Lte High capacity event parameters Prepared By: RAJESH KUMAR

Focus areas Summary of High Capacity Parameter Settings LTE High Capacity Focus Areas Control Channel Dimensioning PUCCH Resources PDCCH Resources UL Noise Rise PRB Utilization / Cell Throughput Capacity MP Load RRC Connection Setup Intensity Due to UE releases by Inactivity Due to UE releases by RLC Supervision Incoming Handover Intensity Hardware expansion Connected Users License Summary of High Capacity Parameter Settings

Focus areas LTE High Capacity Focus Areas Control Channel Dimensioning PUCCH Resources PDCCH Resources UL Noise Rise PRB Utilization / Cell Throughput Capacity MP Load RRC Connection Setup Intensity Due to UE releases by Inactivity Due to UE releases by RLC Supervision Incoming Handover Intensity Hardware expansion Connected Users License Summary of High Capacity Parameter Settings

Control channel resources UL Control Channel Resources PUCCH nRB,PUCCH depends on number of SR and CQI resources  Focus Area for High Capacity Parameters PRACH nRB,PRACH in 1 radio frame is independent of bandwidth and is fixed for different cell range DL Control Channel Resources PDCCH nRE,PDCCH depends on CFI  Focus Area for High Capacity Parameters PCFICH nRE,PCFICH in 1 radio frame is 160, independent of bandwidth and # of antenna ports PHICH nRE,PHICH in 1 radio frame depends on bandwidth and is fixed for different bandwidth PBCH nRE,PBCH in 1 radio frame is 240, independent of bandwidth and # of antenna ports

Pucch resources intro Current setting PUCCH is used for transmitting SR, 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 there’s no free SR resources noOfPucchSrUsers and noOfPucchCqiUsers determine number of resources for SR and CQI per cell PUCCH is allocated by 2 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 setting noOfPucchSrUsers, noOfPucchCqiUsers = 320

Pucch resources highest pucch resources for sr & CQI TSR = 10ms (SR periodicity) nSF,PUCCH = 10 (# sub-frames for PUCCH) ncap = 4 (CQI resources/RB pair) TCQI = 80ms (CQI periodicity) 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) 3rd 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 (<880) 2nd attempt (nRB,format1 = 5, nRB,format2 = 3) nSR,res = (36*5-44)*10*10/10 = 1360 (>810) nCQI,res = 3*4*80*10/10 = 960 (>880) noOfPucchSrUsers (limited by nCQI.res)=noOfPucchCqiUsers=640 This setting will reduce peak UL throughput

Pucch resources number of pucch rb-pairs Recommended setting (noOfPucchSrUsers = noOfPucchCqiUsers = 640) nPUCCH,SR = [640/10 * 10/10] = 64 nRB,Format1 = [(64+44)/36] = 3 nRB,Format2 = [640/(4*80) * 10/10] = 2 nRB,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] = 32 nRB,Format1 = [(32+44)/36] = 3 nRB,Format2 = [320/(4*80) * 10/10] = 1 nRB,PUCCH = 3 + 1 = 4

Pucch resources observability pmPucchSrCqiResCongCqi The 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 resources adaptive 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 commands Number 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 load Bandwidth > 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 resources observability pmPdcchCceUtil PDF of % of CCEs utilized compared with total CCEs available (at the maximum CFI permitted by pdcchCfiMode) each subframe, considering bandwidth and antenna configuration. pmPdcchCfiUtil PDF of number of subframes each CFI value was assigned

Focus areas Summary of High Capacity Parameter Settings LTE High Capacity Focus Areas Control Channel Dimensioning PUCCH Resources PDCCH Resources UL Noise Rise PRB Utilization / Cell Throughput Capacity MP Load RRC Connection Setup Intensity Due to UE releases by Inactivity Due to UE releases by RLC Supervision Incoming Handover Intensity Hardware expansion Connected Users License Summary of High Capacity Parameter Settings

Ul noise rise pzeronominalpucch, pzeronominalpusch pZeroNominalPucch and pZeroNominalPusch can be used to adjust power control target, trade off between coverage and capacity Current setting pZeroNominalPucch = -117dBm pZeroNominalPusch = -96dBm (should be reduced to default -103dBm to reduce UL interference peaks at high load)

Ul noise rise observability pmSinrPucchDistr 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.

Focus areas LTE High Capacity Focus Areas Control Channel Dimensioning PUCCH Resources PDCCH Resources UL Noise Rise PRB Utilization / Cell Throughput Capacity MP Load RRC Connection Setup Intensity Due to UE releases by Inactivity Due to UE releases by RLC Supervision Incoming Handover Intensity Hardware expansion Connected Users License Summary of High Capacity Parameter Settings

Prb utilization / cell throughput capacity schedulingalgorithm Current setting schedulingAlgorithm = 3 (PROPORTIONAL_FAIR_MEDIUM), propose to change to following at high load 4 (PROPORTIONAL_FAIR_LOW) or 5 (MAXIMUM_C_OVER_I) Higher Cell Throughput Higher TTI utilization Higher PRB utilization Performance comparison between different schedulers Best cell throughput (from lowest to highest) RR < ER < PFH < PFM < PFL < MCI System fairness (from lowest to highest) MCI < PFL < PFM < PFL < ER < RR System Fairness Cell Throughput For PFL or Max C/I, user at cell edge may have low throughput, as scheduler has higher weightage for RF condition

