3G Retainability Troubleshooting

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Retainability is defined as the ability of a user to retain Retainability retain its requested service once connected for the desired duration

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The metrics PRESENT within the Ericsson RNC and OSS provide counters and KPI’s  that describe the behavior and experience of the subscribers In the UMT UMTS S network

=100*(sum(pmNoSystemRabReleaseSpeech)/sum(pmNoSystemRabReleaseSpeech)+ sum(pmNoNormalRabReleaseSpeech))

=100*(sum(pmNoSystemRabReleaseCs64)/sum(pmNoNormalRabReleaseCs64)+ sum(pmNoSystemRabReleaseCs64))

=100*(sum(pmNoSystemRabReleasePacket-pmNoSystemRabReleasePacketUrapmNoSystemRbReleaseHs)/sum(pmNoNormalRabReleasePacket+pmNoSystemRabReleasePacketpmNoNormalRabReleasePacketUra-pmNoSystemRabReleasePacketUra+pmChSwitchSuccFachUrapmNoSystemRbReleaseHs-pmNoNormalRbReleaseHs+pmNoSuccRbReconfOrigPsIntDch+ pmUpSwitchFachHsSuccess))

=100*(sum(pmNoSystemRbReleaseHs)+sum(pmNoSystemRabReleasePsStreamHs)/ sum(pmNoSystemRbReleaseHs)+sum(pmNoSystemRabReleasePsStreamHs)+ sum(pmNoNormalRabReleasePsStreamHs)+sum(pmNoNormalRbReleaseHs)+ sum(pmNoSuccRbReconfPsIntDch)+sum(pmPsIntHsToFachSucc))

=100*(sum(pmNoSystemRbReleaseEul)/(sum(pmNoSystemRbReleaseEul)+sum(pmNoNormalRbReleaseEul) +sum(pmNoSuccRbReconfOrigPsIntEul)+sum(pmPsIntHsToFachSucc))

Drops due to Neighbors Drops due to Soft handover Failures Drops due to Uplink Sync Drops due to Congestion

pmNoSysRelSpeechNeighbor pmNoSysRelSpeechSoHo pmNoSysRelSpeechUlSynch pmNoOfTermSpeechCong

pmNoAttOutIratHoSpeech-pmNoSuccessOutIratHoSpeechpmNoFailOutIratHoSpeechReturnOldChPhyChFailIRAT Drops pmNoFailOutIratHoSpeechReturnOldChNotPhyChFailpmNoFailOutIratHoSpeechUeRejection pmNoSystemRabReleaseSpeechpmNoSysRelSpeechUlSynch-pmNoSysRelSpeechSoHoOther Reasons Drops pmNoSysRelSpeechNeighbor-pmNoOfTermSpeechCong-IRAT Drops Overshooting pmPropogationDelay RTWP pmSumUlRssi, pmSamplesUlRssi Cell Availability pmCellDowntimeAuto, pmCellDowntimeMan Alarms/Transmission/ CM & FM Dumps HW Issues

Layer 1 process ensures that there is no parameter discrepancy MO

Parameter

dlcodeadm hsdpauseradm eulServingCellUsersAdm eulServingCellUsersAdmTti2 Maxrate MaxTransmissionPower  primaryCpichPower  Power offset Utrancell

Pwradm sf16adm sf16admUl sf16gAdm sf32Adm sf4AdmUl sf8Adm sf8AdmUl sf8gAdmUl codeThresholdPdu656

Hsdsch

hsMeasurementPowerOffset numHsPdschCodes numHsScchCodes

Iublink

dlhwadm ulHwAdm eulMaxTargetRtwp( numEagchCodes

Eul

numEhichErgchCodes initialAckNackRepetitionFactor  secondarySchPower 

FOLLOWING SET OF Parameters can be CONSIDERED FOR IMPROVING THE retainability performance

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Radio connection supervision (RCS) strategy consISTS OF some PARAMETERS, TIMERS & system constant to supervise the connection at L1 (phySIcal), L2 (RLC) and L3 (RRC) lAYERS in order to dECIDE the best moment to release the connection

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A new RCS strategy has been considered for better handling OF the current 3G traffic & DCR PERFORMANCE IMPROVEMENT

