RRC Setup Failure SummaryFor internal use
For internal use
Objectives
Describe high level 3G RAN KPIs & proposed target value to them
Describe the factors affecting network performance
Understand the UE impact to the KPIs
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For internal use
For internal use
RAN KPI Classification
The RAN KPI can be classified into the following categories :
Accessibility
Retainability
Usage
Mobility
Integrity
For internal use
For internal use
For internal use
Factors Affecting Network Performance
Many factors and network elements can affect the network performance. Here are some of the main examples:
Quality of network equipment, both hardware and software – BTS, RNC, PS Core, CS Core and transmission equipment
Performance of UE and field measurement tools – inter-operability, sensitivities of measurement parameters, level of accuracy
Quality of network planning and optimization – coverage, interference, parameter tuning, capacity dimensioning
Quality of network implementation - site and network equipment installation, integration and commissioning
Quality of network operation and maintenance
Multi-vendor environment – Application servers, IP Backbone
Measurement method – test setup, service dependent, cluster or system level, area type (dense urban, urban, suburban, rural).
* © Nokia Siemens Networks Presentation / Author / Date
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UE Impact on Performance
The functionality of different UEs are not similar, there are differences in
Power control (RACH process)
UE Sensitivity
The malfunctioning of certain UEs will naturally cause drops in setup of active phase
* © Nokia Siemens Networks Presentation / Author / Date
For internal use
For internal use
The KPIs to be monitored from the RAN could be:
Cell availability
Call Drop rate
SHO success rate
ISHO success rate
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Cell Availability
It is important to make sure that cells within the cluster are in normal working order. Missing cells may have negative impact to the analysis process and optimisation decisions
Prior to RAS51, Cell availability counters was based on monitoring the Code tree. From RAS51 onwards, the Cell Availability counters are based on availability of the WCELLs under a Controlling RNC.
RNC_183c Cell Availability KPI counts Cell availability from user point of view
This KPI was changed in RAS51 due the new counters
This replace old Cell Availability KPI based on Code Three
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
* © Nokia Siemens Networks Presentation / Author / Date
For internal use
Cell Availability
There is also Optional Cell availability KPI (RAN5.1), 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, excluding blocked by user state (BLU) KPI Counts Cell availability from network point of view
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
* © Nokia Siemens Networks Presentation / Author / Date
For internal use
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 e)
CS video calls (RNC 566dc)
PS RT Streaming Calls (RNC 575 d)
PS NRT Calls (Interactive & Background) (RNC 576d)
* © Nokia Siemens Networks Presentation / Author / Date
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RRC: Connection Request
RRC: RRC Connection Request Setup
RRC Connection Access phase
RRC: RRC Connection Completed
RANAP: Initial UE Message
RAB Connection Setup phase
RAB Connection Access phase
Call Set-up Success Rate
DIRECT TRANSFER (Call Proceeding)
RANAP: RAB Assignment Request
RRC: Radio Bearer Set-up
RANAP: RAB Assignment Response
For internal use
Call Setup Success Rate (CSSR)
CSSR KPI for CS voice from end user perspective (RNC 565e)
* 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
due to cell reselection for calls established with the cause
originating conversational call. This is the case when the UE has
sent a new RRC connection request to the new cell while the RRC
connection setup phase is still ongoing in the old cell. The RNC
releases resources for the old RRC connection attempt.
UPDATED: When the RRC connection attempt is released before
the RRC Connection Setup Complete message is received from
the UE due to a new RRC connection request to another cell.
DEPENDENCIES WITH OTHER COUNTERS: M1001C241 -
RRC CONNECTION ACCESS RELEASE DUE TO CELL
RESELECTION
For internal use
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
For internal use
Call Drop Rate (CDR)
Call is dropped if one (or more) of the following RAB, RB or RL, drops.
PS call drop is different than the other call type drops, RAB service can still exits even if the RB and/or RL drops
Call drop could be a reason of coverage or interference issues, SHO problems, missing neighbour, inter RNC problems, just to mention some
Call Drop rate (CDR) is calculated based on RAB activation failures, it can be defined separately for different services
Normal RAB releases are taken into account
Drops during the signalling are not included
100 - 100*(failures /success)
For internal use
Call Drop Rate (CDR)
RNC_231c - CDR KPI for CS Voice (RAB success) from end user perspective
For Voice the release due to pre-emption is included
* © Nokia Siemens Networks Presentation / Author / Date
For internal use
Call Drop Rate (CDR)
RNC_736a - PS call drop ratio KPI is currently same than RAB success for NRT services
Includes both Interactive and Background PS calls
For NRT RABs pre-emption is not possible
As the formula is based on active fail counters it means in this case that when RAB drops in CELL_PCH state two fail counters are updated. This is taken into account in the formula (the drops in CELL_PCH subtracted from all drops.)
Both Interactive and Background PS calls
* © Nokia Siemens Networks Presentation / Author / Date
For internal use
SHO success rate
SHO success rate KPI (195a) is informing how many successful Active set updates we will have compared to initial Addition/Replacement/Deletion requests. This formula is excluding periodical reports, which might occur if for example RNC is busy and cannot process immediately initial request.
