WCDMA : KPI ANALYSIS & OPTIMIZATION Network planning& Optimization
Illustration on RAN KPI-RU20
Presentation / Author / Date
SRNC Relocation
RNC
UEBTS2
BTS1
RNCAccessibility:RRC Setup & Access RateRAB Setup & Access Rate
Call Setup Success Rate
PS setup success rate (NRT,HSDPA,
HSUPA)
XRetainability:RRC Drop RateRAB Drop RatePS success rate (NRT, HSDPA,
HSUPA)
Mobility:SHO/ISHO Success
RateSHO Overhead
HDSPA/HSUPA SCC success rate
Usage:Cell Availability
Ave. Uplink Load
Ave. Downlink Load
HSDPA Throughput
Cell Throughput
X Pre-emption
SRNC
Genuine Call Setup Failure Scenarios
– RF issue• Interference / Dominance / Coverage• Missing neighbour
– System Issue - BTS• No response to “RRC Connection Request”• “RRC Connection Reject” to “RRC Connection
Request” – System issue - RNC
• “CC Disconnect” after “Call Proceeding” due to “DL RRC Connection Release”
– Core NW• “CM Service Abort” after “CM Service Request”
– System issue (test number)• “CC Disconnect” after “CC Progress”
Genuine Drop Call scenarios
RF issue– Interference / Dominance / Coverage
– Missing Neighbours
System issue BTS– Sudden “CC Disconnect” due to “DL RRC Connection
Release”– Sudden drop to idle, no disconnect messaging
System issue RNC– Sudden “CC Disconnect” due to “DL RRC Connection
Release”
KPI DefinitionsThe KPIs to be monitored from the RAN could be:
– Cell availability– Call Setup Success Rate (CSSR)– Call Drop rate– SHO/ISHO/HSPA SCC success rate– Packet Session setup/success rate (NRT, HSDPA, HSUPA)
In NOLS:– RNC counter description– NetAct DB description for RNC measurements– WCDMA RAN Key Performance Indicators– Key Indicator Changes– Measurement Changes
Presentation / Author / Date
DRNCUE CNSRNCWBTS
2. RRC connection set-up
6. Service Established
7. Branch addition/deletion & Active set update
1. Cell search, BCCH decoding & RACH access
3. UE <--> CS-CN signalling
4. RAB set-up
8. Service Released
5. UE <--> CS-CN Signalling
AMR CS Call Phases
Start
Best server’s RSCP > -102dBm
Best server’s Ec/No > -12dB
Coverage Optimization
Dominance Optimization
AICH(ACK) received?
YesMissing Neighbour ?
Neighbour list Optimization
No
No
No
Yes
UL coverage & RACH parameter. Optimization(changing serving cell)
“RRC ConnectionSetup” received?
(DCH) “RRC Connection setupCompleted” sent from UE?
“Radio Bearer setup failure”Received?
Report & FinishCheck failure cause (Not radio problem/cell update)
Report & Finish(Check failure cause)
AC optimization (check PrxNoise& interferer around BTS)
Report & Finish
“RRC Setup Reject” received?
Yes
No
Yes
Yes
Yes
Report & Finish (Reason of problem: L1 sync fail)
Report & Finish(Check failure cause)
Call Setup Failure Analysis Process__DT
A
BC
D
E
Yes
Yes
No
No
No
No
Call setup failures – Missing Neighbour
Missing neighbour analysis over the whole route (3G-3G, 3G-2G)
Search for failures due to missing 3G-3G neighbours
Search for failures due to missing 3G –2G neighbours– It is suggested to place 2G scanner to the test vehicle
A
Call Setup Failure Analysis- Block B -
The purpose of this activity is to check the Random Access Process is working adequately by investigating whether AI (Acquisition Indicator) has been received through DL AICH
If AICH was not received by UE, the cause of the problem can be classified into:– Inadequate RAN parameter related to
Random Access: RAN parameter settings for pre-amble transmission or open loop power control information is not correct.
– UL Coverage limit: UL coverage of UE is smaller compared to serving cells DL coverage so that UE’s Tx power cannot reach serving cell.
B
Call Setup Failure Analysis- Block B -UE WBTS RNC
Preamble/RACH
Acquisition Indicator/AICH
RRC: RRC Connection Request/PRACH
NBAP: RADIO LINK SETUP REQUEST
RRC: RRC CONNECTION SETUP/FACH
L1 Synchronisation
NBAP: SYNCHRONISATION INDICATOR
RRC: RRC CONNECTION SETUP COMPLETE/DCH
UE in CELL_DCH state
NBAP: RADIO LINK SETUP RESPONSE
B
RACH Process
DownlinkBS
L1 ACK / AICH
UplinkMS Preamble
1
Not detected
Message partPreamble2
PRACH_preamble_retrans# PRACH preambles transmitted during one PRACH cycle without receiving AICH response
UEtxPowerMaxPRACH
… … … …
RACH_tx_Max# preamble power ramping cycles that can be done before RACH transmission failure is reported
PowerRampStepPRACHpreamble
PowerOffsetLastPreamblePRACHmessage
Initial preample power:•Ptx = CPICHtransmissionPower-RSCP(CPICH) +RSSI(BS) + PRACHRequiredReceivedCI
B
Call Setup Failure Analysis- Block B-
Solutions for RACH optimisationMax UE Tx power hit the UE_P_MAX(24dBm)?