6

8

4 7

1

2 3

1

RKLP101

2

RNGP101

3

RNSK101

4

RPUN103

5

RAUR101

6

RGOA101

7

RPUN101

8

RPUN102

5

9

1

2

3 5 4

E/// 3G Retainability SSP | GRAN/WRAN/D | 2014-07-22 | Page 15 (27)

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High values of RTWP observed PERSISTENTLY in all areas across RAJKOT RNC THROUGHOUT THE MONTH OF MARCH’13 & APRIL’13 HIGH VALUES OF RTWP OBSERVED INTERMITTENTLY ACROSS OTHER RNCs AS WELL Drop Call Rate (Voice, HSDPA, R’99, HSUPA) are significantly affected All other MAJOR KPIs seem to be normal Parameter Audit done on RNC & Cell Level & no MAJOR discrepancies WERE found No common alarms are observed on the affected cells WNCS recording performed and processed to find for new site or missing neighbor issue External Interference suspected due to sudden fluctuation in RTWP Need to use spectrum analyzer and check the source of interference in these towns

Unknown SQN100-3_ Q10_ RFN81UW Galaxy S III BlackBerry 9900 BlackBerry 9360 9320 iPhone 4 (A1332) Torch 9810 A68

23245

409

1.73

14644

212

1.43

8808 7510 5923 4760 3646 3202 216

265 476 393 363 224 239 192

2.92 5.96 6.22 7.09 5.79 6.95 47.06

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WHILE SETTING UP AN EUL RAB, INFORMATION IS SENT BY RNC TO UE DESCRIBING THE MAPPING FOR E-TFCI & E-TBS THIS INFORMATION DEFINES WHICH MINIMUM E-TFCI THE UE IS ALLOWED TO USE, WHICH IS SET BY THE SYSTEM CONSTANT “EDCHMINIMUMSETETFCI” & CAN TUNED PER UERC DEFAULT VALUE OF 1 FOR EUL-10MS RABS CORRESPONDS TO 186BIT/FRAME AS PER 3GPP SPECIFICATIONS SHOWN BELOW, WHICH IS ONLY GOOD ENOUGH FOR SRB BUT NOT ENOUGH TO HAVE A DATA PDU [MINIMUM DATA PDU SIZE CORRESPONDS TO E-TFCI=4] IN COVERAGE LIMITED AREAS, WITH THIS VALUE, ONLY SRB IS SENT IN THE UPLINK & WITH NO DATA IN THE UPLINK, L2 EXPIRES RESULTING IN DROP CALLS

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WHEN UE IS POWER LIMITED & EDCHMINIMUMSETETFCI=1, THE UE CANNOT SCALE TO E-TFCI=4, AND INSTEAD SELECTS E-TFCI=1. SINCE THIS TB SIZE IS LESS THAN THE MIN. DATA PDU SIZE, THE DATA IS REDUCED TO 0.

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THIS WOULD CAUSE EUL USER FREEZE WHICH INTURN WILL RESULT IN DROP CALLS DUE TO RLC LAYER LACK OF RESPONSE IN UL OR TCP TIMEOUT

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WHEN THE UE IS POWER LIMITED ON E-TFCI=4 & EDCHMINIMUMSETETFCI=4, IT SCALES DPCCH, EDPCCH & EDPDCH allowing THE DATA COVERAGE TO CONTINUE

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UE WILL KEEP ON TRYING UNTIL IT GETS AN “ACK” OR FAILS AT THE MAX. NO. OF RETRANSMISSIONS SET BY THE PARAMETER “HARQTRANSULMAX=4”

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DUE TO THE HARQ RETRANSMISSIONS, DATA HAS A CHANCE TO GET THROUGH WHICH INTURN WILL REDUCE THE RLC OR TCP TIME OUT & THUS REDUCE THE DROP CALLS

UeRc=25,UeRcPhyChEdch=1 edchMinimumSetEtfci

1

4

: To reduce the 3G voice drop call & improve network quality : If the quality measure of the new cell in the proposed  Active Set exceeds the quality measure of the best cell in the Active Set by the amount of releaseConnOffset dB's, the connection shall be released if the RADIO LINK cannot be added 