lte high capacity event parameters

Lte High capacity event parameters

Lte High capacity event parameters Prepared By:RAJESH KUMARFocus areasLTE High Capacity Focus Areas Control Channel Dimensioning PUCCH ResourcesPDCCH ResourcesUL Noise RisePRB Utilization / Cell Throughput CapacityMP LoadRRC Connection Setup IntensityDue to UE releases by InactivityDue to UE releases by RLC SupervisionIncoming Handover IntensityHardware expansionConnected Users LicenseSummary of High Capacity Parameter Settings

Focus areasLTE High Capacity Focus Areas Control Channel Dimensioning PUCCH ResourcesPDCCH ResourcesUL Noise RisePRB Utilization / Cell Throughput CapacityMP LoadRRC Connection Setup IntensityDue to UE releases by InactivityDue to UE releases by RLC SupervisionIncoming Handover IntensityHardware expansionConnected Users LicenseSummary of High Capacity Parameter Settings

Control channel resourcesUL Control Channel ResourcesPUCCHnRB,PUCCH depends on number of SR and CQI resources Focus Area for High Capacity ParametersPRACHnRB,PRACH in 1 radio frame is independent of bandwidth and is fixed for different cell rangeDL Control Channel ResourcesPDCCHnRE,PDCCH depends on CFI Focus Area for High Capacity ParametersPCFICHnRE,PCFICH in 1 radio frame is 160, independent of bandwidth and # of antenna portsPHICHnRE,PHICH in 1 radio frame depends on bandwidth and is fixed for different bandwidthPBCHnRE,PBCH in 1 radio frame is 240, independent of bandwidth and # of antenna portsPucch resourcesintroPUCCH is used for transmittingSR, HARQ ACK/NACK (PUCCH Format 1)CQI, RI (PUCCH Format 2)UE is allocated SR and CQI resources during setup procedure, and the resources are kept as long as UE is UL synchronized.UE is not allowed to connect to a cell if theres no free SR resourcesnoOfPucchSrUsers and noOfPucchCqiUsers determine number of resources for SR and CQI per cellPUCCH is allocated by2 RB at the band edges (RB-pair)Time domain sharing, each PUCCH is assigned to a UE with a periodicity deciding which sub-frame UE can access PUCCH (default periodicity for CQI is 80ms, SR is 10ms)Current settingnoOfPucchSrUsers, noOfPucchCqiUsers = 320

Pucch resourceshighest pucch resources for sr & CQI

noOfPucchSrUsers (limited by nCQI.res)=noOfPucchCqiUsers=640 This setting will reduce peak UL throughput3rd attempt (nRB,format1 = 6, nRB,format2 = 2)nSR,res = (36*6-44)*10*10/10 = 1720 (>810)nCQI,res = 2*4*80*10/10 = 640 (810)nCQI,res = 3*4*80*10/10 = 960 (>880)1st attempt (nRB,format1 = nRB,format2 = 4)nSR,res = (36*4-44)*10*10/10 = 1000 (>810)nCQI,res = 4*4*80*10/10 = 1280 (>880)

Pucch resourcesnumber of pucch rb-pairsRecommended setting (noOfPucchSrUsers = noOfPucchCqiUsers = 640)nPUCCH,SR = [640/10 * 10/10] = 64nRB,Format1 = [(64+44)/36] = 3nRB,Format2 = [640/(4*80) * 10/10] = 2nRB,PUCCH = 3 + 2 = 5 (even 6, < max RB pair per DU)

Odd number will leave 1 RB-pair unused by PUCCH and PUSCH Current setting (noOfPucchSrUsers = noOfPucchCqiUsers = 320)nPUCCH,SR = [320/10 * 10/10] = 32nRB,Format1 = [(32+44)/36] = 3nRB,Format2 = [320/(4*80) * 10/10] = 1nRB,PUCCH = 3 + 1 = 4

Pucch resourcesobservabilitypmPucchSrCqiResCongCqiThe number of times a PUCCH allocation request for CQI resource(s) could not be granted

pmPucchSrCqiResCongSr The number of times a PUCCH allocation request for SR resource(s) could not be granted

Pdcch resourcesadaptive pdcch (1/2)PDCCH is used for UL/DL scheduling assignments, e.g. PUSCH/PDSCH resource indication, transport format indication, HARQ info and PUCCH/PUSCH PC commandsNumber of OFDM symbols available for PDCCH in a sub-frame is CFI. Max OFDM symbols, limited by pdcchCfiMode, is not exceeded

Recommended setting:Bandwidth =< 10MHz : CFI_AUTO_MAXIMUM_3 (current setting), to handle peaks of PDCCH loadBandwidth > 10MHz : CFI_AUTO_MAXIMUM_2, since higher number of symbols for PDCCH can increase RB pairs for PUCCH, which leads to reduced UL peak rate

