amdocs_optimization guidelines for accessibility v1

NSN Optimization Guidelines for CS and PS KPIsCS and PS Accessibility

28th Jan, 2014

CS and PS Accessibility

• KPI Formula• RRC Setup & Access Failures• RAB Setup and Access Failures

Information Security Level 1 – Confidential© 2014 – Proprietary and Confidential Information of Amdocs3

Call Setup Success Rate (CSSR)Call setup success Rate (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.●For CS, the Call setup success rate CSSR is essentially

● RRC Setup & Access Success * RAB Setup & Access SuccessFor PS Session setup success

●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)


UERRC: Connection Request

RRC: RRC Connection Request Setup

RRC: RRC Connection CompletedRRC: 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

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

Definition of Accessibility (CSSR)

RRC Connection Access phase RNC waits reply from UE

RRC Connection Setup phaseResource Reservation in RNC, BTS, Transmission

RAB Connection Setup phaseResource Reservation in RNC, BTS, Transmission


KPI FormulaCS Accessibility● KPI Formula : RRC Setup & Access Success * RAB

Setup & Access Success (RNC_5093b >99%)100*sum(MOC_CONV_CALL_ATTS - MOC_CONV_CALL_FAILS + MTC_CONV_CALL_ATTS - MTC_CONV_CALL_FAILS + EMERGENCY_CALL_ATTS - EMERGENCY_CALL_FAILS -RRC_ACC_REL_EMERGENCY - RRC_ACC_REL_MO_CONV - RRC_ACC_REL_MT_CONV +CELL_UPDATE_SUCC_CS_CALL) --------------------------------------------------------------------------------------------------------------------------sum(MOC_CONV_CALL_ATTS + MTC_CONV_CALL_ATTS + EMERGENCY_CALL_ATTS - RRC_ATT_REP_MO_CONV - RRC_ATT_REP_MT_CONV - RRC_ATT_REP_EMERGENCY - RRC_ACC_REL_EMERGENCY - RRC_ACC_REL_MO_CONV - RRC_ACC_REL_MT_CONV - RRC_CONN_STP_REJ_EMERG_CALL+CELL_UPDATE_ATT_CS_CALL) * sum(RAB_ACC_COMP_CS_VOICE) --------------------------------------------------------------------------------------------------------------------------sum(RAB_STP_ATT_CS_VOICE)


KPI FormulaPS Accessibility● KPI Formula : RRC Setup & Access Success * RAB

Setup & Access Success (RNC_576e >99%)100 *sum(MOC_INTER_CALL_ATTS - MOC_INTER_CALL_FAILS + MOC_BACKG_CALL_ATTS - MOC_BACKG_CALL_FAILS + MTC_INTER_CALL_ATTS - MTC_INTER_CALL_FAILS + MTC_BACKG_CALL_ATTS - MTC_BACKG_CALL_FAILS + MOC_HIGH_PRIOR_SIGN_ATTS - MOC_HIGH_PRIOR_SIGN_FAILS + MTC_HIGH_PRIOR_SIGN_ATTS - MTC_HIGH_PRIOR_SIGN_FAILS - RRC_ACC_REL_INTERACTIVE - RRC_ACC_REL_MO_BACKGROUND - RRC_ACC_REL_MO_HIGH_PR_SIGN - RRC_ACC_REL_MO_INTERACTIVE - RRC_ACC_REL_MT_BACKGROUND - RRC_ACC_REL_MT_HIGH_PR_SIGN)-------------------------------------------------------------------------------------------------------------------------------sum(MOC_INTER_CALL_ATTS + MOC_BACKG_CALL_ATTS + MOC_HIGH_PRIOR_SIGN_ATTS + MTC_INTER_CALL_ATTS + MTC_BACKG_CALL_ATTS + MTC_HIGH_PRIOR_SIGN_ATTS -RRC_ATT_REP_INTERACTIVE - RRC_ATT_REP_MO_INTERACTIVE - RRC_ATT_REP_MO_HIGH_PR_SIGN - RRC_ATT_REP_MO_BACKGROUND - RRC_ATT_REP_MT_BACKGROUND - RRC_ATT_REP_MT_HIGH_PR_SIGN - RRC_ACC_REL_INTERACTIVE - RRC_ACC_REL_MO_BACKGROUND - RRC_ACC_REL_MO_HIGH_PR_SIGN - RRC_ACC_REL_MO_INTERACTIVE - RRC_ACC_REL_MT_BACKGROUND - RRC_ACC_REL_MT_HIGH_PR_SIGN) *sum(RAB_ACC_COMP_PS_INTER+RAB_ACC_COMP_PS_BACKG)---------------------------------------------------------------------------------------------------------------------------------sum(RAB_STP_ATT_PS_INTER+RAB_STP_ATT_PS_BACKG)