To increase PRACH_Preamble_retransOr PowerRampStepPRACHPreamble
To increase PRACH_Preamble_retransOr PowerRampStepPRACHPreamble
No
Yes
Is UL Interference abnormally HIGH?
Yes
No
Report there might be an interfering source Nearby the serving cell
Report there might be an interfering source Nearby the serving cell
Change the Serving cell to cover the problem Area=> UE is too far to reach the serving cell
Change the Serving cell to cover the problem Area=> UE is too far to reach the serving cell
B
Call Setup Failure Analysis- Block B
B
Open loop Power Control parameters from RACH Info message
Call setup failures – System issue BTSNo response to “RRC Connection Request”
– Good RF conditions– Wrong MHA settings or cable loss settings can cause the site not to
“hear” the UE– PrxNoise statistics, receive link parameters and HW units to be
checked (faulty MHA, wrong MHA parameters, wrong cable / feeder loss parameters, faulty units)
C
Call setup failures – System issue BTS“RRC Connection Reject” after “RRC
Connection Request”– Good RF conditions– Admission Control can reject too many (or
admit too many) connection requests due to wrong PrxNoise measurements.
– PrxNoise statistics, receive link parameters and HW units to be checked
C
Call Setup Failure AnalysisUE has the appropriate DL/UL coverage but if RNC does not allow to set
up the RRC connection of the requested RAB (Radio Access Bearer), Call setup will fail.
Admission Control (AC) is involved in RRC connection setup. AC can reject RRC reject RRC connection Setup due the DL Load, UL load or DL Spreading codes
– Marginal Load Area: • If measured UL (PrxTotal) or DL (PtxTotal) load exceeds
target thresholds (PrxTarget and PtxTarget) AC can still admit new RAB to the cell if a new non-controllable load keeps below target thresholds (in practice this means that AC can admit only new controllable load RABs i.e. NRT RABs)
– Overload Area: • If measured UL (PrxTotal) or DL (PtxTotal) load exceeds
overload thresholds (PrxTarget + PrxOffset and PtxTarget + PtxOffset) then AC can't admit more RABs to the cell
C
Call Setup Failure Analysis• During the pre-optimization phase it is unlikely that AC will stop an RRC
connection setup during the drive testing because there are normally very few UEs in the network. (Traffic loading is trivial)
• However, it should be checked that measured PtxTotal and PrxTotal are less than PtxTarget (e.g. 40dBm) and PrxTarget (e.g. 4dB, 60% loading) respectively.
• If DL AC does not allow RRC setup check the Tx power of WBTS, # of channels transmitted, Signaling messages.
• If UL AC does not allow RRC setup: Check out if there is an interfering source nearby the serving cell.
C
Call Setup Failure Analysis
To check if Layer 1 Synchronization (slot/frame sync) has failed
If “RRC Connection Setup” was received by UE but UE does not send “RRC Connection Setup Completed”, we will report “L1 synchronization failure” and have to check L1 system messages.
D
• “CC Disconnect” after “Call Proceeding”
• Good RF conditions
• Failures in RAB setup occur between the “RAB Assignment Request” being received from Core Network and the RAN sending out Radio Bearer Setup. Therefore the failure is between BTS and Core Network.
ECall setup failures – System issue RNC
• “CC Disconnect” after “Call Proceeding” (cont.)
• An example (site shows high values on counter “RAB_STP_FAIL_CS_VOICE_BTS” during the drive test
• In the recent check the counter showed no failures.
ECall setup failures – System issue RNC
Call setup failures – Core NW“CM Service Abort” after
“CM Service Request”Good RF conditions“Security Mode
Command”-message not received by UE, thus the failure is believed to be at Core Network.
Security Mode Command
Common ID
UE RNC MGWNode B
RRC Connection Establishment
Initial Direct Transfer (CM Service Request) SCCP: Connection Request
SCCP : Connection ConfirmLocation Reporting Control
• RRC: Initial Direct Transfermessage is sent using acknowledged mode RLC to the CS core domain. Routing is to be based upon the local P-TMSI
• The NAS message is not read by the RNC but is forwarded to the multimedia gateway. The NAS message includes the IMSI as a UE identity
• The SCCP: Connection Requestmessage establishes the connection orientated signalling link in the same way as it was for the RRC connection phase.This does not reserve any resources for the AMR call itself.
• The Connection Confirmmessage identifies the RNC with a destination local reference which is the same as the source reference within the Connection Requestmessage
• The Connection Confirmmessage identifies the CS core with a source local reference
• The CS core sends a RANAP: Location Reporting Controlmessage to the RNC requesting information regarding the location of a particular UE
• The RANAP: Common IDmessage specifies the IMSI belonging to the UE
• The Security Mode Commandmessage triggers the start or stop of ciphering and integrity protection.
