call success and failures cases, withMain specific countersMain protocol timers
Diagnose the main case of failures on A interface traces using K1205 emulation software
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.39
1.39
2.3 Typical call failures Call Setup phasing
4 stages for a call establishment, 2 for a location updateRadio link establishment"SDCCH phase"then only for "Circuit Switch call"TCH assignment "Alerting/connection" phase
Each phase has a specific utility and weaknesses
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.40
1.40
2.3 Typical call failures Radio Link Establishment - OC success
Originated Call: RLE success case
T3101: guard timer for SDCCH allocation (Default: 3 seconds)CR/CC are used to exchange SCCP references
Any further message related to this call will have one (or 2) of these 2 referencesK1205 can extract the call using these references (SLR, DLR!!)
MS BTS BSC MSC
CHANNEL REQUEST-------------(RACH)------------> CHANNEL REQUIRED
----------------------------------------------> MC8CCHANNEL ACTIVATION (SDCCH)
<---------------------------------------------- MC148CHANNEL ACTIVATION ACK
---------------------------------------------->IMMEDIATE ASSIGN COMMAND
IMMEDIATE ASSIGN <---------------------------------------------- start T3101MC8B
<------------(AGCH)-------------SABM (L3 info)
-------------(SDCCH)-----------> ESTABLISH IND (L3 info)UA (L3 info) ----------------------------------------------> stop T3101
<-----------(SDCCH)------------- MC02CR (COMPLETE L3 INFO)---------------------------------->
CC<----------------------------------
B8
NewB8
Specific case of Call establishmentfailure:
Loss of messages due to LapD congestioncan be follow with a new counter (see notes)LapD
The SDCCH resource allocation is performed by the BSC. Once allocated the SDCCH channel is activated by the BTS on BSC request.T3101 is the guard timer for the SDCCH access from the MS. The Default value is 3 seconds. MC8C counts the number of Channels Required received from the MS in a cell.MC148 counts the number of SDCCH channels activated (therefore allocated) in a cell.MC8B counts the number of time an MS is commanded to access an SDCCH channel in a cell.MC02 counts the number of MSs which have successfully accessed an SDCCH in a cell as part of a Mobile Originating (MO) call.
The SCCP Connection Request message is conveyed on an A interface PCM timeslot chosen by the BSC (called COC).The SCCP Connection Confirm message is conveyed on a COC chosen by the MSC which can be located on a different PCM than the one of the COC used by the BSC to send signaling messages to the MSC.
Take care than, when the BSC is congested on the downlink, some messages are discarded. This may result for example in call establishment failures, loss of paging messages or delay in handover procedures.
From B8A new LapD counter that indicates the time a LapD link is congested is created to analyze the cause of a degraded quality of service. This counter is implemented in type 7 and thus only be available in a detailed measurement campaign.
Counter: L1.18: TIME_LAPD_CONGDefinition: Time in seconds during which the LapD link is congested in transmission in the BSC.
© Alcatel University - 8AS 90200 1424 VH ZZA Ed.02 Page 1.41
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2.3 Typical call failures Radio Link Establishment - TC success
Terminated Call: RLE success caseMS BTS BSC MSC
PAGINGPAGING COMMAND <----------------------------------
PAGING REQUEST <---------------------------------------------- start T3113<-------------(PCH)-------------- MC8A
CHANNEL REQUEST-------------(RACH)------------> CHANNEL REQUIRED
----------------------------------------------> MC8CCHANNEL ACTIVATION (SDCCH)
<---------------------------------------------- MC148CHANNEL ACTIVATION ACK
---------------------------------------------->IMMEDIATE ASSIGN COMMAND
IMMEDIATE ASSIGN <---------------------------------------------- Start T3101<------------(AGCH)------------- MC8B
SABM (PAGING RESP)-------------(SDCCH)-----------> ESTABLISH IND (PAGING RESP)
UA (PAGING RESP) ----------------------------------------------> Stop T3101<-----------(SDCCH)------------- MC01
CR (COMPLETE L3 INFO)---------------------------------->
stop T3113CC
<----------------------------------
A paging message is broadcast by the MSC to all BSCs controlling cells belonging to the same Location Area as the one of the paged MS.In case no MS is accessing the SDCCH channel (T3101 expiry) then the BSC does not repeat the Immediate Assignment since the MS may have accessed an SDCCH in another BSS. It is up to the MSC to repeat Paging if T3113 expires (usually around 7 seconds).MC8A counts the number of Paging Command messages sent on a cell.MC01 counts the number of MSs which have successfully accessed an SDCCH in a cell as part of a Mobile Terminating (MT) call.
Caution: A paging Request message sent on the Air interface by the BTS may contain several MS identities. 3 Paging Request types can be used: in Paging Request Type 1: up to 2 MSs (IMSI1,IMSI2) can be included.in Paging Request Type 2: up to 3 MSs (IMSI1,TMSI1,TMSI2) can be included. in Paging Request Type 3: up to 4 MSs (TMSI1,TMSI2,TMSI3,TMSI4) can be included.
On the other hand, a Paging message and a Paging Command message relate to only one MS identity.
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2.3 Typical call failures Radio Link Establishment - Paging
RLE > PagingMC8A=C8A
Normally all cells of the same Location Area must have the same MC8A counter value since all these cells must be paged for an MT call on an MS located in the Location Area they are included in.If not: it means that a cell is not declared in the right LA at NSS level.
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2.3 Typical call failures Radio Link Establishment - RACH counter
RLE > RACHMC8C=C8C
Caution: All Channels Required (therefore RACH) are counted in MC8C: valid and invalid causes (see later). Indeed ghost RACHsare also counted.The Channel Required content corresponds to the Channel Request message sent by the MS to the BTS.This Channel Request message is made up of one byte with 2 Informations Elements (IEs):
8 7 6 5 4 3 2 1 +-----------------------------------------------+│ ESTABLISHMENT │ RANDOM ││ + - - - - - - - - + ││ CAUSE │ REFERENCE │+-----------------------------------------------+
ESTABLISHMENT CAUSEThis information field indicates the reason for requesting the establishment of a connection. This field has a variable length (from 3 bits up to 6 bits).RANDOM REFERENCEThis is an unformatted field with a variable length (from 5 bits down to 2 bits).
Due to the fact that the NECI bit is always set to 1 in Alcatel BSS, Establishment causes can be divided into 2 categories: Valid causes: 5 (6 if GPRS)000: Location Update (Normal, Periodic, IMSI Attach)100: Terminating call101: Emergency call 110: Call Re-establishment111: Originating call (not emergency)011: if GPRS is implemented in the cell
Invalid causes: 3 (2 if GPRS)001: 010: 011: if GPRS is not implemented in the cell
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2.3 Typical call failures Radio Link Establishment - OC success counters split
RLE > success MO splitMC02x=C02x
MC02 = MC02A+MC02B+MC02C+…….+MC02G+MC02H+MC02i
MC02A: LU
MC02B: SMS
MC02C: SS
MC02D: LU follow-on
MC02E: CR
MC02F: unknown
MC02G: IMSI Detach
MC02H: EC or NC
MC02i: LCS
B8
NewB8
MC02A = Number of SDCCHs successfully seized for Normal or Periodic LU request (IMSI Attach also counted).MC02B = Number of SDCCHs successfully seized for Short Message Service.MC02C = Number of SDCCHs successfully seized for Supplementary Service.MC02D = Number of SDCCHs successfully seized for LU with follow-on bit set to 1 (means that the SDCCH phase will be followed by a TCH assignment for speech call establishment).MC02E = Number of SDCCHs successfully seized for Call Re-establishment.MC02F = Number of SDCCHs successfully seized in case of L3 Info (within 08.58 ESTABLISH INDICATION) unknown by the BSC but transferred to the MSC.MC02G = Number of SDCCHs successfully seized for IMSI Detach.MC02H = Number of SDCCHs successfully seized for Normal or Emergency call.MC02i = Number of Mobile Originating SDCCH establishments for LCS purpose.
Also, Evaluation of The Mobiles location (see the next slides)
LCS: Location Services
B8
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2.3 Typical call failures LCS
LCS function (linked to MC02i) and other counters …LCS allows to access the MS location provided by the BSS.
On MS request to know its own location (MC02 impacted, see the previous slide)On network request (especially during Emergency calls)On external request (LCS Client)
Positioning methods provided can be:
Cell-ID or Cell-ID + TA (Timing Advance)Conventional (standalone) GPSAssisted GPS (with the help of A-GPS server to compute location)
MS based (MB): MS is able to perform a pre computation
MS assisted (MA): MS sends info, Network computes
B8
Assisted GPS Method:
Mobile-based: The MS performs OTD signal measurements and computes its own location estimate. In this case the network provides the MS with the additional information such as BTS coordinates and the RTD values. These assistance data can be either broadcast on the CBCH (using SMSCB function) or provided by the BSS in a point to point connection (either spontaneously or on request from the MS).Mobile-assisted: The MS performs and reports OTD signal measurements to the network and the network computes the MS location estimate.With
OTD: Observed Time Difference: the time interval that is observed by an MS between the receptions of signals (bursts) from two different BTSs.RTD: Real Time Difference: This means the relative synchronization difference in the network between two BTSs.
Finally, 4 methods are possible for positioning:Cell ID+ TAConventional (MS equipped with GPS System)A-GPS MS BasedA-GPS MS Assisted
These 4 Methods induce a set of counters (2 per method) to give the average latitude and longitude of mobiles in the cell.These counters are located in the MFS and can be used in RNO (cartographic part).
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2.3 Typical call failures LCS
LCS function: Architecture
B8
SMLCBTS
BTS
MS
BSC
MSC
HLR
GMLC
OSP
Lg
Lh
ExternalLCS client
LeA
Abis
Abis
Lb
SMLC function integrated in MFS:
- receives the loc. Request from the GMLC through the MSC/BSC
- Schedules all the necessary actions to get MS location
- Computes MS location
- Provides the result back to the GMLC
MFSA-GPS server
SAGI
GPS reference network
LCS: Location ServicesSMLC: Serving Mobile Location CenterGMLC: Gateway Mobile Location CenterA-GPS: Assisted GPS
Where is my son?
Where am I?
Where is the accident? Emergency call
MS Request
Network Request
External Request
2
1
3
3
2
1
In case of MS requests for its location, MC02 is impacted: MC02i = Number of Mobile Originating SDCCH establishments for LCS purpose.
In all cases, some counters related to LCS provide specific information (attempts, success, failures)see the next slide.
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2.3 Typical call failures Radio Link Establishment - SDCCH congestion failure
SDCCH ACCESS FAILURE
SDCCH congestionSDCCH congestion
SDCCH RF access failureSDCCH RF access failure
SDCCH access failure BSS pbSDCCH access failure BSS pb
Main failure cases for Radio Link Establishment
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2.3 Typical call failures Radio Link Establishment - SDCCH congestion
RLE > SDCCH congestion
The Immediate Assignment Reject mechanism can be disabled at OMC-R levelAnd is not activated for answer to paging If disabled, no answer to the MS
The MS will repeat automatically its request in case of congestion (next slides)Waiting for T3122 expiry in case of Immediate Assignment RejectWaiting for T3120 expiry otherwise
MS BTS BSCMSC
CHANNEL REQUEST-------------(RACH)------------> CHANNEL REQUIRED
----------------------------------------------> MC8CNo free SDCCH !!MC04
IMMEDIATE ASSIGN COMMAND<----------------------------------------------
IMM. ASS. REJECT (immediate assignment reject) MC8D, and MC8B<-------------(AGCH)------------
In case of Immediate Assignment Reject: T3122 = value of Wait_Indication parameter sent by the BSC to the MS.
Otherwise T3120 is computed by the MS as a random number of slots between:
250 and 250+T-1 for a phase 1 MS where: T=Tx_integer parameter (1 value per cell chosen between 3 to 50 slots)
S and T+S for a phase 2 MS where: T=Tx_integer parameter (1 value per cell chosen between 3 to 50 slots)S is a parameter depending on the CCCH configuration and on the value of Tx_integer as defined in the following table:
TX_integer S(CCCH Not Comb) S(CCCH Combined)
3, 8, 14, 50 55 414, 9, 16 76 525, 10, 20 109 586, 11, 25 163 867, 12, 32 217 115
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2.3 Typical call failures Radio Link Establishment - SDCCH congestion counter
RLE > SDCCH congestionMC04=C04
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2.3 Typical call failures Radio Link Establishment - SDCCH cong. consequence
RLE > SDCCH congestionMAIN CONSEQUENCES
The MS will try "max_retrans +1 " time before giving upImmediately for phase 1 MSAfter T3126 for phase 2 MS (still waiting for Immediate Assignment during this timer)
In case of "max_retrans+1" failures, the MS willEither try an automatic cell reselectionOr do nothing
In case of LU, the MS will attempt a new LU requestIn case of Call establishment, the MS will not re-attempt automatically, it is up to the subscriber to try to set up the call again
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2.3 Typical call failures Radio Link Establishment - SDCCH cong. causes
RLE > SDCCH congestion
MAIN CAUSES
Too much SDCCH "normal" traffic for cell SDCCH designRadio resource capacity not sufficient (too many calls)Inadequate LA design (too many LUs)
"Common Transport Effect"Difficult to avoid for small cells
Abnormal SDCCH traffic”Phantom" channel requests (seen in SDCCH RF failure session)Neighboring cell barred
SDCCH congestion can be too high because of the subscribers' traffic demand in terms of calls / LU.Solution = add a TRX or site / redesign the LA plan
High SDCCH congestion can be observed at peculiar period of the day due to a peak of LU requests generated by a big group of subscribers entering a new LA at the same time (bus, train, plane).
Solution = redesign the LA plan or play on radio parameters (CELL_RESELECT_HYSTERESIS, WI_OP)
High SDCCH congestion can be abnormally observed without real MS traffic in case a high level of noise or the proximity of a non-GSM radio transmitter.
Solution = change the BCCH frequency or put an RX filter
High SDCCH congestion can also be abnormally observed in a cell in case one of its neighboring cell is barred.Solution = Remove the barring
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2.3 Typical call failures Radio Link Establishment - SDCCH cong. Resolution?
RLE > SDCCH congestion
DYNAMIC SDCCH ALLOCATION
Defining too many SDCCHs will lead to a lack of TCH resources... and money. Defining too few SDCCH channels will result in SDCCH congestion. TCH channels cannot be allocated and, once again, the operator 's revenue decreases. At OMC-R level, it is possible to configure:
a set of static SDCCH/x timeslots to handle normal SDCCH traffic;a set of dynamic SDCCH/8 timeslots, which can be used for TCH traffic, or for SDCCH traffic depending on the need.
With the "Dynamic SDCCH allocation" feature, the BSS is automatically looking after varying SDCCH traffic and is particularly adapted to the situations such as: change of LA, change of SMS traffic model, SDCCH traffic varying due to LCS.This feature is particularly useful in very dense (hierarchical) networks, where the effort to optimize the SDCCH configuration becomes more important.
B8
This feature not only improves SDCCH congestion but also successful TCH assignment rates.
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2.3 Typical call failures Radio Link Establishment - SDCCH cong. Resolution?
RLE > SDCCH congestion
DYNAMIC SDCCH ALLOCATION
B8
CHANNEL REQUESTCHANNEL REQUIRED
MS BTS BSC
(RACH)
If No free SDCCH, thenrun dynamic SDCCH/8 timeslot allocationalgorithm. If allocation is successful, then
activate dynamic SDCCH sub-channel and serve request
If allocation was unsuccessful, then reject SDCCH request (possiblyusing the Immediate Assignment Reject procedure).
MC801a&b
MC802a&b
SPECIFIC COUNTERS (Type 110 / Cell Level): MC800 Average number of available dynamic SDCCH/8 timeslots. MC801a Average number of busy dynamic SDCCH/8 timeslots allocated as TCH (FR or HR).MC801b Maximum number of busy dynamic SDCCH/8 timeslots allocated as TCH (FR or HR). MC802a Average number of busy SDCCH sub-channels allocated on the dynamic SDCCH/8 timeslots. MC802b Maximum number of busy SDCCH sub-channels allocated on the dynamic SDCCH/8 timeslots.
These four previous counters are”Inspection Counters” ; that means than the resource is checked regulary by the BSC and at the end of the period, an average is done. Example: 3 physical chanels are defined as Dyn SDCCH and the counter give the following indication:MC801a = 1.7 that means sometimes the 3 Dyn SD are allocated as TCH, sometimes only 2 of them, sometimes 1 or 0 and the average is 1.7
The FOLLOWING COUNTERS ARE IMPACTED BY the Dynamic SDCCH Allocation feature: MC28, MC29 The Number of busy radio timeslots in TCH usage takes into account the busy TCH timeslots and the dynamic SDCCH/8 timeslots allocated as TCH.C30, MC31 The Number of busy SDCCH sub-channels takes into account the SDCCH sub-channels allocated on the static and dynamic SDCCH/8 timeslots.C370a, MC370a, C370b, MC370b The Number of times the radio timeslots are allocated for TCH usage (FR / HR) takes into account the busy TCH timeslots and the dynamic SDCCH/8 timeslots allocated as TCH.C/MC380a/b C/MC381a/b The Cumulated time (in second) the radio timeslots are allocated for TCH usage (FR or HR)does not take care whether the TCHs are allocated on the TCH radio timeslot or on the dynamic SDCCH/8 timeslots. C39, MC390, C40, MC400 The Number of times or the Cumulated time (in second) the SDCCH sub-channels are busydoes not take care whether the SDCCH sub-channels are allocated on the static or dynamic SDCCH/x timeslot.C/MC34 C/MC380 The Cumulated time (in second) all TCHs / SDCCHs in the cell are busydoes not take care whether the TCHs / SDCCHs are allocated on the TCH radio timeslot /SDCCH/x timeslot or on the dynamic SDCCH/8 timeslots.C/MC320a/b/c/d/e Free TCH radio timeslotscount the free TCH timeslots and the free dynamic SDCCH/8 timeslots.
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2.3 Typical call failures Radio Link Establishment - SDCCH radio failure
TYPICAL CALL FAILURES
Main failure cases for Radio Link Establishment
SDCCH ACCESS FAILURE
SDCCH congestionSDCCH congestion
SDCCH RF access failureSDCCH RF access failure
SDCCH access failure BSS pbSDCCH access failure BSS pb
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2.3 Typical call failures Radio Link Establishment - SDCCH radio access failure
RLE > SDCCH RF Failure
MS BTS BSC MSCCHANNEL REQUEST
-------------(RACH)------------> CHANNEL REQUIRED----------------------------------------------> MC8C
CHANNEL ACTIVATION (SDCCH)<---------------------------------------------- MC148
CHANNEL ACTIVATION ACK---------------------------------------------->IMMEDIATE ASSIGN COMMAND
IMMEDIATE ASSIGN <---------------------------------------------- start T3101<------------(AGCH)------------- MC8B
IMMEDIATE ASSIGN-------(SDCCH)-----X
T3101expiry->“radio failure”MC149
MC149 counts the number of SDCCH access failures due to radio problems.
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2.3 Typical call failures Radio Link Establishment - real radio problems
RLE > SDCCH RF Failure
Main causes > real radio problems
Unbalanced cell power budgetBad coverage (for example a moving car)Interference (for example downlink)
In case of radio failure, the MS will retry as for SDCCH congestion
Unbalanced Power Budget:
Bad coverage:
Interference:
DL interference area
AGCH lost
RACH
building
BTS
Channel Request
Access Grant
Max Path Loss ULMax Path Loss DL
AGCH
RACH
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2.3 Typical call failures Radio Link Establishment - Ghost RACH (1/7)
RLE > SDCCH RF Failure
Main causes > "Phantom/Ghost/Spurious/Dummy ... RACH"
Channel request received but not sent: 3 causesNoise decodingReception of channel request sent to a neighboring cellReception of HO_ACCESS sent to a neighboring cell
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2.3 Typical call failures Radio Link Establishment - Ghost RACH (2/7)
RLE > SDCCH RF Failure
Main causes > "Phantom/Ghost/Spurious/Dummy ... RACH"Example of a channel required message
For this Channel Required, the establishment cause is valid (Call re-establishment) but the Access Delay (corresponding to the distance between the MS and the BTS) is high.Indeed the Access Delay being equal to the Timing Advance is coded in slot unit representing a distance of 550m. It can take values from 0 (0m) to 63 (35km).Thus the Channel Required above is received from an MS located at 19km from the site. It may therefore be rather a ghost RACH than a real MS which wants re-establish a call.In Alcatel BSS, there is possibility to filter the Channel Required received from a distance greater than a distance defined as a parameter value: RACH_TA_FILTER tunable on a per cell basis. Caution should be taken since a too low value may reduce the network coverage.
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2.3 Typical call failures Radio Link Establishment - Ghost RACH causes (3/7)
RLE > SDCCH RF Failure
Main causes > "Phantom RACH" >noise decoding
GSM 05.05: " 0.02 % of Rach Frame can be decoded without error without real input signal"
BCCH not combined: 51 Rach/Multi Frame > (3600 * 1000) ms / 4.615 ms at 0.02 %: 156 dummy RACH/hourBCCH combined: 27/51 RACH/Multi-Frame > 83 dummy RACH/hour3/8 of causes (field of channel request, 5 valid causes over 8) will be unvalidExample of induced SDCCH traffic: (5/8*156*T3101 (3 sec))/3600 = 0.08 Erlang SDCCH
This extra-load has no impact for the system
Some tips: Dummy Rach load depends on minimum level for decoding configured in Evolium BTSDuring period with low real traffic (night), high rate of dummy RACHFor dummy RACH, the channel required has a random value of TA
STRUCTURE of the MULTIFRAME in "TIME SLOT" 0
-
R = RACH DOWNLINK
f s b b b b C C C C31 51 1211 2 3 4 5 6 7 8 9 10 20 41
f s f s f s f sC C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C -
(Multiframes of 51 frames)
f = FCCH s = SCH b = BCCH
f s
C C C C = CCCH (PCH or AGCH)
UPLINKR R R RR R R R R R R RR R R R R R R RR R R R R R R RR R R R R R R RR R R RR R R RR R R R R R
(Non-combined BCCH)
(Combined BCCH)
R = RACH
DOWNLINK
F = FCCH S = SCH B = BCCH C = CCCH (PCH or AGCH)
UPLINK
F S B C F S F S F S -F SC C D0 D1 D2 D3 A0 A1
F S B C F S F S F S -F SC C D0 D1 D2 D3 A2 A3
R R R RR R R R R R R RR R R R R R RR R R R R RR RD3 A2 A3 D0 D1 D2
R R R RR R R R R R R RR R R R R R RR R R R R RR RD3 A0 A1 D0 D1 D2
Dn/An = SDCCH/SACCH/4
51 multiframe duration = 51 x 8 x 0,577 = 235ms
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2.3 Typical call failures Radio Link Establishment - Ghost RACH causes (4/7)
RLE > SDCCH RF Failure
Main causes > "Phantom RACH" >noise decoding
No subscriber -> no impact for subscriberBut MC149 incremented -> SDCCH RF access failure is impacted
MS BTS BSC MSC
CHANNEL REQUIRED----------------------------------------------> MC8C
CHANNEL ACTIVATION (SDCCH)<---------------------------------------------- MC148
CHANNEL ACTIVATION ACK---------------------------------------------->IMMEDIATE ASSIGN COMMAND
IMMEDIATE ASSIGN <---------------------------------------------- start T3101<------------ (AGCH) ------------- MC8B
T3101expiry->“radio failureMC149
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2.3 Typical call failures Radio Link Establishment - Ghost RACH causes (5/7)
RLE > SDCCH RF Failure
Main causes > "Phantom RACH" > Channel Request sent to the neighboring cell
Subscriber not impacted (real transaction performed elsewhere)
But MC149 incremented -> SDCCH RF access failure is impacted
Usual radio planning rules are sufficient to avoid the trouble
2 cells must not have same (BCCH, BSIC) couple
M S B T S B S C M S C
C H A N N E L R E Q U IR E D--- -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -> M C 8 C
C H A N N E L A C T IV A T IO N (S D C C H )< --- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - M C 1 4 8
C H A N N E L A C T IV A T IO N A C K--- -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ->
IM M E D IA T E A S S IG N C O M M A N DIM M E D IA T E A S S IG N < --- -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - s ta r t T 3 1 0 1 M C 8 B
< ---- - - - - - - - - (A G C H )--- - - - - - - - - - -
T 3 1 0 1 e x p iry M C 1 4 9-> “ra d io fa ilu re
BSIC = BCC (3 bit) + NCC (3 bit)BCC: BTS Color Code NCC: Network Color Code
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2.3 Typical call failures Radio Link Establishment - Ghost RACH causes (6/7)
RLE > SDCCH RF Failure
Main causes > "Phantom RACH" > Channel Request due to handover
During HO, the first message sent to the target cell is HO AccessThis message is an Access Burst like Channel Request
If received on BCCH, can be understood as a Channel Request (RACH)A new case of "Phantom RACH"
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2.3 Typical call failures Radio Link Establishment - Ghost RACH causes (7/7)
RLE > SDCCH RF Failure
Main causes > "Phantom RACH" > Channel Request due to handover
This case is the most dangerousThe MS sends usually a sequence of HO Access message, every frameIn some cases, this can create a phantom RACH if
The frequency of the TCH is identical or adjacent to the one of interfered BCCH
Characteristics of such phantom RACH (Channel Required)Subsequent frame numberRandom, but stable timing advance
Can block very easily SDCCH
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2.3 Typical call failures Radio Link Establishment - BSS failure
TYPICAL CALL FAILURES
Main failure cases for Radio Link Establishment
SDCCH ACCESS FAILURE
SDCCH congestionSDCCH congestion
SDCCH RF access failureSDCCH RF access failure
SDCCH access failure BSS pbSDCCH access failure BSS pb
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2.3 Typical call failures Radio Link Establishment - BSS problem
RLE > BSS problem
No specific counter
MS BTS BSC MSCCHANNEL REQUEST
-------------(RACH)------------> CHANNEL REQUIRED----------------------------------------------> MC8C
CHANNEL ACTIVATION (SDCCH)<---------------------------------------------- MC148
CHANNEL ACTIVATION ACK---------------------------------------------->IMMEDIATE ASSIGN COMMAND
IMMEDIATE ASSIGN <---------------------------------------------- start T3101<------------(AGCH)------------- MC8B
SABM (L3 info)------------(SDCCH)------------>
BSS Problems are difficult to specify a priori. It is better to deduce them from other counters which are easier to implement thus more reliable.
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RLE counters
2.3 Typical call failures Radio Link Establishment - counters
Request MC8C
GPRS causes P62CGSM invalid causes unknown
Preparation GSM valid causes unknown
Congestion MC04BSS Pb unknown
Execution Attempt MC148
Radio Access Failure MC149BSS Pb MC148 - (MC01+MC02) - MC149
Success MC01+MC02
Radio Link Establishment
REQUEST
Congestion
ATTEMPT
Radio access failure
SUCCESS
BSS problem
Preparation Failure
Execution Failure
GPRS causes GSM/GPRS invalid causes GSM valid causes
BSS problem
Statistically a ghost RACH can correspond to any kind of establishment cause: valid and invalid.As ghost RACH which corresponds to a GSM valid cause will lead to an SDCCH allocation which will not be seized by an MS, it will lead to the incrementation of MC149 counter and therefore counted as an SDCCH access failure due to radio.
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2.3 Typical call failures Radio Link Establishment - indicators
TYPICAL CALL FAILURES: RLE indicators
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS: GLOBAL Quality of service INDICATORS > SDCCH > Assignment Phase
SDNAUR: SDCCH assignment unsuccess rateSDNACGR: SDCCH assignment failure rate due to congestion (Global)SDNAFLRR: SDCCH assignment failure rate due to radioSDNAFLBR: SDCCH assignment failure rate due to BSS problem
A SDCCH radio access failure due to ghost RACH occurrence is easily observed during low traffic hour (night time) since ghost RACHs are almost the only cause of failure.
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2.3 Typical call failures SDCCH phase - OC success
Successful SDCCH phase: OC call
transparent message: no dedicated counters
MS BTS BSC MSCSDCCH Phase : Originating Call case
< -------------------------------------------------------------------------------------------------------------------------AUTHENTICATION REQUEST
------------------------------------------------------------------------------------------------------------------------- >AUTHENTICATION RESPONSE
< -------------------------------------------------------------------------------------------------------------------------CIPHERING MODE COMMAND
------------------------------------------------------------------------------------------------------------------------- >CIPHERING MODE COMPLETE
------------------------------------------------------------------------------------------------------------------------- >SETUP
< -------------------------------------------------------------------------------------------------------------------------CALL PROCEEDING
Transparent messages (DTAP) are used in order the NSS performs control procedures to enable the MS to set up a speech call.Authentication: Checks that the Mobile Station is the required station and not an intruder.Ciphering: All Information (signaling, Speech and Data) is sent in cipher mode, to avoid monitoring and intruders (who could analyze signaling data).Setup/Call Processing: call is being processed between the calling Party and the Called Party.
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2.3 Typical call failures SDCCH phase - TC success
Successful SDCCH phase: TC call
transparent message: no dedicated counters
MS BTS BSC MSCSDCCH Phase : Terminating Call case
< -------------------------------------------------------------------------------------------------------------------------AUTHENTICATION REQUEST
------------------------------------------------------------------------------------------------------------------------- >AUTHENTICATION RESPONSE
< -------------------------------------------------------------------------------------------------------------------------CIPHERING MODE COMMAND
------------------------------------------------------------------------------------------------------------------------- >CIPHERING MODE COMPLETE
< -------------------------------------------------------------------------------------------------------------------------SETUP
------------------------------------------------------------------------------------------------------------------------- >CALL CONFIRM
Setup/Call Confirm: the call is being processed between the Calling Party and the Called Party.