* © Nokia Siemens Networks Presentation / Author / Date
For internal use
ISHO Success Rate
Normally ISHO may fail due to missing target cell or the cell is not good enough
coverage, interference or configuration problem
From the measurement point of view the ISHO is divided into two phases:
Inter-system measurement
Inter-system handover
The Real Time and Non Real Time Inter System HO differs in nature. Therefore the ISHO KPI can be splitted in RT and NRT parts
In case of Multi-RAB having at least one RT RAB only RT counters are updated and the Handover is performed using RT handover procedure
* © Nokia Siemens Networks Presentation / Author / Date
For internal use
ISHO Success Rate
Example NBAP and RRC compressed mode signalling for a CS service inter-system HO
IS_HHO_Att_xx
UE
RRC: Physical Channel Reconfiguration
NBAP: Compressed Mode Command
GSM BSIC Verification
GSM RSSI Measurement
For internal use
ISHO Success Rate III
KPIs for ISHO measurement started for RT and NRT (RNC_294c, RNC_295c)
KPIs for not good enough cells for RT and NRT, RNC_296a, and RNC_297a)
ISHO success rate for RT services (RNC_300c)
ISHO success rate for NRT services (RNC_301c)
RAS51 features;
For internal use
Load and Service (RAS51)
Load and Service (RAS51)
This KPI cover both NRT and RT ISHO success
* © Nokia Siemens Networks Presentation / Author / Date
For internal use
For internal use
Achievable Today in Well Optimized Networks
KPIs are based on field and counter measurements in Customer Networks
KPIs are based on field and counter measurements in customer networks
Values will be updated on quarterly basis
New CSSR formulas
Projects reporting values below these are performing under par level compared to peer networks.
Use only static throughput values if nothing else not specifically required by customer.
Depending on GSM network Quality
Values are reached when RRC “pollution” is properly addressed if present.
Cell_PCH not used.
Note !!: These values are only indicative and for discussion purposes, the values could be better or worse depending on the case
UE, Coverage, Interference (indoor/outdoor), Exclusions, Used formulas
Sheet1
KPI
KPI
Highest
Average
Highest
Average
3GIS
Cegetel
Starhub
TMO
98.50
98.50
97.75
0.98
99.00
98.50
97.75
98.00
97.50
97.00
98.50
98.50
99.0
98.50
98.50
96.88
99.00
98.50
96.88
96.00
96.00
97.00
98.50
98.00
99.0
98.50
98.50
97.25
99.00
98.50
97.25
96.00
97.50
97.00
98.50
98.50
99.2
57.00
58.00
58.00
58.00
58.00
55.00
56.00
54.33
60.00
56.00
54.33
N/A
58.50
58.00
29.00
58.00
29.00
N/A
56.50
55.00
55.00
60.00
55.00
55.00
N/A
119.00
115.00
113.50
115.00
113.50
N/A
116.00
110.00
110.00
120.00
110.00
110.00
N/A
350.00
340.00
340.00
340.00
340.00
N/A
340.00
336.00
328.00
350.00
336.00
328.00
N/A
N/A
5/100
95.00
95.00
-
-
-
N/A
Value below highest customer commitment
No customer commitments made or committed values very low
0.0098347107
For internal use
AMR CSSR example
Customer average ~99%
For internal use
AMR CCSR example
Customer average ~99%
Start TX/RX
UE
NBAP: Radio Link Addition Response
RNCBTS
Start TX/RX
UE
NBAP: Radio Link Addition Response
REQ_ON_SHOCELL_REPL_
EQ_ON_SHOCELL_DEL_R
EQ_ON_SHOCELL_ADD_R
ES_ON_SHOSUCC_UPDAT
MEASUREMENT REPORT (1A,1B,1C)
MEASUREMENT REPORT (1A,1B,1C)
RECEIVED BY THE CELL UNDER OBSERVATION
RECEIVED BY THE CELL UNDER OBSERVATION
UPDATED FOR ALL THE CELLS WITHIN AS WHEN MEAS. REPORT IS RECEIVE
UPDATED FOR ALL THE CELLS WITHIN AS WHEN MEAS. REPORT IS RECEIVE
D
D
REQ_ON_SHOCELL_REPL_
EQ_ON_SHOCELL_DEL_R
EQ_ON_SHOCELL_ADD_R
ES_ON_SHOSUCC_UPDAT
MEASUREMENT REPORT (1A,1B,1C)
MEASUREMENT REPORT (1A,1B,1C)
RECEIVED BY THE CELL UNDER OBSERVATION
RECEIVED BY THE CELL UNDER OBSERVATION
UPDATED FOR ALL THE CELLS WITHIN AS WHEN MEAS. REPORT IS RECEIVE
UPDATED FOR ALL THE CELLS WITHIN AS WHEN MEAS. REPORT IS RECEIVE
D
D
1.00Call Drop Rate AMR (%)1.0
2.00Call Drop Rate UDI (%)1.0
1.00Call Drop Rate PS (%)1.0
N/ARRC Setup Success Rate (%)99.0
55.00
N/A
53.00
N/A
57.00
N/A
55.00
N/A
118.00
N/A
115.00
N/A
355.00
N/A
330.00
N/A
250
N/A
N/A