E
Call setup failures – System Issue (test number)“CC Disconnect” after “CC
Progress”Cause: recovery on timer expiryThe call goes via IN SCP to a
recording. A static test was done by Nokia
Customer Care and in few instances the call dropped after 30 seconds of recording passed. Hence the problem is associated with the test number not the RAN
30 sec
Cause: recovery on timer expiry
E
CELL_PCHURA_PCH
CELL_FACHCELL_DCH
UTRA RRC Connected Mode
Fast call setup from URA_PCH
IDLE Mode
Fast call setup from CELL_PCH
After RT call with inactive PS RABs
After RT call with inactive PS RABs & high mobility in CELL_DCH
RRC Setup / Release
Phys. Reconfiguration UL/DL activation timer
Phys. Reconfiguration Cell Update, UL data, paging
Phys. Reconfiguration Frequent cell updates
Phys. Reconfiguration URA Update, UL data, Paging
RB. Reconfiguration Traffic Volume, RACH load
RB. Reconfiguration Inactivity Timer, Overload
State Transition triggers
State Transition triggersIDLE
FACH
PCH
DCH
FACH
DCH
IDLE
Call Setup 1.2 sec
Transition DCH-FACH due to inactivity 10 sec )Parameter)
Transition FACH-PCH due to inactivity 2 sec )Parameter)
Wake up time PCH – DCH due to activity 3 sec
25 © 2006 Nokia Layer 3 (RRC) / Kittipong Thamapa
CELL_DCH State
active setcell
active setcell
• DCCH and – if configured – DTCH
• Dedicate physical channel in use
• UE location known on active set cell level
• UE responsible for measurement reporting
• Cell system information on BCCH
• RRC messages on DCCH
26 © 2006 Nokia Layer 3 (RRC) / Kittipong Thamapa
CELL_FACH State
servingcell
• DCCH and – if configured – DTCH
• FACH used for higher layer data transfer,
• UE monitors FACH permanently
• Uplink transmission on RACH
• UE location known on serving cell level
• UE performs cell re-selection• UE responsible for
measurement reporting• Cell system information on
BCCH• RRC messages on BCCH,
CCCH and DCCH
27 © 2006 Nokia Layer 3 (RRC) / Kittipong Thamapa
CELL_PCH and URA_PCH State
URA – UTRAN Registration Area
URA 1
URA 2URA 3
RNCsupply
area
•one or several cells•independent from LA
/RA
• no DCCH and DTCH• Before uplink transmission ⇒ UE moves to
CELL_FACH• UE must be paged• RRC messages on BCCH and PCCH• In CELL_PCH
- UE location known on cell level- UE performs cell re-selection and cell updates
• In URA_PCH- UE location known on URA level- UE performs cell re-selection and URA updates
RU20 New Counters & Measurements
/
Cell Availability
RNC_183c Cell Availability KPI counts Cell availability from user point of view:
Presentation / Author / Date
( )( )DBRNWINEXISTWCELLAVAILsum
STATEWOINWCELLAVAILsumtyAvailabiliCell
_____
____*100_ =
M1000C178 AVAILABILITY WCELL IN WORKING STATE
• # of samples when WCELL is in WO State. Counter M1000C180 is always updated along with this counter
• Counter is updated with the value 1 once in approx. 5 seconds when the WCELL is in WO State
M1000C180 AVAILABILITY WCELL EXIST IN RNW DATABASE
• # of samples when WCELL is configured in the database. This counter is used as a denominator for cell availability calculation
• Counter is updated with the value 1 one in approx. 5 seconds when the WCELL is configured in the radio network database
Cell Availability
– There is also Optional Cell availability KPI, which counts Cell Availability from network point of view. Situation where WCELL is blocked by User are excluded from the formula.
– RNC_727a Cell Availability KPI, excluding blocked by user state (BLU), Counts Cell availability from network point of view:
Presentation / Author / Date
( )
−
=
USERBYBLOCKEDWCELLAVAIL
DBRNWINEXISTWCELLAVAILsum
STATEWOINWCELLAVAILsumstateBLUexcludingtyAvailabiliCell
____
_________*100
____
M1000C179 AVAILABILITY WCELL BLOCKED BY USER
• # of samples when WCELL is BLU State. Counter M1000C180 is always updated along with this counter
• Counter is updated with the value 1 once in approx. 5 seconds when the WCELL is in BLU state
CSSR definition
DNO Optimization Processes / JC Ejarque
Low in CSSR?
Identify call setup failure phases
DNO Optimization Processes / JC Ejarque
Call Setup PhasesCSSR affected if any of the
followings take place.
1. RRC Conn. Setup Fail2. RRC Conn. Access Fail3. RAB Setup Fail4. RAB Setup Access Fail
Call Setup Phase
RRC
Conn. Req
RRC
Conn. Setup
RRC
Conn. Acc
RRC
Conn. ActRAB Setup RAB Drop
Call Setup Success Call Drop
Connected
Low in CSSR?
RRC/RAB Setup & Access Analysis Process Flow Chart
DNO Optimization Processes / JC Ejarque
Sites OK ? Cell and Neighbour
Cells availabilityAlarms/Tickets
Setup /Access
Yes
Setup /Access
Setup Failure Cause?
