Lte Call Setup Optimization

Call Setup OptimizationLast Updated: November, 2013 Version 1.1 Latest version of this module can be downloaded from: https://sharenet-ims.inside.nokiasiemensnetworks.com/Overview/D505370850 For internal use Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. Content • Introduction - Call setup process and phases • KPIs: - Important KPIs/Counters This module is for connection - Target values and NSN and Project References setup. Call drops after setup phase are discussed in the Call • Optimization actions/analysis Drop Module. - Signalling flows and counter triggering - Possible failure causes with examples • Summary - Parameters Summary • Impact of different Features • Project examples • Links to further material For internal use 2 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. Call setup process 1. PRACH phase 2. SRB1 setup 3. NAS security 4. RRC security + UE AS security set up Capability Enquiry 5. SRB2/DRB setup For internal use 3 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. . RRC SRB2 + setup setup setup security DRB eNB resources are reserved for signalling connection between UE and eNB NAS security Success UE has RRC connection. Success Complete Complete complete complete complete complete SRB2 RRC security + UE capability enquiry +DRB Security setupSRB2 + DRB setup Attempts complete failures UE has RAB connection S1 setup failures failures Call setup is affected if any of the followings SRB1 setup take failures place. Call Setup Phases PRACH + Msg3 RRC and E-RAB phases Initial network access process between UE and eNB SRB1 setup Phase: PRACH SRB1 S1 conn. • PRACH setup failures PRACH failures • SRB 1 setup failures (blocking) • S1 connection failures For internal use • RRC security + UE cap failures 4 • Networks. If dropped. ©2013 Nokia Solutions and SRB2 & DRB All rights setup failures reserved. also S1 S1 conn RRC SRB2 Success Success PRACH PRACH SRB1 SRB1 conn RRC SRB2 active setup setup Setup Setup complete complete security security +DRB +DRB RAB is dropped. Call setup process and phases • KPIs: .Possible failure causes with examples • Summary .Important KPIs/Counters . All rights reserved. Content • Introduction .Parameters Summary • Impact of different Features • Project examples • Links to further material For internal use 5 Presentation / Author / Date ©2013 Nokia Solutions and Networks.Signalling flows and counter triggering . .Target values and NSN and Project References • Optimization actions/analysis . All rights reserved. 100% RRC Setup Failure Rate in a cell is an indication that the site needs recovery actions LTE_5017a E-UTRAN E-RAB Setup Success Ratio LTE_5009a S1 Initial Context Setup Success Ratio LTE_5096a E-UTRAN S1 Initial Context Setup Failure Ratio per Cause OTH LTE_5095a E-UTRAN S1 Initial Context Setup Failure Ratio per Cause RESOURC LTE_5094a E-UTRAN S1 Initial Context Setup Failure Ratio per Cause TRPORT LTE_5093a E-UTRAN S1 Initial Context Setup Failure Ratio per Cause RNL LTE_138a RACH Setup Complete Success ratio LTE_806a Maximum of RRC connected users LTE_1056b Complete RACH Setup Success Rate LTE_5a SRB1 setup Success Ratio LTE_5003a E-UTRAN Data Radio Bearer Setup Success Ratio LTE_5009a E-UTRAN S1 Initial Context Setup Success Ratio For internal use 6 Presentation / Author / Date ©2013 Nokia Solutions and Networks. List of important KPIs Related to Call Setup LTE_5218c Total E-UTRAN RRC Connection Setup Success Ratio If the value is lower than 99.5%. there are clear problems in network stability. . 