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2.3 Typical call failures SDCCH phase - LU success
successful SDCCH phase: Location Update
transparent message: no dedicated counters
MS BTS BSC MSCSDCCH Phase : Location Update Case (with TMSI reallocation)
------------------------------------------------------------------------------------------------------------------------- >LOCATION UPDATE REQUEST
< -------------------------------------------------------------------------------------------------------------------------AUTHENTICATION REQUEST
------------------------------------------------------------------------------------------------------------------------- >AUTHENTICATION RESPONSE
< -------------------------------------------------------------------------------------------------------------------------CIPHERING MODE COMMAND
------------------------------------------------------------------------------------------------------------------------- >CIPHERING MODE COMPLETE
< -------------------------------------------------------------------------------------------------------------------------LOCATION UPDATE ACCEPT
------------------------------------------------------------------------------------------------------------------------- > TMSI REALLOCATION COMPLETE
Some transparent messages are also exchanged between the MS and the network in case of a Location Update transaction.
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2.3 Typical call failures SDCCH phase - drops
SDCCH phase
Loss of connection during SDCCH phase = "SDCCH drop"
3 origins of SDCCH dropRadio problems when connected on SDCCHBSS problemsCall lost during an SDCCH HO (handover failure without reversion to old channel)
Generally SDCCH handover are disabled in the network since the average SDCCH duration is only around 2 to 3 seconds.
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2.3 Typical call failures SDCCH phase - radio drop
SDCCH phase > drop radio
Connection lost due to radio problem
MS BTS BSC MSCSDCCH Phase established
Radio connection lost---------------------------------------------------- > MC138CONNECTION FAILURE INDICATION
(cause : radio link failure)--------------------------------------- >CLEAR REQUEST
Cause : radio interface failure
MC138 counts the number of SDCCH channel drops due to radio problems.Radio problems can be due to coverage, interference and sometimes BSS dysfunction which is not detected as a system alarm the by O&M Fault Management application.
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2.3 Typical call failures SDCCH phase - BSS drop
SDCCH phase > drop BSS
Connection lost due BSS problem
MS BTS BSC MSCSDCCH Phase established
MC137
--------------------------------------- >CLEAR REQUEST
Cause : O&M interventionCause : radio interface failure
MC137 counts the number of SDCCH channel drops due to BSS problems.A BSS problem can be a BTS/BSC hardware or software failure. It can also be due to a problem on the Abis interface (due to Micro Wave transmission for instance).
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SDCCH phase > drop HO
Connection lost during HandOver
MS BTS BSC MSCSDCCH Phase established
HO FAILURE WITHOUT REVERSION MC07--------------------------------------- >
CLEAR REQUESTRadio Interface Message Failure (Alcatel)
2.3 Typical call failures SDCCH phase - HO drop
MC07 counts the number of SDCCH channel drops due to handover failure.
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SDCCH phase counters
2.3 Typical call failures SDCCH phase - counters
SDCCH connection MC01+MC02+MC10
SDCCH Drop Drop radio MC138Drop BSS MC137Drop HO MC07
SDCCH Phase
TCH assignment phase SDCCH drop
SDCCH connection
Normal release
Drop radio
Drop BSS
Drop HO
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2.3 Typical call failures SDCCH phase - indicators
SDCCH phase indicators
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: GLOBAL Quality of service INDICATORS > SDCCH > Established phase
SDCDR: SDCCH drop rate (Global)SDCDRR: SDCCH drop rate due to radio problemSDCDBR: SDCCH drop rate due to BSS ProblemSDCDHR: SDCCH drop rate due to HO failure
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2.3 Typical call failures TCH assignment - success
TCH assignment success case
T3107: guard timer for TCH assignment
MS BTS BSC MSCTCH ASSIGNMENT PHASE (OC or TC)
< -----------------------------------ASSIGNMENT REQUEST
< --------------------------------------------------------PHYSICAL CONTEXT REQUEST
-------------------------------------------------------- >PHYSICAL CONTEXT CONFIRM
< -------------------------------------------------------- MC703CHANNEL ACTIVATION (TCH)
-------------------------------------------------------- >CHANNEL ACTIVATION ACKNOWLEDGE
< ----------------------------------------------------------------------------------- Start T3107 (SDCCH) ASSIGNMENT COMMAND
---------------------- >TCH SABM -------------------------------------------------------- >
< ---------------------- ESTABLISH INDICATIONUA
----------------------------------------------------------------------------------- > Stop T3107ASSIGNMENT COMPLETE MC718
----------------------------------- >ASSIGNMENT COMPLETE
MC140a
MC140b
B8
MC460a New B8
MC140a
MC140b
MC460a
(see comments)
MC703 counts the number of TCH channels activated (therefore allocated) in a cell.MC718 counts the number of MSs which have successfully accessed a TCH in a cell as part of a call establishment (Normal Assignment).Both counters are new from B7 since they are now implemented at TRX level.
MC140a counts the number of normal assignment requests for TCH establishment.MC140b counts the number of normal assignment commands for TCH establishment.Both counters are new in B8 in order to discriminate BSS problems in Preparation and Execution phases.
MC460a is a new counter in B8 for type 110: NB_TCH_EMERGENCY_HO_PRESERVATION: Definition: Number of high priority TCH requests served when:
the number of free TCH timeslots is less than or equal to NUM_TCH_EGNCY_HO.the queue for this cell is not empty.
MC140a, MC140b and MC460 are given at Cell level
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TCH assignment > congestion
5 causes of congestion ⇒ 5 counters: C612A, B, C, D, E whenever
Queuing is not allowedQueue is FullT11 expiresRTCH request is removed from the queue due to a higher priority request to be queuedNo Abis-TCH resource is available (Restriction in B8)
MS BTS BSC MSCTCH ASSIGNMENT PHASE (OC or TC)
< -----------------------------------------------ASSIGNMENT REQUEST
No RTCH available on requested cell MC812
------------------------------------------------ >ASSIGNMENT FAILURE
Cause No Radio Resource Available
2.3 Typical call failures TCH assignment - TCH congestionB8 (See comments)
New counter in B8: C612E: Number of 08.08 ASSIGNMENT REQUEST for TCH normal assignment rejected due to congestion on the Abis interface.Therefore B6 counter MC612 is replaced by MC812 from B7. MC812 = C612A+C612B+C612C+C612D+C612E of PM Type 1.But as C612E is in restriction in B8 (always = 0) then MC812(B7) = MC612(B6)MC612A, MC612B, MC612C, MC612D also exist in PM Type 110.A TCH request is attached a Priority Level from 1 (highest priority) to 14 (lowest priority).
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TCH assignment > radio failure
Radio problemMS BTS BSC MSC
TCH ASSIGNMENT PHASE (OC or TC)< -----------------------------------ASSIGNMENT REQUEST
< --------------------------------------------------------PHYSICAL CONTEXT REQUEST
-------------------------------------------------------- >PHYSICAL CONTEXT CONFIRM
< -------------------------------------------------------- MC703CHANNEL ACTIVATION (TCH)
-------------------------------------------------------- >CHANNEL ACTIVATION ACKNOWLEDGE
< ----------------------------------------------------------------------------------- Start T3107 (SDCCH) ASSIGNMENT COMMAND
SABM----(TCH)------X
T3107 ExpiryMC746B----------------------------------- >
ASSIGNMENT FAILURERadio interface failure
2.3 Typical call failures TCH assignment - radio failure
MC140a
MC140b
MC746B counts the number of TCH access failures due to radio problems.MC746B counter is implemented at TRX level from B7.In case of TCH access failure, the MS will try to revert back to the SDCCH channel. Whether it succeeds in reverting to the SDCCH or not the call establishment fails. On the other hand some MSCs may resend the ASSIGNMENT REQUEST again.
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TCH assignment > BSS problem
BSS problem (Abis, BTS/BSC HW or SW)
2.3 Typical call failures TCH assignment - BSS problem
MS BTS BSC MSCTCH ASSIGNMENT PHASE (OC or TC)
< -----------------------------------ASSIGNMENT REQUEST
< --------------------------------------------------------PHYSICAL CONTEXT REQUEST
-------------------------------------------------------- >PHYSICAL CONTEXT CONFIRM
< -------------------------------------------------------- MC703CHANNEL ACTIVATION (TCH)
-------------------------------------------------------- >CHANNEL ACTIVATION ACKNOWLEDGE
< ----------------------------------------------------------------------------------- Start T3107 (SDCCH) ASSIGNMENT COMMAND
SABM----(TCH)---- >
MC14B
MC140a
MC140b
No specific counter
B8
The number of TCH Assignment failures due to BSS Pb can be correctly deduced and distinguished for preparation and execution phases from B8 with the 2 new counters MC140a and MC140b.(see the next slide)
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TCH assignment counters
2.3 Typical call failures TCH assignment - counters
Congestion
ATTEMPT
Radio access failure
SUCCESS
BSS problem
Preparation Failure
Execution Failure
REQUEST
BSS problemTCH Assignment
Preparation Request MC140a
Congestion MC812
BSS Pb MC140a-MC140b-MC812
Execution Attempt MC140b
Radio Access Failure MC746b
BSS Pb MC140b-MC718-MC746b
Success MC718
B8
NewB8
BSS PB
discrimination
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TCH Assignment indicators
2.3 Typical call failures TCH assignment - indicators
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: GLOBAL Quality of service INDICATORS > RTCH > Assignment Phase
TCNAUR: TCH assignment unsuccess rate (Global)TCNACGR: TCH assignment failure rate due to congestionTCNAFLRR: TCH assignment failure rate due to radio problemsTCNAFLBR: TCH assignment failure rate due to BSS Problems.
From B7.2 some indicators can be provided on a per TRX basis due to the availability of new counters provided per TRX in Type 110:
TCNAEFR = RTCH_assign_efficiency_rate (RNO name) = MC718 / MC703Rate of successful RTCH seizures in relation to all RTCHs allocated, during the TCH assignment procedure.
TCNAAFLRR = RTCH_assign_allocated_fail_radio_rate (RNO name) = MC746B / MC703Rate of RTCH seizures failed during the normal assignment procedure because of radio problems in relation to all RTCHs allocated for TCH assignment procedure.
This will help a lot to detect bad QOS due to TRX hardware related problem.
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TCH phase
Transparent messages for BSS, no specific countersTCH DROP: any problems occurring after TCH assignment (during or after connection) cannot be discriminated
MS BTS BSC MSCAlerting Connection Phase (OC case) : ringing phase
< ---------------------------------------------------------------------------------------------------------------------------ALERTING
< ---------------------------------------------------------------------------------------------------------------------------CONNECT
--------------------------------------------------------------------------------------------------------------------------- >CONNECT ACK
MS BTS BSC MSCAlerting Connection Phase : TC case
--------------------------------------------------------------------------------------------------------------------------- >ALERTING
--------------------------------------------------------------------------------------------------------------------------- >CONNECT
< ---------------------------------------------------------------------------------------------------------------------------CONNECT ACK
2.3 Typical call failures TCH phase - success
MS BTS BSC MSCTCH ASSIGNMENT PHASE (OC or TC)
< -----------------------------------ASSIGNMENT REQUEST
< --------------------------------------------------------PHYSICAL CONTEXT REQUEST
-------------------------------------------------------- >PHYSICAL CONTEXT CONFIRM
< --------------------------------------------------------CHANNEL ACTIVATION (TCH)
-------------------------------------------------------- >CHANNEL ACTIVATION ACKNOWLEDGE
< ----------------------------------------------------------------------------------- Start T3107 (SDCCH) ASSIGNMENT COMMAND
---------------------- >TCH SABM -------------------------------------------------------- >
< ---------------------- ESTABLISH INDICATIONUA
----------------------------------------------------------------------------------- > Stop T3107ASSIGNMENT COMPLETE
----------------------------------- >ASSIGNMENT COMPLETE
< ---------------------------------------------------------------------------------------------------------------------------ALERTING
< ---------------------------------------------------------------------------------------------------------------------------CONNECT
---------------------------------------------------------------------------------------------------------------------------->CONNECT ACK
Call Setup
Call phase
Call Setup
Call phase
The Call setup phase and the Stable call phase are not corresponding between the BSS and the NSS. For the BSS, a call is established when the MS has successfully accessed a TCH channel on the Air interface. For the NSS, a call is established when the speech data exchanged is started between end users.Thus the Call setup phase is shorter and the Call phase is longer in the BSS.Therefore Call Setup Success rate is worse in the NSS and the Call Drop rate is worse in the BSS.
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TCH phase > drop radio
Radio problem
MS BTS BSC MSCAlerting Connection Phase or Communication : at any time
Radio problem-------------------------------------------------------- > MC736
CONNECTION FAILURE INDICATION --------------------------------------- >Cause radio link failure CLEAR REQUEST
Cause radio interface failure(alcatel)
2.3 Typical call failures TCH phase - radio drop
MC736 counts the number of TCH channel drops due to radio problems.MC736 counter is implemented at TRX level from B7.Radio problems can be due to coverage, interference and sometimes BSS dysfunction which is not detected as a system alarm by the O&M Fault Management application.
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TCH phase > drop TC
Remote TransCoder problem
MS BTS BSC MSCAlerting Connection Phase or Communication : at any time
Radio problem-------------------------------------------------------- > MC739
CONNECTION FAILURE INDICATION --------------------------------------- >Remote transcoder failure CLEAR REQUEST
Equipment failure
2.3 Typical call failures TCH phase - remote TC drop
MC739 counts the number of TCH channel drops due to BSS problems reported as "remote TransCoder failure".MC739 counter is implemented at TRX level from B7.It can usually be a bad quality of the transmission on the Abis interface (Micro Wave) or a faulty hardware component in the TransCoder or even sometimes BSS software/hardware problems.
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TCH phase > drop BSS internal
Other internal BSS problem (excluding TC)
MS BTS BSC MSCAlerting Connection Phase or Communication : at any time
MC14C--------------------------------------- >
CLEAR REQUESTO&M intervention
Radio interface failure
2.3 Typical call failures TCH phase - BSS internal drop
MC14C counts the number of TCH channel drops due to BSS problems other than the ones reported by the TransCoder.A BSS problem can be a BTS/BSC hardware or software failure.
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TCH phase > drop HO
Handover failure
MS BTS BSC MSCAlerting Connection Phase or Communication : at any time
HO FAILURE WITHOUT REVERSION MC621--------------------------------------- >
CLEAR REQUESTRadio Interface Message Failure (Alcatel)
2.3 Typical call failures TCH phase - HO drop
MC621 counts the number of TCH channel drops due to Handover failure.MC621 counter is implemented at TRX level from B7.This event is also counted in the set of Handover counters as an Outgoing handover failure without reversion to the old channel.
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TCH phase > drop preemption
TCH preempted
MS BTS BSC MSCAlerting Connection Phase of a call
with priority level pl2 and preemption vulnerability indicator pvi=1no TCH free
ASSIGNMENT REQUEST<---------------------------------------
Priority level pl1 > pl2preemption capability indicator pci=1
MC921C--------------------------------------- >
CLEAR REQUESTpreemption
2.3 Typical call failures TCH phase - preemption drop
MC921C counts the number of TCH channel drops due to preemption for another call to be established.MC921C counter exists from B7 as linked to the feature Preemption.
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TYPICAL CALL FAILURES: TCH phase counters
2.3 Typical call failures TCH phase - counters
TCH connection MC718+MC717A+MC717B
Outgoing HO success MC712
Call drop Drop radio MC736Drop TC MC739Drop internal BSS MC14CDrop HO MC621Drop preemption MC921C
Normal release unknownNSS abnormal release unknown
TCH Phase
Outgoing HO success Call drop
TCH connection
Normal release
Call drop radio
Call drop BSS
Call drop HO
Call drop preemption
TC
BSS internal
NSS abnormal release
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TYPICAL CALL FAILURES: TCH phase indicators
Call drop rate = call drop / RTCH success end
RTCH success end = RTCH assignment success + RTCH incoming (HO+DR) success - RTCH outgoing HO
2.3 Typical call failures TCH phase - call drop rate
Incoming internal HO+DR
BSS1 BSS2
Incoming external HO+DR
outgoing HO
TCH assignment
QSCDN = call drop = drop radio + drop TC + drop internal BSS + drop HO + drop Preemption= MC736 + MC739 + MC14C + MC621 + MC921C
TCQHCCN = RTCH success end = assignment success + incoming (HO+DR) success - outgoing HO= MC718 + (MC717A+MC717B) - MC712
As MC718, MC717A, MC717B and MC712 are provided per TRX, the “RTCH success end” indicator (TCAHCCN) can be computed per TRX.But since only MC736 (drop radio), MC739 (drop TC) and MC621 (drop HO) are provided per TRX, the “call drop rate” indicator (QSCDR) can be computed per CELL only.On the other hand the following call drop indicators can be computed per TRX:
call drop radio rate (QSCDRR) = call drop radio / RTCH success endcall drop HO rate (QSCDHR) = call drop HO / RTCH success end call drop TC rate (QSCDBTR) = call drop TC / RTCH success end
Note: MC718 counts the number of successful TCH assignments.MC717A counts the number of successful internal DRs.MC717B counts the number of successful incoming internal and external (HOs+DR) as well as the number of intra cell HOs successfully performed.MC712 counts the number of successful outgoing internal and external HOs as well as the number of intra cell HOssuccessfully performed.
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TYPICAL CALL FAILURES: TCH phase indicators
RTCH drop rate = call drop / RTCH success begin
RTCH success begin = RTCH assignment success+ RTCH incoming (HO+DR) success- RTCH intra cell HO success
2.3 Typical call failures TCH phase - RTCH drop rate
BSS1 BSS2
Incoming internal HO+DR
TCH assignment
Incoming external HO+DR
outgoing HO
Intra-cell HO
QSCDN = call drop = drop radio + drop TC + drop internal BSS + drop HO + drop Preemption= MC736 + MC739 + MC14C + MC621 + MC921C
TCQHSUBN = RTCH success begin = assignment success + incoming (HO+DR) success - intra cell HO= MC718 + (MC717A+MC717B) - MC662
As MC662 is not provided per TRX, the “RTCH success begin” indicator (TCAHSUBN) cannot be computed per TRX but per CELL only.Therefore all “RTCH drop rate” indicators can be computed per CELL only.
Note: MC662 counts the number of successful TCH intracell HOs.
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TYPICAL CALL FAILURES: TCH phase indicators
TRX TCH drop rate = call drop / RTCH success
RTCH success = RTCH assignment success+ RTCH incoming (HO+DR) success
2.3 Typical call failures TCH phase - TRX TCH drop rate
Incoming internal HO+DR
TCH assignment
outgoing HOBSS1 BSS2
Incoming external HO+DRIntra-cell HO
QSCDN = call drop = drop radio + drop TC + drop internal BSS + drop HO + drop Preemption= MC736 + MC739 + MC14C + MC621 + MC921C
TCAHSUN = RTCH success = assignment success + incoming (HO+DR) success= MC718 + (MC717A+MC717B)
Whereas some call drop rate indicators are defined per TRX and per CELL, TRX RTCH drop rate indicators are defined at TRX level only.As MC718, MC717A, MC717B are provided per TRX, the “RTCH success” indicator (TCAHSUN) can be computed per TRX.But since only MC736 (drop radio), MC739 (drop TC) and MC621 (drop HO) are provided per TRX, a global“TRX RTCH drop rate”indicator cannot be provided.On the other hand, the following TRX RTCH drop indicators can be computed:
TRX_RTCH_drop_radio_rate (TCAHCDRTR) = call drop radio / RTCH successTRX_RTCH_drop_HO_rate (TCHOCDTR) = call drop HO / RTCH successTRX_RTCH_drop_BSS_remote_TC_rate (TCTRTCDTR) = call drop TC / RTCH success
CAUTION: Intra-cell HO being counted in MC717B and not deduced in the RTCH success computation in order to provide the TRX RTCH drop indicators at TRX level then these indicators may be abnormally low (good) if a large amount of intra-cell HOs are performed in the cell (concentric cell, multiband cell).
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Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8:
call drop indicators: all of them are available per CELL only and some of them per TRX
GLOBAL Quality of service INDICATORS > Call Statistics > Call dropQSCDR: call drop rate (Global): CELLQSCDRR: call drop rate due to radio: CELL + TRXQSCDBIR: call drop rate due to BSS internal problem: CELLQSCDBTR: call drop rate due to TransCoder reported problem: CELL + TRXQSCDHR: call drop rate due to HO failure: CELL + TRXQSCDPR: call drop rate due to preemption: CELL
RTCH drop indicators: all of them are available per CELL only
GLOBAL Quality of service INDICATORS > RTCH > Established phaseQSTCCDR: RTCH drop rateTCAHCDRR: RTCH drop rate due to radio problemTCTRICDBR: RTCH drop rate due to BSS internal problemTCTRTCDR: RTCH drop rate due to TransCoder reported problemTCHOCDR: RTCH drop rate due to HO failureTCPPCDR: RTCH drop rate due to preemption
TRX TCH drop indicators: all of them are available per TRX only
GLOBAL Quality of service INDICATORS > RTCH > Established phaseTCAHCDRTR: TRX TCH drop rate due to radio problemTCTRTCDTR: TRX TCH drop rate due to TransCoder reported problemTCHOCDTR: TRX TCH drop rate due to HO failure
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TYPICAL CALL FAILURES: summary
call stage A interface cause field related problem
radio linkestablishment
no message - - SDCCH congestion- radio problem- dummy rach
SDCCH phase Clear Request - radio interface failure- radio interface failure- O&M intervention
- radio problem- BSS system HW/SW pb- recovery/operator
TCH assignment Assignment Failure - no radio resource avalaible- Radio Interface Failure
- TCH congestion- Radio problem
Alerting/connectioncall established
Clear Request - radio interface failure- radio interface message failure- equipment failure- O&M intervention- radio interface failure-preemption
- radio problem- HO failure w/o reversion- Transcoder failure- operator action/recovery- BSS system HW/SW pb- preemption
2.3 Typical call failures summaryB8 (See comments)
NewB8 New LAPD counter to analyze the cause of call establishment failures
When the BSC is congested on the downlink, some messages are discarded. This may result for example in call establishment failures, loss of paging messages or delay in handover procedures.
A new LapD counter that indicates the time a LapD link is congested is created to analyze the cause of a degraded quality of service. This counter is implemented in type 7 and thus is only available in a detailed measurement campaign.
Counter: L1.18: TIME_LAPD_CONGDefinition: Time in seconds during which the LapD link is congested in transmission in the BSC.
B8
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2 GLOBAL INDICATORS
2.4 Description of global indicators
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2.4 Description of global indicatorsrecall
Global Indicators areA set of indicators selected by Alcatel Useful to monitor the overall network
What are the user and or system impacts if a GI is bad?
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SDCCH CONGESTION rate: may have impact for subscriberCall setup failure only after 3 subsequent congestionsIf not, only some extra delay for call establishment
(less than 1 second) without immediate_assign_rejectCan be longer with reject (but usually short values are used for call request)
2.4 Description of global indicatorsSDCCH congestion rate
INDICATOR(G)
SDCCH ASSIGN CONG FAIL RATE
DEFINITION Rate of SDCCH not allocated during radio link establishment procedure due to congestion on the Airinterface
FORMULA B7.2 Σ cell (MC04) / SDCCH ASSIGN REQUESTSTHRESHOLD > 5%COMMENT Check SDCCH Erlang : if not critical, SDCCH availability/allocation problem, or HO access on a
nearby cell side effect or interference on the carrier handling SDCCH (the last 2 can lead to highrate of « phantom RACH »)
REF NAME SDNACGR UNIT %
(G) means that the indicator is Global, i.e. it is important to provide it at a Network level.
INDICATOR SDCCH ASSIGN REQUESTS
DEFINITION Number of SDCCH seizure requests during radio link establishment procedureFORMULA B7.2 Σcell (MC148 + MC04)THRESHOLDCOMMENT This includes requests rejected due to congestion on SDCCHREF NAME SDNARQN UNIT Number
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DESCRIPTION OF GLOBAL INDICATORSSDCCH CONGESTION rate
2.4 Description of global indicatorsSDCCH congestion rate
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: GLOBAL Quality of service INDICATORS > SDCCH > Assignment phase
SDNACGR: SDCCH assignment failure rate due to congestion (Global)
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SDCCH DROP rateUser impact: call setup failure
2.4 Description of global indicatorsSDCCH drop rate
INDICATOR(G)
SDCCH DROP RATE
DEFINITION Rate of dropped SDCCH (SDCCH is established for any transaction OC, TC, LU,etc.)FORMULA B7.2 Σcell (MC138 + MC07 + MC137) / SDCCH ASSIGN SUCCESSTHRESHOLD > 4%COMMENT Drop radio + Drop HO + Drop BSSREF NAME SDCDR UNIT %
In a dense network SDCCH drop rate should be lower than 1%. Indeed the probablity to drop a radio link when the MS is on SDCCH is less than on TCH since the SDCCH phase is shorter (less than 5 seconds) than TCH phase (several tens of seconds).
INDICATOR SDCCH ASSIGN SUCCESS
DEFINITION Total number of SDCCHs successfully seized by mobile during radio link establishmentprocedure
FORMULA B7.2 Σcell (MC01 + MC02)THRESHOLDCOMMENTREF NAME SDNASUN UNIT Number
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TCH ASSIGN UNSUCCESS rate: congestionradio problemBSS problems
2.4 Description of global indicatorsTCH assign unsuccess rate
INDICATOR(G)
TCH ASSIGN UNSUCCESS RATE
DEFINITION Rate of unsuccessful RTCH seizures for normal assignment purpose (congestion + HO&radiofailures)
FORMULA B7.2 (TCH ASSIGN REQUESTS – TCH ASSIGN SUCCESS) / TCH ASSIGN REQUESTSTHRESHOLD > 3%COMMENTREF NAME TCNAUR UNIT %
In a dense network, the TCH assignment unsucess rate should be lower a 1%.
INDICATOR TCH ASSIGN REQUESTS
DEFINITION Number of TCH seizure requests for normal assignment procedureFORMULA B7.2 Σ cell (MC703 + MC812)THRESHOLDCOMMENT This includes requests rejected due to congestion
In B7 : MC703 = MC16 (B6) but per TRXIn B7.1 : MC812 = MC612 (B6)In B7.2 : MC812 = [MC612(B6)]+[Congestion on Abis(C612e)]Congestion on Abis in restriction in B7.2, so finally MC812 = MC612 (B6)
REF NAME TCNARQN UNIT Number
INDICATOR TCH ASSIGN SUCCESS
DEFINITION Number of TCHs successfully seized by the MS for normal assignment procedureFORMULA B7.2 Σ TRX (MC718)THRESHOLDCOMMENT MC718 is new in B7.
MC718 = MC18 (B6) but per TRX.So indicator extended per TRX in B7
REF NAME TCNASUN UNIT Number
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GLOBAL RADIO CONGESTION LEVEL (TCH congestion rate)Subscriber impact: call setup failureMore a management indicator: % of network which has congestion
S2: GLOBAL 2.4 Description of global indicatorsGlobal radio congestion level
INDICATOR(G)
GLOBAL RADIO CONGESTION LEVEL
DEFINITION Global radio congestion level : number or rate of cells recurrently congestedFORMULA B7.2 COUNT_OF_CELLS (AVERAGE (MAX (TCH ASSIGN FAIL CONG RATE)) > 2%))THRESHOLD According to operatorCOMMENT This indicator reports the global radio congestion rate on the network. We define a specific
indicator counting the number of cells that are in congestion in a recurrent manner.MAX (TCH ASSIGN FAIL CONG RATE) : is the peak of failures due to congestion observedduring the period (the day normally). See the definition of TCH ASSIGN FAIL CONG RATE in theQuality of Service chapter)AVERAGE: is an averaging function of the blocking rate over the selected period, that is over BHof days for a week, or over BH of weeks for a monthCOUNT_OF_CELL : is a function counting the number of cells for which condition between () isrespected.The number of cells can be used as indicator, or the rate of cells over the total number of cells in thenetwork or area.
REF NAME QSCGR UNIT Number
This counter intends to give a measurement of the TCH congestion of the whole network.It is implemented on the Alcatel tools but other indicators can be defined.
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CALL DROP rate: The most important indicatorUsed with call setup success rate to compare PLMN (GSM and otherone)Subscribers impact: call drop!!
2.4 Description of global indicatorsCall drop rate
INDICATOR(G)
CALL DROP RATE
DEFINITION Rate of dropped calls (system + radio+ HO + preemption) over the total amount of calls with asuccessful end
FORMULA B7.2 Σcell (MC621 + MC14c + MC736 + MC739 + MC921c) / TCH SUCCESS ENDTHRESHOLD > 4%COMMENT Drop system + Drop radio + Drop HO + Drop preemption
TCH drops occurring after successful assignment but before speech connection are considered ascall drops even if from the customer point of view it is a call setup failureMC739, MC736 and MC621 derive from B6 counters C139, C136 and C21. These new countersare per TRXMC921c is new in B7.2
REF NAME QSCDR UNIT %
In a dense network, the Call Drop Rate should be lower than 2%. It should even go down to 1% or less in case Slow Frequency Hopping is used.
The RTCH drop rate is defined below:
The TRX TCH drop radio rate is defined below:
INDICATOR GLOBAL TCH DROP
DEFINITION Rate of TCHs dropped (system + radio + handover + preemption) over the total amount ofcalls established in the cell
FORMULA B7.2 Σcell (MC14c + MC739 + MC736 + MC621+ MC921c) / TCH SUCCESS BEGINTHRESHOLD > 3%COMMENT Drop System + Drop radio + Drop HO + Drop preemption
Indicator relevant at cell level mostly.MC739, MC736 and MC621 derive from B6 counters C139, C136 and C21. These new
counters are per TRXMC921c is new in B7.2
REF NAME QSTCCDR UNIT %
INDICATOR TRX TCH DROP RADIO RATE
DEFINITION Rate of TCHs dropped due to radio problems, per TRXFORMULA B7.2 (MC736) / TCH SUCCESSTHRESHOLD > 3%COMMENT New in B7
MC736 derives from B6 counters C136. This new counter in B7 is per TRX.Indicator only per TRX because intracell handovers are taken into account
REF NAME TCAHCDRTR UNIT %
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CALL SETUP SUCCESS rate: the second most important indicatorUsed to compare PLMNSubscriber: call not established at the first attempt
Beware: call setup failures due to a lack of coverage are not taken into account in this indicator!!