Capacity Optimisation
BTS/TRANS/FROZBSUL/DL
Interference (DL codes)
AC
TroubleshootingRNC
RF Optimisation
Top (N) RRC Setup and Access failures
Top (N) RAB Setup and Access failures
Coverage/Interference
setup
setup
Interference
Coverage
3G cell at inter-RNC border ?
SRNS Relocation troubleshooting
Yes
NO
Access
Access
Sites OK ? Cell and Neighbour
Cells availabilityAlarms/Tickets
Setup /Access
Yes
Setup /Access
Setup Failure Cause?
Capacity Optimisation
BTS/TRANS/FROZBSUL/DL
Interference (DL codes)
AC
TroubleshootingRNC
RF Optimisation
Top (N) RRC Setup and Access failures
Top (N) RAB Setup and Access failures
Coverage/Interference
setup
setup
Interference
Coverage
3G cell at inter-RNC border ?
SRNS Relocation troubleshooting
Yes
NO
Access
Access
Call Setup Success Rate (CSSR) Poor CSSR could be a result of
– Poor coverage or dominance or interference issues in Radio interface
– Capacity issues in Radio or Iub interface– Configuration issues in WBTS (parameters or HW)
CSSR is essentially RRC Setup Success * RAB Setup Success (or successful PS session setups in case of PS call)
CSSR covers all the steps from the initial RRC connection request from the UE to the network, through the RRC setup phase and the RAB setup phase, and until user data is starting to get transferred.
The CSSR formulas are for different traffic classes like: – CS voice calls (RNC 565 f)– CS video calls (RNC 566e)– PS RT Streaming Calls (RNC 575 d) – PS NRT Calls (Interactive & Background) (RNC 576d)
Presentation / Author / Date
Definition of Call Set-Up Success Rate (CSSR)
Presentation / Author / Date
UERRC: Connection Request
RRC Connection Setup phaseResource Reservation in RNC, BTS, Transmission
RRC: RRC Connection Request Setup
RRC Connection Access phase RNC waits reply from UE
RRC: RRC Connection Completed
RRC: Initial Direct Transfer cm service request
RANAP: Initial UE MessageDIRECT TRANSFER (Call
Proceeding)RANAP: RAB Assignment
Request
RRC: Radio Bearer Set-up
RRC: Radio Bearer Setup Complete
RAB Connection Setup phaseResource Reservation in RNC, BTS, Transmission
RANAP: RAB Assignment ResponseDIRECT TRANSFER (Alerting)
BTS RNC CN
DIRECT TRANSFER (Connect)DIRECT TRANSFER (Connect
Acknowledge)
RAB Connection Access phase RNC waits reply from UE
Call Set-up
Success Rate
Call Set-up Time
RRC Connection Setup & Access and Active
Presentation / Author / Date
BTSUE RNC CN
RRC: RRC connection Request
RRC: RRC connection Setup
RRC SETUP phase
(Resource Reservation in RNC, BTS, Transport)
RRC ACCESS phase
(RNC waits for Reply from UE)
RRC: RRC connection Setup Complete
RR
C S
etu
p tim
e
RRC: Initial Direct Transfer
RANAP: Initial UE Message
RANAP: Iu Release Command
UE-CN Signalling
(E.g. RAB Establishment and Release)
RRC: RRC connection Release
RRC: RRC connection Release Complete
Release RRC resources in RNC, BTS, Transport
RRC ACTIVE phase
RRC ACCESS fails if the UE does not reply to RRC: RRC CONNECTION SETUP message with the RRC: RRC CONNECTION SETUP COMPLETE message in given time, if the BTS reports a radio link synchronisation failure or in an RNC internal failure occurs
RRC SETUP fails if some of the needed resources (RNC, BTS, AIR, Transport) are not available. When an RRC setup failure occurs the RNC sends an RRC: RRC CONNECTION REJECT message to UE
RRC ACTIVE fails when an interface related (Iu, Iur , Iub, or Radio) or RNC internal failure occurs, and the failure causes the release of the RRC Connection. When an RRC active failure occurs, the RRC send a RANAP: IU RELEASE REQUEST to all involved CNs and waits for RANAP: IU RELEASE COMMAND message (s)
RRC ACTIVE release cause can be either ISHO, IFHO, SRSN relocation or pre-emption
RAB Setup & Access and Active
Presentation / Author / Date
RAB Reconfiguration Actions
(Reconfigure RAB resources in RNC, BTS, Transport)
BTSUE RNC CN
RRC: Radio Bearer Setup
RAB SETUP phase
(Resource Reservation in RNC, BTS, Transport)
RAB ACCESS phase
(RNC waits for Reply from UE)
RRC: RB Setup Complete
RA
B S
etup
time
RRC: RB Reconfiguration
RANAP: RAB Assignment Response
RANAP: RAB Assignment Response
Release RAB resources in RNC, BTS, Transmission
RRC Connection Active Phase, UE-CN Signalling
RANAP: RAB Assignment Request
RANAP: RAB Assignment Response
RAB ACTIVE phase
(User Plane Data Transfer)
RANAP: RAB Assignment Request with IE: RAB reconfiguration
RRC: Radio Bearer Release
RRC: RB Reconfiguration Complete
RANAP: RAB Assignment Request with IE: RAB Release
RRC: Radio Bearer Release Complete
RA
B H
olding T
ime
RAB SETUP fails if some of the needed resources (RNC, BTS, AIR, Transport) are not available. When an RAB setup failure occurs the RNC sends a RANAP: RAB ASSINGMENT RESPONSE message to the CN with an appropriate failure cause
RAB ACCESS fails if the UE replies with an RRC: RADIO BEARER SETUP FAILURE message or the connection cannot be established in a give time. When a RAB access failure occurs, the RNC sends a RANAP: RAB ASSINGMENT RESPONSE message to the CN with an appropriate failure cause. Immediately after this, the RNC sends also a RANAP: IU RELEASE REQUEST to the CN and waits for RANAP: IU RELEASE COMMAND message
RAB ACTIVE fails when an interface related (Iu, Iur, Iub, or Radio) or RNC internal failure occurs, and the failure causes the release of the RAB connection.