Prb utilization / cell throughput capacity observability Average Cell Throughput UL = pmUeThpVolUl/(pmSchedActivityCellUl/1000) Average Cell Throughput DL = pmPdcpVolDlDrb/(pmSchedActivityCellDl/1000) pmPrbUtilUl A 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) pmPrbUtilDl A 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/pmSchedActivityCellUl Average # Simultaneous Active UE DL = pmActiveUeDlSum/pmSchedActivityCellDl

Focus areas LTE High Capacity Focus Areas Control Channel Dimensioning PUCCH Resources PDCCH Resources UL Noise Rise PRB Utilization / Cell Throughput Capacity MP Load RRC Connection Setup Intensity Due to UE releases by Inactivity Due to UE releases by RLC Supervision Incoming Handover Intensity Hardware expansion Connected Users License Summary of High Capacity Parameter Settings

Mp load mp load control mechanism (new in L13A) Main contributors (signaling) for MP Load RRC Connection Setups Incoming Handovers Paging Requests

Mp load 1.1 RRC Connection setup intensity (due to UE releases by inactivity) The time a UE can be inactive before it is released is controlled by tInactivityTimer Current setting for tInactivityTimer is 10s, requirement from UE vendor Recommend 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 load 1.2 RRC Connection setup intensity (due to UE releases by rLC Supervision) – cont’ As part of Radio Connection Supervision, RLC failures are caused by T310 expiry Max RLC re-transmissions reached T310 is controlled by After receiving N310 consecutive “out-of-sync” indications, start timer T310 After receiving N311 consecutive “in-sync” indications, stop timer T310 After T310 expired  Radio Link Failure Current 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 load 1.2 RRC Connection setup intensity (due to UE releases by rLC Supervision) RLC re-transmissions are controlled by Max # 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) Re-Tx count 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) #1 … #8 RLC Failure

Mp load 2. incoming handovers intensity Current setting for handover is ReportConfigEUtraBestCell::a3offset = 3dB ReportConfigEUtraBestCell:: hysteresisA3 = 1dB ReportConfigEUtraBestCell:: 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 retainability Will review feasibility to use alternative approach on ‘UE Level Oscillating Handover Minimization’ feature

Mp load 3. hardware expansion MP capacity for DUS is higher than MP capacity on DUL

Mp load observability pmProcessorLoad pmProcessorLoadDistr The average CPU load on the whole MP system (all the CPU cores). pmProcessorLoadDistr A 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. pmPagS1Received This counter counts the number of received S1AP paging messages in the RBS. pmPagS1Discarded The number of discarded S1AP paging messages not routed to any cell due to high load (MP Load Control). pmRrcConnEstabFailHighLoad The total number of failed RRC connection establishments due to high load (MP Load Control). pmRrcConnEstabFailOverload The total number of failed RRC connection establishments due to overload (Procedure Latency Supervision). pmHoPrepRejInHighLoad The number of Handover Preparation Failure messages sent by the target eNodeB due to high load (MP Load Ccontrol). pmHoPrepRejInOverload The number of Handover Preparation Failure messages sent by the target eNodeB due to overload (Procedure Latency Supervision).

Focus areas LTE High Capacity Focus Areas Control Channel Dimensioning PUCCH Resources PDCCH Resources UL Noise Rise PRB Utilization / Cell Throughput Capacity MP Load RRC Connection Setup Intensity Due to UE releases by Inactivity Due to UE releases by RLC Supervision Incoming Handover Intensity Hardware expansion Connected Users License Summary of High Capacity Parameter Settings

Connected users license Current Connected Users License is 800 per DUL Connected Users license should be topped-up for high traffic sites on demand basis Increase Connected Users License may have impact on signaling load DUL Rrc Conn user DUL21 1500 DUL31 2500 DUL41 3000 Connected Users License check is part of RRC Setup procedure

Connected users observability pmRrcConnEstabFailLic The total number of failed RRC Connection Establishments due to lack of connected users license

Focus areas LTE High Capacity Focus Areas Control Channel Dimensioning PUCCH Resources PDCCH Resources UL Noise Rise PRB Utilization / Cell Throughput Capacity MP Load RRC Connection Setup Intensity Due to UE releases by Inactivity Due to UE releases by RLC Supervision Incoming Handover Intensity Hardware expansion Connected Users License Summary of High Capacity Parameter Settings

Summary of high cap parameters Current Recommended Objective noOfPucchSrUsers 320 640 Maximize number of allowed SR users noOfPucchCqiUsers Maximize number of allowed CQI users pdcchCfiMode (10MHz) CFI_AUTO_MAXIMUM_3 CFI_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 set pZeroNominalPusch -96 -103 Reduce UL noise rise at high load schedulingAlgorithm 3 (PROPORTIONAL_FAIR_MEDIUM) 4 (PROPORTIONAL_FAIR_LOW) or 5 (MAXIMUM_C_OVER_I) Increase cell throughput and PRB utilization tInactivityTimer 10s 30s Reduce signaling load SRB/DRB::dlMaxRetxThreshold SRB/DRB::ulMaxRetxThreshold 8/8 8/8 (no change) Max # RLC re-Tx in UL/DL (control signaling load). Recommended setting is already set SRB/DRB::tPollRetransmitDl SRB/DRB::tPollRetransmitUl 45ms/50ms 80ms/80ms Increase poll timer for RLC re-Tx (if no status report received) to avoid RLC failures, reduce signaling load T310 / T311 20 / 1 20 / 1 (no change) Recommended setting is already set, for RLC supervision N310 / N311 2s / 3s 2s / 3s (no change) a3Offset 30 (3dB) 50 (5dB) (low priority) Reduce signaling load. Will review feasibility to use alternative approach on ‘UE Level Oscillating Handover Minimization’ feature

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