No way to quantify them (as there is no initial access)
2.4 Description of global indicatorsCall setup success rate
INDICATOR(G)
CALL SETUP SUCCESS RATE (BSS view)
DEFINITION Rate of calls going until TCH successful assignment, that is not interrupted by SDCCH DROPneither by Assignment failures
FORMULA B7.2 (1 – ( SDCCH DROP / SDCCH ASSIGN SUCCESS ) ) * (1 TCH ASSIGN UNSUCCESS RATE)THRESHOLD > 95%COMMENT SDCCH assignment failures are not considered in CSSR as :
• ghost (spurious) RACH cannot be discriminated from a real access failure• effect of re-attempts performed autonomously by the MS cannot be quantified
REF NAME QSCSSR UNIT %
Ghost Racks which correspond to a valid establishment cause are not identified by the BSS. Therefore they can lead to a high SDCCH assignment failure rate if they are too numerous.As the end user is not impacted by this phenomenon if no SDCCH congestion is induced, the SDCCH assignment phase is not considered in the computation of the Call Setup Success rate provided by Alcatel tools.In a dense network, the Call Setup Success Rate should be greater than 98%.The SDCCH congestion rate should also be considered to have a complete picture of Call Setup efficiency.
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1 call success =1 call successfully establishedWithout any call drop
2.4 Description of global indicatorsCall success rate
INDICATOR(G)
CALL SUCCESS RATE (BSS view)
DEFINITION Rate of calls going until normal release , that is not interrupted by SDCCH DROP, neither byAssignment Failures nor by CALL DROP
FORMULA B6.2 (CALL SETUP SUCCESS RATE) * (1 – CALL DROP RATE)THRESHOLD < 92%COMMENTREF NAME QSCCR UNIT %
In a dense network, the Call Setup Success Rate should be greater than 97%.
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CALL SETUP SUCCESS rate CALL SUCCESS rate
2.4 Description of global indicatorsCall (setup) success rate
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: GLOBAL Quality of service INDICATORS > Call statistics > Call success
QSCSSR: Call setup success rate (Global)QSCCR: Call success rate (Global)
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2.4 Description of global indicatorsHandover cause distribution
Indicator aiming at measuring the efficiency of planning /optimization
INDICATOR(G)
HO CAUSE DISTRIBUTION
DEFINITION Distribution of Handover attempts by cause X : UL/DL Qual, UL/DL Lev, UL/DL Interference,Distance, Better Cell, Interband, Micro cells HO, Concentric cell, Traffic, AMR, TFO causes.
FORMULA B7.2 Σ cell (MC67w or MC785x or MC586y or MC10zz or MC447 or MC461)Σcell (MC67all + MC785all + MC586all + MC10all + MC447 + MC461)
MC67all = MC671+MC672+MC673+MC674+MC675+MC676+MC677+MC678+MC679+MC670MC785all = MC785a + MC785d + MC785e + MC785f (microcell)MC586all = MC586a + MC586b + MC586c (concentric)MC10all = MC1040 + MC1044 + MC1050
THRESHOLD Quality DL > 10%, Qual UL > 10%, Level UL > 20%, Level DL > 20%Interf UL > 5%, Interf DL > 5%, Better Cell < 30%
COMMENTREF NAME HCSTBPBR, HCCCELVDR, HCCCELVUR, HCCCBCPR,
HCSTEDIR, HCSTEIFDR, HCSTELVDR, HCSTEQLDR,HCSTBDRR, HCMBBCPR, HCMCEBSR, HCMCELVDR,HCMCBCPR, HCMCELVUR, HCSTEMIR, HCSTEIFUR,HCSTELVUR, HCSTEQLUR, HCSTAMR, HCSTBTFR
UNIT %
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2.4 Description of global indicatorsHandover standard cause distribution
Indicator aiming at measuring the efficiency of planning / optimizationInteresting for comparing HO distribution after concentric or micro cell implementation
INDICATOR(G)
DISTRIBUTION HO CAUSE STANDARD
DEFINITION Distribution of Handover attempts by standard cause : Power Budget, quality too low, level too low,high interference and MS-BTS distance too long.
FORMULA B7.2Σ cell ( (MC67x) / GLOBAL HO CAUSE STANDARD)
MC67x = MC670 or MC672 or MC671 or MC673 or MC676 or MC677 or MC678 or MC674 or(MC670+MC672) or (MC671+MC673) or (MC676+M677)
THRESHOLDCOMMENTREF NAME HCSTEIFDSR, HCSTEIFUSR, HCSTEIFSR, HCSTELVDSR,
HCSTELVUSR, HCSTELVSR, HCSTEQLDSR,HCSTEQLUSR, HCSTEQLSR, HCSTBPBSR, HCSTEDISR
UNIT %
The Global HO cause standard indicator is defined as below:
where: MC670: Number of handover attempts cause 2: "uplink quality too low" MC672: Number of handover attempts cause 4: ”downlink quality too low" MC671: Number of handover attempts cause 3: "uplink level too low"MC673: Number of handover attempts cause 5: "downlink level too low"MC676: Number of handover attempts cause 15: "too high uplink interference level"MC677: Number of handover attempts cause 16: "too high downlink interference level"MC678: Number of handover attempts cause 12: "too low power budget"MC674: Number of handover attempts cause 6: "MS-BTS distance too long"
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2.4 Description of global indicatorsHandover cause distribution
HANDOVER CAUSE rates
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Handover statistics INDICATORS > Handover causes
HCXXYYYYR: Rate of specific HO cause xxyyyy versus all HO causes (Global)where XX = ST (standard) or MC (micro cell) or CC (concentric cell) or MB (multi band)and YYYY is specific to the cause
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Global success rate of Outgoing HO
Success rate of execution of Outgoing HO
2.4 Description of global indicatorsOutgoing handover success rate
INDICATOR(G)
OUTGOING HO SUCCESS RATE
DEFINITION Rate of successful outgoing external and internal intercell SDCCH and TCH handoversFORMULA B7.2 Σcell (MC646 + MC656) / Σcell (MC645a + MC655a)THRESHOLD < 90%COMMENT This indicator includes preparation and execution.REF NAME HOORSUR UNIT %
INDICATOR(G)
EFFICIENCY OF OUTGOING HANDOVER EXECUTION
DEFINITION Rate of successful outgoing external and internal intercell SDCCH and TCH handoversFORMULA B7.2 Σcell (MC646 + MC656) / Σcell (MC650 + MC660)THRESHOLD < 90%COMMENT This indicator takes into account HO execution only (not ho preparation).REF NAME HOOREFR UNIT %
Global Outgoing HO success rate: represents the global efficiency ot the outgoing handovers performed from one cell to any of its neighboring cells (same BSS or not).Efficiency of Outgoing HO execution: represents the efficiency of the channel change procedure during outgoing handovers performed from one cell to any of its neighboring cells (same BSS or not). It does not take into account the HO failures that can occur during the preparation phase when the new channel is being selected and activated.
From B7 MC645A replaces MC645 of B6.
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Global success rate of Incoming HO
Success rate of execution of Incoming HO
2.4 Description of global indicatorsIncoming handover success rate
INDICATOR(G)
INCOMING HANDOVER SUCCESS RATE
DEFINITION Rate of successful incoming external and internal intercell SDCCH and TCH handovers.FORMULA B7.2 Σcell (MC642 + MC652) / Σcell(MC820 + MC830)THRESHOLD < 90%COMMENTREF NAME HOIRSUR UNIT %
INDICATOR(G)
EFFICIENCY OF INCOMING HANDOVERS
DEFINITION Rate of successful incoming external and internal intercell SDCCH and TCH HOsFORMULA B7.2 Σcell (MC642 + MC652) / Σcell (MC821 + MC831)THRESHOLD < 90%COMMENT Excluding congestion failures and BSS preparation failures from requests.REF NAME HOIREFR UNIT %
Global Incoming HO success rate: represents the global efficiency of the incoming handovers performed to one cell from any of its neighboring cells (same BSS or not).Efficiency of Incoming HO execution: represents the efficiency of the channel change procedure during incoming handovers performed to one cell from any of its neighboring cells (same BSS or not). It does not take into account the HO failures that can occur during the preparation phase when the new channel is being selected and activated.
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The highest, the best is the cellBut the traffic handled is not taken into account
2.4 Description of global indicatorsCall quality factor absolute
INDICATOR(G)
CELL QUALITY FACTOR ABSOLUTE
DEFINITION Indicator summarizing the cell behavior and allowing the operator to sort out cell for investigation.This indicator is based on failure events. For each part of the indicator,twothresholds are used: Topt and TQoS. TQoS is the QoS warning threshold (e.g. above or belowthe threshold, a warning is generated on the cell. Topt + TQoS is the optimal valuethat should be acheived. Each part as a weighting factor (WF) according to the impact on the subscriber’s point of view.
investigation. This indicator is based on failure events. For each part of the indicator, two
FORMULA B6.2 ((1 – SDCCH CONGESTION rate) - TQoS)/ Topt * WF+ (CALL SETUP SUCCESS rate - TQoS)/ Topt *WF+ ((1 – CALL DROP rate - TQoS)/ Topt * WF+ (OUTGOING HO SUCCESS rate - TQoS)/ Topt * WF+ ((1 – HO QUALITY rate - TQoS)/ Topt * WF
THRESHOLD SDCCH CONGESTION rate : TQoS = 0.97, Topt = 0.03, WF = 0.1CALL SETUP SUCCESS rate : TQoS = 0.9, Topt = 0.09, WF = 0.2CALL DROP rate : TQoS = 0.96, Topt = 0.04, WF = 0.3OUTGOING HO SUCCESS rate : TQoS = 0.85, Topt = 0.12, WF = 0.15HO QUALITY rate : TQoS = 0.85, Topt = 0.1, WF = 0.25
COMMENTREF NAME QSCQAR UNIT %
This counter intends to compute for every cell of the network a global indicator taking into account the major causes of bad Quality of Service.Each cause is weighted according to the impact on the end user.
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For optimizationTry to improve cells with the worst CQFR
2.4 Description of global indicatorsCall quality factor relative
INDICATOR(G)
CELL QUALITY FACTOR RELATIVE
DEFINITION This indicator is the Cell Quality Factor Absolute weighted by the cell traffic.Investigation shouldbe done in priority on the cell having a high rate of failures with high traffic (the traffic is the rate oftraffic handled by the cell over the total network traffic – traffic is TCH seizure attempts)
FORMULA B7.2 CQFA * ((MC15a + MC15b + MC703)cell / (MC15a + MC15b + MC703)network)THRESHOLD N/ACOMMENTREF NAME QSCQRR UNIT %
Normalizing the previous Cell Quality Factor Absolute by the traffic of the cell will allow to compare the QoS of the cell between each other and raise the list of top worst cells candidate for analysis.From B7, MC703 replaces MC16 of B6.
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Management indicator, maintenance oriented, assessingQuantity of stability problemsReaction time to problems
2.4 Description of global indicatorsNetwork TCH availability
INDICATOR(G)
NETWORK (TCH) AVAILABILITY
DEFINITION Rate of TCHs able to carry traffic (upon the total number of traffic channels)FORMULA B7.2 (Σcell (MC250) / #Available TCH)THRESHOLD < 95%COMMENT #Available TCH : according to channel configurationREF NAME TCAVAR UNIT %
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GLOBAL INDICATORS
2.4 Description of global indicatorsExercise
Indicator value OK ? Impact
SDCCH congestion 10 % NOK difficulties to establish call
Call drop 5 %
Call success 95 %
Efficiency of outgoing HO 91 %
Network TCH availability 94 %
TCH assignment failure 2,4 %
Call drop 2,3 %
SDCCH drop 2 %
HO cause distribution(ratio of better cell)
45 %
Call success 88 %
SDCCH drop 1 %
Time allowed: 10 minutes
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2.5 Traps and restrictions of global indicators
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2.5 Traps and restrictions of global indicatorsObjective
Beaware of traps and restrictions about some global indicators
So as to be able to provide a reliable interpretation
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2.5 Traps and restrictions of global indicatorsCall set-up success rate / Call drop rate
CALL SETUP SUCCESS The radio link establishment failure is not taken into account, because:
most of failures during RLE are due to ghost RACHthe MS is attempting MAX_RETRANS+1 times before giving updifficult to assess subscriber's impact, anyhow very low
CALL DROPFor BSS, the last stage is considered as established, although it is not the cause from a user point of viewIf a TCH drop occurs during this phase
for the user, it is a setup failurefor the OMC-R indicators, counted as a call drop
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2.5 Traps and restrictions of global indicatorsCall duration
IMPACT OF CALL DURATION
The longest a call is, the highest the risk to have a drop isIf statistics are done on abnormally long or short calls, the result can be less accurate Typical case: drive testTypical call duration: 80/90 seconds in most of European countries
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2.5 Traps and restrictions of global indicatorsMobility
IMPACT OF MOBILITYMost of drop problems are due to mobility
Usually 2/3 of calls are static (no HO will be done)For example, if 40 drops are observed for 1000 calls
40/1000 = 4% of global call dropbut most of call drops are generated by "moving calls"
40/(1000*1/3) = 40/333 = 12 % of call drop rate for moving call0 % for static call
Typical trap when comparing drive tests results with OMC-R statistics
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2.5 Traps and restrictions of global indicatorsExercise
TRAPS AND RESTRICTIONS OF GLOBAL INDICATORS: Case conclusion OK ? why
global call drop : 2% for 1 call of 20 mn,The risk of drop is 2%
NOK The call duration is higher than the average
In 1 BSS, some transcoders arefaulty : as soon as TCHs areestablished on these TCs, they are lost
The call setup successrate indicatorwill beincreased due to thisproblem
In 1 network, drive test are showinga general call drop of 7%. The OMC-R call drop indicator isgiving 2.1%.
The OMC-R indicatoris erroneous (drive
test is the reality)
In 1 network, the global call setup success is 92 %
For moving calls, callsetup success will beabout 76 %
In a pedestrian zone, 80 % of callsare static
The measured call drop is 1,7 %
For taxi, calldone in Taxi in this zone willbe droppedat 5.1 %
Time allowed: 10 minutes
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2 GLOBAL INDICATORS
2.6 Global indicators interpretation
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2.6 Global indicators interpretation Exercise 1
Is this network OK? N a m e v a lu e
S D C C H c o n g e s t i o n 1 %
S D C C H d r o p 3 %
T C H a s s i g n m e n t f a i l u r er a t e
2 %
C a l l d r o p 1 %
C a l l s e t u p s u c c e s s r a t e 9 6 %
C a l l s u c c e s s r a t e 9 4 %
E f f i c i e n c y o f o u t g o i n gH O
9 2 %
E f f i c i e n c y o f i n c o m in gH O
9 3 %
H O c a u s e d i s t r i b u t i o nb e t t e r / l e v e l / q u a l i t y
7 0 / 2 0 / 1 0
N e t w o r k T C Ha v a i l a b i l i t y
9 8 %
Time allowed: 5 minutes
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2.6 Global indicators interpretation Exercise 2
Can one say that : all indicators are OK? the coverage of the network is 95%? the call success of all the cells are 95% (minimum)?
N a m e v a l u e
S D C C H c o n g e s t i o n 5 %
S D C C H d r o p 2 %
T C H a s s i g n m e n t f a i l u r er a t e
1 %
C a l l d r o p 1 %
C a l l s e t u p s u c c e s s r a t e 9 7 %
C a l l s u c c e s s r a t e 9 5 %
E f f i c i e n c y o f o u t g o i n gH O
9 2 %
E f f i c i e n c y o f i n c o m i n gH O
9 2 %
H O c a u s e d i s t r i b u t i o nb e t t e r / l e v e l / q u a l i t y
7 5 / 1 5 / 1 0
N e t w o r k T C Ha v a i l a b i l i t y
9 8
Time allowed: 5 minutes
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2.6 Global indicators interpretation Exercise 3
Results of field tests on a network
Is the network better if QSCDR = 2%?
Name value
SDCCH congestion
SDCCH drop
TCH assignment failurerateCall drop 4.6 %
Call setup success rate 92 %
Call success rate
Efficiency of outgoingHOEfficiency of incomingHOHO cause distributionbetter/level/qualityNetwork TCHavailability
Time allowed: 5 minutes
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3. DETAILED INDICATORS
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3 Detailed indicatorsSession presentation
Objective: to be able to use the BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS document in order to get some more detailed indicators of the Alcatel BSS
Program: 3.1 Indicator reference name3.2 Indicators classification
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3. DETAILED INDICATORS
3.1 Indicator reference name
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3.1 Indicator reference nameDescription
each QOS indicator has a unique REFERENCE NAME of 10 characters
UnitFamily
Procedure Type JokerPrefix Sub-type
mandatory
optional
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3. DETAILED INDICATORS
3.2 Indicators classification
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3.2 Indicators classification Main categories
Classification in BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS document
Control Channels
SCCP
TCH
SDCCH
Traffic load
Call statistics
RTCH
SDCCH
Global QoS
Couple of cells
SDCCH /TCHHO repartition
Intracell HO
Incoming HO
Outgoing HO
HO causes
Handoverstatistics
Resourceavailability
Multiband
Multilayer / MultibandNetwork
Concentric cells
Directed retry
Densificationtechniques
GSMindicators
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3.2 Indicators classification SDCCH traffic
Traffic Load and Traffic Model > SDCCH traffic
Estab
SDCCH Traffic
TrafficMT
TrafficMO
Loc. Update
IMSI Detach
Sup. Service
Call
LU Follow on
SMS
CallRe-Estab
Other
MSPenetration Rate
TrafficDual Band
ResourceOccupancy
SDCCHErlang
SDCCH MeanHolding TimeGlobal
Traffic
GlobalRequests
TrafficModel
HandoverNormalAssignment
NormalAssignment
Handover
The Traffic model section includes indicators for: – number of SDCCH connection requests and successses (Immediate Assignment, HO).– distribution of SDCCH connection success (MO and MT connections versus all MO+MT connections, type of MO
connections versus all MO connection types).
The MS penetration rate section includes the indicator for: – percentage of multiband MS SDCCH access (except LU) versus all MS SDCCH accesses.
The Resource occupancy section includes indicators for: – SDCCH traffic in Erlang.– average duration in seconds of SDCCH channel usage.
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3.2 Indicators classification TCH traffic
Traffic Load and Traffic Model > TCH traffic
RTCH Traffic
ResourceOccupancy
TCHErlang
Full RateErlang
Full RateAllocated
Full RateMean TCH
Time
Half RateErlang
Half RateAllocated
Half RateMean TCH
Time
Blocking Peak
Ratio ofHR Traffic
TCHMultibandOccupancy
Traffic Model
REQUESTSAssign / HO / DR
SUCCESSAssign / HO / DR
HO PER CALL
REQUESTSFR, DR, DR/EFR, AMR, DATA
Speech Version&Channel Type
ALLOCATIONSFR, HR, EFR, AMR, DATA
SUCCESSAMR / TFO
The Speech Version and Channel Type section includes indicators for: – distribution of TCH allocation requests (FR/DR/DR+EFR/AMR/DATA).– distribution of TCH allocation successes (FR/DR/DR+EFR/AMR/DATA).– rate of TCH AMR allocation successes.– rate of TFO calls versus all speech calls.
The Traffic model section includes indicators for: – number of TCH connection requests and successes (Normal Assignment, HO, DR).– rate of TCH allocation successes for HO+DR versus all TCH allocations (NA+HO+DR).– number of HOs per call.
The Resource occupancy section includes indicators for: – RTCH traffic in Erlang (FR+HR, FR, HR, multiband).– average duration in seconds of RTCH channel usage (FR+HR, FR, HR).– number of TCH FR allocations and number of TCH HR allocations.– rate of TCH HR allocations versus all TCH allocations (FR+HR).– TCH peak of blocking (TCH congestion time).
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3.2 Indicators classificationSCCP resource occupancy / Control channels traffic
Traffic Load and Traffic Model > SCCP resource occupancySCCP traffic in Erlang
Traffic Load and Traffic Model > Control Channels trafficPCH channel loadAGCH channel loadRACH channel load
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3.2 Indicators classificationQoS SDCCH
GLOBAL Quality of service > SDCCH
Drop BSS
SDCCH
EstablishedPhase
Drop Rate
Drop Radio Drop HO
Unsuccess
Congestion
Assignment Phase/
Handover
RadioFailure
BSS Failure
Access Reject
Dynamic Allocation
B8
New B8
(See comments)
The Assignment phase section includes indicators for the Radio Link Establishment procedure: global SDCCH access failure rate. specific SDCCH access failure rate per type of problem (SDCCH congestion, radio, BSS).specific indicators for Dynamic SDCCH Allocation:
Stored Indicators (see Dynamic SDCCH Allocation in the Global Indicators section)DYTROFN.= MC800DYAHCATAN = MC801aDYAHCATMN = MC801bDYAHCASAN. = MC802aDYAHCASMN.= MC802bDYN = number of Dynamic timeslots (given by configuration file) = Cell_NB_DYNComputed indicatorsDYAHCATAR: average rate of busy TCH (FR of HR) allocated on dynamic SDCCH/8 timeslotsFormula: tdiv (DYAHCATAN,DYTROFN,0,0)DYAHCATMR: maximum rate of busy TCH (FR of HR) allocated on dynamic SDCCH/8 timeslotsFormula: tdiv (DYAHCATMN,DYTROFN,0,0)DYAHCASAR: average rate of busy SDCCH sub-channels allocated on the dynamic SDCCH/8timeslotsFormula: tdiv (DYAHCASAN,DYTROFN,0,0)Impact on existing Indicators: Apart of modification due to introduction of Dynamic SDCCH/8 timeslot, the general formula of these indicators are redesigned, to be simpler.TCRRDN, TCRROFN, TCAHCGUN, TCAVAR (removed as it is the same as TCTRAR), TCTRAVE, TCTRAR, TCTRTCE, SDAHCGUN, SDAVAR, SDRRDN, SDRROFN, SDTRAVE
The Handover procedure section includes the indicator for the preparation of the SDCCH HO procedure: rate of SDCCH HO failure due to SDCCH congestion
The Established phase section includes indicators for SDCCH Phase: global SDCCH drop rate.specific SDCCH drop rate per type of problem (radio, HO, BSS).
B8
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3.2 Indicators classificationQoS RTCH
GLOBAL Quality of service > RTCH
DirectedRetry
RTCH
Unsuccess
Assignment Phase/
Handover
Global RadioCongestion Level
Congestion
RadioFailure
BSSFailure
EstablishedPhase
Drop rate
Drop Radio
Drop BSS
Drop HO
Preemption
PreemptionPhase
PCI =1 PVI =1
Requests
Allocationwith / withoutPreemption
Failure
Success
Success
QueuingPhase
Queue Length
AssignQueuing Fail
AssignQueued
& Reject
QueuedSuccess
Queue Full
HigherPriority
Timeout
AssignQueued
NormalAssign.
The Assignment phase section includes indicators for the TCH Normal Assignment procedure: global RTCH assignment failure rate (called unsuccess rate).specific RTCH assignment failure rate per type of problem (RTCH congestion, radio, BSS).global radio congestion level (number of cells congested in the network).
The Handover procedure section includes indicators for the global HO procedure (intracell+intercell internal + intercell external): rate of RTCH incoming HO failure due to RTCH congestion.specific RTCH outgoing HO failure rate per type of problem (congestion, radio - Reversion Old Channel, radio drop, BSS).
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3.2 Indicators classificationQoS call statistics
GLOBAL Quality of service > Call statistics
Call Statistics
Call Success
Call SetupSuccess Rate
CallSuccess Rate
Cell QualityFactor Absolute
Cell QualityFactor Relative
Call Drop
Call Drop Rate
Drop Radio Drop BSSDrop HO
Transcoder Failure
BSS Internal Failure
Call DropEnd User Rate
Preemption
The Call Drop section includes indicators for the TCH Phase: global call drop rate.specific call drop rate per type of problem (radio, HO, BSS int., TransCoder, preemption).
The Call Success section includes indicators for the global call procedure (speech): rate of call setup success.rate of call success.global cell quality factor.
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Handover STATISTICS > Handover causes
3.2 Indicators classificationHandover causes
Handover causes
HO causes
All HO
cause distribution
Outgoing HO Incoming HOHO standard
cause distribution
HO cause category
distribution
HO causes per Adjacency
HO cause category
distribution
B8
Fast traffic HO taken into account
New type of counter for dual band HO
(See comments)
New B8
The Handover causes section includes indicators of HO causes distribution corresponding to outgoing handovers relating to a cell: distribution of HO causes taking into account all possible HO causes (quality UL, level DL, distance, power budget,
concentric cell cause, micro cell cause, traffic, etc.).distribution of HO standard causes taking into account only HO standard causes (quality UL, quality DL, level UL, level DL,
interference UL, interference DL, distance, power budget).
The Handover causes per adjacency section includes indicators of HO causes distribution corresponding to outgoing and incoming handovers relating to a couple of serving/target cells:
distribution of HO cause categories taking into account 3 categories (emergency [quality, level, interference, distance, power budget]), better condition [power budget, capture], traffic, forced directed retry).
B8: Introduction of C449 (type 6) in type 110 (as MC449) improves the result of all HO cause Indicators:C449 = MC449 = number of handover attempts with cause 28 (Fast traffic handover)The Indicator TOTALHO (HCN) is impacted as well as the following indicators:
HCSTBPBR, HCCCR, HCSTEDIR, HCSTEDMR, HCSTIFDR, HCSTLVDR, HCSTQLDR, HCSTEIFR, HCSTELVR, HCMCR, HCSTEQLR, HCSTIFUR, HCSTLVUR, HCSTQLUR, HCNTBDR, HCSTBTFR, HCSTAMR, HCSTAMFR, HCSTAMHR, HCSTBTRFR
B8: Introduction of a new type of counter (Type 32: Change of frequency band measurements)Type 32 is defined as Standard and provides information to observe handovers between different frequency bands.C403a = NB_INC_EXT_TCH_HO_NEW_BAND_ATPT = Number of incoming external TCH (in HR or FR usage) handover attempts including a change of the (TCH) frequency band.C403b = NB_INC_EXT_TCH_HO_NEW_BAND_SUCC = Number of incoming external TCH (in HR or FR usage) handover successes including a change of the (TCH) frequency band.C404a = NB_OUT_EXT_TCH_HO_NEW_BAND_ATPT = Number of outgoing external TCH (in HR or FR usage) handover attempts including a change of the (TCH) frequency band.C404b = NB_OUT_EXT_TCH_HO_NEW_BAND_SUCC = Number of outgoing external TCH (in HR or FR usage) handover successes including a change of the (TCH) frequency band.C420a = NB_INC_INT_TCH_HO_NEW_BAND_ATPT = Number of incoming internal TCH (in HR or FR usage) handover attempts including a change of the (TCH) frequency band.C420b = NB_INC_INT_TCH_HO_NEW_BAND_SUCC = Number of incoming internal TCH (in HR or FR usage) handover successes including a change of the (TCH) frequency band.C421a NB_OUT_INT_TCH_HO_NEW_BAND_ATPT = Number of outgoing internal TCH (in HR or FR usage) handover attempts including a change of the (TCH) frequency band.C421b NB_OUT_INT_TCH_HO_NEW_BAND_SUCC = Number of outgoing internal TCH (in HR or FR usage) handover successes including a change of the (TCH) frequency band.
B8
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Handover STATISTICS > Outgoing handovers
3.2 Indicators classificationOutgoing handovers
Failure With Reversion
Call Drop Rate
Efficiency
Preparation Success Rate
Intra-BSC
Failure With Reversion
Call Drop Rate
Efficiency
Preparation Success Rate
External
Call Drop Rate
Efficiency
Success Rate
Intra-BSC & External
Outgoing HO
B8
New B8 New LAPD counter to analyze the cause of delay in HO procedures
The Outgoing Intra BSC intercell section includes indicators corresponding to the efficiency of outgoing intercell internal handovers relating to a cell (serving):
efficiency ot the preparation phase (target TCH allocation) of the outgoing handovers performed from one cell to any of its neighboring cells belonging to the same BSS.
efficiency ot the execution phase (old to new TCH channel change) of the outgoing handovers performed from one cell to any of its neighboring cells belonging to the same BSS.
distribution of outgoing intra BSC intercell HO failures per type of problem (radio drop, radio - Reversion Old Channel, BSS).
The Outgoing Inter BSC intercell section includes indicators corresponding to the efficiency of outgoing intercell external handovers relating to a cell (serving):
efficiency ot the preparation phase (target TCH allocation) of the outgoing handovers performed from one cell to any of its neighboring cells not belonging to the same BSS.
efficiency ot the execution phase (old to new TCH channel change) of the outgoing handovers performed from one cell to any of its neighboring cells not belonging to the same BSS.
distribution of outgoing inter BSC intercell HO failures per type of problem (radio drop, radio - Reversion Old Channel, BSS).
The Outgoing Intra BSC + Inter BSC intercell section includes indicators corresponding to the efficiency of all outgoing intercellhandovers relating to a cell (serving):
global efficiency ot the outgoing handovers performed from one cell to any of its neighboring cells whether they belong to the same BSS or not
efficiency ot the execution phase (old to new TCH channel change) of the outgoing handovers performed from one cell to any of its neighboring cells whether they belong to the same BSS or not.
outgoing intra BSC + inter BSC intercell HO drop rate per type of problem (radio drop, radio - Reversion Old Channel, BSS).
When the BSC is congested on the downlink, some messages are discarded. This may result for example in call establishment failures, loss of paging messages or delay in handover procedures.
A new LapD counter that indicates the time an LapD link is congested is created to analyze the cause of a degraded quality of service. This counter is implemented in type 7 and thus is only available in a detailed measurement campaign.
Counter: L1.18: TIME_LAPD_CONGDefinition: Time in seconds during which the LapD link is congested in transmission in the BSC.