5%.99% 1 K 99.nsn-net.97% LTE_5017>99. <98.98% 2 L 99.90% 7 Q 99.92% 6 P 99.net/Alpaca/Acco 5 E 99.94% 4 N 99.3% (bad) 2 B 99. 8 H 99.97% 3 M 99.90% 8 R 99.87% For internal use 7 Presentation / Author / Date ©2013 Nokia Solutions and Networks.91% unt/Login?ReturnUrl=/Alpaca/ 6 F 99. KPI Targets and reference values Internal Use only!! Top 10 customers .7% (bad) 1 A 99.8%. Top 10 customers - LTE_5017 LTE_5218 DATED: Oct 2013 DATED: Oct 2013 KPI Rank Customer value Rank Customer KPI value NSN Recommended values : LTE_5218 >99.93% 3 C 99.89% 7 G 99. All rights reserved.85% .93% Up to date NSN recommended values can be KPI Bench marker Tool (apply 4 D 99.92% 5 O 99.92% the access rights through the tool): https://alpaca. <99.emea. For internal use 8 Presentation / Author / Date ©2013 Nokia Solutions and Networks. . All rights reserved. In In case case ofof RRC RRC releases releases initiated initiated by by EPC: EPC: •• Check Check MMEMME statistics statistics regarding regarding TAUTAU and andAttach Attach procedures procedures for for troubleshooting. troubleshooting. (e.g. In In case case ofof Admission Admission Control Control Rejections: Rejections: •• Increase Increase PUCCH PUCCH capacity capacity ifif the the number number of of connected users in a cell is exceeding connected users in a cell is exceeding physical physical capacity capacity and/or and/or setset RAC RAC thresholds thresholds as per PUCCH capacity.g. as per PUCCH capacity. congestion. RRC Connection Establishment System program Report (RRC) Note: Note: •• The The majority majority of of RRC RRC connections connections are are successfully successfully established established but but possible possible site site issues issues due due toto no no response response to to RRC RRC setup setup message message or or admission admission control control failures failures due due to to congestion. •• High High number number of of RRC RRC releases releases areare initiated initiated by EPC -> MME mobility by EPC -> MME mobility management management failures failures (e. TAU TAU oror Attach Attach rejects). rejects). E-RAB Connection System program Report (E-RAB) Note: Note: •• The The majority majorityof of EPS EPS Bearer Bearer connection connection establishments establishments problems problems (if (if RRC RRC SR SR is is good) good) indicate indicate the the transport transport oror the the core core network network issues issues ••E-RAB E-RAB dropdrop ratio ratio depends depends on on RRC RRC inactivity inactivitytimer timer ••3GPP 3GPP recommends recommends normalizing normalizing drops drops by by time time (drops (drops per per minute) minute) for for non-GBR non-GBR bearers bearers ••Core Core network network KPIs KPIs need need to to be be analyzed analyzed for further problem isolation for further problem isolation For internal use 9 Dept. / Author / Date ©2013 Nokia Solutions and Networks. . All rights reserved. All rights reserved.Signalling flows and counter triggering .Call setup process and phases • KPIs: .Important KPIs/Counters .Possible failure causes with examples • Summary .Parameters Summary • Impact of different Features • Project examples • Links to further material For internal use 10 Presentation / Author / Date ©2013 Nokia Solutions and Networks. . Content • Introduction .Target values and NSN and Project References • Optimization actions/analysis . NAS security setup (optional) 4. SRB1 setup 3. All rights reserved. . Counter and KPI analysis for Call setup Phase Call setup has five phases: 1. RRC security + UE Capability Enquiry (UE Cap Enquiry optional) 5. PRACH