Pdcch resourcesobservabilitypmPdcchCceUtilPDF of % of CCEs utilized compared with total CCEs available (at the maximum CFI permitted by pdcchCfiMode) each subframe, considering bandwidth and antenna configuration.

pmPdcchCfiUtilPDF of number of subframes each CFI value was assigned


Ul noise risepzeronominalpucch, pzeronominalpuschpZeroNominalPucch and pZeroNominalPusch can be used to adjust power control target, trade off between coverage and capacityCurrent settingpZeroNominalPucch = -117dBmpZeroNominalPusch = -96dBm (should be reduced to default -103dBm to reduce UL interference peaks at high load)

Ul noise riseobservabilitypmSinrPucchDistr Distribution of the SINR values calculated for PUCCH

pmSinrPuschDistr Distribution of the SINR values calculated for PUSCH

pmRadioRecInterferencePwr The measured Noise and Interference Power on PUSCH, according to 36.214 of the SINR values calculated for PUSCH

pmRadioRecInterferencePwrPucch The measured Noise and Interference Power on PUCCH, according to 36.214

pmRadioTbsPwrRestricted The number of Transport Blocks on MAC level scheduled in uplink where the UE was considered to be power limited.

pmRadioTbsPwrUnrestricted The number of Transport Blocks on MAC level scheduled in uplink where the UE was NOT considered to be power limited.


Prb utilization / cell throughput capacityschedulingalgorithm

System FairnessCell ThroughputCurrent setting schedulingAlgorithm = 3 (PROPORTIONAL_FAIR_MEDIUM), propose to change to following at high load4 (PROPORTIONAL_FAIR_LOW) or5 (MAXIMUM_C_OVER_I)Higher Cell ThroughputHigher TTI utilizationHigher PRB utilization

Performance comparison between different schedulersBest cell throughput (from lowest to highest)RR < ER < PFH < PFM < PFL < MCISystem fairness (from lowest to highest)MCI < PFL < PFM < PFL < ER < RR

For PFL or Max C/I, user at cell edge may have low throughput, as scheduler has higher weightage for RF conditionPrb utilization / cell throughput capacityobservabilityAverage Cell Throughput UL = pmUeThpVolUl/(pmSchedActivityCellUl/1000)Average Cell Throughput DL = pmPdcpVolDlDrb/(pmSchedActivityCellDl/1000)

pmPrbUtilUlA distribution that shows the uplink Physical Resource Block (PRB) pair utilization (total number of used PRB pairs by available PRB pairs) on the Physical Uplink Shared Channel (PUSCH)pmPrbUtilDlA distribution that shows the downlink Physical Resource Block (PRB) pair utilization (total number of used PRB pairs by available PRB pairs) on the Physical Downlink Shared Channel (PDSCH)

Average # Simultaneous Active UE UL = pmActiveUeUlSum/pmSchedActivityCellUlAverage # Simultaneous Active UE DL = pmActiveUeDlSum/pmSchedActivityCellDl


Mp loadmp load control mechanism (new in L13A)

Main contributors (signaling) for MP LoadRRC Connection SetupsIncoming HandoversPaging Requests

Mp load1.1 RRC Connection setup intensity(due to UE releases by inactivity)The time a UE can be inactive before it is released is controlled by tInactivityTimerCurrent setting for tInactivityTimer is 10s, requirement from UE vendorRecommend to change to 30s to reduce signaling load for high capacity cells

For tInactivityTimer set to 30s, E-RAB drop rate will increase due to the E-RAB drops only consider the abnormal E-RAB Releases if there was data in buffer (i.e. active).

Number of UEs stay in RRC_Connected state will be larger, thus lowering the number of available Connected Users License for new users Mp load1.2 RRC Connection setup intensity(due to UE releases by rLC Supervision) cont

As part of Radio Connection Supervision, RLC failures are caused byT310 expiryMax RLC re-transmissions reachedT310 is controlled byAfter receiving N310 consecutive out-of-sync indications, start timer T310After receiving N311 consecutive in-sync indications, stop timer T310After T310 expired Radio Link FailureCurrent settings:N310 = 20 (recommended, no change)N311 = 1 (recommended, no change)T310 = 2s (recommended, no change) UE is released after T310 (2s) + T311 (3s)

Mp load1.2 RRC Connection setup intensity(due to UE releases by rLC Supervision) RLC re-transmissions are controlled byMax # RLC re-transmissions before stopping and indicating to RRC max RLC re-tx reached SRB/DRB :: dlMaxRetxThreshold (Current setting: 8/8, recommended, no change)SRB/DRB :: ulMaxRetxThreshold (Current setting: 8/8, recommended, no change)Poll timer for RLC re-Tx (if no status report received)SRB/DRB :: tPollRetransmitDl (Current: 45ms/50ms, recommend 80ms/80ms)SRB/DRB :: tPollRetransmitUl (Current: 45ms/50ms, recommend 80ms/80ms)