B8
(See comments)
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Handover STATISTICS > Incoming handovers
3.2 Indicators classificationIncoming handovers
Failure BSS
Failure Radio
Congestion
Efficiency
Intra-BSC
Failure BSS
Failure Radio
Failure No CIC
Congestion
Efficiency
External
Efficiency
Intra-BSC & External
Incoming HO
B8
New counters and indicators for:
Incoming external HO 3G - > 2G
Incoming external HO 2G - > 2G only
New B8
(See comments)
The Incoming Intra BSC intercell section includes indicators corresponding to the efficiency of incoming intercell internal handovers relating to a cell (target):
efficiency ot the execution phase (old to new TCH channel change) of the incoming handovers performed to one cell from any of its neighboring cells belonging to the same BSS.
distribution of incoming intra BSC intercell HO failures per type of problem (congestion, radio, BSS).
The Incoming Inter BSC intercell section includes indicators corresponding to the efficiency of incoming intercell external handovers relating to a cell (target):
efficiency ot the preparation phase (target TCH allocation) of the incoming handovers performed to one cell from any of its neighboring cells not belonging to the same BSS.
distribution of incoming inter BSC intercell HO failures per type of problem (RTCH congestion, TTCH (CIC) congestion, radio, BSS)
Using new counters introduced in B8 for 3G to 2G Incoming External Handovers,MC922a: NB_INC_EXT_3G_2G_HO_REQ (REQUESTS)MC922b: NB_INC_EXT_3G_2G_HO_SUCC (SUCCESS)MC922c: NB_INC_EXT_3G_2G_HO_EXEC_FAIL_MS_ACC (FAILURES)MC922d: NB_INC_EXT_3G_2G_HO_ATPT (ATTEMPTS)
Creation of 4 new stored indicators based on the 4 new counters: HOIMRQUN= MC922a HOIMSUUN = MC922b HOIMFLRRUN = MC922c HOIMCAUN = MC922d
As existing PM counters related to incoming handovers keep a global view, so consider handovers from 2G cells as well as handovers from 3G cells. The pure 2G-2G results can then be obtained by comparing them with the new introduced counters:
Creation of 4 new stored indicators for incoming external handover 2G -2G only: HOIMRQGN = MC820 - MC922a (REQUESTS) HOIMSUGN = MC642 - MC922b (SUCCESS)HOIMFLGN = MC643 - MC922c (FAILURES) HOIMCAGN = MC821 - MC922d (ATTEMPTS)
And New calculated indicators are defined: 3G-2G HO Success rate: HOIMSUUR = MC922b / MC922a2G-2G HO Success rate: HOIMSUGR = (MC642-MC922b) / (MC820-MC922a)preparation and execution 3G-2G HO failure rate HOIMFLUR = 1 -(MC922b/MC922a)preparation and execution 2G-2G HO failure rate HOIMFLGR = 1 -((MC642-MC922b) / (MC820-MC922a))
B8
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Handover STATISTICS > Intracell handovers
3.2 Indicators classificationIntra-cell handovers
CDR Radio CDR BSS
Failure With Reversion
Failure BSS
Call Drop Rate
Congestion
Efficiency
Intracell HO
The Intracell section includes indicators corresponding to the efficiency of intracell handovers performed within a cell: efficiency ot the execution phase (old to new TCH channel change) of the intracell handovers performed within a cell.distribution of intracell HO failures per type of problem (congestion, radio drop, radio - Reversion Old Channel, BSS).
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Handover STATISTICS > Handover statistics per couple of cell
3.2 Indicators classificationHandover statistics per couple of cells
HO Success Distribution
Success Rate
Efficiency
Preparation Success Rate
HO statisticsper Couple of Cell
The Indicators with counters type 180 section includes indicators corresponding to the efficiency of incoming internal+external intercell SDCCH+TCH handovers performed between two cells (serving/target):
global efficiency of the incoming intercell handovers performed between two cells (serving/target).efficiency ot the preparation phase (old to new TCH channel change) of the incoming intercell handovers performed
between two cells (serving/target).efficiency ot the execution phase (old to new TCH channel change) of the incoming intercell handovers performed between
two cells (serving/target).distribution per couple of (serving/target) cells of the incoming intercell handovers performed to a cell from any of its
neighboring cells whether they belong to the same BSS or not.
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4 Handover indicatorsSession presentation
Objective: to be able to explain what are the main Handover counters and indicators provided by the Alcatel BSS in order to monitor the quality of handovers
Program: 4.1 Intra-cell handover indicators per cell4.2 Internal handover indicators per cell4.3 External handover indicators per cell4.4 Handover indicators per couple of cells
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4 HANDOVER INDICATORS
4.1 Intra-cell handover indicators per cell
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4.1 Intra-cell handover indicators per cell Handover types
HO FAIL. CASES > HO ReminderIntra-Cell: Handover between two TCHs of the same cellInternal
between two cells of the same BSCalso called intra BSCand not using the forced external handover mode
Externalbetween two cells of different BSCsalso called inter BSCor between two cells of the same BSC when using the forced external handover mode
TCH/(SDCCH) HandoverSynchronous
between 2 cellssharing the same clockscollocatedusually 2 sectors of the same BTS
tunable at OMC-R level
Asynchronousnot synchronous for any reasonno dedicated monitoring for synchronous/asynchronous HO
Incomingas considering the target cell
Outgoingas considering the serving cell
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4.1 Intra-cell handover indicators per cell Intracell HO - success
HO FAIL. CASES > intracell HO > successful caseMS BTS BSC MSC
MEAS REPORT-----------------------------> MEASUREMENT RESULT
--------------------------------------------------------------> MC870PHYSICAL CONTEXT REQUEST (old channel)<--------------------------------------------------------------PHYSICAL CONTEXT CONFIRM (old channel)
-------------------------------------------------------------->CHANNEL ACTIVATION (new channel)
<--------------------------------------------------------------CHANNEL ACTIVATION ACK (new channel)
-------------------------------------------------------------->ASSIGNMENT CMD ASSIGNMENT COMMAND (old channel) MC871
<----------------------------- <-------------------------------------------------------------- start T3107SABM
-----------------------------> ESTABLISH INDICATION (new channel)UA -------------------------------------------------------------->
<-----------------------------ASSIGNMENT CMP ASSIGNMENT COMPLET(new channel)-----------------------------> --------------------------------------------------------------> stop T3107
MC662HANDOVER
PERFORMED------------------->
RF CHANNEL RELEASE (old channel)<--------------------------------------------------------------
RF CHANNEL RELEASE ACK (old channel)-------------------------------------------------------------->
Both SDCCH and TCH are counted together.The T3107 timer is also used as the guard timer of the channel change procedure during an intra cell handover. The Default valuefor T3107 is 14 seconds.
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4.1 Intra-cell handover indicators per cell Intracell HO - failures
HO FAIL. CASES > intracell HO failures
Handover Preparation: congestion BSS problem (no specific counter)
Handover Execution: reversion to old channeldrop radioBSS problem (no specific counter)
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HO FAIL. CASES > intracell HO failure: congestionMC561TCH+MC101SDCCH
4.1 Intra-cell handover indicators per cell Intracell HO - congestion
MS Serving BTS Serving BSC MSC
MEAS REPORT-----------------------------> MEASUREMENT RESULT
--------------------------------------------------------------> MC870No free TCH
MC561
From B7, MC561 replaces MC61of B6.As the counting of the Abis-TCH congestion case is in restriction in B8:
MC61(B6) = MC561(B7)
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4.1 Intra-cell handover indicators per cell Intracell HO - radio failure ROC
HO FAIL. CASES > intracell HO failure: reversionold channel
Serving ServingMS BTS BSC MSC
MC871ASSIGNMENT CMD ASSIGNMENT COMMAND (old channel)<----------------------------- <----------------------------------------------------------------- start T3107 (= T10)start T200
SABM (new channel)-----------------------------> ESTABLISH INDICATION (new channel)
----------------------------------------------------------------->UA (new channel)
X- - - - - --------------------SABM (new channel)
----------------------------->UA (new channel)
X- - - - - --------------------
SABM (old channel)-----------------------------> ESTABLISH INDICATION (old channel)
UA (old channel) -----------------------------------------------------------------><-----------------------------ASSIGNMENT FAIL ASSIGNMENT FAILURE-----------------------------> -----------------------------------------------------------------> stop T3107
MC667PHYSICAL CONTEXT REQUEST (new channel)
<-----------------------------------------------------------------PHYSICAL CONTEXT CONFIRM (new channel)
----------------------------------------------------------------->RF CHANNEL RELEASE (new channel)
<-----------------------------------------------------------------RF CHANNEL RELEASE ACK (new channel)
----------------------------------------------------------------->
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HO FAIL. CASES > intracell HO failure: radio dropMC663=C63TCH+C103SDCCH
Serving ServingMS BTS BSC MSC
MC871ASSIGNMENT CMD ASSIGNMENT COMMAND (old channel)<----------------------------- <----------------------------------------------------------------- start T3107 (= T10)
MC663Release of old and new channels T3107 expiry
4.1 Intra-cell handover indicators per cell Intracell HO - radio failure drop
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HO FAIL. CASES > intracell HO failure: BSS drop
no specific counter
Serving ServingMS BTS BSC MSC
MC871ASSIGNMENT CMD ASSIGNMENT COMMAND (old channel)<----------------------------- <----------------------------------------------------------------- start T3107 (= T10)
--------------------------------------- >CLEAR REQUEST
O&M interventionRadio interface failure
4.1 Intra-cell handover indicators per cell Intracell HO - BSS problem
Intra cell HO failures due to BSS problems are deduced from other counters.
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HO FAIL. CASES > intracell HO counters
4.1 Intra-cell handover indicators per cell Intracell HO - counters
Request MC870
Congestion MC561+MC101BSS Pb MC870-MC871-(MC561+MC101)
Attempt MC871
Reversion old channel MC667Drop radio MC663BSS Pb MC871-MC662-MC667-MC663
Success MC662
Preparation
Execution
INTRACELL Handover
REQUEST
CONGESTION
ATTEMPT
REVERSION OLD CHANNEL
DROP RADIO
BSS PB
SUCCESS
BSS PB
Preparation Failure
Execution Failure
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4.2 Internal handover indicators per cell
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HO FAIL. CASES > internal HO > success case
4.2 Internal handover indicators per cell Internal HO - success
The same inter-cellhandover procedure leads to an incrementation of two sets of counters: incoming HO counters for the target cell: MC830, MC831, MC652, etc.outgoing HO counters for the serving cell: MC655A, MC660, MC656, etc.In HO_PERFORMED MESSAGE
Target cell (CI,LAC)"cause" of HO
MS serving cell target cell BSC MSCMEAS REP
-----------------------> MEASUREMENT RESULT------------------------------------------------------------------------> MC830, MC655A
CHANNEL ACTIVATION<----------------------------------
CHAN ACTIV ACK---------------------------------->
HO CMD HANDOVER COMMAND<----------------------- <------------------------------------------------------------------------ start T3103
MC831, MC660start T3124
HANDOVER ACCESS------------------------------------------------------------->-------------------------------------------------------------> HO DETECTION
PHYSICAL INFORMATION ----------------------------------><------------------------------------------------------------- start T3105stop T3124start T200------------------------ SABM ---------------------------> stop T3105<-------------------------- UA ----------------------------- ESTABLISH INDICATIONstop T200 ---------------------------------->
HANDOVER COMPLETE HO CMP stop T3103-------------------------------------------------------------> ----------------------------------> HO PERFORMED
------------------------>Release of old TCH MC652, MC656
Both SDCCH and TCH are counted together.
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HO FAIL. CASES > Incoming internal HO failures:
Handover procedure from the target cell point of view
Handover Preparation: congestion: no RTCH available in the target cell
does not concern the outgoing side (serving cell point of view)BSS problem (no specific counter)
Handover Execution: radio problem: the MS fails to access the new channel
the reversion/drop discrimination concerns only the serving cellBSS problem (no specific counter)
4.2 Internal handover indicators per cell Incoming internal HO - failures
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HO FAIL. CASES > Incoming internal HO fail: congestionMC551TCH+MC91SDCCH
4.2 Internal handover indicators per cell Incoming internal HO - congestion
MS Serving Cell Serving BSC MSC
MEAS REPORT-----------------------------> MEASUREMENT RESULT
--------------------------------------------------------------> MC830No free TCH
MC551MC91
If no free SDCCH
From B7, MC551 replaces MC51of B6.As the counting of the Abis-TCH congestion case is in restriction in B8:
MC51(B6) = MC551(B7)
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HO FAIL. CASES > Incoming internal HO fail: MS access problem
4.2 Internal handover indicators per cell Incoming internal HO - radio failure
MS serving cell target cell BSC MSCMEAS REP
-----------------------> MEASUREMENT RESULT------------------------------------------------------------------------>
CHANNEL ACTIVATION<----------------------------------
CHANNEL ACTIV ACK---------------------------------->
HO CMD HANDOVER COMMAND<----------------------- <------------------------------------------------------------------------ start T3103
MC660SABM
-----------x T3103 expiry MC653
MS Serving cell Target Cell BSC
HO CMD HANDOVER COMMAND<----------------------- <------------------------------------------------------------------------ start T3103
HANDOVER ACCESS MC660------------------------------------------------------------->-------------------------------------------------------------> HO DETECTION
PHYSICAL INFORMATION ----------------------------------><------------------------------------------------------------- start T3105
SABM-------------------------------------------------------------> ESTABLISH INDICATION
UA ----------------------------------><------------------------------------------------------------- stop T3105
HANDOVER COMPLETE----------------------------------------------------- - - - -X
SABM-----------------------> ESTABLISH INDICATION
UA ------------------------------------------------------------------------><-----------------------
HO FAILURE HANDOVER FAILURE-----------------------> ------------------------------------------------------------------------> MC653
Release of new channel
All incoming internal HO failures due to radio problems are counted in the same counter MC653. Both radio failures with Reversion Old Channel and radio drop are counted together.
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HO FAIL. CASES > Incoming internal HO counters
4.2 Internal handover indicators per cell Incoming internal HO - counters
Request MC830
Congestion MC551+MC91BSS Pb MC830-MC831-(MC551+MC91)
Attempt MC831
Radio (MS access problem) MC653BSS Pb MC831-MC652-MC653
Success MC652
Execution
Preparation
INCOMING INTERNAL Handover
REQUEST
CONGESTION
ATTEMPT
MS ACCESS PB
BSS PB
SUCCESS
BSS PB
Preparation Failure
Execution Failure
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4.2 Internal handover indicators per cell Incoming internal HO - indicators
SUCCESS
HO FAIL. CASES > Incoming internal HO indicators
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Handover Statistics INDICATORS > Incoming handover > Incoming Intra BSC
HOIBEFR: efficiency of the incoming internal HO executionHOIBCGR: rate of incoming internal HO failures due to congestionHOIBPFR: rate of incoming internal HO failures due to BSS during the preparation phaseHOIBFLRR: rate of incoming internal HO failures due to radio problemsHOIBFLBR: rate of incoming internal HO failures due to BSS during the execution phase
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HO FAIL. CASES > Outgoing internal HO failures
Handover procedure from the serving cell point of view
Handover Preparation: congestion on the target cell (no specific counter on the serving cell)BSS problem (no specific counter)
Handover Execution: radio problem: the MS reverts to the old channelradio problem: the MS dropsBSS problem (no specific counter)
4.2 Internal handover indicators per cell Outgoing internal HO - failures
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HO FAIL. CASES > Outgoing internal HO fail: reversionold channel
4.2 Internal handover indicators per cell Outgoing internal HO - radio failure ROC
MS Serving cell Target Cell BSC
HO CMD HANDOVER COMMAND<----------------------- <------------------------------------------------------------------------ start T3103
HANDOVER ACCESS MC660------------------------------------------------------------->-------------------------------------------------------------> HO DETECTION
PHYSICAL INFORMATION ----------------------------------><------------------------------------------------------------- start T3105
SABM-------------------------------------------------------------> ESTABLISH INDICATION
UA ----------------------------------><------------------------------------------------------------- stop T3105
HANDOVER COMPLETE----------------------------------------------------- - - - -X
SABM-----------------------> ESTABLISH INDICATION
UA ------------------------------------------------------------------------><-----------------------
HO FAILURE HANDOVER FAILURE-----------------------> ------------------------------------------------------------------------> MC657
Release of new channel
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HO FAIL. CASES > Outgoing internal HO fail: drop
clear_request: ask the MSC to release the connectionIn case of call drop due to HO, the cause is "radio interface message failure" (for Alcatel)
MS serving cell target cell BSC MSCMEAS REP
-----------------------> MEASUREMENT RESULT------------------------------------------------------------------------> MC655A
CHANNEL ACTIVATION<----------------------------------
CHAN ACTIV ACK---------------------------------->
HO CMD HANDOVER COMMAND<----------------------- <------------------------------------------------------------------------ start T3103
MC660SABM
----------xT3103 expiryMC658
Clear_request------------------------>
Clear_commandRelease of old and new TCH <------------------------
4.2 Internal handover indicators per cell Outgoing internal HO - radio failure drop
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HO FAIL. CASES > Outgoing internal HO counters
4.2 Internal handover indicators per cell Outgoing internal HO - counters
Preparation Request MC655A
Any preparation failure MC655A-MC660
Attempt MC660
Reversion old channel MC657Drop radio MC658BSS Pb MC660-MC656-MC657-MC658
Success MC656
Execution
OUTGOING INTERNAL Handover
REQUEST
CONGESTION
ATTEMPT
REVERSION OLD CHANNEL
DROP RADIO
BSS PB
SUCCESS
BSS PB
Preparation Failure
Execution Failure
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4.2 Internal handover indicators per cell Outgoing internal HO - indicators
SUCCESS
HO FAIL. CASES > Outgoing internal HO indicators
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Handover Statistics INDICATORS > Outgoing handover > Outgoing Intra BSC
HOOBRQR: efficiency of the outgoing internal HO preparation.HOOBEFR: efficiency of the outgoing internal HO execution.HOOBOCR: rate of outgoing internal HO failures due to radio problems with Reversion Old Channel.HOOBCDRR: rate of outgoing internal HO failures due to radio problems with drop.HOOBCDR: rate of incoming internal HO failures with drop (radio + BSS).
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4.3 External handover indicators per cell
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4.3 External handover indicators per cell External HO - success
HO FAIL. CASES > External HO > successful case
B8
MS serving_cell BSC MSC BSC target_cell MS- MEAS_REPORT ->
------- MEAS_RESULT -------->MC645A ------ HO_REQUIRED ---------->
----------CR (HO_REQUEST) -----> MC820<--------- CC ------------------------ ---- CHANNEL_ACTIVATION ------>
<- CHANNEL_ACT_ACK-------------<----- HO_REQUEST_ACK -------- Start T9113
(HO_COMMAND) MC821<------------------------- HO_COMMAND ------------------------------------------------------ <---- HO_ACCESS -----
MC650 Start T8 <---- HO_ACCESS -----<------ HO_DETECTION--------------
<-- HO_DETECTION -------------- --- PHYSICAL_INFO -->
<--- SABM ---------------<----- ESTABLISH_INDICATION ---- ----- UA -------------->
<----------- HO_COMPLETE ----------------------------------------<--- HO_COMPLETE --------------- Stop T9113
<---- CLEAR_COMMAND ------ MC642MC646 Cause : HO_SUCCESSFUL
Release of TCH Stop T8
MC462A
MC462B
MC462C
MC463A
MC463B
MC463C
(See comments)
Both SDCCH and TCH are counted together.From B7, MC645A replaces MC645 of B6.MC645a is only counting HANDOVER REQUIRED messages that are linked to a handover trial and not those that are linked to the update of the candidate cell list for handover / directed retry. This is leading to a more accurate computation of the External outgoing HO success rate.
B7.2: Only Outgoing inter PLMN HO is allowed but no counters.B8: 6 new counters provide information for "Inter-PLMN HO" (Incoming and Outgoing)
MC462a (equivalent of MC645A for intra PLMN external HO)Number of inter-PLMN TCH outgoing handovers or directed retry requests: HANDOVER REQUIRED sent to the MSC for an external TCH HO or an external DR triggered towards a cell belonging to a PLMN different from the PLMN of the serving cell.MC462b (equivalent of MC650 for intra PLMN external HO)Number of inter-PLMN TCH outgoing handovers or directed retry attempts: HANDOVER COMMAND sent to the MS on Abis for an external TCH HO or an external DR triggered towards a cell belonging to a PLMN different from the PLMN of the serving cell.MC462c (equivalent of MC646 for intra PLMN external HO)Number of inter-PLMN TCH outgoing handovers or directed retry successes: CLEAR COMMAND with Cause "Handover successful" received from the MSC for an external TCH HO or an external DR triggered towards a cell belonging to a PLMN different from the PLMN of the serving cell.MC463a (equivalent of MC820 for intra PLMN external HO)Number of inter-PLMN TCH incoming handovers or directed retry requests: HANDOVER REQUEST received from the MSC for an external TCH HO or an external DR triggered towards the target cell from a serving cell belonging to a PLMN different from the PLMN of the target cell.MC463b (equivalent of MC821 for intra PLMN external HO)Number of inter-PLMN TCH incoming handovers or directed retry attempts: HANDOVER REQUEST ACK sent by the target BSC containing the HANDOVER COMMAND for an external TCH HO or an external DR triggered towards the target cell from a serving cell belonging to a PLMN different from the PLMN of the target cell.MC463c (equivalent of MC642 for intra PLMN external HO)Number of inter-PLMN TCH incoming handovers or directed retry successes: HANDOVER COMPLETE received from the MS on Abis for an external TCH HO or an external DR triggered towards the target cell from a serving cell belonging to a PLMN different from the PLMN of the target cell.
Note than all other (previous) counters related to HO continue to be based on Intra PLMN only.
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4.3 External handover indicators per cell External HO - failures
HO FAIL. CASES > Incoming external HO failures
Handover procedure from the target cell point of view
Handover Preparation: congestion: no RTCH available in the target cell OR no TTCH available on the A interface
does not concern the outgoing side (serving cell point of view)BSS problem (no specific counter)
Handover Execution: radio problem: the MS fails to access the new channel
the reversion/drop discrimination concerns only the serving cellBSS problem (no specific counter)
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4.3 External handover indicators per cell Incoming external HO - RTCH congestion
HO FAIL. CASES > Incoming external HO fail: Air/Abis cong.MC541ATCH+MC81SDCCH
MS serving_cell BSC MSC BSC target_cell MS- MEAS_REPORT ->
------- MEAS_RESULT -------->MC645A ------ HO_REQUIRED ------->
----------CR (HO_REQUEST) -----> MC820
<----- HO_FAILURE --------------- MC541A( <-HO_REQUIRED_REJECT-) Cause: no radio resource available
From B7, MC541A replaces MC41A of B6.As the counting of the Abis-TCH congestion case is in restriction in B8:
MC41A(B6) = MC541A(B7)
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4.3 External handover indicators per cell Incoming external HO - TTCH congestion
HO FAIL. CASES > Incoming external HO fail: A int. cong.MC41B
MS serving_cell BSC MSC BSC target_cell MS- MEAS_REPORT ->
------- MEAS_RESULT -------->MC645A ------ HO_REQUIRED ------->
----------CR (HO_REQUEST) -----> MC820
<----- HO_FAILURE --------------- MC41BCause: terrestrial circuit already allocatedRequested terrestrial resource unaivalableBSS not equiopoed
( <-HO_REQUIRED_REJECT-)
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HO FAIL. CASES > Incoming external HO fail: MS accessproblem
4.3 External handover indicators per cell Incoming external HO - radio failure
MS serving_cell BSC MSC BSC target_cell MS- MEAS_REPORT ->
------- MEAS_RESULT -------->MC645A ---- HO_REQUIRED ------->
----------CR (HO_REQUEST) -------------------> MC820<-------- CC --------------------------------------- - CHANNEL_ACT ---------->
<--- CHA_ACT_ACK --------Start T9113
<----- HO_REQUEST_ACK----------------------- Start T9113<-------------------------- HO_COMMAND ------------------------------------------------ HO-COMMAND) included° MC821
Start T8 X --- HO_ACCESS -----X ---- HO_ACCESS -----
----- SABM --- X----- SABM --- X
----- SABM --- X T9113 expiryMC643
Release of connection
MS serving_cell BSC MSC BSC target_cell MS- MEAS_REPORT ->
------- MEAS_RESULT -------->MC645A ---- HO_REQUIRED ------->
----------CR (HO_REQUEST) -------------------> MC820<-------- CC --------------------------------------- - CHANNEL_ACT ---------->
<--- CHA_ACT_ACK --------<----- HO_REQUEST_ACK----------------------- Start T9113 (HO-COMMAND) included MC821
<-------------------------- HO_COMMAND ------------------------------------------------Start T8 X --- HO_ACCESS -----
X ---- HO_ACCESS ---------- SABM --------><--- UA ------------- -- ESTABLISH_INDICATION->
----- HO_FAILURE (reversion to old channel) ------------------------------------------>----- CLEAR_COMMAND ----------------------> MC643Radio interface fail : Reversion to old channel Release of connection
All incoming external HO failures due to radio problems are counted in the same counter MC643. Both radio failures with Reversion Old Channel and radio drop are counted together.
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HO FAIL. CASES > Incoming external HO counters
4.3 External handover indicators per cell Incoming external HO - counters
Request MC820
Congestion MC541+MC81BSS Pb MC820-MC821-(MC541+MC81)
Attempt MC821
Radio (MS access problem) MC643BSS Pb MC821-MC642-MC643
Success MC642
Execution
Preparation
INCOMING EXTERNAL Handover
REQUEST
CONGESTION
ATTEMPT
MS ACCESS PB
BSS PB
SUCCESS
BSS PB
Preparation Failure
Execution Failure
ATTEMPT SUCCESS
REQUEST
RATIO
Inter PLMN HO Intra PLMN HO
B8
New B8
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4.3 External handover indicators per cell Incoming external HO - indicators
ATTEMPT
BSS PB
SUCCESS
HO FAIL. CASES > Incoming external HO indicators
B8 (See comments)
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Handover Statistics INDICATORS > Incoming handover > Incoming Inter BSC
HOIMEFR: efficiency of the incoming external HO execution.HOIMCGR: rate of incoming external HO failures due to radio congestion (Air or Abis TCH).HOIMAMR: rate of incoming external HO failures due to CIC congestion (A TCH).HOIMPFR: rate of incoming external HO failures due to BSS during the preparation phase.HOIMFLRR: rate of incoming external HO failures due to radio problems.HOIMFLBR: rate of incoming external HO failures due to BSS during the execution phase.
B8: Inter PLMN Incoming External HO Indicators
An indicator is created for each new counter.REQUESTSATTEMPTSSUCCESS
In addition, new indicators show: the success rate of incoming inter-PLMN HOs,the ratio of incoming inter-PLMN HO to incoming intra-PLMN and inter-PLMN HO,
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4.3 External handover indicators per cell Outgoing external HO - failures
HO FAIL. CASES > Outgoing external HO failures
Handover procedure from the serving cell point of view
Handover Preparation: congestion on the target cell (no specific counter on the serving cell)BSS problem (no specific counter)
Handover Execution: radio problem: the MS reverts to the old channelradio problem: the MS dropsBSS problem (no specific counter)
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4.3 External handover indicators per cell Outgoing external HO - radio failure ROC
HO FAIL. CASES > Outgoing external HO fail: reversion old channel
MS serving_cell BSC MSC BSC target_cell MS- MEAS_REPORT ->
------- MEAS_RESULT -------->MC645A ---- HO_REQUIRED ------->
----------CR (HO_REQUEST) -------------------><-------- CC --------------------------------------- - CHANNEL_ACT ---------->
<--- CHA_ACT_ACK --------<----- HO_REQUEST_ACK----------------------- Start T9113 (HO-COMMAND) included
<-------------------------- HO_COMMAND ------------------------------------------------Start T8 X --- HO_ACCESS -----MC650 X ---- HO_ACCESS -----
----- SABM --------><--- UA ------------- -- ESTABLISH_INDICATION->
----- HO_FAILURE (reversion to old channel) ------------------------------------------>MC647 ----- CLEAR_COMMAND ---------------------->
Radio interface fail : Reversion to old channelRelease of connection
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4.3 External handover indicators per cell Outgoing external HO - radio failure drop
HO FAIL. CASES > Outgoing external HO fail: drop
MS serving_cell BSC MSC BSC target_cell MS- MEAS_REPORT ->
------- MEAS_RESULT -------->MC645A ---- HO_REQUIRED ------->
----------CR (HO_REQUEST) -------------------><-------- CC --------------------------------------- - CHANNEL_ACT ---------->
<--- CHA_ACT_ACK --------<----- HO_REQUEST_ACK----------------------- Start T9113 (HO-COMMAND) included
<-------------------------- HO_COMMAND ------------------------------------------------Start T8 X --- HO_ACCESS -----MC650 X ---- HO_ACCESS -----
----- SABM --- X----- SABM --- X
----- SABM --- X
T8 expiry ----- CLEAR_REQUEST ->MC648 Radio interface message fail
Release of connection
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HO FAIL. CASES > Outgoing external HO counters
4.3 External handover indicators per cell Outgoing external HO - counters
Preparation Request MC645A
Any preparation failure MC645A-MC650
Attempt MC650
Reversion old channel MC647Drop radio MC648BSS Pb MC650-MC646-MC647-MC648
Success MC646
Execution
OUTGOING EXTERNAL Handover
REQUEST
CONGESTION
ATTEMPT
REVERSION OLD CHANNEL
DROP RADIO
BSS PB
SUCCESS
BSS PB
Preparation Failure
Execution Failure
ATTEMPT SUCCESS
REQUEST
RATIO
Inter PLMN HO Intra PLMN HO
B8
New B8
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4.3 External handover indicators per cell Outgoing external HO - indicators
ATTEMPT
SUCCESS
HO FAIL. CASES > Outgoing external HO indicators
B8 (See comments)
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Handover Statistics INDICATORS > Outgoing handover > Outgoing Inter BSC
HOOMRQR: efficiency of the outgoing external HO preparation.HOOMEFR: efficiency of the outgoing external HO execution.HOOMOCR: rate of outgoing external HO failures due to radio problems with Reversion Old Channel.HOOMCDRR: rate of outgoing external HO failures due to radio problems with drop.HOOMCDR: rate of incoming external HO failures with drop (radio + BSS).