phase (also applies to handover) 2. SRB2 + DRB setup (DRB optional in TAU)  Success of phases 1-2 must be monitored from PRACH and RRC signaling counters  Success of phases 3-5 is monitored from S1AP and E-RAB counters: ”S1 view” – s1 counters For internal use 11 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. KPI /counter analysis from Air –Interface view For internal use 12 Presentation / Author / Date ©2013 Nokia Solutions and Networks. . including Msg3 UE eNB M8001C6:RACH_STP_ATT_SMALL_MSG M8001C6:RACH_STP_ATT_SMALL_MSG 1 PRACH MAC Random Access Preamble M8001C7:RACH_STP_ATT_LARGE_MSG M8001C7:RACH_STP_ATT_LARGE_MSG M8001C286:RACH_STP_ATT_DEDICATED M8001C286:RACH_STP_ATT_DEDICATED 2 PDCCH MAC RA-RNTI 2 PDSCH MAC Random Access Response M8001C8: M8001C8: RACH_STP_COMPLETIONS RACH_STP_COMPLETIONS 3 PUSCH RLC TM SRB0 RRC-ConnectionRequest M8013C17:SIGN_CONN_ESTAB_ATT_MO_S M8013C17:SIGN_CONN_ESTAB_ATT_MO_S M8013C18:SIGN_CONN_ESTAB_ATT_MT M8013C18:SIGN_CONN_ESTAB_ATT_MT 4 PDSCH MAC Contention Resolution M8013C19:SIGN_CONN_ESTAB_ATT_MO_D M8013C19:SIGN_CONN_ESTAB_ATT_MO_D NOTE: No counters for Msg4 in RL30 M8013C20:SIGN_CONN_ESTAB_ATT_OTHERS M8013C20:SIGN_CONN_ESTAB_ATT_OTHERS M8013C21:SIGN_CONN_ESTAB_ATT_EMG Analysis: M8013C21:SIGN_CONN_ESTAB_ATT_EMG • LTE_138a RACH Setup Complete Success ratio indicates RAR blocking in scheduler only • To detect Msg2/Msg3 problems compare M8001C8 to sum of M8013C17-C21 • Compare drive test logs to Emil logs if Msg2 heard by UE • CompareFordrive test internal use logs to Emil logs if Msg3 heard by eNB 13 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. 1. PRACH phase. . 2. SRB1 setup phase NOTE: Successful case • No RLC layer DL retransmissions in RRC Conn Setup UE eNB • Default MCS and number of PRBs 3 PUSCH RLC TM SRB0 used. RRC-ConnectionRequest PDSCH RLC TM SRB0 RRC-ConnectionSetup M8007C7: M8007C7: SRB1 SRB1 SETUP SETUP ATT ATT PUSCH RLC AM SRB1 M8007C8: M8007C8: SRB1 SRB1 SETUP SETUP SUCC SUCC RRC-ConnectionSetupComplete (NAS) M8013C5: SIGN_CONN_ESTAB_COMP M8013C5: SIGN_CONN_ESTAB_COMP Analysis: • LTE_5a SRB1 setup Success Ratio Presentation For internal use / Author / Date 14 ©2013 Nokia Solutions and Networks. . All rights reserved. All rights reserved. . 2. SRB1 setup phase Unsuccessful Case 1 UE eNB SRB1 may be rejected due to: • Insufficient PUCCH resources 3 PUSCH RLC TM SRB0 RRC-ConnectionRequest • Max number of RRC connected users exceeded RAC rejects RRC Connection Request M8013C8 M8013C8 SIGN_CONN_ESTAB_FAIL_RRMRAC SIGN_CONN_ESTAB_FAIL_RRMRAC PDSCH RLC TM SRB0 RRC Connection Reject For internal use 15 Presentation / Author / Date ©2013 Nokia Solutions and Networks. 2. . All rights reserved. SRB1 setup phase Unsuccessful case 2 UE eNB 3 PUSCH RLC TM SRB0 RRC-ConnectionRequest PDSCH RLC TM SRB0 RRC-ConnectionSetup PUSCH RLC AM SRB1 M8013C7 M8013C7 SIGN_EST_F_RRCCOMPL_ERROR SIGN_EST_F_RRCCOMPL_ERROR RRC-ConnectionSetupComplete (NAS) Erroneous or incomplete message For internal use 16 Presentation / Author / Date ©2013 Nokia Solutions and Networks. . 