• If the UE has more than one RAB connection and the failure is not so critical that it would lease to an RRC Connection drop, only the failed RAB connection is released. The RNC sends a RANAP: RAB RELEASE REQUEST message to the CN and waits for a RANAP: RAB RELEASE COMMAND or RANAP: IU RELASE COMMAND from CN
• Otherwise, both the RRC connection and RAB connection (s) are released. The RNC send a RANAP: IU RELASE REQUEST message to the CN and waits for a RANAP: IU RELEASE COMMAND MESSAGE from the CN
RAB Access failures are not so Common
RRC connection set up failure
RRC Connection is rejected ICSU can not process the callNo processing power on ICSU unit
Incoming call request can not be handled due to lack of ICSU processing
“No hand free” is RNC internal clear code.
RRC Connection Reject
Cause: congestion
UE BS RNC
RRC Connection RequestICSU overload
Failure Counter M1001C618
Call Setup Failures
Presentation / Author / Date
RRC connection setupRAN resources are reserved for signaling connection between UE and RNC
RRC accessConnection between UE and RRC
RRC activeUE has RRC connection. If dropped, also active RAB is dropped.
RAB setupAttempts to start the call
RAB setup access
RAB active phaseUE has RAB connection
CSSR affected if any of the followings take
place.
• RRC Conn. Setup Fail
• RRC Conn. Access Fail
• RAB Setup Fail
• RAB Setup Access Fail
SetupComplete
SetupComplete
AccessCompleteAccess
Complete
ActiveComplete
ActiveComplete
SetupSetup AccessAccess ActiveActive
Atte
mpts
Setup failures(blocking)
Access failures
Acce
ss
ActiveReleaseActive
Release
ActiveFailuresActive
Failures
RRCDrop
Succe
ss
Phase:
RRC and RAB phases
Call setup Success rate -CSSR
/
Call Setup Success Rate (CSSR)
CSSR KPI for CS voice from end user perspective (RNC 565f)
RRC request repetitions done by UE after RRC reject are excluded from denominator (not necessarily seen as failures from the user's perspective)– Emergency calls re-directed to GSM layer are excluded from
denominatorThe occurred cell re-selections are subtracted both from the numerator
and denominator because they are not considered as call attempts from mobile end-user point of view. The UE has made a new RRC connection via another cell and Attempts-counter is updated in the new cell for the new attempt.
))____(
)____((*
)_________
_______
_______
______
______(
)____
_______
____
______
______((*100
_VOICECSATTSTPRABsum
VOICECSCOMPACCRABsum
CALLEMERGREJSTPCONNRRCCONVMTRELACCRRC
CONVMORELACCRRCEMERGENCYRELACCRRC
EMERGENCYREPATTRRCCONVMTREPATTRRC
CONVMOREPATTRRCATTSCALLEMERGENCY
ATTSCALLCONVMTCATTSCALLCONVMOCsum
CONVMTRELACCRRC
CONVMORELACCRRCEMERGENCYRELACCRRC
FAILSCALLEMERGENCYATTSCALLEMERGENCY
FAILSCALLCONVMTCATTSCALLCONVMTC
FAILSCALLCONVMOCATTSCALLCONVMOCsum
CSSRAMR
−−−−
−−−+
+−
−−−+
−+−
=
Presentation / Author / Date
RRC part
RAB part
_PACKET CALL SETUP SUCCESS RATE
Presentation / Author / Date
PS Call Setup Success Rate (CSSR)
))____
____(
)____
____((
*
))________
_______
________
_______
______
______(
)________
_______
____
______
______
______
______((*100
_
BACKGPSATTSTPRAB
INTERPSATTSTPRABsum
BACKGPSCOMPACCRAB
INTERPSCOMPACCRABsum
BACKGMTRELACCRRCINTERMORELACCRRC
BACKGMORELACCRRCINTERRELACCRRC
BACKGMTREPATTRRCBACKGMOREPATTRRC
INTERMOREPATTRRCINTERREPATTRRC
ATTSCALLBACKGMTCATTSCALLINTERMTC
ATTSCALLBACKGMOCATTSCALLINTERMOCsum
BACKGMTRELACCRRCINTERMORELACCRRC
BACKGMORELACCRRCINTERRELACCRRC
FAILSCALLEMERGENCYATTSCALLEMERGENCY
FAILSCALLBACKGMTCATTSCALLBACKGMTC
FAILSCALLINTERMTCATTSCALLINTERMTC
FAILSCALLBACKGMOCATTSCALLBACKGMOC
FAILSCALLINTERMOCATTSCALLINTERMOCsum
CSSRPS
+
+
−−−−
−−−−+
+−−
−−−+−+
−+−+
−
=
Presentation / Author / Date
RNC_576d- Packet Call Setup Success Ratio [%] over the reporting period.