B8: Inter PLMN Outgoing External HO Indicators
An indicator is created for each new counter.REQUESTSATTEMPTSSUCCESS
In addition, new indicators show: the success rate of outgoing inter-PLMN HOs,the ratio of outgoing inter-PLMN HO to outgoing intra-PLMN and inter-PLMN HO.
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4 HANDOVER INDICATORS
4.4 Handover indicators per couple of cells
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4.4 Handover indicators per couple of cells Type 180 counters
Some handover indicators available per couple of (serving, target) cells:
permanently for all adjacencies through PM type 180 counters 3 counters for each (Serving,Target)
adjacency: C400(S,T): Incoming handovers requested to cell T from cell SC401(S,T): Incoming handovers attempted to cell T from cell SC402(S,T): Incoming handovers successfully performed to cell T from cell S
both internal and external inter cell handovers are counted
both SDCCH and TCH handoversare counted
a
e
d
c
b
f
C40i(f,d)
C40i(a,b)C40i(c,b)
C40i(c,d)
According to the definition of C40i counters: ∑ C400(Sn,T) = MC820(T) + MC830(T)
∑ C401(Sn,T) = MC821(T) +MC831(T)
∑ C402(Sn,T) = MC642(T) + MC652(T)
where
Sn are the serving cells considering the incoming adjacencies to cell T.
MC820(T), MC821(T), MC642(T) are the counters relating to the incoming external handovers requested, attempted and successfully performed to cell T.
MC830(T), MC831(T), MC646(T) are the counters relating to the incoming internal handovers requested, attempted and successfully performed to cell T.
n
n
n
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4.4 Handover indicators per couple of cells Type 180 indicators
The following indicators can be computed from PM Type 180 counters in order toDetect the most important neighboring cells as per their traffic
Distribution of incoming handovers performed to cell T from serving cells Sn
= C402(Sx,T) / ∑ C402(Sn,T)
Ease the diagnosis of the bad handover performance of a cell Global efficiency of incoming handovers to cell T from cell S
HOOASUR = C402(S,T) / C400(S,T)
Efficiency of the incoming handover preparation to cell T from cell SHOOACAR = C401(S,T) / C400(S,T)
Efficiency of the incoming handover execution to cell T from cell SHOOAEFR = C402(S,T) / C401(S,T)
n
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Handover Statistics > HO Statistics per couple of cells > Indicators with counter type 180
These indicators can also be to check if a recently handover relationship is generating handover as expected.They will also allow to identify the handover relationships which should be deleted since no (or very few) handover is observed.
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counters for each (Serving,Target x) adjacency: C720(S,Tx): Outgoing handovers attempted from
cell S to cell TxC721(S,Tx): Outgoing handovers successfully
performed from cell S to cell TxC722(S,Tx): Outgoing handovers failed from cell
S to cell Tx with Reversion Old ChannelC723(S,Tx): Outgoing handovers failed from cell
S to cell Tx with drop
these type 26 counters are available for several cells at the same time (40 cells)
4.4 Handover indicators per couple of cells Type 26 counters
Some handover indicators are available per couple of (serving, target) cells:
on demand for all outgoing adjacencies of a serving cell through PM type 26
Target a
Te
Serving
Tc
Tb
Tf
C72i(S,Te)
C72i(S,Tc)
B8
Modified in B8
Other counters are provided: C724(S,Tx): Outgoing handovers attempted from S to Tx for an emergency cause.C725(S,Tx): Outgoing handovers attempted from S to Tx for a better cell cause.C727(S,Tx): Outgoing handovers attempted from S to Tx for a traffic cause.C728(S,Tx): Outgoing handovers attempted from S to Tx for a forced directed retry cause.
Previously the set of Type 26 counters could be retrieved for only one cell per BSS at once.40 cells at the same time in B8.
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4.4 Handover indicators per couple of cells Type 26 indicators
The following indicators can be computed from PM Type 26 counters in order to:ease the diagnosis of the bad outgoing handover performance of acell
Efficiency of the outgoing handover execution from cell S to cell TxHOOXSUR = C721(S,Tx) / C720(S,Tx)Rate of outgoing ho execution failures due to radio problems from S to Txwith dropHOOXCDRR = C723(S,Tx) / C720(S,Tx)Rate of outgoing ho execution failures due to radio problems from S to Txwith Reversion Old ChannelHOOXOCR = C722(S,Tx) / C720(S,Tx)Rate of outgoing ho execution failures due to BSS problems from S to TxHOOXCDBR = [C720(S,Tx)-C721(S,Tx)-C722(S,Tx)-C723(S,Tx)] / C720(S,Tx)
these type 26 counters are available for several cells at once (40 cells)
B8
Modified in B8
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Handover Statistics > HO Statistics per couple of cells > Indicators with counter type 26.In B8, these type 26 counters are available for several cells at once (40 cells).
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counters for each (Serving,Target x) adjacency:
C730(Sx,T): Incoming handovers attempted to cell T from cell Sx
C731(Sx,T): Incoming handovers successfully performed to cell T from cell Sx
C733(S,Tx): Incoming handovers failed due to MS radio access problems to cell T from cell Sx
4.4 Handover indicators per couple of cells Type 27 counters
Some handover indicators are available per couple of (serving, target) cells:
on demand for all incoming adjacencies of a target cell through PM type 27
Serving a
Se
Target
Sc
Sb
Sf
C73i(Se,T)
C73i(Sc,T)
Other counters are provided: C734(Sx,T): Incoming handovers attempted from Sx to T for an emergency cause.C735(Sx,T): Incoming handovers attempted from Sx to T for a better cell cause.C737(Sx,T): Incoming handovers attempted from Sx to T for a traffic cause.C738(Sx,T): Incoming handovers attempted from Sx to T for a forced directed retry cause.
The set of Type 27 counters can be retrieved for only one cell per BSS at once.
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4.4 Handover indicators per couple of cells Type 27 indicators
The following indicators can be computed from PM Type 27 counters in order toEase the diagnosis of the bad incoming handover performance of a cell
Efficiency of the incoming handover execution to cell T from cell SxHOIXSUR = C731(Sx,T) / C730(Sx,T)
Rate of incoming ho execution failures due to MS radio access problems to cell T from cell Sx
HOIXCDRR = C733(Sx,T) / C730(Sx,T)
Rate of incoming ho execution failures due to BSS problems to cell T from cell Sx
HOIXCDBR= [C730(Sx,T)-C731(Sx,T)-C733(Sx,T)] / C730(Sx,T)
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Handover Statistics > HO Statistics per couple of cells > Indicators with counter type 27
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5 DIRECTED RETRY INDICATORS
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5 Directed retry indicatorsSession presentation
Objective: to be able to describe the counters and indicators used for monitoring the efficiency of the directed retry feature
Program: 5.1 Internal directed retry indicators5.2 External directed retry indicators
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5 DIRECTED RETRY INDICATORS
5.1 Internal directed retry indicators
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5.1 Internal directed retry indicators Queuing on TCH assignment
When there is no TCH available in a cell for TCH normal assignment:
Queuing: TCH request is put in a queue, waiting for a TCH to be released in this cell
With default BSS tuning: the call establishment fails if no TCH has been freed after T11 seconds
but an optional mechanism can be activated
The queuing of TCH requests is also performed for incoming external TCH handovers but not for incoming internal TCH handovers.
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5.1 Internal directed retry indicators Directed retry definition
Directed Retry (DR): When a TCH request is in queue, the BSC tries to establish the TCH connection on a neighboring cell if:
the normal handover condition is met (Normal DR)
specific directed retry conditions are met (Forced DR): the MS receives a sufficient signal level from a neighboring cell
the number of free TCHs in this neighboring cell is sufficient
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5.1 Internal directed retry indicators Directed retry types
DR FAIL. CASES > DR ReminderDR as an SDCCH to TCH handover can be
Internalbetween two cells of the same BSCalso called intra BSC
Externalbetween two cells of different BSCsalso called inter BSC
Incomingas considering the target cell
Outgoingas considering the serving cell
Synchronousbetween 2 cellssharing the same clockscollocatedusually 2 sectors of the same BTS
tunable at OMC-R levelAsynchronous
not synchronous for any reasonno dedicated monitoring for synchronous/asynchronous HO
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DR FAIL. CASES > internal DR > success case
5.1 Internal directed retry indicators Internal DR - success
The same internal DR procedure leads to an incrementation of two sets of counters: incoming DR counters for the target cell: MC153, MC151, etc.outgoing DR counters for the serving cell: MC144E, MC142E, etc.
MCx counters belong to Standard Type 110 reported permanentlyCx counters belong to Detailed Type 29 reported on demand in B7.
Becomes a Standard type in B8.
MS serving cell target cell BSC MSCTCH ASSIGNMENT PHASE (OC or TC)
< -----------------------ASSIGNMENT
REQUESTNo free TCH
TCH request queuedQueuing allowed
Start T11 ----------------------- >QUEUING_INDIC.
MC13A
IDR condition met MC153, MC144e,
CHANNEL ACTIV. (TCH)<---------------------------------- MC15A
CHAN ACTIV ACK---------------------------------->
HO CMD HANDOVER COMMAND<----------------------
(SDCCH)<------------------------------------------------------------------------ start T3103
C154, MC607start T3124 C145A+C145C
HANDOVER ACCESS------------------------(TCH)---------------------------->-------------------------------------------------------------> HO DETECTION
PHYSICAL INFORMATION ----------------------------------><------------------------------------------------------------- start T3105stop T3124start T200------------------------ SABM --------------------------> stop T3105<-------------------------- UA ----------------------------- ESTABLISH INDICATIONstop T200 ---------------------------------->
HANDOVER COMPLETE HO CMP stop T3103-------------------------------------------------------------> ----------------------------------> ASSIGNMENT
COMPLETE------------------------>
Release of old SDCCH MC151,MC717A,MC142e
B8 (see comments)
Modified inB8
The following DR counters are provided in Type 110for the target cell:
MC13A: TCH requests for Normal Assignment that are put into the queue,MC153: incoming internal DR requests,MC15A: TCH allocations for incoming internal DR,MC151: incoming internal DR successes per cell,MC717A: incoming internal DR successes per TRX.
for the serving cell: MC144E: outgoing internal DR requests,MC142E: outgoing internal DR successes,MC607: outgoing internal+external DR attempts.
The following DR counters are provided in Type 29 (this type becomes a standard type in B8)for the target cell:
C153: incoming internal DR requests,C154: incoming internal DR attempts,C151: incoming internal DR successes.
for the serving cell: C144A: forced outgoing internal DR requests,C144C: normal outgoing internal DR requests,C145A: forced outgoing internal DR attempts,C145C: normal outgoing internal DR attempts,C142A: forced outgoing internal DR successes,C142C: normal outgoing internal DR successes.
All the counters here and in the next slides concerning directed retry and relative to type 29 can be activated for all cells of the BSC at once from B8. (Type 29 becomes a standard type in B8):
C142a, C142b, C142c, C142d, C143a, C143b, C143c, C143d, C143e, C143f, C143g, C143h, C144a, C144b, C144c, C144d, C145a, C145b, C145c, C145d, C151, C152,C153, C154, C555
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DR FAIL. CASES > Incoming internal DR failures:
Directed Retry procedure from the target cell point of view
DR Preparation: congestion: no RTCH available in the target cell
does not concern the outgoing side (serving cell point of view)BSS problem (no specific counter)
DR Execution: radio problem: the MS fails to access the new channel
the reversion/drop discrimination concerns only the serving cellBSS problem (no specific counter)
5.1 Internal directed retry indicators Incoming internal DR - failures
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DR FAIL. CASES > Incoming internal DR fail: congestionMC555=C155
5.1 Internal directed retry indicators Incoming internal DR - congestion
MS serving cell target cell BSC MSCTCH ASSIGNMENT PHASE (OC or TC)
< ----------------------------------------------------ASSIGNMENT REQUEST
No free TCHIn serving cell
Queuing allowed
Start T11 --------------------------------------------------- >QUEUING_INDIC.
MC13A
IDR condition met MC153, MC144e,MC607
No free TCHIn target cell
MC555
B8 (see comments)
type 29 becomes
a standard type:
Available in PMC
C155 is available in Type 29. (Standard type in B8)
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DR FAIL. CASES > Incoming internal DR fail: MS access problem
5.1 Internal directed retry indicators Incoming internal DR - radio failure
MS serving cell target cell BSC MSCMEAS REP
-----------------------> MEASUREMENT RESULT------------------------------------------------------------------------>
CHANNEL ACTIVATION<----------------------------------
CHANNEL ACTIV ACK---------------------------------->
HO CMD HANDOVER COMMAND<----------------------- <------------------------------------------------------------------------ start T3103
C154SABM
-----------x T3103 expiry C152
MS Serving cell Target Cell BSC
HO CMD HANDOVER COMMAND<----------------------- <------------------------------------------------------------------------ start T3103
HANDOVER ACCESS C154------------------------------------------------------------->-------------------------------------------------------------> HO DETECTION
PHYSICAL INFORMATION ----------------------------------><------------------------------------------------------------- start T3105
SABM-------------------------------------------------------------> ESTABLISH INDICATION
UA ----------------------------------><------------------------------------------------------------- stop T3105
HANDOVER COMPLETE----------------------------------------------------- - - - -X
SABM-----------------------> ESTABLISH INDICATION
UA ------------------------------------------------------------------------><-----------------------
HO FAILURE HANDOVER FAILURE-----------------------> ------------------------------------------------------------------------> C152
Release of new channel
B8 (see comments)
Modified inB8 Becomes a standard type
All incoming internal DR failures due to radio problems are counted in the same counter C152. This counter is provided in Type 29 (this type becomes a standard type in B8).Both radio failures with Reversion Old SDCCH Channel and radio drop are counted together.
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DR FAIL. CASES > Incoming internal DR counters
5.1 Internal directed retry indicators Incoming internal DR - counters
Request MC153, C153
Congestion MC555, C155BSS Pb C153-C154-C155
Attempt C154
Radio (MS access problem) C152BSS Pb C154-C151-C152
Success MC151, C151
Execution
Preparation
INCOMING INTERNAL Directed Retry
REQUEST
CONGESTION
ATTEMPT
MS ACCESS PB
BSS PB
SUCCESS
BSS PB
Preparation Failure
Execution Failure
B8 (see comments)
Modified inB8
Type 29 counters becomes a standard (PMC)
All MCxxx counters are available in Type 110.All Cxxx counters are available in Type 29.Type 29 counters becomes a standard in B8.
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Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Specific indicators for densification techniques > Directed Retry > Incoming DR
DRIBCAR: efficiency of the incoming internal DR preparation = MC15A/MC153DRIBCNR: rate of incoming internal DR failures due to congestion = MC155/MC153DRIBEFR: efficiency of the incoming internal DR execution = MC717A/MC153
Other indicators can be computed from Type 110 counters:
DRIBSUR: global efficiency of incoming internal DR = MC717A/MC153 = MC151/MC153
from Type 29 counters: (Type 29 becomes a standard type in B8)
rate of incoming internal DR preparation failures due to BSS problems = (C153-C154-C155)/C153rate of incoming internal DR execution failures due to BSS problems = (C154-C151-C152)/C154rate of incoming internal DR execution failures due to radio access problems = C152/C154
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DR FAIL. CASES > Outgoing internal DR failures
Directed Retry procedure from the serving cell point of view
DR Preparation: congestion on the target cell (no specific counter on the serving cell)BSS problem (no specific counter)
DR Execution: radio problem: the MS reverts to the old channelradio problem: the MS dropsBSS problem (no specific counter)
5.1 Internal directed retry indicators Outgoing internal DR - failures
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DR FAIL. CASES > Outgoing internal DR fail: reversionold channel
C144A, C143A: Forced DR
C144C,C143E: Normal DR
5.1 Internal directed retry indicators Outgoing internal DR - radio failure ROC
MS Serving cell Target Cell BSC
HO CMD HANDOVER COMMAND<-------SDCCH----- <------------------------------------------------------------------------ start T3103
HANDOVER ACCESS MC144E----------------------TCH--------------------------------> C144A or C144C-------------------------------------------------------------> HO DETECTION
PHYSICAL INFORMATION ----------------------------------><------------------------------------------------------------- start T3105
SABM-------------------------------------------------------------> ESTABLISH INDICATION
UA ----------------------------------><------------------------------------------------------------- stop T3105
HANDOVER COMPLETE----------------------------------------------------- - - - -X
SABM-----------------------> ESTABLISH INDICATION
UA ------------------------------------------------------------------------><-----------------------
HO FAILURE HANDOVER FAILURE-----------------------> ------------------------------------------------------------------------> C143A or C143E
Release of new channel
B8 (see comments)
Type 29 counters becomes a standard in B8.
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DR FAIL. CASES > Outgoing internal DR fail: drop
M S serving ce ll ta rge t ce ll B S C M S C
H O C M D H A N D O V E R C O M M A N D<----------------------- <------------------------------------------------------------------------ start T 3103
M C 144ES A B M C 144A or C 144C
----------x
T 3103 exp iryC 143B o r C 143F------------------------>
A S S IG N M E N TFAILU R E
“R ad io in te rfacem essage fa ilu re ”
R elease o f S D C C H and TC H
5.1 Internal directed retry indicators Outgoing internal DR - radio failure drop
C144A,C143B: Forced DR
C144C,C143F: Normal DR
(See comments)B8
Counters C144A, C143B, C144C, C143F are type 29.Type 29 becomes a standard type in B8.
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DR FAIL. CASES > Outgoing internal DR counters
5.1 Internal directed retry indicators Outgoing internal DR - counters
Preparation Request MC144E, C144A+C144C
Any preparation failure (C144A+C144C) - (C145A+C145C)
Attempt C145A+C145C
Reversion old channel C143A+C143EDrop radio C143B+C143FBSS Pb (C145A+C145C) - (C143A+C143E+C143B+C143F)
Success MC142E, C142A+C142C
Execution
OUTGOING INTERNAL Directed Retry
REQUEST
CONGESTION
ATTEMPT
REVERSION OLD CHANNEL
DROP RADIO
BSS PB
SUCCESS
BSS PB
Preparation Failure
Execution Failure
(See comments)B8
Modified in B8
Detailed Pb available in standard type
B8: Pb details available in PMC (type 29 becoming standard)
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Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Specific indicators for densification techniques > Directed Retry > Outgoing DR
DROBSUR: global efficiency of outgoing internal DR = MC142E/MC144E
Other indicators can be computedfrom Type 29 counters:
efficiency of the outgoing internal DR preparation = (C145A+C145C)/(C144A+C144C)efficiency of the outgoing internal DR execution = (C142A+C142C)/(C145A+C145C)rate of outgoing internal DR execution failures due to BSS problems = [(C145A+C145C) - (C143A+C143E+C143B+C143F)] / (C145A+C145C)rate of outgoing internal DR execution failures due to radio problems with reversion old channel = (C143A+C143E) / (C145A+C145C)rate of outgoing internal DR execution failures due to radio problems with drop = (C143B+C143F) / (C145A+C145C)
In B8, as Type 29 becomes a standard, 10 new stored indicators based on type 29 counters are defined:
DRFOSUIN C142a NB_OUT_FORCED_IDR_SUCC DRFOSUEN C142b NB_OUT_FORCED_EDR_SUCCDROBSUIN C142c NB_OUT_NOR_IDR_SUCCDROMSUEN C142d NB_OUT_NOR_EDR_SUCCDRFORDIN C144a NB_OUT_FORCED_IDR_REQDRFORDEN C144b NB_OUT_FORCED_EDR_REQDROBRDIN C144c NB_OUT_NOR_IDR_REQDROMRDEN C144d NB_OUT_NOR_EDR_REQDROBRQIN C145c NB_OUT_NOR_IDR_ATPTDROMRQEN C145d NB_OUT_NOR_EDR_ATPT
Type 29 counters becomes a standard in B8.
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5.2 External directed retry indicators
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5.1 External directed retry indicators External DR - success
DR FAIL. CASES > External DR > successful case
MS serving_cell BSC MSC BSC target_cell MSTCH request queued <------ASSIGNT REQUEST-------
EDR condition met ------ HO_REQUIRED ---------->MC144F ----------CR (HO_REQUEST) -----> MC820
<--------- CC ------------------------ ---- CHANNEL_ACTIVATION ------><- CHANNEL_ACT_ACK-------------
<----- HO_REQUEST_ACK -------- Start T9113(HO_COMMAND) MC821
<------------------------- HO_COMMAND ------------------------------------------------------ <---- HO_ACCESS -----C145B+C145D Start T8 <---- HO_ACCESS -----
<------ HO_DETECTION--------------<-- HO_DETECTION -------------- --- PHYSICAL_INFO -->
<--- SABM ---------------<----- ESTABLISH_INDICATION ---- ----- UA -------------->
<----------- HO_COMPLETE ----------------------------------------<--- HO_COMPLETE --------------- Stop T9113
<---- CLEAR_COMMAND ------ MC642MC142F Cause : HO_SUCCESSFUL
Release of SDCCH Stop T8
The same external DR procedure leads to an incrementation of two sets of counters: incoming external HO counters for the target cell: MC820, MC821, etc.outgoing external DR counters for the serving cell: MC144F, MC142F, etc.
B8 (see comments)
The following DR counters are provided in Type 110for the serving cell:
MC144F: outgoing external DR requests,MC142F: outgoing external DR successes.
The following DR counters are provided in Type 29for the serving cell:
C144B: forced outgoing external DR requests,C144D: normal outgoing external DR requests,C145B: forced outgoing external DR attempts,C145D: normal outgoing external DR attempts,C142B: forced outgoing external DR successes,C142D: normal outgoing external DR successes.
As for internal DR, external DR Counters are available permanently (Type 29 becomes a standard type in B8)
No counter is provided for the target cell for an external DR since an incoming DR cannot always be discriminated from an incoming external HO. Therefore incoming external DRs are counted together with incoming external HOs in the related counters.
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5.1 External directed retry indicators Outgoing external DR - failures
DR FAIL. CASES > Outgoing external DR failures
Directed Retry procedure from the serving cell point of view
DR Preparation: congestion on the target cell (no specific counter on the serving cell)BSS problem (no specific counter)
DR Execution: radio problem: the MS reverts to the old channelradio problem: the MS dropsBSS problem (no specific counter)
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5.1 External directed retry indicators Outgoing external DR - radio failure ROC
DR FAIL. CASES > Outgoing external DR fail: reversionold channel
MS serving_cell BSC MSC BSC target_cell MSASSIGNT REQUEST---------------------> TCH request queued
EDR condition met ---- HO_REQUIRED ------->MC144F ----------CR (HO_REQUEST) ------------------->
<-------- CC --------------------------------------- - CHANNEL_ACT ----------><--- CHA_ACT_ACK --------
<----- HO_REQUEST_ACK----------------------- Start T9113 (HO-COMMAND) included
<-------------------------- HO_COMMAND ------------------------------------------------Start T8 X --- HO_ACCESS -----
C145B+C145D X ---- HO_ACCESS ---------- SABM --------><--- UA ------------- -- ESTABLISH_INDICATION->
----- HO_FAILURE (reversion to old channel) ------------------------------------------>C143C+C143G ----- CLEAR_COMMAND ---------------------->
Radio interface fail : Reversion to old channel Release of connection
C145B,C143C: Forced DR
C145D,C143G: Normal DR
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5.1 External directed retry indicators Outgoing external DR - radio failure drop
DR FAIL. CASES > Outgoing external DR fail: drop
MS serving_cell BSC MSC BSC target_cell MSASSIGNT REQUEST---------------------> TCH request queued
EDR condition met ---- HO_REQUIRED ------->MC144F ----------CR (HO_REQUEST) ------------------->
<-------- CC --------------------------------------- - CHANNEL_ACT ----------><--- CHA_ACT_ACK --------
<----- HO_REQUEST_ACK----------------------- Start T9113 (HO-COMMAND) included
<-------------------------- HO_COMMAND ------------------------------------------------Start T8 X --- HO_ACCESS -----
C145B+C145D X ---- HO_ACCESS ---------- SABM --- X----- SABM --- X
----- SABM --- X
T8 expiry ----- CLEAR_REQUEST ->C143D+C143H Radio interface message fail
Release of connection
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DR FAIL. CASES > Outgoing external DR counters
5.1 External directed retry indicators Outgoing external DR - counters
Preparation Request MC144F, C144B+C144D
Any preparation failure (C144B+C144D) - (C145B+C145D)
Attempt C145B+C145D
Reversion old channel C143C+C143GDrop radio C143D+C143HBSS Pb (C145+C145D) - (C143C+C143G+C143D+C143H)
Success MC142F, C142B+C142D
Execution
OUTGOING EXTERNAL Directed Retry
REQUEST
CONGESTION
ATTEMPT
REVERSION OLD CHANNEL
DROP RADIO
BSS PB
SUCCESS
BSS PB
Preparation Failure
Execution Failure
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Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Specific indicators for densification techniques > Directed Retry > Outgoing DR
DROMSUR: global efficiency of outgoing external DR = MC142F/MC144F
Other indicators can be computedfrom Type 29 counters:
efficiency of the outgoing internal DR preparation = (C145B+C145D)/(C144B+C144D)efficiency of the outgoing internal DR execution = (C142B+C142D)/(C145B+C145D)rate of outgoing internal DR execution failures due to BSS problems = [(C145B+C145D) - (C143C+C143G+C143D+C143H)] / (C145B+C145D)rate of outgoing internal DR execution failures due to radio problems with reversion old channel = (C143C+C143G) / (C145B+C145D)rate of outgoing internal DR execution failures due to radio problems with drop = (C143D+C143H) / (C145B+C145D)
Interesting indicator: TCQUSUDSR: rate of outgoing internal and external directed retries (forced + normal) successfully performed over all RTCH requests queued during normal assignment.
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6 Radio Measurement Statistics indicatorsSession presentation
Objective: to be able to describe the RMS indicators used for radio quality assessment of a TRX or cell and to use them in thedetection of some typical radio problemsProgram:
6.1 Radio Measurement Statistics objectives6.2 RMS implementation in the BSS6.3 RMS data6.4 Call quality statistics per TRX6.5 Radio quality statistics per TRX6.6 C/I statistics6.7 RMS indicators usage6.8 Additional information
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6.1 Radio Measurement Statistics objectives
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6.1 Radio Measurement Statistics objectivesRMS objectives
RMS objectivesAssess the quality of cell coverageAssess the radio link quality of a TRX / a cellAssess Carrier/Interference ratio of a TRX / a cellEstimate of the voice quality of a TRX / a cell
In order to: Optimize the neighborhood & frequency planningImprove the network coverageDetect faulty hardware components responsible for bad QoSHelp logical parameters fine tuning
The RMS feature provides statistics on Voice Quality. VQ data are now needed since the Call Drop rate is not sufficient to have a clear picture of the QoS in a network using Slow Frequency Hopping as a densification technique.
The RMS feature is a "plus" providing additional information to help radio engineer in their Fault detection and Network optimization tasks.
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6.1 Radio Measurement Statistics objectivesRMS objectives
RMS objectives
Provide Radio Measurement Statistics On all the network elements (all TRXs/cells)Permanently (RMS results available every day)
In order to Reduce the cost of Radio Network Optimization
Today's solutions for Radio Measurements are limited and very expensive: drive tests: provide a mobile user with the perception of the network but cannot be done on the whole network and on an
very day basis since:they are costly (tool+car+manpower).they need to be post-processed.they are limited to part of the network.they are available on the DownLink path only.
Abis interface traces: provide a complete Uplink and Downlink radio quality assessment of a cell but cannot be done on the whole network and on an every day basis since:
they are costly (protocol analyzer+manpower).they need to be post-processed.they are limited to a few cells at once per analyzer.
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6.2 RMS implementation in the BSS
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6.2 RMS implementation in the BSSRMS management
RMS results are reported permanently (once a day) by the BSS as new PM counters to the OMC-R
The RMS job is defined and activated on a per BSS basis
RMS job parameters are managed through RMS templates
RMS templates provide means to tune RMS parameters according to Cell Planning (cell profile, cell class)
The cell profile can be: micro, indoor, multiband, etc.The cell class can be: rural, urban, rural rapid (covering express railway), etc.Templates parameters define the intervals or Received level, Consecutive frame erasure, Radio link counter, Path balance, C/I …for which RMS counters are provided.
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6.2 RMS implementation in the BSSRMS configuration in the OMC-R
PM
RMS in binary filesTemplatesTemplates
RMS with OMC-R only
Templates are defined on the OMC-R
RMS results are retrieved once a day from the BSC
Binary files can be exported for post-processing
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6.2 RMS implementation in the BSSRMS configuration in RNO
RMS with OMC-R, NPA & RNOTemplates are defined on RNO
RMS results are retrieved once a day from the BSC
Binary files are transferred to NPA
RMS warnings on NPARMS QoS reports on RNORMS reports used in RNO
CheckQoS follow-upDiagnosisTuning
The Experience matrix can be generated for network planningExcel export is adapted to RMS
Benefit to whole RNO
Templates
PMComputeexperience
matrix
The cell profile can be: micro, indoor, multiband, etc.The cell class can be: rural, urban, rural rapid (covering express railway), etc.
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6.2 RMS implementation in the BSSRMS data flow
RNO defines and sends RMS templates to the OMC-RThe OMC-R activates an RMS campaignin the BSSRMS counters are transferred tothe OMCRMS counters are stored in NPA RMS indicators requested by RNORMS QOS reportdisplayedRNO calculates and exports the Experience matrix to RNP
1
2
3
4
5
A9156 RNO
NPA
RNP
OMC-R
BSS
Template
1
Experience matrix
7
PM4
7
2PM
3
6
5QOS
6
QOS
RNO is able to define the templates for the RMS jobs and helps in defining the MAFA frequencies.The tuning function of RNO defines a preferred RMS template depending on cell characteristics (type, class, capacity, etc.).RNO manages the frequencies to monitor through MAFA jobs depending on the neighborhood and the frequency bands.
RNO is a reference for RMS templates:16 templates stored in the RNO database,Reference values for templates available,Extra editor in the administration tool to modify templates:
a given value or a reference one.