Increase Poll timer may reduce SE/TTI usage for re-Tx and free SE/TTI for traffic, but re-Tx time is extended from 360-400ms to 640ms (80ms x 8)

Re-Tx count#1#8RLC FailureMp load2. incoming handovers intensityCurrent setting for handover isReportConfigEUtraBestCell::a3offset = 3dBReportConfigEUtraBestCell:: hysteresisA3 = 1dBReportConfigEUtraBestCell:: timeToTriggerA3 = 40ms

Propose to change a3offset to 5dB (handover margin increased to 6dB) for high capacity cells to reduce signaling load. a3offsetAnrDelta remains unchanged

Increase handover margin reduces handovers and may impact retainabilityWill review feasibility to use alternative approach on UE Level Oscillating Handover Minimization feature

Mp load3. hardware expansionMP capacity for DUS is higher than MP capacity on DUL

Mp loadobservabilitypmProcessorLoadThe average CPU load on the whole MP system (all the CPU cores).pmProcessorLoadDistrA distribution of the CPU load of the MP corresponding to the definition of the CPU load used by MP Load Management.This counter also includes CPU load consumption from execution on priorities below traffic priority. This includes CPU load from performance management and some O&M tasks.

pmPagS1ReceivedThis counter counts the number of received S1AP paging messages in the RBS.pmPagS1DiscardedThe number of discarded S1AP paging messages not routed to any cell due to high load (MP Load Control).

pmRrcConnEstabFailHighLoadThe total number of failed RRC connection establishments due to high load (MP Load Control).pmRrcConnEstabFailOverloadThe total number of failed RRC connection establishments due to overload (Procedure Latency Supervision).

pmHoPrepRejInHighLoadThe number of Handover Preparation Failure messages sent by the target eNodeB due to high load (MP Load Ccontrol). pmHoPrepRejInOverloadThe number of Handover Preparation Failure messages sent by the target eNodeB due to overload (Procedure Latency Supervision).


Connected users licenseCurrent Connected Users License is 800 per DULConnected Users license should be topped-up for high traffic sites on demand basis

Increase Connected Users License may have impact on signaling load

Connected Users License check is part of RRC Setup procedureDULRrc Conn user DUL211500DUL312500DUL413000Connected usersobservabilitypmRrcConnEstabFailLicThe total number of failed RRC Connection Establishments due to lack of connected users licenseFocus areasLTE High Capacity Focus Areas Control Channel Dimensioning PUCCH ResourcesPDCCH ResourcesUL Noise RisePRB Utilization / Cell Throughput CapacityMP LoadRRC Connection Setup IntensityDue to UE releases by InactivityDue to UE releases by RLC SupervisionIncoming Handover IntensityHardware expansionConnected Users LicenseSummary of High Capacity Parameter Settings

Summary of high cap parametersParameterCurrentRecommendedObjectivenoOfPucchSrUsers320640Maximize number of allowed SR usersnoOfPucchCqiUsers320640Maximize number of allowed CQI userspdcchCfiMode (10MHz)CFI_AUTO_MAXIMUM_3CFI_AUTO_MAXIMUM_3 (no change)Recommended setting is already set, just monitor CCE and CFI usage pZeroNominalPucch-117-117 (no change)Recommended setting is already setpZeroNominalPusch-96-103Reduce UL noise rise at high loadschedulingAlgorithm3 (PROPORTIONAL_FAIR_MEDIUM)4 (PROPORTIONAL_FAIR_LOW) or 5 (MAXIMUM_C_OVER_I) Increase cell throughput and PRB utilizationtInactivityTimer10s30sReduce signaling loadSRB/DRB::dlMaxRetxThresholdSRB/DRB::ulMaxRetxThreshold8/88/88/8 (no change)8/8 (no change)Max # RLC re-Tx in UL/DL (control signaling load). Recommended setting is already setSRB/DRB::tPollRetransmitDlSRB/DRB::tPollRetransmitUl45ms/50ms45ms/50ms80ms/80ms80ms/80msIncrease poll timer for RLC re-Tx (if no status report received) to avoid RLC failures, reduce signaling loadT310 / T31120 / 120 / 1 (no change)Recommended setting is already set, for RLC supervisionN310 / N3112s / 3s2s / 3s (no change)Recommended setting is already set, for RLC supervisiona3Offset30 (3dB)50 (5dB) (low priority)Reduce signaling load. Will review feasibility to use alternative approach on UE Level Oscillating Handover Minimization feature THNAK YOU

lte high capacity event parameters

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