Includes both Interactive and Background PS calls
RRC request repetitions done by UE after RRC reject are included in the formula* The occurred cell re-selections are subtracted both from the numerator and
denominator because they are not considered as call attempts from mobile end-user point of view. The UE has made a new RRC connection via another cell and Attempts-counter is updated in the new cell for the new attempt.
RRC part
RAB part
Low in CSSR: Failure CountersRRC Conn Setup & Access
Analysis
DNO Optimization Processes / JC Ejarque
RRC_CONN_STP_FAIL_AC
Check UL Interference, DL Power & Code occupancy if there is need to upgrade radio capacity
RRC_CONN_STP_FAIL_BTS
Evaluate NBAP counters (radio link reconf. Failures) and KPIs for troubleshooting BTS resources
Check BTS configuration in terms of CE allocation – Use Channel Element (5001) Counters in order to
evaluate lack of Channel Elements
Expand the Capacity or decrease the traffic offered to the site until the problem is solved
In case BTS is not responding delete and re-create COCO
RRC_CONN_STP_FAIL_TRANS
Evaluate Number of reconfiguration failure due the transmission
Check COCO Configuration
Expand the capacity or decrease the traffic offered to the site until the problem is solved
RRC_CONN_STP_FAIL_RNC
Typically RNC fault or Incoming SRNC Relocation Failure (inter-RNC border)
Required ICSU log tracing if no RNC fault or SRNC relocation problem
Communicate the problem to Care department
RRC_CONN_STP_FAIL_RNTI ALLO FAIL
RNC decides to reject RRC connection request due to RNTI allocation failure caused by RRMU overload
Low in CSSR: Failure CountersRRC Conn Setup & Access
Analysis
DNO Optimization Processes / JC Ejarque
RRC_CONN_STP_FAIL_IUB_AAL2_TRANS
Updated when there is shortage or blocking of AAL2 resource
A subset of RRC_CONN_FAIL_TRANS which include ERQ/ECF fail due to some reason such as DMPG
problem in RNC + ERQ/ECF fail due to transport resource needed in RNC between RNC/MGW
RRC_CONN_ACC_FAIL_RADIO
Dominant failure causes due to wrong UL or DL coverage
UL Coverage -> Check if cell is affected by an external interference (Thermal Noise measurements).
DL Coverage -> Tune SCCPCH Power if UE does not receive the RRC Setup Message
-> If UE does not synchronize, reduce N312 from 2 to 1 (depends on UE model) or tune CPICHToRefRABOffset vs.
Qqualmin (or Qrxlevmin)
RRC_CONN_ACC_FAIL_MS
UL Coverage -> Tune Cell Dominance (or CPICH) in order to balance UL and DL (if UL interference if not the cause).
Check if cell is affected by an external interference (Thermal Noise measurements).
Low in CSSR: Failure CountersRAB setup & Access Fail Root Cause Analysis: RT and NRT
(I/B) domains
DNO Optimization Processes / JC Ejarque
RAB_STP_FAIL_XXX_AC
Check UL Interference, DL Power & Code occupancy if there is need to upgrade radio capacity using the already distributed Nokia Capacity Check BO report.
Check PrxTarget / PrxOffset / of the affected cells
RAB_STP_FAIL_XXX_BTS
Evaluate NBAP counters (radio link reconf. Add failures) and KPIs for troubleshooting BTS resources
Check BTS configuration in terms of CE allocation – Use Channel Element (5001) Counters in order to evaluate lack of Channel Elements
Expand the Capacity or decrease the traffic offered to the site until the problem is solved.
In case BTS is not responding delete and re-create COCO
RAB_STP_FAIL_XXX_TRANS
Evaluate Number of reconfiguration failure due the transmission
Check M1005C128 CANC_ADD_SRNC_TRAN_STP_FAIL
Check RAB_STP_FAIL_XXX_IUB_AAL2, M1001C531-C533
Check COCO Configuration
RAB_STP_FAIL_XXX_RNC
Typically RNC fault or Incoming SRNC Relocation Failure (inter-RNC border)
Required ICSU log tracing if no RNC fault or SRNC relocation problem
Communicate the problem to Care department
Low in CSSR: Failure CountersRAB setup & Access Fail Root Cause Analysis: RT and NRT (I/B)
domains
DNO Optimization Processes / JC Ejarque
RAB_ACC_FAIL_XXX_UE
Evaluate Cell resource Prx and Ptx parameters (same as RAB_STP_FAIL_XXX_AC Case)
RAB_ACC_FAIL_XXX_RNC
Typically RNC fault or Incoming SRNC Relocation Failure (inter-RNC border)
Required ICSU log tracing if no RNC fault or SRNC relocation problem
Communicate the problem to Care department.