NPANPA stores RMS jobs measurements, at Cell & TRX levels (15 days).NPA makes some consolidations (voice quality, averages, etc.).NPA manages some warnings on RMS indicators (path balance).
The Experience Matrix generated by RNO is an interference matrix computed from C/I measurements provided through RMS counters.
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In all this chapter
System parameters (user tunable or not) will always be written in BLUE BOLD FONT
Indicators and counters will be typedin ITALIC and SHADOW EFFECT FONTITALIC and SHADOW EFFECT FONT
The light blue font highlights important points
6.2 RMS implementation in the BSSRMS data presentation
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6.3 RMS data
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3 main RMS statistics types
Call quality statistics which qualify calls according to coverage/interference criteria
based on samples corresponding to measurement results averaged over a number of SACCH multi-frames
Radio statistics:
UL/DL level, UL/DL qual,
CFE
C/I statistics on neighboring freq/MAFA freq
last 2 statistics types based on samples corresponding to measurement results
6.3 RMS dataRMS data presentation
Annex 1
The first RMS Statistics type is based on calls.The two others are based on TRX/Cell.
additional informationMeasurement results, TRX, BS/MS max power
MAFA = Mobile Assisted Frequency Allocation is a GSM Phase 2+ feature allowing to request a mobile to measure and report through Extended Measurement Report message a C/I value for each frequency specified in an Extended Measurement Order message.
CFE: Consecutive Frame Erasure
1 SACCH multi-frame (SACCH mfr) corresponds to 4 consecutive sequences of 26 TDMA frames during which, in the uplink, a measurement report message is received by the BTS from the MS.
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6.4 Call quality statistics per TRX
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6.4 Call quality statistics per TRX
6.4.1 Generalities
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6.4.1 GeneralitiesVoice Quality problem
Suspecting a Voice Quality problemPercentage of Noisy calls
The fact that FER measurements are more reliable than RXQUAL ones to assess the VQ is even more true when using Slow Frequency Hopping. In this case RXQUAL values are not anymore correlated to Voice Quality as perceived by the end user.FER measurements are available for the uplink path only.These RMS indicators are provided on the RNO tool per TRX, per Cell:
Number of Noisy calls suffering from problem of bad coverage on the uplink pathRMVQULVN = RMS_call_noisy_UL_bad_coverageNumber of Noisy calls suffering from problem of interference on the uplink pathRMVQUIFN = RMS_call_noisy_UL_interferenceNumber of Noisy calls suffering from problem of interference and bad coverage considered together on the uplink pathRMVQUUKN = RMS_call_noisy_UL_undefinedRate of Noisy calls suffering from problems of interference or/and bad coverage on the uplink pathRMVQUNOR = RMS_call_noisy_UL_rate
Note: The 4 indicators above can be provided for Noisy calls suffering from VQ problems on the dowlink path.Rate of Noisy calls but with good FER measurements on the uplink pathRMVQFEGR = RMS_call_noisy_good_FER_rateRate of Noisy calls and also with bad FER measurements on the uplink pathRMVQFEBR = RMS_call_noisy_bad_FER_rateRate of calls with fair quality measurements but with bad FER measurements on the uplink pathRMVQFEAR = RMS_call_abnormal_bad_FER_rate
This last indicator can be used in order to tune the RMS VQ parameters used to characterize a call as Noisy.
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6.4.1 GeneralitiesCall Quality measurements
VQ_AVERAGE = 4 SACCH
AV_RXLEV_UL_VQ = (RxlevUL1+RxlevUL2+RxlevUL3+RxlevUL4) / 4AV_RXLEV_DL_VQ = (RxlevDL1+RxlevDL2+RxlevDL3+RxlevDL4) / 4
AV_RXQUAL_UL_VQ = (RxqualUL1+RxqualUL2+RxqualUL3+RxqualUL4) / 4AV_RXQUAL_DL_VQ = (RxqualDL1+RxqualDL2+RxqualDL3+RxqualDL4) / 4
AV_RXFER_UL_VQ = (Nb of speech frames wrongly decoded (BFI=1)/ Total nb of speech frames of the CQS)
Average level, quality and FER of a Call Quality Sample
SACCH meas.begin end
CALL
480ms
CQS1 CQS2 CQS3 CQS4 CQS5 CQS6 CQS7 CQS8 CQS9 CQS10 CQS11 CQS12 CQS13 CQS14 CQS15 CQS16 CQS375
1 measurement report⇔
1 SACCH mfr
CQS: Call Quality Sample
VQ_AVERAGE = Number of consecutive SACCH measurements from which the reported Level and Quality notes (UL and DL) are averaged. The resulting averages represent the level and quality of the corresponding Call Quality Sample, i.e. the portion of the call over which level and quality have been measured.
AV_RXLEV_xx_VQ = Average xx level measured over a Call Quality Sample (VQ_AVERAGE SACCH)
AV_RXQUAL_xx_VQ = Average xx quality measured over a Call Quality Sample (VQ_AVERAGE SACCH)
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6.4.1 GeneralitiesClassification of a CQS and Noisy Call identification
quality
Level (dBm)
7
0
-110 -47VQ_RXLEV
bad quality + good level
interfered CQS
bad quality & level
bad coverage CQS
VQ_RXQUAL
CQS
How to qualify the quality of a call? By looking at the repartition of the CQS!!:
VQ_RXLEV = radio level threshold to classify a CQS as bad coverage CQS.VQ_RXQUAL = radio quality threshold to classify a CQS as bad coverage CQS.VQ_INTF_THRESHOLD = Ratio of bad CQS (interference or bad coverage) to classify a Call as Noisy.A call is classify as:
Noisy xx Interference if Ratio of xx interfered CQS > VQ_INTF_THRESHOLD Noisy xx Coverage if Ratio of xx bad coverage CQS > VQ_INTF_THRESHOLDNoisy xx Undefined if Ratio of (xx interfered CQS + xx bad coverage CQS) > VQ_INTF_THRESHOLD
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6.4 Call quality statistics per TRX
6.4.2 Call quality parameters
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6.4.2 Call quality parametersRMS parameters
Call quality statisticsParameters used to determine if a call is noisy (according to
RXQUAL) and of bad voice quality (according to FER)
VQ_AVERAGE: averaging window size on measurement results to obtain Call Quality Samples (CQSs) (0 SACCH mfr to 128 Smf)
VQ_RXLEV: radio level threshold to specify a bad coverage CQS for noisy call statistics (-110 to -65 dBm)
VQ_RXQUAL: radio quality threshold to specify a bad quality (RXQUAL) CQS for noisy call statistics (0 to 7)
VQ_RXQUAL_VS_RXFER: radio quality threshold to specify a bad or a good quality CQS correlated to bad or good FER measurements for noisy call statistics (0 to 7)
All these parameters are included in the RMS PM Type 31 result files as RMS counters: RMSpc = PAR_VQ_AVERAGERMSpd = PAR_VQ_RXLEVRMSpe = PAR_VQ_RXQUALRMSpf = PAR_VQ_RXQUAL_VS_RXFER
Call Quality Sample (A CQS) will be qualified as “of bad level” if the Average RxLevel is lower than VQ_RXLEVA CQS will be qualified as “of bad quality” if the Average RxQuality is greater than VQ_RXQUAL
For FER counters, VQ_RXQUAL_VS_RXFER is used instead of VQ_RXQUAL to qualify a CQS as “of bad quality” if the Average FER is also checked (compared to VQ_xx_RXFER).
Note: For CQS, the averaging process is non-sliding.
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6.4.2 Call quality parametersRMS parameters
call quality statistics
VQ_GOOD_RXFER: Frame Erasure Rate threshold to specify a good FER CQS for noisy call statistics (0 to 20%)
VQ_BAD_RXFER: FER threshold to specify a bad FER CQS for noisy call statistics (0 to 20%)
VQ_INTF_THRESHOLD: Call Quality Samples threshold to characterize a call as noisy (0 to 100%)
VQ_FER_THRESHOLD: Call Quality Samples threshold to characterize a call as “of bad or good” voice quality (0 to 100%)
All these parameters are included in the RMS PM Type 31 result files as RMS counters: RMSpg = PAR_VQ_GOOD_RXFERRMSph = PAR_VQ_ BAD_RXFERRMSpi = PAR_VQ_INTF_THRESHOLDRMSpj = PAR_VQ_FER_THRESHOLD
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6.4 Call quality statistics per TRX
6.4.3 Call quality counters
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6.4.3 Call quality countersRMS counters (1/4)
VQ_NOISY_UL_INTERFERENCEVQ_NOISY_UL_INTERFERENCERMS10 = Number of calls suffering from interference problem on the uplink path
VQ_NOISY_UL_INTERFERENCEVQ_NOISY_UL_INTERFERENCE is incremented whenever a call verifies: 100*(INTERFERED_UL_SAMPLES / NUM_UL_SAMPLES) > VQ_INTF_THRESHOLD
with INTERFERED_UL_SAMPLES = nb of times where AV_RXQUAL_UL_VQ > VQ_RXQUALand AV_RXLEV_UL_VQ>VQ_RXLEV
Call Quality Statistics counters are related only to speech channels.
Considering:AV_RXQUAL_UL_VQ: average on VQ_AVERAGE measurements of RXQUAL_ULAV_RXLEV_UL_VQ: average on VQ_AVERAGE measurements of RXLEV_ULNUM_UL_SAMPLES: total number of averages calculated on UL measurements during the call on the considered TRX
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VQ_NOISY_UL_INTERFERENCEVQ_NOISY_UL_INTERFERENCERMS10 = Number of calls suffering from interference problem on the uplink pathVQ_NOISY_DL_INTERFERENCEVQ_NOISY_DL_INTERFERENCERMS11 = Number of calls suffering from interference problem on the downlink pathVQ_NOISY_UL_COVERAGEVQ_NOISY_UL_COVERAGERMS12 = Number of calls suffering from bad coverage problem on the uplink pathVQ_NOISY_DL_COVERAGEVQ_NOISY_DL_COVERAGERMS13 = Number of calls suffering from bad coverage problem on the downlink path
6.4.3 Call quality countersRMS counters (2/4)
RMS10 = VQ_NOISY_UL_INTERFERENCE is incremented whenever a call verifies: 100*(INTERFERED_UL_SAMPLES / NUM_UL_SAMPLES) > VQ_INTF_THRESHOLD
with INTERFERED_UL_SAMPLES = nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUAL and AV_RXLEV_UL_VQ>VQ_RXLEV
consideringAV_RXQUAL_UL_VQ: average on VQ_AVERAGE measurements of RXQUAL_ULAV_RXLEV_UL_VQ: average on VQ_AVERAGE measurements of RXLEV_ULNUM_UL_SAMPLES: total number of averages calculated on UL measurements during the call on the considered TRX
RMS11 = VQ_NOISY_DL_INTERFERENCE is incremented whenever a call verifies: 100*(INTERFERED_DL_SAMPLES / NUM_DL_SAMPLES) > VQ_INTF_THRESHOLD
with INTERFERED_DL_SAMPLES = nb of times when AV_RXQUAL_DL_VQ > VQ_RXQUAL and AV_RXLEV_DL_VQ>VQ_RXLEV
consideringAV_RXQUAL_DL_VQ: average on VQ_AVERAGE measurements of RXQUAL_DLAV_RXLEV_DL_VQ: average on VQ_AVERAGE measurements of RXLEV_DLNUM_DL_SAMPLES: total number of averages calculated on DL measurements during the call on the considered TRX
RMS12 = VQ_NOISY_UL_COVERAGE is incremented whenever a call verifies: 100*(BAD_COVERAGE_UL_SAMPLES / NUM_UL_SAMPLES) > VQ_INTF_THRESHOLD
with BAD_COVERAGE_UL_SAMPLES = nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUAL and AV_RXLEV_UL_VQ<=VQ_RXLEV
RMS13 = VQ_NOISY_DL_COVERAGE is incremented whenever a call verifies: 100*(BAD_COVERAGE_DL_SAMPLES / NUM_DL_SAMPLES) > VQ_INTF_THRESHOLD
with BAD_COVERAGE_DL_SAMPLES = nb of times when AV_RXQUAL_DL_VQ > VQ_RXQUAL and AV_RXLEV_DL_VQ<=VQ_RXLEV
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VQ_NOISY_UL_UNDEFINEDVQ_NOISY_UL_UNDEFINEDRMS14 = Number of calls suffering from both problems of interference and bad coverage on the uplink path
These calls are not counted in VQ_NOISY_UL_COVERAGE or VQ_NOISY_UL_INTERFERENCE
VQ_NOISY_DL_UNDEFINEDVQ_NOISY_DL_UNDEFINEDRMS15 = Number of calls suffering from both problems of interference and bad coverage on the downlink path
These calls are not counted in VQ_NOISY_DL_COVERAGE or VQ_NOISY_DL_INTERFERENCE
6.4.3 Call quality countersRMS counters (3/4)
RMS14 = VQ_NOISY_UL_UNDEFINED is incremented whenever a call verifies: 100*(BAD_COVERAGE_UL_SAMPLES / NUM_UL_SAMPLES) <= VQ_INTF_THRESHOLDand 100*(INTERFERED_UL_SAMPLES / NUM_UL_SAMPLES) <= VQ_INTF_THRESHOLDand 100*(BAD_QUALITY_UL_SAMPLES / NUM_UL_SAMPLES) > VQ_INTF_THRESHOLD
with BAD_COVERAGE_UL_SAMPLES = nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUAL and AV_RXLEV_UL_VQ<=VQ_RXLEVINTERFERED_UL_SAMPLES = nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUALand AV_RXLEV_UL_VQ > VQ_RXLEVBAD_QUALITY_UL_SAMPLES = INTERFERED_UL_SAMPLES + BAD_COVERAGE_UL_SAMPLES= nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUAL
RMS15 = VQ_NOISY_DL_UNDEFINED is incremented whenever a call verifies: 100*(BAD_COVERAGE_DL_SAMPLES / NUM_DL_SAMPLES) <= VQ_INTF_THRESHOLDand 100*(INTERFERED_DL_SAMPLES / NUM_DL_SAMPLES) <= VQ_INTF_THRESHOLDand 100*(BAD_QUALITY_DL_SAMPLES / NUM_DL_SAMPLES) > VQ_INTF_THRESHOLD
withBAD_COVERAGE_DL_SAMPLES = nb of times when AV_RXQUAL_DL_VQ > VQ_RXQUAL and AV_RXLEV_DL_VQ<=VQ_RXLEVINTERFERED_DL_SAMPLES = nb of times when AV_RXQUAL_DL_VQ > VQ_RXQUAL and AV_RXLEV_DL_VQ > VQ_RXLEVBAD_QUALITY_DL_SAMPLES = INTERFERED_DL_SAMPLES + BAD_COVERAGE_DL_SAMPLES= nb of times when AV_RXQUAL_DL_VQ > VQ_RXQUAL
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VQ_NOISY_UL_BAD_FERVQ_NOISY_UL_BAD_FERRMS16 = Number of calls with bad quality measurements and with bad FER measurements on the uplink path
Bad quality means bad RXQUAL whatever RXLEV is
VQ_NOISY_UL_GOOD_FERVQ_NOISY_UL_GOOD_FERRMS17 = Number of calls with bad quality measurements but with good FER measurements on the uplink path
VQ_ABNORMAL_BAD_FERVQ_ABNORMAL_BAD_FERRMS18 = Number of calls with fair quality measurements but with bad FER measurements on the uplink path
6.4.3 Call quality countersRMS counters (4/4)
RMS16 = VQ_NOISY_UL_BAD_FER is incremented whenever a call verifies: 100*(BAD_QUALITY_UL_SAMPLES / NUM_UL_SAMPLES) > VQ_INTF_THRESHOLDand 100*(BAD_QUAL_BAD_FER_UL_SAMPLES / BAD_QUALITY_UL_SAMPLES) > VQ_FER_THRESHOLD
withBAD_QUALITY_UL_SAMPLES = INTERFERED_UL_SAMPLES + BAD_COVERAGE_UL_SAMPLES= nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUALBAD_QUAL_BAD_FER_UL_SAMPLES = nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUAL_VS_RXFER and AV_RXFER_UL_VQ > VQ_BAD_RXFER
consideringAV_RXFER_UL_VQ: average on VQ_AVERAGE measurements of FER
RMS17 = VQ_NOISY_UL_GOOD_FER is incremented whenever a call verifies: 100*(BAD_QUALITY_UL_SAMPLES / NUM_UL_SAMPLES) > VQ_INTF_THRESHOLDand 100*(BAD_QUAL_GOOD_FER_UL_SAMPLES / BAD_QUALITY_UL_SAMPLES) > VQ_FER_THRESHOLD
with BAD_QUALITY_UL_SAMPLES = INTERFERED_UL_SAMPLES + BAD_COVERAGE_UL_SAMPLES= nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUALBAD_QUAL_GOOD_FER_UL_SAMPLES = nb of times when AV_RXQUAL_UL_VQ > VQ_RXQUAL_VS_RXFER and AV_RXFER_UL_VQ <= VQ_GOOD_RXFER
RMS18 = VQ_ABNORMAL_BAD_FER is incremented whenever a call verifies: 100*(FAIR_QUAL_BAD_FER_UL_SAMPLES / FAIR_QUALITY_UL_SAMPLES) > VQ_FER_THRESHOLD
withFAIR_QUALITY_UL_SAMPLES = nb of times when AV_RXQUAL_UL_VQ < VQ_RXQUAL_VS_RXFER FAIR_QUAL_BAD_FER_UL_SAMPLES = nb of times when AV_RXQUAL_UL_VQ<VQ_RXQUAL_VS_RXFER and AV_RXFER_UL_VQ>VQ_BAD_RXFER
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6 RADIO MEASUREMENT STATISTICS INDICATORS
6.5 Radio quality statistics per TRX
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6 RADIO MEASUREMENT STATISTICS INDICATORS
6.5 Radio quality statistics per TRX
6.5.1 Generalities
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6.5.1 Generalities TRX hardware problem
Suspecting a TRX hardware problem Average Path Balance
These RMS indicators are provided on the RNO tool per TRX, per Cell: Vector of the Number of Measurement Results per Path Balance bandRMPBV = RMS_PathBalance_sampleAverage Path Balance valueRMPBAN = RMS_PathBalance_avg
A Templates modification is needed to have more details.
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6.5.1 Generalities Vector counter
The real number of Measurement Results in which Path balance is in PATH BALANCE band j is equal to:
S(PATH BALANCE band j) x Max / 254 TPR_PATH_BALANCE(j) x MAX_PATH_BALANCE / 254
RMS7a=TPR_PATH_BALANCETPR_PATH_BALANCE RMS7b=MAX_PATH_BALANCEMAX_PATH_BALANCE
The vector counter system is used to provide: Path balance repartitionRadio Link counter (Consecutive Frame Erasure) repartitionC/I repartition
AMR FR/HR/DL/UL usage repartitionTA repartition (improved) B8
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6.5.1 Generalities Cell coverage problem
Suspecting a cell coverage problem
Distribution of samples per RxQual value and RxLev band
Distribution of samples per RxLev band
A coverage problem is observed when a significant amount of the traffic of a cell is suffering from both low level and bad quality (RxQual).To confirm the distribution of samples per RXLEV band, should also be considered to know the proportion of calls which are experiencing a low signal level.If a lot of samples of low level and bad quality are observed for only a sub-part of the TRXs (can be one only) then a BTS hardware problem or a problem on the aerials should be suspected.If all the TRXs are experiencing a lot of samples of low level and bad quality then a coverage problem shall be suspected. These RMS indicators are provided on the RNO tool per TRX, per Cell:
Matrix of Number of Measurement Results per DL RxQual value and per DL RxLev bandRMQLDSAM = RMS_DL_RxQuality_RxLevel_sampleVector of Percentage of Samples per DL RxLev bandRMQLDLVDV = RMS_DL_RxLevel_distribVector of Percentage of Samples per DL RxQual bandRMQLDQUDV = RMS_DL_RxQuality_distrib
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6.5.1 Generalities Matrix counter
TPR_RXQUAL_UL_RXLEV_ULTPR_RXQUAL_UL_RXLEV_UL TMR_RXQUAL_UL_RXLEV_ULTMR_RXQUAL_UL_RXLEV_UL
This counter RMS3a=TPR_RXQUAL_UL_RXLEV_UL is a matrix represented on the left side
This counter RMS3b=TMR_RXQUAL_UL_RXLEV_UL is a vectorrepresented on the right side
The real number of Measurement Results in which UL RxQual is equal to i and UL RxLev is in RXLEV band j, is equal to :
S(RXQUAL i, RXLEV band j) x Max j / 254
TPR_RXQUAL_UL_RXLEV_UL(i,j) x TMR_RXQUAL_UL_RXLEV_UL(j) / 254
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6 RADIO MEASUREMENT STATISTICS INDICATORS
6.5 Radio quality statistics per TRX
6.5.2 Radio quality parameters
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6.5.2 Radio quality parametersRMS parameters (1/3)
Radio quality statisticsparameters used to define intervals for RXLEV, Path Balance,
Radio Link Counter and Consecutive Frame Erasure statistics
MEAS_STAT_LEV1 to MEAS_STAT_LEV9: 9 thresholds on the received radio level value defining 10 RXLEV bands
-110 ≤ MEAS_STAT_LEV(i+1) ≤ MEAS_STAT_LEV(i) < -47 dBm
MEAS_STAT_PATH_BAL1 to MEAS_STAT_PATH_BAL9: 9 thresholds on the radio signal propagation loss difference between UL and DL defining 10 Path Balance bands
-110 < MEAS_STAT_PATH_BAL(i) ≤ MEAS_STAT_PATH_BAL(i+1) ≤ +110 dB
All these parameters are included in the RMS PM Type 31 result files as RMS counters: RMSpt5 = TAB_PAR_MEAS_LEV = Table of 9 parameters MEAS_STAT_LEViRMSpt4 = TAB_PAR_MEAS_PATH_BALANCE = Table of 9 parameters MEAS_STAT_PATH_BALi
The Path Balance is computed by the BTS from each Measurement Result message as the difference between: Path loss on the uplink: received level by the BTS - MS power levelPath loss on the downlink: received level by the MS - BS power level
where the BTS power level is computed as the BTS nominal power minus by the BTS power relative level.Therefore the Path balance is computed as follows:
Path Balance = (RXLEV_UL - MS_TXPWR) - (RXLEV_DL - [BTS_MAX_OUTPUT_POWER - abs(BS_TXPWR)])
where RXLEV_UL is the received signal levels measured by the BTS on the uplink path (in dBm).MS_TXPWR is the MS transmitted power converted by the BTS from the MS power level into dBm value according to the frequency band of the TRX.BS_TXPWR is the BTS transmitted power offset defined relatively to the maximum absolute output power of the BTS (negative value in dB).BTS_MAX_OUTPUT_POWER is the maximum power of the BTS after Combiner (in dBm).RXLEV_DL is the received signal levels measured by the MS on the downlink path (in dBm).
NOTE: Additional asymetric DL loss (external combiner) or UL gain (TMA) are not taken into account in the computation, so they must be considered when interpreting the RMS results.
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6.5.2 Radio quality parametersRMS parameters (2/3)
Radio quality statistics
TA_STAT: threshold on the timing advance value defining a priori the range of the cell (0 to 64 bits)
MEAS_STAT_S1 to MEAS_STAT_S9: 9 thresholds on the BTS Radio Link Counter S value defining 10 S bands
0 < MEAS_STAT_S(i) ≤ MEAS_STAT_S(i+1) ≤ 128 SACCH mfrS: counter managed by the BTS on a per call basisS = RADIOLINK_TIMEOUT_BS if good radio conditionsS decremented if bad radio conditionsThe BSS triggers a call drop when S = 0
All these parameters are included in the RMS PM Type 31 result files as RMS counters: RMSpt3 = TAB_PAR_MEAS_STAT_S = Table of 9 parameters MEAS_STAT_SiRMSpb = PAR_TA_STAT
Recall on the Uplink Radio Link Supervision procedure:
For each active dedicated radio channel in a cell, a counter “S” called Radio Link Counter is:
decremented by 1 by the BTS each time an SACCH measurement from the mobile cannot be decoded (SACCH_BFI=1).
incremented by 2 by the BTS each time a valid SACCH measurement is received from the mobile (SACCH_BFI=0).
Initial value of S = RADIOLINK_TIMEOUT_BS (cell parameter)
if S reaches N_BSTXPWR_M, a radio link recovery is triggered (BTS and MS power increased at their maximum).
if S reaches 0, a Radio Link Failure is triggered (channel drop).
Therefore the value of S gives a measure of the “quality” of the radio uplink.
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6.5.2 Radio quality parametersRMS parameters (3/3)
Radio quality statistics
MEAS_STAT_BFI1 to MEAS_STAT_BFI9: 9 thresholds on the number of consecutive speech frames with BFI set to 1 defining 10 BFI bands
0 < MEAS_STAT_BFI(i) ≤ MEAS_STAT_BFI(i+1) ≤ 25 speech frame
The BTS decodes 24 speech frames (sf) from 1 uplink SACCH multi-frame:
and 1 SACCH frame (or block)
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
SACCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
SACCH mfrTDMA: 4,616ms
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
SACCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
SACCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
SACCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
TCH
Sf 1 Sf 2 Sf 3 Sf 4 Sf 5 Sf 6 Sf 7 Sf 8 Sf 9 Sf 10 Sf 11 Sf 12 Sf 13 Sf 14 Sf 15 Sf 16 Sf 17 Sf 18 Sf 19 Sf 20 Sf 21 Sf 22 Sf 23 Sf 24
All these parameters are included in the RMS PM Type 31 result files as RMS counters: RMSpt2 = TAB_PAR_MEAS_STAT_BFI = Table of 9 parameters MEAS_STAT_BFIi
Consecutive Frame Erasure (CFE):
MEAS_STAT_BFIi parameters define 9 intervals of cumulated numbers of consecutive speech frames which have a Bad Frame Indicator value set to 1 (it means that the speech frame is considered as erroneous by the BTS).As the TC will erase speech frames for which a Bad Frame Indicator flag (BFI) has been set to the value 1 by the BTS, a BFI is used in the RMS counters description whereas the CFE is used in the RMS indicators defined in the RNO tool.
Note: By default, a BFI relates to a speech frame. When considering SACCH measurement, SACCH_BFI should be used.
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6 RADIO MEASUREMENT STATISTICS INDICATORS
6.5 Radio quality statistics per TRX
6.5.3 Radio quality counters
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6.5.3 Radio quality counters RMS counters (1/7)
Radio quality statistics TPR_RXQUAL_UL_RXLEV_ULTPR_RXQUAL_UL_RXLEV_UL: matrix of 8x10 elements UL(RXQUAL i, RXLEV band j), each element is made up of:
Samplesij: norm of number of measurement result samples in which UL RxQual is equal to i and UL RxLev is reported in RXLEV band jMS PWR levelij: average value of MS power (in dBm) from pwr levels reported in these samplesTiming Advanceij: average value of TAs reported in these samples
TMR_RXQUAL_UL_RXLEV_ULTMR_RXQUAL_UL_RXLEV_UL: vector of 10 elements ULRXQUAL(RXLEV band j), each element is made up of:
the maximum value of the 8 real numbers of samples in which UL RxQual is equal to i (i=0 to 7) and UL RxLev is reported in RXLEV band j
RMS3a=TPR_RXQUAL_UL_RXLEV_UL RMS3b=TMR_RXQUAL_UL_RXLEV_UL
The real number of Measurement Results in which UL RxQual is equal to i and UL RxLev is in RXLEV band j, is equal to: S(RXQUAL i, RXLEV band j) x Max j / 254 TPR_RXQUAL_UL_RXLEV_UL(i,j) x TMR_RXQUAL_UL_RXLEV_UL(j) / 254
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6.5.3 Radio quality counters RMS counters (2/7)
Radio quality statistics TPR_RXQUAL_DL_RXLEV_DLTPR_RXQUAL_DL_RXLEV_DL: matrix of 8x10 elements DL(RXQUAL i, RXLEV band j), each element is made up of:
Samplesij: norm of number of measurement result samples in which DL RxQual is equal to i and DL RxLev is reported in RXLEV band jBS PWR levelij: average value of BS power (in dBm) from pwr levels reported in these samplesTiming Advanceij: average value of TAs reported in these samples
TMR_RXQUAL_DL_RXLEV_DLTMR_RXQUAL_DL_RXLEV_DL: vector of 10 elements DLRXQUAL(RXLEV band j), each element is made up of:
the maximum value of the 8 real numbers of samples in which DL RxQual is equal to i (i=0 to 7) and DL RxLev is reported in RXLEV band j
RMS4a=TPR_RXQUAL_DL_RXLEV_DL RMS4b=TMR_RXQUAL_DL_RXLEV_DL
The real number of Measurement Results in which DL RxQual is equal to i and DL RxLev is in RXLEV band j, is equal to:S(RXQUAL i, RXLEV band j) x Max j / 254 TPR_RXQUAL_DL_RXLEV_DL(i,j) x TMR_RXQUAL_DL_RXLEV_DL(j) / 254
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6.5.3 Radio quality counters RMS counters (3/7)
Radio quality statistics
TPR_PATH_BALANCETPR_PATH_BALANCE: vector of 10 elements UL/DL(PATH BALANCE band j), each element is made up of:
the norm of number of measurement result samples for which the computed Path Balance is in PATH BALANCE band j
MAX_PATH_BALANCEMAX_PATH_BALANCE: the maximum value of the 10 real numbers of samples for which the computed Path Balance is in PATH BALANCE band j (j=1 to 10)
RMS7a=TPR_PATH_BALANCE RMS7b=MAX_PATH_BALANCE
The real number of Measurement Results in which Path balance is in PATH BALANCE band j, is equal to: S(PATH BALANCE band j) x Max / 254 TPR_PATH_BALANCE(j) x MAX_PATH_BALANCE / 254
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6.5.3 Radio quality counters RMS counters (4/7)
Radio quality statistics
TPR_RADIO_LINKTPR_RADIO_LINK: vector of 10 elements UL(S band j), each element is made up of:
the norm of number of measurement result samples for which the Uplink Radio Link Counter is in S band j
MAX_RADIO_LINKMAX_RADIO_LINK: the maximum value of the 10 real numbers of samples for which the Uplink Radio Link Counter is in S band j (j=1 to 10)
RMS6a=TPR_RADIO_LINK RMS6b=MAX_RADIO_LINK
The real number of Measurement Results in which Uplink Radio Link Counter is in S band j, is equal to: S(S band j) x Max / 254 TPR_RADIO_LINK(j) x MAX_RADIO_LINK / 254
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6.5.3 Radio quality counters RMS counters (5/7)
Radio quality statistics
TPR_BFI_RXLEV_ULTPR_BFI_RXLEV_UL: matrix of 10x10 elements UL(BFI i, RXLEV band j), each element is made up of:
the norm of number of SACCH multi-frames in which the number of consecutive speech frames with BFIs set to 1 is in BFI band i and UL RxLev reported in the corresponding measurement results is in RXLEV band j
TMR_BFI_RXLEV_ULTMR_BFI_RXLEV_UL: vector of 10 elements ULBFI(RXLEV band j), each element is made up of:
the maximum value of the 10 real numbers of SACCH multi-frames in which the number of consecutive speech frames with BFIs set to 1 is in BFI band i (i=0 to 9) and UL RxLevreported in the corresponding measurement results is in RXLEV band j
RMS5a=TPR_BFI_RXLEV_UL RMS5b= TPM_BFI_RXLEV_UL
The real number of Measurement Results in which the number of consecutive speech frames with BFIs set to 1 is in BFI band i and UL RxLev is in RXLEV band j, is equal to: S(BFI i, RXLEV band j) x Max j / 254 TPR_BFI_RXLEV_UL(i,j) x TMR_BFI_RXLEV_UL(j) / 254
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6.5.3 Radio quality counters RMS counters (6/7)
Radio quality statistics
The BTS increments the BFI (or CFE) counter as soon as consecutive speech frames cannot be decoded
isolated speech frames with BFIs set to 1 are not countedsequences of not decoded speech frames are cumulated
SACCH mfr
CFE0 0 0 0 0 0 0 0 1 2 3 3 3 3 4 4 4 5 6 6 6 6 6 7 7
BFI
Sf 1 Sf 2 Sf 3 Sf 4 Sf 5 Sf 6 Sf 7 Sf 8 Sf 9 Sf 10 Sf 11 Sf 12 Sf 13 Sf 14 Sf 15 Sf 16 Sf 17 Sf 18 Sf 19 Sf 20 Sf 21 Sf 22 Sf 23 Sf 24 SACCH f.