2. Setup. RRC-ConnectionRequest the the UE shall perform cell re-selection during the UE shall perform cell re-selection during the procedure and silently disappears. procedure and silently disappears. All rights reserved. PDSCH RLC TM SRB0 RRC-ConnectionSetup UE does not receive RRC Conn Setup and timer T300 expires. IfIf 3 PUSCH RLC TM SRB0 the the conditions conditions for for cell cell re-selection re-selection are are fulfilled. No response from UE M8013C6 M8013C6 SIGN_EST_F_RRCCOMPL_MISSING SIGN_EST_F_RRCCOMPL_MISSING (timer tHalfRrcCon) • UE timer T300 (def=200ms) may expire if DL RRC Conn Setup reception fails • eNB has a vendor-file timer parameter for half-open RRC connections tHalfRrcCon (def=2000ms) to wait for RRC Conn Setup Complete from UE For internal use 17 Presentation / Author / Date ©2013 Nokia Solutions and Networks. or UE reselects another cell. Having Having some some hysteresis hysteresis for for cell cell reselection reselection maymay (or (or may may not) not) help help in in reducing reducing RRCRRC setup setup problems. problems. fulfilled. SRB1 setup phase Unsuccessful Case 3 NOTE: NOTE: UEUE continues continues cell cell re-selection re-selection related related measurements as well as cell re-selection measurements as well as cell re-selection UE eNB evaluation evaluation until until itit receives receives RRCRRC Conn Conn Setup. NOTE: there is no RRC For internal use Connection Connection to to release release 18 Presentation / Author / Date ©2013 Nokia Solutions and Networks. NOTE: there is no RRC deletes user. TUP TUP deletes user. . All rights reserved. SRB1 setup phase Unsuccessful Case 3: Emil example tHalfRrcCon tHalfRrcCon expires expires after after 2sec. 2. 2sec. it can still be successful from RRC pov Default T3460 is usually larger than radio link fail timers (3GPP default = 6sec). NAS security Successful Case UE eNB PDSCH RLC AM SRB1 NAS transfer (AUTH REQ) start T3460 MME timer stop T3460 MME timer PUSCH RLC AM SRB1 NAS transfer (AUTH RSP) PDSCH RLC AM SRB1 NAS transfer (SEC CMD) start T3460 MME timer stop T3460 MME timer PUSCH RLC AM SRB1 NAS transfer (SEC CMP) No RRC counters for NAS procedure failures Even if Auth or SecMod NAS procedure fails on NAS layer.after which NAS retransmission follow For internal use 19 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. 3. . since RRC is possible for UE. point. up. PUSCH RLC AM SRB1 UE Cap Info No RRC counters for this phase NSN implementation may send UE Capability Enquiry (if required) and RRC Connection Reconfiguration before receiving RRC Security Complete For internal use 20 Presentation / Author / Date ©2013 Nokia Solutions and Networks. then then RRC RRC Re-Est Re-Est is is not possible and UE makes cell reselection + not possible and UE makes cell reselection + TAU Req if it drops the TAU Req if it drops the call. . All rights reserved. If If call call drops drops after after PUSCH RLC AM SRB1 RRC Security Complete PRACH PRACH butbut before before this this point. RRC security Successful + Unsuccessful UE eNB S1AP Init Ctxt Setup Req (NAS) PDSCH RLC AM SRB1 RRC Security Cmd PDSCH RLC AM SRB1 UE Cap Enquiry 3GPP: 3GPP: After After this this point point RRC RRC Conn Conn Re-Re- Establishment Establishment is possible for UE. 4. call. since RRC security security has has beenbeen set set up. This This includes includes the the • no RRC counters For internal use for expiry case case when when UE UE sends sends RRC RRC Conn Conn Re-EstRe-Est to to eNB. All rights reserved.957: If If RRC RRC Conn Conn Re-EstRe-Est Req Req received received • RRC Security Mode Command from from UE UE before before S1 S1 context context has has been been successfully successfully setset up. re- re- 21 Presentation / Author / Date establishment establishment is ©2013 is rejected Nokia Solutions rejected and Networks.957: BEARERMAN. . up. 4. eNB. eNB eNB shall abort the Initial Context Setup procedure by the shall abort the Initial Context Setup procedure by the • UE Capability Enquiry S1AP message INITIAL CONTEXT S1AP message INITIAL CONTEXT SETUP FAILURE with SETUP FAILURE with • RRC Connection Reconfiguration cause cause “Radio “Radio Connection Connection With With UE UE Lost”. RRC security Unsuccessful Case UE eNB S1AP Init Ctxt Setup Req (NAS) PDSCH RLC AM SRB1 RRC Security Cmd rrcGuardTimer PDSCH RLC AM SRB1 UE Cap Enquiry • rrcGuardTimer expires • eNB triggered RLF • RRC Conn Re-Est Reject rrcGuardTimer S1AP Init Ctxt Setup Failure RRC Guard Timer supervises NSN NSN BEARERMAN.Lost”. 