High in DCR?
DNO Optimization Processes / JC Ejarque
Top (N) drops
Cell and its Neighbour Cells availabilityAlarms/Tickets
Configuration & Parameter audit
SHO Success Rate < 90%?
Conf OK ?
Site OK ?
ISHO Failures
Iur performance Investigation Iur
Audit adjacent sites for alarms, Availability, configuration and
capacity
TrafficNeighbours’ Performance
(use SHO success per adjs counters to identify badly
performing neighbours) & Map
3G Cell at RNC
border?
NO
YES
New site ?
Analyse last detailed radio measurements
RF and IF/IS HO neighbour optimisation
No cell found
ratio >40 %
ISHO Success Rate <
95%
RF and ISHO neighbour optimisation
3G cell covers over a coverage
hole ?
3G cell at inter-RNC border ?
Coverage issue (new site needed)
No cell found ratio > 90 % and enough
ADJG
Core: Inners / Outersaudit
2G : TCH blocking3G : Wrong N’
borgs definition
NO
YES
YES
YES
NO
YES
NO
YES
YES
SHO
ISHO
Top
issues
Call drop analysis process
Presentation / Author / Date
Start
Best server’s RSCP> -102dBm
Best server’s Ec/No> -12dB
Coverage Optimization
Dominance Optimization
Yes Neighbour list Optimization
Missing Neighbour
Yes
SHO Failed
Investigate possible BTS or RNC problem
NoISHO Failed
No
ISHO Failure Analysis
YesSHO Failure Analysis
No
No
No
AB
Call Drop Analysis process – SHO Analysis
Presentation / Author / Date
DL ASU received
SC Clash
UE Tx Power Max
Fix SC Clash
CPICH Optimisation
Uplink Interference
Load Optimisation/ External Interferer
Link Unbalanced
Inter RNC HOCheck Iur
Congestion on target cell
Load Optimisation
Check neighbor definition parameters
Check RF Levels
DL Tx Power Max
Start
Yes
No
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
No
No
No
Yes
No
C
D
Drop call failures – RF issue
Presentation / Author / Date
RF drops mostly due to poor dominance or interference
Poor coverage could lead to ISHO, although poor dominance or interference can cause ISHO to fail.
Rapid field drop can cause drop due to coverage
Poor dominance or interference can cause Compressed Mode (CM) to start even if RSCP is still good.
In CM UE transmits with higher power (more interference) and spends less time on 3G (less accurate measurement reporting)
Poor dominance or interference can lead to Active Set update failures and eventually to drop call.
Poor dominance causes Active Set update failures
A
Drop call failures – RF issue
Presentation / Author / Date
DL synchronisation is lost -> UE has stopped transmitting
TrChAgg and DL DPCCH BER high
A
Drop call failures – RF issue
Presentation / Author / Date
Transport Channel BER. Btw UE<->RNC (MAC layer)
Sometimes DPCCH BER (btw UE<->WBTS) can be a better indicator of what's happening to the dedicated channel than the CPICH EcNo, in particular in the case that power control may not be tracking well
Fairly good CPICH Pilot EcNo
A
Drop Call Failures – System issue BTS
Sudden drop to idle, no disconnect messaging– Site malfunctions to be checked– In the example below site had faulty unit (WTR)
Presentation / Author / Date
B
Drop to IDLE
Drop Call Failures – System Issues RNC
Presentation / Author / Date
Sudden “RRC Connection Release”
DPCCH BER“CC Disconnect” due to
“DL RRC Connection Release”
No response to UL Measurement Reports
In the example site had no alarms, good RF & BER
Not able to add SC265 to Active Set, next call on the same cell => no failure.
Difficult to troubleshoot if the failure does not happen systematically => follow up in the next weeks drive / do a separate drive test in the area
B
Drop call failures (SC conflict)
Presentation / Author / Date
Sudden drop to idle mode (no disconnect messaging)
Cause of the failure: overshooting site and SC reuse
Short term solution to add overshooting neighbour in ADJS definitions
Cell ABC, SC258
Transport channel BLER 100%
C
Drop call failures – Uplink Interference
Presentation / Author / Date
DUL interference from the SIB7 message
Drop call failures – Link Balance
Presentation / Author / Date
DUL & DL Power Control commands can help indicating problems in link balance.
PC frequency is 1500 Hz, thus ideally the sum of PC commands to increase or decrease power is 1500
E.g. if the sum of UL PC commands is < 1500, this would indicate UE is starting to loose synchronization
in Compressed Mode there is less PC commands, UE spends time on 2G
UE RX power control message: DL reception weak -> UE is ordering WBTS to increase power.
Sum of UL PC commands < 1500, UE not receiving all the PC commands.
Drop call failures – System issue RNC or BTS ?