0 0 0 1 0 0 0 1 1 1 1 0 0 1 1 0 1 1 1 0 1 0 1 1 0
RxLev UL10 11 9 12 12 11 11 10 3 2 0 8 9 5 3 7 2 1 2 7 3 8 2 3 5
Av_RxLev_UL= - 110 + INT[(10+11+9+12+12+11+11+10+3+2+0+8+9+5+3+7+2+1+2+7+3+8+2+3+5)/25]= -104 dBm
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6.5.3 Radio quality counters RMS counters (7/7)
Radio quality statistics
PERC_TA_GT_TA_STATPERC_TA_GT_TA_STAT: percentage of measurement results reported with a Timing Advance value > TA_STAT parameter
MAX_TAMAX_TA: maximum value of Timing Advance among all TA values reported in the measurement results used for RMS
Corresponding RMS counter numbers: RMS36 = PERC_TA_GT_TA_STATRMS37 = MAX_TA
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6 RADIO MEASUREMENT STATISTICS INDICATORS
6.6 C/I statistics
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6 RADIO MEASUREMENT STATISTICS INDICATORS
6.6 C/I statistics
6.6.1 C/I Generalities
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6.6.1 C/I Generalities Storage and computation methods
In order to provide an efficient storage, the "vector method" already seen for previous RMS statistics will be used for C/I counters
C/I expressed in logarithmic scale (dB)(C/I)dB = CdBm - IdBm = 10 log10(CmW) - 10 log10(ImW)
= 10 log10(C/I)mW
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6 RADIO MEASUREMENT STATISTICS INDICATORS
6.6 C/I statistics
6.6.2 C/I Parameters
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6.6.2 C/I parameters RMS parameters
C/I statistics parameters defining intervals for C/I statistics
MEAS_STAT_C_I1 to MEAS_STAT_C_I9: 9 thresholds on the Carrier/Interference ratio defining 10 C/I bands
-63 < MEAS_STAT_C_I(i) ≤ MEAS_STAT_C_I(i+1) ≤ +63 dB
EN_BALANCED_CI: boolean indicating if the C/I value reported by the BTS is balanced or not
NEIGB_CELL_ID: (BCCH,BSIC) of the neighboring cell for which the C/I statistics per neighboring cell are reported
Frequency ARFCN: ARFCN of the frequency for which the C/I statistics per MAFA frequency are reported Annex 2
All these parameters are included in the RMS PM Type 31 result files as RMS counters: RMSpt1 = TAB_PAR_MEAS_STAT_C/I = Table of 9 parameters MEAS_STAT_C_IiRMSpa = PAR_EN_BALANCED_CIRMSp80 = NEIGB_CELL_IDRMSp90 = Frequency ARFCN
For C/I statistics per neighboring cell: The C/I ratio is computed by the BTS from each Measurement Result message as the difference between:
the downlink signal level measured by the MS on the serving TCH channel = C (dBm)the downlink signal level measured by the MS on the neighboring BCCH channel = I (dBm)
Two computation formulae may be used taking into account a corrective factor in case DL Power Control is used in the serving cell:
If EN_BALANCED_CI = Falsethen C/I (dB) = RXLEV_DL (dBm) - RXLEV_NCELL (dBm) else C/I (dB) = RXLEV_DL + abs(BS_TXPWR - BS_TXPWR_MAX) - RXLEV_NCELL
The expression (RXLEV_DL + abs(BS_TXPWR - BS_TXPWR_MAX)) can be seen as a kind of normalized received power level in case the BTS would always have used the maximum allowed transmit power level on the TCH channel.
For C/I statistics per MAFA frequency: The C/I ratio is computed by the BTS from each Extended Measurement Report message in the same way as the C/I ratio per neighboring cell.
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6.6 C/I statistics
6.6.3 C/I Counters
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6.6.3 C/I counters RMS counters
C/I statistics per neighboring cell
TPR_CINTPR_CIN: vector of 10 elements C/In(C/I band j), each element is made up of:
the norm of number of measurement result samples for which the computed Carrier/Interference ratio is in C/I band j
MR_CINMR_CIN: maximum value of the 10 real numbers of samples for which the computed Carrier/Interference ratio is in C/I band j (j=1 to10)
TPR_CINTPR_CIN and MR_CINMR_CIN counters are provided for up to 42 neighboring cells
RMS8a=TPR_CIN RMS8b=TMR_CIN
For each reported neighboring cell (BCCH/BSIC): the Real number of Measurement Results for which the computed Carrier/Interference ratio is in C/I band j, is equal to: S(C/I band j) x Max / 254 TPR_CIN(j) x TMR_CIN / 254
For each declared/reported neighboring cell, the identification of this cell shall be done as follows:BCCH_ARFCN and BSIC. The BCCH ARFCN is deduced in the BTS from the BCCH frequency index and the list of indexed frequencies (sent by the BSC at the beginning of the RMS job). The RMS results report shall include all reported neighboring cells. Some of them correspond to known cells at the BSS level (i.e. their BSIC matches what is expected at the BSC side) but some of them are unknown (their BSIC does not match). However, the BTS will handle the same for both cases.The list of frequencies to be monitored by the mobile is limited to 33 but due to ‘resurgence’, the same frequency can be reported several times (each time with a different BSIC). If the number of reported cells is above the dimensioning limit (maximum 42 CI-vectors are reported), the extra new reported frequencies are not taken into account anymore. In the result report, the related overflow indicator is set accordingly.
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6.6.3 C/I counters RMS counters
C/I statistics per MAFA frequency
TPR_CIFTPR_CIF: vector of 10 elements C/If(C/I band j), each element is made up of:
the norm of number of Extended Measurement Results samples for which the computed Carrier/Interference ratio is in C/I band j
MR_CIFMR_CIF: maximum value of the 10 real numbers of samples for which the computed Carrier/Interference ratio is in C/I band j (j=1 to10)
TPR_CIFTPR_CIF and MR_CIFMR_CIF counters are provided for up to 21 frequencies (serving cell BCCH + 20 MAFA frequencies)
RMS9a=TPR_CIF RMS9b=TMR_CIF
For each reported MAFA frequency (ARFCN): the Real number of Extended Measurement Results for which the computed Carrier/Interference ratio is in C/I band j, is equal to: S(C/I band j) x Max / 254 TPR_CIF(j) x TMR_CIF / 254
For each reported MAFA frequency, the identification of this frequency shall be done as follows: Frequency ARFCN .
In case of a frequency reported via an Extended Measurement Reporting, no BSIC is required: the frequency ARFCN is not directly linked to a BCCH frequency. The ARFCN value of the frequency is deduced in the BTS from the place of the measurement in the EXTENDED_ MEASUREMENT_REPORT and from the ordered frequency list in the Extended Measurement Order. This list is built by the OMC-R and passed via BSC to BTS at the beginning of the RMS job.
The maximum number of frequencies in the order (EMO) is the maximum defined in GSM (=21). Hence the maximum in the report is 21 also. When in exceptional cases, more results are available (future expansion in GSM), only the first 21 are reported.
The BCCH frequency of the serving cell shall always be part of the EMO-frequency list.
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6.7 RMS indicators usage
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6.7 RMS indicators usage Voice quality problem
Suspecting a Voice Quality problem RMS indicatorsPercentage of Noisy calls
FER is more reliable than RXQUAL to assess VQNoisy calls indicators can also be computed from FER measurements
Noisy calls with bad or good FERCalls not detected as noisy but with bad FER
Voice Quality indicators are based on calls
Noisy calls are associated with a cause of
bad coverage, interference or with an undefined cause
The fact that FER measurements are more reliable than RXQUAL ones to assess the VQ is even more true when using Slow Frequency Hopping. In this case, RXQUAL values are not anymore correlated to Voice Quality as perceived by the end user.FER measurements are available for the uplink path only.These RMS indicators are provided on the RNO tool per TRX, per Cell:
Number of Noisy calls suffering from problem of bad coverage on the uplink pathRMVQULVN = RMS_call_noisy_UL_bad_coverageNumber of Noisy calls suffering from problem of interference on the uplink pathRMVQUIFN = RMS_call_noisy_UL_interferenceNumber of Noisy calls suffering from problem of interference and bad coverage considered together on the uplink pathRMVQUUKN = RMS_call_noisy_UL_undefinedRate of Noisy calls suffering from problems of interference or/and bad coverage on the uplink pathRMVQUNOR = RMS_call_noisy_UL_rate
Note: The 4 indicators above can be provided for Noisy calls suffering of VQ problems on the dowlink path.Rate of Noisy calls but with good FER measurements on the uplink pathRMVQFEGR = RMS_call_noisy_good_FER_rateRate of Noisy calls and also with bad FER measurements on the uplink pathRMVQFEBR = RMS_call_noisy_bad_FER_rateRate of calls with fair quality measurements but with bad FER measurements on the uplink pathRMVQFEAR = RMS_call_abnormal_bad_FER_rate
This last indicator can be used in order to tune the RMS VQ parameters used to characterize a call as Noisy.
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6.7 RMS indicators usage Cell coverage problem
Suspecting a cell coverage problem
Distribution of samples per RxQual value and RxLev band
Distribution of samples per RxLev band
Not acceptablecoverage limit: Too low level Too bad quality
A coverage problem is observed when a significant amount of the traffic of a cell is suffering from both low level and bad quality (RxQual).To confirm the distribution of samples per RXLEV band, should be also considered to know the proportion of calls which are experiencing a low signal level.If a lot of samples of low level and bad quality are observed for only a sub-part of the TRXs (can be one only) then a BTS hardware problem or a problem on the aerials should be suspected.If all the TRXs are experiencing a lot of samples of low level and bad quality then a coverage problem shall be suspected. These RMS indicators are provided on the RNO tool per TRX, per Cell:
Matrix of Number of Measurement Results per DL RxQual value and per DL RxLev bandRMQLDSAM = RMS_DL_RxQuality_RxLevel_sampleVector of Percentage of Samples per DL RxLev bandRMQLDLVDV = RMS_DL_RxLevel_distribVector of Percentage of Samples per DL RxQual bandRMQLDQUDV = RMS_DL_RxQuality_distrib
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6.7 RMS indicators usage Cell coverage problem
Suspecting a cell coverage problem RMS indicatorsAverage TA values per RxQual value and RxLev band
Not acceptablecoverage limit: Too low level Too bad quality
Acceptable coverage limit: Sufficient level and good quality
% of TA value over TA threshold has also to be considered
In order to know if the coverage problem is due to a big amount of traffic at the cell border or rather to indoor calls, the average TA value per RXQUAL value and RXLEV band as well as the Percentage of TA values over the TA threshold should be observed.
Matrix of Average TA per UL RxQual value and per UL RxLev bandRMQLUTAM = RMS_UL_RxQuality_RxLevel_TimingAdvanceRate of Measurements Results whose TA is greater than the TA thresholdRMTAGTR = RMS_TimingAdvance_greater_threshold_rateMaximum TA value of all values reported in Measurement Results RMTAMXN = RMS_TimingAdvance_max
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6.7 RMS indicators usage RMS Exercise 1
Give the list of the RMS counters and parameters used in the 3 previous slides
Time allowed: 10 minutes
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6.7 RMS indicators usage RMS exercise 2
What does this graph represent?Interpret this graph
Time allowed: 10 minutes
These RMS indicators are provided on the RNO tool per TRX, per Cell: Vector of the Number of Measurement Results per Path Balance bandRMPBV = RMS_PathBalance_sampleAverage Path Balance valueRMPBAN = RMS_PathBalance_avg
A fair average Path Balance at Cell level can hide a bad value for one TRX.
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6.7 RMS indicators usage Cell interference problem
Suspecting a cell interference problemNumber of samples per RxQual value and RxLev band
Average DL RxQuality = 0.34
RMS results show no problemof radio link quality in this cell
Average RxQual value per RxLevband has also to be considered
These RMS indicators are provided on the RNO tool per TRX, per Cell: Matrix of Number of Measurement Results per DL RxQual value and per DL RxLev bandRMQLDSAM = RMS_DL_RxQuality_RxLevel_sampleVector of Average DL RxQual per RxLev bandRMQLDQUAV = RMS_DL_RxQuality_avg_per_RxLevelAverage DL RxQualityRMQLDQUAN = RMS_DL_RxQuality_avg
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6.7 RMS indicators usage RMS exercise 3
Average RxQual value per RxLevband has also to be considered
Average DL RxQuality = 2.81
Time allowed: 10 minutes
Interpret this graph
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6.7 RMS indicators usage RMS exercise 4
Time allowed: 15 minutes Interpret this graph
These RMS indicators are provided on the RNO tool per TRX, per Cell: Matrix of the Number of Measurements Results per CFE band (or BFI band) and per UL RxLev band RMFEM = RMS_UL_ConsecutiveFrameErasure_RxLevel_sampleVector of the Average number of Consecutive Frame Erasure per UL RxLev bandRMFEBFAV = RMS_UL_ConsecutiveFrameErasure_avg_per_RxLevelVector of the Average UL RxQual per RxLev bandRMQLUQUAV = RMS_UL_RxQuality_avg_per_RxLevel
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6.7 RMS indicators usage RMS exercise 5
Interpret this graph
Time allowed: 10 minutes
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6.8 Additional information
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6.8 Additional information RMS counters (1/3)
Counters used for: post-processing the RMS results provided per TRX
TOT_SEIZ_TCH: number of TCH channels successfully seized by the MSTOT_MEAS: number of Measurement Results used for RMSTOT_MEAS_L1INFO_NOL3INFO: number of Measurement Results used for RMS statistics for which Layer 1 info is present but Layer 3 is missingTOT_MEAS_DTX_UL: number of Measurement Results used for RMS statistics for which DTX UL was used in the corresponding SACCH mfrTOT_MEAS_DTX_DL: number of Measurement Results used for RMS statistics for which DTX DL was used in the corresponding SACCH mfrTOT_EMR: number of Extended Measurement Results used for RMS statistics
Corresponding RMS counter numbers: RMS31 = TOT_SEIZ_TCHRMS32 = TOT_MEASRMS33 = TOT_MEAS_L1INFO_NOL3INFORMS34 = TOT_MEAS_DTX_ULRMS35 = TOT_MEAS_DTX_DLRMS38 = TOT_EMR
Note: If during an SACCH measurement, DTX is applied on the uplink path (DTX_UL =1), the counters on consecutive BFIs(RMS5a, RMS5b) shall not be incremented and the corresponding measurement result shall not be taken into account in these RMS counters.If during an SACCH measurement, DTX is applied on the uplink path (DTX_UL = 1), the FER measurement does not take place.
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6.8 Additional information RMS counters (2/3)
Counters used for: interpreting the RMS results provided per TRX
TRE_BAND: frequency band of the TRX BS_TX_PWRMAX: effective maximum output power of the BTS on any channel of the TRX as an offset from the maximum absolute outputpower (in dB)MS_TX_PWRMAX: effective maximum output power of the MS using any channel of the TRX (in dBm)IND_TRE_OVERLOAD: boolean indicating if the TRE handling the TRX function has experienced a data loss due to a processor overload during the RMS campaignIND_RMS_RESTARTED: boolean indicating if the RMS job has been restarted on the concerned TRE during the RMS campaign due to a modification of the RMS parameter values or a TRE reset
Corresponding RMS counter numbers: RMS20 = TRE_BANDRMSpw1 = BS_TX_PWRMAXRMSpw2 = MS_TX_PWRMAXRMS21 = IND_TRE_OVERLOADRMS22 = IND_RMS_RESTARTED
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6.8 Additional information RMS counters (3/3)
Counters used for: interpreting the C/I RMS results provided per TRX
IND_CI_PARTIAL_OBSERVATION: made up of 2 booleans indicating that:
C/In computation has been restarted due to the modification of the list of neighboring cells during the RMS campaign
C/If computation has been restarted due to the modification of the list of MAFA frequencies during the RMS campaign
IND_CI_OVERFLOW: boolean indicating that the upper limit of 42 C/I sets of counters has been exceeded (each new reported neighboring cell (BCCH, BSIC) has not been taken into account in RMS statistics)
Corresponding RMS counter numbers: RMS23 = IND_CI_PARTIAL_OBSERVATIONRMS24 = IND_CI_OVERFLOW
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7 Traffic indicatorsSession presentation
Objective: to be able to describe BSS traffic indicators used for radio resource dimensioning
Program: 7.1 Call mix definition7.2 Basis of traffic theory7.3 TCH resource allocation indicators7.4 Resource occupancy indicators7.5 Traffic model indicators7.6 Preemption indicators
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7.1 Call mix definition
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7.1 Call mix definitionGSM transactions
In a GSM Network, there are a lot of different transactions : location update: periodic, new updating, ~imsi_attach, ~imsi_detachHand Over (intra-cell, internal, external, etc.)SMS (Short Message Service, originating or terminating)SS (Supplementary Service)Pagingand also Originating and Terminating calls, etc.and so on (data, SMS-CB, etc.)
In a GSM network, telecom procedures involve different kinds of resource in the BSS: Location Update: RACH, AGCH, SDCCH and SCCPOriginated Call: RACH, AGCH, SDCCH, TCH and SCCPTerminated Call: PCH, RACH, AGCH, SDCCH, TCH and SCCPHandover: TCH, SCCP
etc.
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7.1 Call mix definitionGSM transactions
One can quantify the number of each transaction per hour
For example, for one cell, one can measure: 900 calls (600 TCs, 300 OCs)3600 LUs (any type)1350 HOs (900 internal, 450 external)100 SMSs5 SSs6000 pagings
With the following characteristicsmean call duration on TCH: 50 secondsmean SDCCH duration: 3.2 seconds
A Call mix can be defined through: data given by the Marketing team.data measured from the living network.
Before network design, a Call Mix is assessed from Marketing Studies or observations from other networks.After commercial opening, a Call Mix is measured from the real traffic.
Caution: Call duration means here TCH duration. The duration of a call from call setup to call release is an NSS notion.
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7.1 Call mix definitionExample
Set of such measurements is called "call mix"sometimes improperly called "traffic model"
Usually presented in the following way: Calls /hour : 900 (2/3 TC)LU/call : 4HO/Call : 1.5 (2/3 internal, 1/3 external)SMS/Call : 11 %SS/call : 5 %Paging/hour : 6000mean call duration on TCH : 90 secondsmean SDCCH duration : 4.2 seconds
After commercial opening, the number of calls per hour will be measured from traffic counters.Usually the Marketing team will provide:
on a per geographical area or morphostructure basis: the traffic per km2 (in Erlang),the traffic per subscriber (in mErl).
the number of calls per hour.
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7.1 Call mix definitionVariation
A call mix is varying a lot: from a cell to another
TCH traffic (induced by subscribers)number of LU/call and HO/call (induced by network design)
from one hour to anotherby default: busy hour
from one year to anothermodification of traffic intensity and distribution
On some university campus, an SMS/call is often higher than the average.
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7.1 Call mix definitionUsage
Interests of call mix: Input data for dimensioningCell and BSC resources dimensioning
RTCH, SDCCH, TTCH, BTS, BSC and MSC CPU processor
Some examples of "risky" call mix too many LU/Calls: SDCCH congestion, TCU load, MSC overloadtoo many HO/calls: speech quality, call drop, DTC loadtoo many calls: TCH congestiontoo many pagings: DTC processor load, PCH congestion
A Call Mix will be used at Radio Network Design and Radio Network Planning stages in order to define the capacity of the network(number of sites, TRXs per site, radio configuration, number of Abis-PCM, A-PCM).When the network is in operation, a Call Mix is used in order to anticipate network extension or re-dimensioning.
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7.1 Call mix definitionAdvises
Some advises
LU/CALL: 1 is "good", 2 is "bad", 4 and more can be dangerous
beware of the Network or BSC averages which can hide critical cells
HO/Call: less critical (1 is good)2 or 3 is not a direct problem, but the trend has to be monitored
Call: to be checked with an Erlang table (seen in next session)
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7.1 Call mix definitionExercise
Training exercise
Compute the call mix of a cell according the following information256 call/hour1300 LU/hour450 HO/hour
Is it complete? What are the risks of such a call mix?
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7.2 Basis of traffic theory
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7.2 Basis of traffic theory Erlang definition
ERLANG: unit used to quantify traffic (intensity)T = (resource usage duration) / (total observation duration) [ERLANG]Example:
For 1 TCH, observed during 1 hourone can observe 2 calls: 1 of 80 seconds and 1 of 100 seconds
T = (80+100)/3600 = 0.05 ERLANG
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7.2 Basis of traffic theory Erlang from call mix
CALL MIX => ERLANGCall mix example:
350 call/hour3 LU/callTCH mean call duration: 85 secondsSDCCH mean duration: 4.5 seconds
Computation of Carried Erlang TCH = (350*85)/3600: 8.26 ERLANGSSDCCH = [ (350+350*3) * 4.5 ] / 3600 = 1.75 Erlang
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7.2 Basis of traffic theory Erlang B law
In a Telecom system, the call arrival frequency is ruled by the POISSON lawErlang B law: relationship between:
offered trafficnumber of resourcesblocking rate
call/second
0
1
2
3
4
5
6
7
8
9
10
1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93 97
call/second
0
1
2
3
4
5
6
7
8
9
10
1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93 97
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The call request arrival rate (and leaving) is not stablenumber of resources = average number of requests * mean durationis sometimes not sufficient => probability of blocking
=> Erlang B law Pblock: blocking probabilityN: number of resourcesE: offered traffic [Erlang]
Good approximation when the blocking rateis low (< 5 %)
7.2 Basis of traffic theory Erlang B law
Telecom system
Offered Carried
Rejected
P b lo ck N
k
N
k
k
N
EE
=
=∑!
!0
The Erlang B law is not fully accurate since it assumes that: the subscriber requests are not queued which is not always the case (TCH queued in the BSC),the subscriber does not repeat his call request if rejected, which is almost never the case.
Therefore the higher the blocking rate the worse is the approximation of the Erlang B law.
The Erlang C law modelizes better the TCH resource usage of the BSS since it takes into account the queuing. However the Erlang C law is never used since parameters like size of the queue and time spent into the queue have to be tuned.
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7.2 Basis of traffic theory Erlang B formulae
There are two different ways to use this law
Using Abacus
Using SW (here Excel)Pblock = f (T, Nc)Offered = f (Nc, Pblock)Channels = f (T, Pblock)
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7.2 Basis of traffic theory Erlang B abacus
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Example: 1 cell with 8 TRXs, with 60 TCH channels
Maximum blocking rate: 2 %
Erlang law: 50 Offered Erlang
83 % of TCH resources used to reach 2% of blocking
7.2 Basis of traffic theory Erlang B example
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But be careful, the Erlang B law is not linear:
In B4, we use for example a combined BCCH with a micro BTS.
4 SDCCHs, Pblock = 2% => T = 1.1 E25% resources used to reach 2% blocking
In B5, if we decide to provide SMSCB (Cell Broadcast information), 1 SDCCH stolen for CBCH
3 SDCCH, Pblock = 2% => T = 0.6 E25 % resources less => 50 % Traffic less!!
7.2 Basis of traffic theory Non linearity of Erlang B
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Given an Offered traffic, compute the number of TRXs (and SDCCH) needed to carry it => What is the accepted blocking rate?
default blocking rateRTCH: 2 %SDCCH: 0.5 %(for BSC TTCH: 0.1%)
7.2 Basis of traffic theory Cell dimensioning
The Erlang B law is less relevant for SDCCH dimensioning since SDCCH traffic cannot be modelized like TCH traffic. Indeed SDCCH is not only due to subscriber traffic but also to Location Update, SMS, IMSI Detach, etc.For SDCCH dimensioning, some typical configurations are used according to the number of TRXs in the cell, the LA plan.
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Cell dimensioning from call mix (bid, architecture)
to handle an offered traffic of 12 Erlangs (RTCH), compute the number of channels, then the number of TRXs
Channels (12;2%) = 19
example: 3 TRXs, 21 TCHs, 1 BCCH, 2 SDCCHs/8
7.2 Basis of traffic theory Dimensioning "a priori"
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Cell dimensioning from measurement (re-planning)
one is measuring a traffic of 15 Erlangs, with a blocking rate of 10 %how to dimension the cell?
Offered traffic = 15 / (1-10%) = 16.7 Erlangs!!!!Channels (16.7;2%) -> 25 TCHs -> 4 TRXs needed
7.2 Basis of traffic theory Dimensioning "a posteriori"
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Forecast traffic
traffic forecasting must be computed according to the offered traffic
not directly on the measured trafficIn order to plan the necessary actions soon enough, one must compute regularly the date when the traffic of a cell will become critical
Critical trafficcritical traffic: when the offered traffic will induce 2% of blocking traffic capacity of a cell = critical traffic of this cell
7.2 Basis of traffic theory Forecast / Critical traffic
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7.2 Basis of traffic theory Exercise
Training exercise: complete the form to get less than 2% of blocking
cell call mix info Erlang TCHOffered traffic
traffic forecast proposed config
12, 743 450 call/hourmean TCH call duration : 80secblocking rate TCH : 0.8%
10,08 Erlang TCH 30 % offered trafficincrease
13,1 Erlang TCH - > 20 TCH3 TRX
12,675 330 call/hourmean TCH call duration 129secblocking rate 4%
30 % offered trafficincrease
12,865 600 call/hourmean TCH call duration 96secblocking rate 8 %
30 % offered trafficincrease
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7.3 TCH resource allocation indicators
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7.3 TCH resource allocation indicators Radio Allocation and Management
Radio resource allocation and management aim at:
managing pools of TCH resources by: evaluating the load and traffic situation of one celladapting the handling of resources according to these evaluations
Allocating dedicated radio resources by: determining the type of resource to be provided for a request and checking the availability of such resourceselecting the best resource according to several criteria
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7.3 TCH resource allocation indicators TCH allocation process
TCH request
TCH rejected TCH queued
TCH allocation
TCH selection
channel type (FR,HR,DR)speech version (FR, HR, EFR, AMR FR, AMR HR)request type (NA or HO)
cell channel type capabilitycell codec type capability
cell load
TCH free?