Failure analysis for low CSSR/PSSR cells

RRC, RAB Setup, PS Setup Failure due AC

RRC, RAB, HSPA Setup Performance KPI/counters

Follow-UpYes

No

Air Interface

RRC, RAB Setup, PS Setup Failure due

BTS

Yes

No

BTS

RRC, RAB Setup, PS Setup Failure due Iub

Yes

No

Iub

RRC, RAB Setup, PS Setup Failure due RNC, DMCU

YesRNC

RRC, RAB Setup failure due to Frozen BTS

No

YesHigh Traffic Event


Failure and abnormal release causesThe failure and abnormal release causes for RRC and RAB phases are presented in the tables below:

* In this case, RRC/RAB phase may fail due to left-hand –side failure reason, but instead of that failure counter the ‘RNC internal’ failure counter is updated.


RRC Setup and Access FailuresRRC setup failure causes● RRC setup failure causes :1) Handover Control Fails (RNC_2217a)

2) Admission Control Fails (RNC_2218a)

3) BTS Fails (RNC_2219a)

4) Transport Fails (RNC_2220a)

5) RNC Fails (RNC_2221a)

6) Frozen BTS Fails (RNC_2222a)

7) Iub AAL2 Fails (M1001C530)

8) RNTI Fails (M1001C247)

9) ICSU Fails (M1001C618)


1. Check cell power load is in marginal area or overload area if power parameter setting are correct from RSRAN067/ RSRAN086 report.

2. Check power related parameter settings (Ptxcellmax, MaxDLPowercapability, Ptxtarget PtxmaxHSDPA etc.). Ensure Ptxcellmax = MaxDLPowercapability and Ptxtarget should be accordingly up to 90% of transmitted power. And Ptxoffset value should be 5-8%.

3. Check CPICH Power value i.e. 8-10% of transmitted power.4. Check PRACH propagation delay report, 90% sample must be below 1st tier neighbours, downtilt the

sector if overshooting is there.5. Check SHO overhead value, it should be between 20-30% to save radio resources for other services.

Check tilt of site. Fine tune addition window and drop window size/time to reduce SHO overhead.6. Check RRC EC mapping with SRB bit rates to 3.4 kbps and 13.6 kbps.7. Check MaxBitRateDLPSNRT and InitialBitRateDL. Max bitrate used should not exceed 128 Kbps and

initial bit rate can be downgraded to 8 kbps. Also MinAllowedBitRateDL should be 8 Kbps.8. Check Dylo, TBO implementation for better PS NRT bitrate optimization.9. Check other carrier load and balance the traffic if required by DRRC, Cell reselection criteria, Azimuth

planning and also check compressed mode. 10. Implement AMR Directed retry feature.11. Check max and min power of radio link.

Maximum Radio Link Power: RT Service Ptx_max_RL: Minof( ( cpich power – cpichtorefraboffset +SF_Adjustment), (ptxtotalmax- ptxdpchmax))

and PS & multiRab: : Ptx_max_RL:Min of (( cpichpower- cpichrefraboffset+SF_Adjustment), (Ptxtotalmax- ptxdpchmax), ptxabsmax))

Minimum Radio Link Power: Max( (ptx_max_RL – PcrangeDL), ( Ptxmax-Ptxdpchmin)) for every service.

Note : Increase PA power if possible or Plan for another carrier.