“CC Disconnect” due to “DL RRC Connection Release” is just a consequence of failure which can be due to different reasons
– From UE point of view L3-messaging does not identify the point of failure distinctly
– BTS or RNC failure? => Suspect BTS first, then RNCRule out BTS failures
– Check the site performance from Counters (Iub, Service level, cell resources SHO, etc) and that site is carrying traffic
– PrxNoise, receive link parameters, alarms – SC–reuse– UE performance ?
Identified causes for Active Set Update failure– “Deaf” sites (PrxNoise)– Faulty HW– SC-reuse Presentation / Author / Date
/
HSDPA low throughput?
DNO Optimization Processes / JC Ejarque
OSS counters measurement data
collection
Identify Low
throughput areas if
exist
Low throughput due to low Ec/No or CQI Identify reason for low
throughput if not RF• Mobility (cell change too frequent)• No HSDPA coverage• Iub / Iu User Plane Capacity• Other HSDPA users in same WBTS/Cell• DCH traffic too High (DPA, HSDPA Priority)Start Parameter Optimisation by tuning• HSPDA Mobility parameters (FMCS)• PtxMaxHSDPA (WCEL)• Dynamic Flow Control set to ON (WBTS)
If low throughput due to low Ec/No or Poor CQI, identify reason • Bad Coverage Planning• Quality issue due the neighbour planning
No Optimisation Required
Implement Changes
NO
• HSDPA Parameters are correctly set up• Change Antenna tilt etc.
START
NO
If throughput is low in network level, the reason can be also FTP/HTTP server
settings (fire wall), Measurement tools
etc.
• Low HSDPA throughput root causes analysis process
Business Object report already delivered in order to measure all
related HSDPA throughput KPIs
YES
YES
RU10 Reporting Suite• RNC level
system program added
• Corrections to Capacity report
• Modifications to Service level report (Streaming class added+ some other corrections)
Report Topic Name Report Name Report ID1. System Program System Program RNC Level RSRAN0841. System Program System Program Cell Level RSRAN0002. Capacity RNC Capacity RSRAN0682. Capacity Node B Capacity RSRAN0662. Capacity Cell Capacity RSRAN0672. Capacity NRT Radio Bearer Statistics RSRAN0133. Service Level Service/Session Accessibility Analysis RSRAN0733. Service Level Service/Session Retainability Analysis RSRAN0793. Service Level RAB Holding Times RSRAN0213. Service Level Service Summary RSRAN0034. Traffic Allocated Traffic Amounts (R99 + HSPA) RSRAN0704. Traffic Cell Data Volume and Throughput at RNC RSRAN0774. Traffic Traffic Summary RSRAN0264. Traffic Used CE Capacity per RB Type in RNC RSRAN0224. Traffic Utilization Shares of Total Traffic Allocation Amounts RSRAN0715. Mobility and Handover Active Set Size for NRT-RT Traffic RSRAN0785. Mobility and Handover HSPA Serving Cell Change RSRAN0335. Mobility and Handover IFHO Adjacencies RSRAN0445. Mobility and Handover Inter-System Handover per Cause RSRAN0195. Mobility and Handover Inter-System Handover Performance RSRAN0235. Mobility and Handover Inter-System Handover Reasons RSRAN0185. Mobility and Handover ISHO Adjacencies RSRAN0455. Mobility and Handover Load Based HO Related Resources RSRAN0475. Mobility and Handover Load Based IFHO/ISHO Performance RSRAN0485. Mobility and Handover Load Based IFHO/ISHO Triggering RSRAN0495. Mobility and Handover Service Based IFHO/ISHO Performance RSRAN0505. Mobility and Handover SHO Adjacencies RSRAN0465. Mobility and Handover Soft Handover Performance RSRAN028
Presentation / Author / Date
RNC_169e:DR + GAN HO
added, but load & service based
counters removed
RU10 Reporting Suite• Modifications
to KPIs due to streaming class + 64 HSDPA users/cell
Report Topic Name Report Name Report ID8. Transport ATM Interface Traffic Load RSRAN0818. Transport ATM VCC Traffic Load RSRAN0838. Transport ATM VPC Traffic Load RSRAN0828. Transport FTM Packet Transport Performance RSRAN0768. Transport FTM Performance RSRAN0728. Transport Iu-PS Throughputs RSRAN0648. Transport Iub Throughputs RSRAN0808. Transport Traffic on AAL5 RSRAN0318. Transport Traffic on ATM Layer RSRAN0298. Transport Traffic on Physical Medium Sub-Layer RSRAN0308. Transport Transport Resource Reservations RSRAN0697. HSPA Channel Switching and HSPA Layering RSRAN0757. HSPA CQI Distribution RSRAN0397. HSPA HSPA Code and Modulation Usage RSRAN0347. HSPA HSPA Power Distribution RSRAN0747. HSPA MAC-hs Efficiency RSRAN0407. HSPA MAC-hs Retransmissions by Code and Modulation Usage RSRAN0417. HSPA Number of HSPA Users and UE capability RSRAN0516. Signalling NBAP Signalling RSRAN0276. Signalling RRC Signalling RSRAN038
Presentation / Author / Date
/