Queuing?
no yes
no yesTCH pool (FR,DR,HR) selecting criteria
Inputs for TCH allocation function: requirements from the MSC:
channel type (mandatory) is one of the following:
list of preferred speech version (optional): GSM full rate speech version 1 = FRGSM full rate speech version 2 = EFRGSM full rate speech version 3 = AMR FRGSM half rate speech version 1 = HRGSM half rate speech version 3 = AMR HR
capabilities of the cell: FR TCHs only if only FR TRXs / FR+HR TCHs if some DR TRXscodec supported among: FR, EFR, AMR FR, HR, AMR HR
FR Full Rate onlyHR Half Rate onlyDR FR P NCA Dual Rate Full Rate Preferred No Changes Allowed after first channel allocation
as a result of the requestDR FR P CA Dual Rate Full Rate Preferred Changes Allowed after first channel allocation as a
result of the requestDR HR P NCA Dual Rate Half Rate Preferred No Changes Allowed after first channel allocation
as a result of the requestDR HR P CA Dual Rate Half Rate Preferred Changes Allowed after first channel allocation as a
result of the requestDR SV P NCA Dual Rate No Changes of channel rate Allowed after first channel allocation as a
result of the requestDR SV P CA Dual Rate Changes of channel rate Allowed after first channel allocation as a
result of the request
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7.3 TCH resource allocation indicators TCH pools
3 pools of TCH resources are managed per cell: Full Rate TCH pool containing the free resources of FR TRXs
Dual Rate TCH pool containing the free resources of DR TRXs
Half Rate TCH pool containing the free HR resources of DR TRXs whose mate HR TCH is busy
FR channels can be allocated on both FR and DR TRXs whereas HR can only be allocated on DR TRXs
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7.3 TCH resource allocation indicators Cell load influence
TCH allocation with list of preferred speech versionscell load = False
preferred SV list kept as given by the MSCcell load = True
preferred SV list reordered: HR SV 1st, FR SV 2nd
TCH allocation without list of preferred speech versionsif DR HR Preferred request
try to allocate HR TCHif DR FR Preferred request
try to allocate HR TCH if cell load = Truetry to allocate FR TCH if cell load = False
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7.3 TCH resource allocation indicators HR allocation and release
Example of pool management: HR allocation and release
HR pool preferred DR pool selected if HR pool empty
DR HR
Request for a TCH HR Release of a TCH HR
BTS dual rateBTS dual rate
+1 TCH HR (2)
-1 TCH DR
(1)(2)
(2)
(1) : Pool HR not empty(2) : Pool HR empty
DR HR
-1TCH HR (1)
+ 1TCH DR
(2)(1)
(1)
(1) : Associated HR free(2) : Associated HR busy
+1TCH HR (2)
- 1 TCH HR (1)
FR FR
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7.3 TCH resource allocation indicators FR / HR allocation
FR / HR allocation discrimination for DR HR requestcell load AV_LOAD() computed from
load samples = (NB_BUSY_TS / NB_TS) * 100non-sliding window (LOAD_EV_PERIOD) averaging process
∑ −1- RIODLOAD_EV_PE
0 =i
i)e(kLoad_sampl RIODLOAD_EV_PE
1 = AV_LOAD(k)
100%
AV_LOAD()
THR_FR_LOAD_U_SV1= 80%
THR_FR_LOAD_U_SV3=60%
timeTHR_FR_LOAD_L_SV1=50%
THR_FR_LOAD_L_SV3=40%
Load samples are computed by the BSC every TCH_INFO_PERIOD = 5 seconds.LOAD_EV_PERIOD is the averaging window size for cell load computation. It is equal to 12 but it can be changed at the OMC-R level on a per cel basis.Therefore the cell load process has a periodicity of 1mn by default (TCH_INFO_PERIOD*LOAD_EV_PERIOD).The allocation of Half rate resources is decided upon the load evaluation in the serving cell.AMR HR (HR SV3) offers a better speech quality than HR SV1. The Alcatel BSS offers thus the possibility to define a set of thresholds specific for AMR. If the load increases, AMR HR capable MSs can be the first to be allocated in HR (HR SV3) for load reasons, and if the load still increases, then all the MSs HR capable can be allocated in HR (HR SV1 & HR SV3) for load reasons.That is why two variables of load are defined: LOAD_SV3 and LOAD_SV1.Each load variable is calculated through its own threshold set: the thresholds related to the variable LOAD_SV3 (THR_FR_LOAD_U_SV3 and THR_FR_LOAD_L_SV3). They are less restrictive than the ones related to the variable LOAD_SV1 (THR_FR_LOAD_U_SV1 and THR_FR_LOAD_L_SV1).As a consequence, if the load of the cell increases, then the variable LOAD_SV3 will first equal TRUE, and if the load still increases, the variable LOAD_SV1 will then equal TRUE.The variable LOAD_SV1 corresponds to a level of load where it is important to put as many MSs on half rate TCH as possible: HR SV3 or HR SV1.
The same computation is done to compute LOAD_SV3 with the thresholds: THR_FR_LOAD_U_SV3 and THR_FR_LOAD_L_SV3 with the following relations:
THR_FR_LOAD_L_SV3 ≤ THR_FR_LOAD_U_SV3THR_FR_LOAD_U_SV3 ≤ THR_FR_LOAD_U_SV1THR_FR_LOAD_L_SV3 ≤ THR_FR_LOAD_L_SV1
Previous stateAV_LOAD
LOAD_SV1 = FALSE LOAD_SV1 = TRUE
AV_LOAD ≤ THR_FR_LOAD_L_SV1 LOAD_SV1 = FALSE LOAD_SV1 = FALSETHR_FR_LOAD_L_SV1 <
AV_LOAD ≤THR_FR_LOAD_U_SV1
LOAD_SV1 = FALSE LOAD_SV1 = TRUE
THR_FR_LOAD_U_SV1 < AV_LOAD LOAD_SV1 = TRUE LOAD_SV1 = TRUE
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7.3 TCH resource allocation indicators TCH pool selection
TCH allocation without list of preferred speech versionsFR request: FR pool DR poolHR request: HR pool DR poolDR FR Preferred request:
cell load=False: FR pool DR pool HR pool cell load=True: HR pool DR pool FR pool
DR HR Pref. request: HR pool DR pool FR pool
TCH allocation with a list of preferred speech versionsFR SV: FR pool DR poolHR SV: HR pool DR pool
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7.3 TCH resource allocation indicators TCH selection
The TCH is chosen from the selected pool according to the following criteria:
The Best quality of service for TCH calls is performed by selecting the TCH resources according to the following ordered criteria: 1. Exclusion of TS reserved for GPRS
In the PDCH groups defined by the BSC to support GPRS traffic, the TS consecutive to the already allocated PDCHs (or the TS on the left side of the PDCH group if no PDCH is allocated) shall be put in the lowest selection priority so that GRPS connections can be more easily established.
2. TS with the highest Trx Preference Mark
According to the frequency plan, the coverage and interference probability of a cell (or according to measurements), the operator may know which TRX should be a priori favored for TCH selection. For that purpose, it is possible for operators to give a preference mark to each TRX of a cell. This mark is given through the parameters TRX_PREF_MARK (TPM) changeable at OMC-R side per TRX. The range of TRX_PREF_MARK will be from 0 (lowest priority) to 7 (highest priority). The TCH selection function favours the channels with the highest TPM.
3. TS with the biggest Mobile Allocation
Considering that the number of frequencies is a key factor for the average quality of channels, the TCH selection function favors the TS with the biggest MA (i.e. with the most frequencies in their frequency hopping sequence). This selection criterion is enabled/disabled via the flag EN_MA_SELECTION changeable at the OMC-R side on a per cell basis.
4. TS from the best Interference Band
Considering that the uplink received level measured by the BTS on an idle channel is a means to assess the quality when in connected mode, the TCH selection function favors the TS belonging to the best Interference Band (IB). Five IBs are defined through 5 parameters INTFBD1 to INTFBD5 where INTFBD(i)< INTFBD(i+1) and INTFBD5 = -47 all changeable at the OMC-R side on a per BTS basis.
5. TS with the highest TS index on the TRX with the highest TRX idThis last criterion allows to separate the TCH and PDCH allocations so as to avoid CS and PS conflicts on a given TRX. Furthermore, it aims at optimizing radio resource allocations to provide the best throughput for GPRS traffic.
If more than one TRX is considered, select the TRX with the highest TRX-id.If more than one timeslot is candidate, select the candidate TS having the highest timeslot index (at the right side of the TRX).
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7.3 TCH resource allocation indicators MS access
MS access types distribution (NA only)B8: Accessibility in type 110
TCH requests from FR only MSTCNARQMN= MC701A
TCH requests from DR MSTCNARQBN= MC701B
TCH requests from DR+EFR MSTCNARQTN= MC701C
TCH requests from AMR MSTCNA3RQTN= MC701D
TCH requests from Data callsTCNARQDN= MC701E
B8 (See comments)
Modified in B8
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Traffic Load and Traffic Model > TCH traffic > Speech version and Channel type
These indicators can only be computed if PM Type 1 is activated in B7.In B8, the counters needed for these indicators are added to type 110.
The following indicators are also computed: Ratio of TCH normal assignment requests from FR mobiles over all TCH normal assignment requests from all mobile types = TCNARQMTO = MC701A / (MC701A+MC701B+MC701C+MC701D+MC701E)Ratio of TCH normal assignment requests from DR mobiles over all TCH normal assignment requests from all mobile types = TCNARQBTO = MC701B / (MC701A+MC701B+MC701C+MC701D+MC701E)Ratio of TCH normal assignment requests from DR+EFR mobiles over all TCH normal assignment requests from all mobile types = TCNARQTTO = MC701C / (MC701A+MC701B+MC701C+MC701D+MC701E)Ratio of TCH normal assignment requests from AMR mobiles over all TCH normal assignment requests from all mobile types = TCNA3RQTTO = MC701D / (MC701A+MC701B+MC701C+MC701D+MC701E)Ratio of TCH normal assignment requests for Data calls over all TCH normal assignment requests from all mobile types = TCNARQDTO = MC701E / (MC701A+MC701B+MC701C+MC701D+MC701E)
Number of handover intracell attempts with cause 27: "FR to HR channel adaptation due to a good radio quality" on a TCH channel= HCSTAMFN = MC448BNumber of handover intracell attempts with cause 26: "HR to FR channel adaptation due to a bad radio quality" on a TCH channel= HCSTAMHN = MC448A
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7.3 TCH resource allocation indicators Speech coding version
Speech coding Version capabilities distribution (NA only)B8: Accessibility in type 110
TCH allocations with FR SV1TCNACAFN= MC702A
TCH allocations with HR SV1 TCNACAHN= MC702B
TCH allocations with FR SV2 (EFR) TCNACAEN= MC702C
TCH allocations with FR SV3 (AMR FR) TCNA3CAFN= MC704A
TCH allocations with HR SV3 (AMR HR) TCNA3CAHN= MC704B
TCH allocations for data call TCNACADN= MC705
B8 (See comments)
Modified in B8
These 2 counters are
new in B8.
In B7, only one
without details: MC704
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Traffic Load and Traffic Model > TCH traffic > Speech version and Channel type
These indicators can only be computed if PM Type 1 is activated in B7.In B8, the counters needed for these Indicators are added to type 110.
The following indicators are also computed: Ratio of TCH allocations with FR SV1 over all TCH allocations during normal assignment = TCNACAFTO = MC702A / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)Ratio of TCH allocations with HR SV1 over all TCH allocations during normal assignment = TCNACAHTO = MC702B / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)Ratio of TCH allocations with EFR over all TCH allocations during normal assignment = TCNACAETO = MC702C / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)Ratio of TCH allocations with AMR FR over all TCH allocations during normal assignment = TCNA3CAFTO = MC704A / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)Ratio of TCH allocations with AMR HR over all TCH allocations during normal assignment = TCNA3CAHTO = MC704A / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)Ratio of TCH allocations for Data calls over all TCH allocations during normal assignment = TCNACADTO = MC705 / (MC702A+MC702B+MC702C+MC704A+MC704B+MC705)
Rate of successful TCH allocations with AMR SV over all AMR MS requests= TCNA3SUR = (MC704A+MC704B) / MC701D
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7.3 TCH resource allocation indicators Distributions
FR/HR calls distribution (NA+HO) FR TCH allocation ratioTCAHCAFO = MC370A / (MC370A+MC370B)
HR TCH allocation ratioTCAHCAHO = MC370B / (MC370A+MC370B)
NA/HO distribution Normal Assignment TCH allocation ratioTCNACAO = MC703 / (MC703 + [MC15A+MC15B])
Handover TCH allocation ratio TCHOCAO = [MC15A+MC15B] / (MC703 + [MC15A+MC15B])
TCH allocation distribution per TRXNumber of TCH allocations for Normal AssignmentTCNACAN = MC703
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Traffic Load and Traffic Model > TCH traffic > Resource occupancy
MC370A = Number of FR TCH allocations (FR+EFR+AMR FR)MC370B = Number of HR TCH allocations (HR+AMR HR)
MC703 = Number of TCH allocations for Normal Assignment.MC15A = Number of TCH allocations for Internal Directed Retry.MC15B = Number of TCH allocations for Handover (intra cell, internal, external).
TCNACAN indicator is also available as the MAX value of the day on the A9156 RNO tool.
Some of these indicators are also available for SDCCH: SDCCH allocation distribution per TRX through the number of SDCCH allocations
SDAHCAN = MC390SDCCH Assignment/HO distribution through the ratio of SDCCH allocations for Assignment
SDNACAO = MC148 / MC390
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7 TRAFFIC INDICATORS
7.4 Resource occupancy indicators
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7.4 Resource occupancy indicatorsTCH resource
TCH resource occupancyTCH traffic in ErlangTCTRE= (MC380A+MC380B) / 3600
TCH mean holding time (TCH average duration)TCTRMHT= (MC380A+MC380B) / (MC370A+MC370B)
FR TCH traffic in ErlangTCTRE= MC380A / 3600
FR TCH mean holding timeTCTRFMHT= MC380A/ MC370A
HR TCH traffic in ErlangTCTRE= MC380B / 3600
HR TCH mean holding timeTCTRHMHT= MC380B/ MC370B
B8 (See comments)
New B8
A split of the counters 380a and b
provides information about multiband
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Traffic Load and Traffic Model > TCH traffic > Resource occupancy
MC380A = Cumulated FR TCH duration per TRXMC380B = Cumulated HR TCH duration per TRX
The following indicators can also be computed: TCTRME = Multiband MS TCH traffic in Erlang = MC381 / 3600TCTRSE = Single band MS TCH traffic in Erlang = ([MC380A+MC380B] - MC381) / 3600
MC381 = Cumulated (FR+HR) TCH duration of Multiband mobiles per TRX
In B8, a split of counters (MC380a and MC380b) is added to make the distinction between traffic in different frequency bands: here after the corresponding stored indicators (type 110):
TCTRFTTGT = Time (in seconds) during which the TCH radio timeslot or dynamic SDCCH/8 timeslot in the GSM frequency band is busy in FR usage = MC380CTCTRHTTGT = Time (in seconds) during which the TCH radio timeslot or dynamic SDCCH/8 timeslot in the GSM frequency band is busy in HR usage = MC380DTCTRFTTDT = Time (in seconds) during which the TCH radio timeslot or dynamic SDCCH/8 timeslot in the DCS/PCS frequency band is busy in FR usage = MC380ETCTRHTTDT = Time (in seconds) during which the TCH radio timeslot or dynamic SDCCH/8 timeslot in the DCS/PCS frequency band is busy in HR usage = MC380F
B8
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7.4 Resource occupancy indicatorsSDCCH / ACH resource
SDCCH resource occupancySDCCH traffic in ErlangSDTRE= MC400 / 3600
SDCCH mean holding time (SDCCH average duration)SDTRMHT= MC400 / MC390
ACH resource occupancyACH traffic in ErlangC750 / 3600
ACH mean holding time (ACH average duration) QSTRN =C750 / C751
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Traffic Load and Traffic Model > SDCCH traffic > Resource occupancy
MC400 = Cumulated SDCCH duration per TRXMC380 = Number of SDCCH allocations per TRX
C750 and C751 are 2 counters introduced from B7 in type 18. Both are provided per TTCH (A channel): C750 = TIME_A_CHANNEL_BUSY: Time (in seconds) during which the A channel is busy (allocated).C751 = NB_A_CHANNEL_ALLOC: Number of allocations of the A channel.
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7 TRAFFIC INDICATORS
7.5 Traffic model indicators
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7.5 Traffic model indicatorsSDCCH establishment
SDCCH establishment cause distributionRatio of MT callsTMMTO= MC01 / SDCCH ASSIGN SUCCESS
Ratio of MO normal and emergency callsTMMTO= MC02H / SDCCH ASSIGN SUCCESS
Ratio of LU normal (resp. follow-on)TMMOLUR = MC02A (resp. MC02D) / SDCCH ASSIGN SUCCESS
Ratio of IMSI detachTMMOLUDR= MC02G / SDCCH ASSIGN SUCCESS
Ratio of Short Message ServiceTMMOSMSR= MC02B / SDCCH ASSIGN SUCCESS
Ratio of Supplementary ServiceTMMOSSR= MC02C / SDCCH ASSIGN SUCCESS
Ratio of Call re-establishmentTMMOCRR= MC02E / SDCCH ASSIGN SUCCESS
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Traffic Load and Traffic Model > SDCCH traffic > Traffic model
SDCCH ASSIGN SUCCESS = Total number of SDCCH establishments for network access = MC01 + MC02
These indicators allow to get call mix data from the network.
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7.5 Traffic model indicatorsMobiles penetration
E-GSM mobiles penetrationRatio of E-GSM MS access over all MS accesses (except LU)TMMSEGR = MC706 / ([MC01+MC02]-[MC02A+MC02D+MC02G])
Multiband mobiles penetrationRatio of Multiband MS access over all MS accesses (except LU)TMMSMBR = MC850 / ([MC01+MC02]-[MC02A+MC02D+MC02G])
AMR mobiles penetrationRatio of TCH allocation for AMR MS over all TCH allocationsTCTR3CATTO = MC704A+ MC704B / MC703
TFO calls ratioRatio of successful TFO establishment over all TCH allocationsQSTRCCTR = MC170 / MC703
Handover per CallNumber of Handovers (intra cell,internal,external) per Normal AssignmentTMHOCO = (MC717A+MC717B) / MC718
B8
New B8
(See comments)
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: Traffic Load and Traffic Model > SDCCH traffic > MS penetration rateTraffic Load and Traffic Model > TCH traffic > Speech version and Channel type
[MC01+MC02]-[MC02A+MC02D+MC02G] = Total number of initial accesses for call establishment (except location update) MC706 = Number of initial accesses for call establishment (except location update) of MS supporting the E-GSM bandMC850 = Number of initial accesses for call establishment (except location update) of MS supporting two frequency bands (ex: GSM900 and DCS1800)MC703 = Total number of TCH allocations (FR+HR) for Normal AssignmentMC704A = Number of TCH allocations (FR) for Normal Assignment of AMR mobiles onlyMC704B = Number of TCH allocations (HR) for Normal Assignment of AMR mobiles only
MC704 (Allocation AMR FR+HR) is removed in B8MC170 = Number of TCH calls for which a TFO has been successfully established
B8
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7 TRAFFIC INDICATORS
7.6 Preemption indicators
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7.6 Preemption indicatorsPreemption principle
Preemption attributes (in Assignment or HO Request): pci : preemption capability indication
indicates if the call can preempt another call (pci=1) or not
pvi : preemption vulnerability indicationindicates if the call is preemptable (pvi=1) or not
priority level: 1=highest priority / 14=lowest priority
Preemption rules:A TCH request with pci=1 and priority level=p1 will preempt an on-going call with pvi=1 and priority level=p2, p2 lower than p1 (whatever pcivalue)the on-going call with the lowest priority level value shall be elected first and if several calls have the same lowest p2 value, one of them with pcibit set to 0 is preferred
On Preemption capable TCH Request occurrence: 1. The TCH is established through Preemption if a lower priority level on-going call is preemptable. In this case, the on-going
call is released and the freed TCH is served to the new request.2. If no preemption is possible:
If queuing is possible: the TCH request is queued and either a Directed Retry or a Fast Traffic HO can be performed.If queuing is not possible: the TCH request is rejected and an ASSIGNMENT or HANDOVER FAILURE "no radio resource available" message is sent to the MSC.
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7.6 Preemption indicatorsPreemption counters
MC921A = Number of TCH Requests with the capability to preempt another call with lower priority (pci=1) MC921B = Number of preemption capable TCH Requests (pci=1) served with TCH resource (with or without using the preemption feature).MC921C = Number of preempted callsMC921D = Number of preemption capable TCH Request (pci=1) successfully served in a neighboring cell with the help of the directed retry procedureMC921E = Number of preemptable calls successfully established (pvi=1)
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: GLOBAL Quality of service INDICATORS> RTCH > Preemption feature
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7.6 Preemption indicators
Preemption capable TCH Request rejection rateTCPPFLCR = (MC921A-MC921B-MC921D) / MC921A
Ratio of preemption capable TCH Request which led to a successful Directed Retry
TCPPDSUCR = MC921D / MC921A
Ratio of preemptable calls established over all callsTCPPSUVO = MC921E / (MC718+MC717A+MC717B)
Refer to BSS - DEFINITION OF QUALITY OF SERVICE INDICATORS RELEASE B8: GLOBAL Quality of service INDICATORS> RTCH > Preemption feature
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Thank you for answeringthe self-assessment
of the objectives sheet
Introduction to QoS and Traffic Load monitoring / B8Evaluation
Objective: to be able to interpret:
Global indicators, in order to assess the general quality of the networkDetailed indicators, in order to detect / identify / locate the main malfunctionsHandover indicators, in order to quantify the efficiency and the reason for HODirected retry indicators, in order to quantify the efficiency of a directed retryIndicators provided by the new RMS feature to ease radio optimization and fault detectionTraffic indicators, in order to detect/predict overload and compute adequate cell dimensioning as well as to understand how RTCH resources are used in the network
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Radio Measurement Reporting
ANNEX 1
Radio Measurement Reporting
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Radio measurement mechanismsMS connected (TCH or SDCCH)The serving cell gives to the MS the list of the neighboringcells to listenEvery SACCH, the MS reports to the serving cell: measurement report message
Received level of 6 best cells (which can change)DL level and quality of serving cell
Radio Measurement Reporting
MeastReport
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Radio measurement mechanismsFor each MS connected to the BTS (TCH or SDCCH)
Radio Measurement Reporting
BSC
DL measurements UL+DL measurements
The UL received level and quality are measured every SACCH
The Timing advance (TA) is computed
The UL information is gathered into a measurement report
this is the message result sent by the BTS to the BSC
MeastReport
MeastResult
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Measurement Result message
Radio Measurement Reporting
L1 Info
L3 Info
MeasurementReportFrom the MS
Back
Basically, the MEASUREMENT RESULT message is composed of: L1 info: SACCH Layer 1 header containing MS_TXPWR_CONF and TOA.L3 info: MEASUREMENT REPORT from the MS. This message contains the downlink measurements and neighboringcell measurements.Uplink measurements performed by the BTS.BTS power level used.
SUB frames correspond to the use of DTXif the mobile is in DTX, the rxlevsub or rxqualsub is used to avoid measuring the ts where there is nothing to transmit in order not to false measurements.else rxlevfull is used that is to say all TSs are measured.
MS TXPOWER CONF: what is the actual power emitted by the MS.
TOA is the timing advance.
SACCH BFI: bad frame indicator; 2 values 0 or 1; 0 means that the BTS succeeded in decoding the measurement report from the MS.
How the neighboring cells are coded:BCCH1 index in BA list /BSIC1; BCCH2 index in BA list/BSIC2. Why? Because when the mobile is connecting to a new cell, it does not receive LAC/CI (too long) but the list of BCCH frequencies of the neighboring cells (in Band Allocation: BA list). When it reports the radio measurements, it gives the index of the BCCH frequency in the BA list instead of BCCH ARFCN due to the length in case of 1800 frequency coding. Besides the mobile may report a BCCH index / BSIC which does not correspond to a neighboring cell. Of course the BSC will not trigger any handover except if this BCCH index / BSIC couple correspond to a neighboring cell.
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Extended Measurement Reporting
ANNEX 2
Extended Measurement Reporting(MAFA)
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Extended Measurement Reporting
The Extended Measurement Reporting is a feature allowing the BSS to request an MS to measure and report up to 21 frequencies of the band that are not included in its BA list
Such phase 2+ mobiles must support the optional MAFA feature (Mobile Assisted Frequency Allocation)
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MS BTS BSC MSCTCH ASSIGNMENT PHASE (OC or TC)
< -----------------------------------ASSIGNMENT REQUEST
< --------------------------------------------------------PHYSICAL CONTEXT REQUEST
-------------------------------------------------------- >PHYSICAL CONTEXT CONFIRM
< --------------------------------------------------------CHANNEL ACTIVATION (TCH)
(EMO included)-------------------------------------------------------- >CHANNEL ACTIVATION ACKNOWLEDGE
.
.TCH establishment.
--------TCH---------> .ASSIGNT COMPLETE ------------------------------------------------------- >
ASSIGNMENT COMPLETE ----------------------------------- ><------SACCH-------- ASSIGNMENT COMPLETE
--------SACCH------><------SACCH--------
--------SACCH------><-------SACCH--------
EMO(MAFA freq. List)
--------SACCH------>EMR
(MAFA freq. RxLev)<------SACCH--------
--------SACCH------>
Extended Measurement Reporting mechanisms
Extended Measurement Reporting
The Extended Measurement Order includes the MAFA frequencies the MS is asked to measureEMO sent once to the MS on SACCH after TCH seizureExtended Measurement Results include the average signal level measured on each MAFA frequency over one SACCH mf durationEMR received once per call on SACCH
Back
When the BTS receives a CHANNEL ACTIVATION with the Extended Measurement Order (EMO) included, it shall send this information on the SACCH to the corresponding mobile only once.When the BTS has to send this information, it shall replace the sending of system information 5, 5bis, 5ter or 6 by this information. At the next SACCH multi-frame, the BTS shall resume the sending of this system information by the replaced one. The EMO shall be sent after 2 complete sets of SYS_INFO5 and 6, i.e. after the 2nd SYSINFO 6 after the reception of SABM. This guarantees the MS has received a complete set.Then, the BTS normally receives from the MS an EXTENDED MEASUREMENT RESULT with the level of the frequencies to monitor. The BTS shall make the correlation between these levels and the frequencies contained in the latest EMO information, after having decoded them, according to the order of the ARFCN. The ‘EXTENDED_MEASUREMENT_RESULT’ is NOT forwarded to the BSC, instead a ‘MEASUREMENT_RESULT’ with indication ‘no_MS_results’ is sent to the BSC.In particular, the BTS shall identify the level of the BCCH frequency of the serving cell (which shall always be part of the frequencies to monitor) and apply it as the RXLEV_DL in the Radio Measurement Statistics. The other frequencies will be considered in the same way as BCCH frequency of neighboring cells: they will be linked to the neighboring level and C/I statistics.
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ANNEX 3
GSM BSS Protocol Stacks
GSM BSS Protocol Stacks
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Signaling Links
A-Interface MT-Link signaling #7 System with SCCPMSC BSC
BSC BTSAbis Interface RSL with LAPD Protocol
BTS MSAir-Interface (CCCH/SACCH/FACCH) with LAPDm Protocol
BSC OMC-ROML Link with X25 connection LAPB Protocol
GSM BSS Protocol Stacks
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The reference Model
7 Application
6 Presentation
4 Transport
5 Session
2 Data Link
3 Network
1 Physical
User of Transport Service
Transport ServiceNetworkService
GSM BSS Protocol Stacks
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Layer 1Physical; Responsible for the transparent transmission of information across the physical medium (HDB3, PCM, AMI)
Layer 2Data Link; Responsible for providing a reliable transfer between the terminal and the network (#7, LAPD,etc.)
Layer 3Network; responsible for setting up and maintaining the connection across a network (CM, MM, RR, Message routing, etc.)
GSM BSS Protocol Stacks
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Layer 4Transport; responsible for the control of quality of service (Layer of information)
Layer 5Session; Handles the coordination between the user processes (Set up transfer of information)
Layer 6Presentation; responsible for ensuring that the information is presented to the eventual user in a meaningful way (Type format. Ex. ASCII)
Layer 7Application; provides user interface to lower levels (Operating System)
GSM BSS Protocol Stacks
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BTS PSTNISDN
Air Intfc Abis Intfc A Intfc B .. F Intfc
MS BSC MSC
CM
MM
RR
LAPDm
digit
radio
RR BSSAP
LAPDm LAPD
digit
radio64 kb/s 64 kb/s 64 kb/s 64 kb/s
LAPD
RR
BTSM
BSSAP
CM
MM
BSSAP
SCCP
MTP
SCCP
MTP LAYER 2
LAYER 1
LAYER 3
GSM BSS Protocol Stacks
BSS protocol stacks
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GSM BSS Protocol Stacks
SSCS
SSTM 3
SSTM 2
SSCS
SSTM 3
SSTM 2
SSGT
MAP
SSGT
MAP
SSCS
SSTM 3
SSTM 2
PCM TS
DTAP
SSCS
SSTM 3
SSTM 2
PCM TS
DTAP
LAPDLAPDm LAPD
SS (SMS)SS (SMS)
BSSMAP
MM
CC
BSSMAPRR
RR
RR' BTSMBTSM
LAPDm
(SMS)SSCC
MM
(Relay)
MS BTS BSC MSC / VLR NSS(ex. : HLR)
Um A bis A (D)1
2
3
(Relay
64 kbit/sor PCM TS
64 kbit/sor PCM TS PCM TS PCM TSPhycal
Layer
BSS protocol stacks (detailed)
PhycalLayer
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Signaling on the A InterfaceUses #7 with Signaling Connection Control Part (SCCP) with a new Application Base Station Application Part (BSSAP). BSSAP is divided into Direct Transfer Application Part (DTAP) and Base Station Subsystem Management Application Part (BSSMAP)
DTAP
BSSMAP
SCCP
MTP 1-3
User Data
Layer 1-3
BSSAP
GSM BSS Protocol Stacks
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BSSMAPContains the messages, which are exchanged between the BSC and the MSC and which are evaluated from the BSC. In fact all the messages, which are exchanged as RR (Radio Resource Management Services between the MSC, BSC and MS). Also control Information concerning the MSC and BSC.Example: Paging, HND_CMD, Reset
DTAPMessages which are exchanged between an NSS and an MS transparent. In this case, the BSC transfers the messages without evaluation transparent. Mainly Messages from Mobility Management(MM) and Call control (CC)
GSM BSS Protocol Stacks
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Relationship between DTAP, CC, MM, BSSMAP, RR
MSBSS MSC
Call Control (CC) DTAP
Radio Resource (RR)BSSMAP
GSM BSS Protocol Stacks
Back
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ANNEX 4
B8 Improvements summary
B8 Improvements summaryB8
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Location Services (LCS)SDDCH Dynamic allocationCounters Improvement
Inter PLMN HO3G to 2G HO (and 2G to 2G only)Dual band HO (New type: 32)LapD congestion counterQOS Followup
TCH assignment failure BSS PB now detailedHO Attempts for Fast Traffic added in type 110AMR counters added in type 110MS penetration (per speech version and channel type) was type 1 counters now available in type 110HO Causes: type 26 extended from 1 to 40 cellsDirected retry: type 29 becomes a standard (for PMC)
B8 Improvements summaryB8