Admission Control Fails due to DL Power


Effects of CPICH Power modification

CPICH Transmit Power

Increased soft handover overhead

Too much power

Too little power

Less Power Available for traffic

CPICH coverage holes

code detection

Unreliable channel estimation

Early cell reselection /handover

Increased Eb/No requirement

Reduced system capacity


Reduced system coverage

Slow initial synchonisation

Non- ideal traffic distribution

Late cell reselection /handover


CPICH Transmit Power

Increased soft handover overhead

Less Power Available for traffic

CPICH coverage holes

Unreliable scrambling code detection

Unreliable channel estimation

Early cell reselection /handout too early

Increased Eb/No requirement



Reduced system coverage

Slow initial synchonisation


Late cell reselection /handout too late



DL Common Control Channel

● DL Common control channels must be heard over the whole cell, thus their power setting is designed for “cell edge”.

● DL Common Channels do not have a power control.

● The power of the common physical channels are set relative to the CPICHPtxSecSCH -3 dB 30 dBmPtxPrimaryCCPCH -5 dB 28 dBmPtxSCCPCH 1 (SF=64) 0 dB 33 dBmPtxSCCPCH 2 (SF=256) -5 dB 28 dBmPtxSCCPCH 3 (SF=128) -2 dB 31 dBmPtxPICH -8 dB 25 dBmPtxAICH -8 dB 25 dBmPtxOffsetEAGCH -5 dB 28 dBmPtxOffsetERGCH -11 dB 22 dBm

defaultvalues


Total DL Common Channel Power without HSPA

Service Type

DefaultPower

MinimumActivity

Minimum Average

Power

Maximum Activity

Maximum Average

PowerCPICH 33 dBm 100 % 33 dBm 100 % 33 dBm

P-SCH 30 dBm 10 % 20 dBm 10 % 20 dBm

S-SCH 30 dBm 10 % 20 dBm 10 % 20 dBm

P-CCPCH

28 dBm 90 % 27.5 dBm 90 % 27.5 dBm

S-CCPCH

33 dBm 25 % 27 dBm 115 %* 33.6 dBm

PICH 25 dBm 96 % 24.8 dBm 96 % 24.8 dBm

AICH 25 dBm 0 % - 80 % 24 dBm

Total - - 35.5 dBm3.5 W

- 37.5 dBm5.6 W

* S-CCPCH control (TFCI) bits transmitted with higher power than data bits


1. Check Code tree blocking rate from RSRAN067 report. High code blocking does not necessary mean the call setups are failing. Dynamic resource allocation will downgrade codes allocated for HSDPA if R99 traffic increase. Ensure Code blocking rate per SF to see what traffic is cause of the blocking. E.g. voice use SF128.

2. Check that code tree optimization is enabled. Fine tune parameters CodeTreeOptimisation, CodeTreeOptTimer and CodeTreeUsage for code tree optimization.

3. Check SHO overhead value, it should be below 35% to save radio resources for other services. Check tilt of site. Fine tune addition window and drop window size /time to reduce SHO overhead.

4. Check MaxBitRateDLPSNRT and InitialBitRateDL. Max bitrate used should not exceed 128 Kbps and initial bit rate can be downgraded to 8 kbps. Also MinAllowedBitRateDL should be 8 Kbps.

5. Check FACH load and reduce FACH to DCH transitions by tuning parameter TrafVolThresholdDLHigh/ Low to increase buffer size for FACH state. And check timer values for state transition.

6. Implement HSDPA dynamic resource allocation and Fine tune HSPDSCHCodeSet, HSPDSCHMarginSF128 for HSDPA code upgrade and downgrade.

7. Implement TBO feature which use resources more efficiently. 8. Implement F-DPCH feature.9. Add additional carrier if still congestion is there.

Admission Control Fails due to DL Code


1. Check uplink load is in marginal or overload area and RTWP from RSRAN067.

2. Check UL power based RRM parameters Prxtarget, PrxTargetPSMax and PrxTargetPSMin, If Prxtarget >=30, means UL AC is disabled.

3. Check Missing neighbors which can cause high interference.

4. Check antenna cables and connectors which cause interference in the network and pushing extra traffic to cells. It can be checked in non-busy hour by simultaneous HSPA users.

5. Analyze network signaling Load (Delayed handover makes similar effect as missing neighbor).

6. Fine Tune parameter setting of RRM UL activity factor for HSDPA UL return channel.

7. Fine tune initial R99 SIR and HSUPA SIR targets. Need to optimize min and max SIR target values for radio link for OLPC.

8. Optimize RACH load and fine tune RACH capacity, PRACH preambles..

9. Analyze UEs acknowledging RRC Connection Setup erroneously (Fast dormancy highlights this as RRC Connection Setup happens more often).

10. Check PRACH propagation delay as coverage decreases when the UEs in the cell edge run out of tx power

11. Check PrxNoise parameter whose setting affects the capacity of cell (PrxNoise too low: overestimation of cell load and can lead to unnecessary call blocking, PrxNoise too high: underestimation of cell load and can lead to overload situation). Enable PrxNoiseAutotuning.

Admission Control Fails due to UL Load


1. Check simultaneous HSUPA users and limit no. of users using 2ms TTI if required. Disable higher SF utilizing HSUPA users using parameter MaxTotalUplinkSymbolRate setting..

2. Check MaxBitRateULPSNRT and InitialBitRateUL. Max bitrate used should not exceed 128 Kbps and initial bit rate can be downgraded to 8 kbps. Also MinAllowedBitRateUL should be 8 Kbps.

3. Implement HSDPA 16Kbps UL return channel feature and fine tune HSDPAMaxBitrateUL to 128 Kbps.

4. Implement CPC feature.

5. Fine tune load control parameters like RRIndperiod, PrxMeasAveWindow and PrxMeasFilterCoeff to report optimum load to AC.

Admission Control Fails due to UL Load


1. Analyse R99CEs and Subunit utilization from RSRAN131 report.

2. Check alarms if indicating HSDPA/HSUPA configuration fail reflecting. Also check system module failure alarm.

3. Check NodeB behavior, sometimes high number of BTS fails observed if RRC setup fails.

4. Check MaxBitRatePSNRT and InitialBitRate. Max bitrate used should not exceed 128 Kbps and initial bit rate can be downgraded to 8 kbps. Also MinAllowedBitRate should be 8 Kbps.

5. Check SHO overhead value, it should be below 35% to save radio resources for other services. Fine tune addition window and drop window size /time to reduce SHO overhead.

6. Increase CE steps if CE utilization is high (> 80-85%).

7. Evaluate NBAP counters (radio link reconfiguration failures)-- NBAP Signalling Per cause Report

8. Check any mass event occurred if frozen BTS fails are observed.

9. Enhance FSMxx module if still congestion observed.

BTS / Frozen BTS Fails


1. Check Iub utilization for ATM and IP sites. Refer report number RSRAN087.

2. Check M800 report to identify failures due to lack of Iub Bandwidth, lack of RNC capacity and AAL2 signalling failure.

3. Check COCO configuration for ATM sites.

4. Check AAL2 CAC resource reservation, VPC/VCC utilization measuremements.

Transport / Iub AAL2 Fails


1. Check avg. and max RNC units utilization by M592 reports.

2. Implement URA-PCH in network. And fine tune state transitions parameters.

3. Enable Fast dormancy handing.

4. Fine tune RRC wait timers parameters and decrease RACH capacity.

5. Fine tune Active set size and addition and drop window size and time for Active set update.

6. Fine tune FACH capacity parameters to avoid DCH selection for short message due to high penetration of smartphones.

7. Increase RNC capacity to minimize RACH load.

RNC / ICSU, DMPG Fails


1) Check common channel Load PRACH Message Load RACH Throughput (increase RACHCapacity if required) Check PCH load and throughput. Monitor FACH-c and u Load and throughput.

2) Enable Common channel setup feature and its mapping with different RRC causes.

3) Enable DRRC for traffic balancing.

4) Fine tune RRC wait timers parameters to decrease uplink load and avoiding aggressively RRC retry.

5) Enable Directed Retry feature.

6) Enable PCH24kbps using PtxSCCPCH2.

Miscellaneous


1) Parameters Details

2) Counters Details

Appendix


Thank You

amdocs_optimization guidelines for accessibility v1

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