5. SRB2/DRB setup Successful Case UE eNB PDSCH RLC AM SRB1 RRC Conn Reconf M8007C0 M8007C0 DATA_RB_STP_ATT DATA_RB_STP_ATT M8007C10: M8007C10: SRB2 SRB2 SETUP SETUP ATT ATT PDSCH RLC AM SRB1 RRC Conn Reconf Complete M8007C1 M8007C1 DATA_RB_STP_COMP DATA_RB_STP_COMP M8007C11: SRB2 M8007C11: SRB2 SETUP SETUP SUCC SUCC S1AP Init Ctxt Setup Response Analysis: • LTE_5003a Data Radio Bearer Setup Success Ratio For internal use 22 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. 5. SRB2/DRB setup Unsuccessful Case UE eNB PDSCH RLC AM SRB1 RRC Conn Reconf M8007C0 M8007C0 DATA_RB_STP_ATT DATA_RB_STP_ATT M8007C10: M8007C10: SRB2 SRB2 SETUP SETUP ATT ATT rrcGuardTimer, default =2000ms M8007C2 M8007C2 DATA_RB_STP_FAIL DATA_RB_STP_FAIL M8007C12 M8007C12 SRB2_SETUP_FAIL SRB2_SETUP_FAIL • rrcGuardTimer expires • eNB triggered RLF • UE RRC Conn Re-Est Reject S1AP Init Ctxt Setup Failure • M8007C0 is triggered for incoming Handover in case of a successful handover preparation procedure indicated e.g. by the transmission of the HANDOVER REQUEST ACKNOWLEDGE message. • M8007C2 triggered also when Data Radio Bearers failed to setup during incoming Handover at the target cell, unsuccessfully completed Handover Execution phase at the target eNB (e.g. expiration of TS1Relocexec/Tx2Relocexec). For internal use 23 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. KPI/Counter analysis from S1 point of view For internal use 24 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. S1 Context Setup Successful Case eNB MME RRC Connection Setup 1 S1AP Init UE Message (NAS) M8000C12 M8000C12 UE_LOG_S1_SETUP UE_LOG_S1_SETUP NAS security 2 S1AP Init Ctxt Setup Req (NAS) M8000C0 M8000C0 INI_CONT_STP_REQ INI_CONT_STP_REQ M8006C0 EPS_BEARER_SETUP_ATTEMPTS M8006C0 EPS_BEARER_SETUP_ATTEMPTS RRC security SRB2 + DRB setup 3 S1AP Init Ctxt Setup Response M8000C1 M8000C1 INI_CONT_STP_COMP INI_CONT_STP_COMP M8006C1 M8006C1 EPS_BEARER_SETUP_COMPLETIONS EPS_BEARER_SETUP_COMPLETIONS Analysis: • LTE_5009a S1 Initial Context Setup Success Ratio • LTE_5017a E-RAB Setup Success Ratio For internal use 25 Presentation / Author / Date ©2013 Nokia Solutions and Networks. . All rights reserved. All rights reserved. S1 Context Setup M8000C12 M8000C12 UE_LOG_S1_SETUP UE_LOG_S1_SETUP Unsuccessful Case 1 eNB MME M8000C0 M8000C0 INI_CONT_STP_REQ INI_CONT_STP_REQ RRC Connection Setup M8006C0 EPS_BEARER_SETUP_ATTEMPTS M8006C0 EPS_BEARER_SETUP_ATTEMPTS 1 S1AP Init UE Message (NAS) M8000C2 M8000C2 INI_CONT_STP_FAIL_RNL INI_CONT_STP_FAIL_RNL NAS security M8000C3 M8000C3 INI_CONT_STP_FAIL_TRPORT INI_CONT_STP_FAIL_TRPORT 2 S1AP Init Ctxt Setup Req (NAS) M8000C4 M8000C4 INI_CONT_STP_FAIL_RESOUR INI_CONT_STP_FAIL_RESOUR M8000C5 M8000C5 INI_CONT_STP_FAIL_OTHER INI_CONT_STP_FAIL_OTHER RRC security failure M8006C2 M8006C2 EPS_BEARER_SETUP_FAIL_RNL EPS_BEARER_SETUP_FAIL_RNL SRB2 + DRB setup M8006C3 M8006C3 EPS_BEARER_SETUP_FAIL_TRPORT EPS_BEARER_SETUP_FAIL_TRPORT M8006C4 M8006C4 EPS_BEARER_SETUP_FAIL_RESOUR EPS_BEARER_SETUP_FAIL_RESOUR 3 S1AP Init Ctxt Setup Failure M8006C5 M8006C5 EPS_BEARER_SETUP_FAIL_OTHER EPS_BEARER_SETUP_FAIL_OTHER Analysis: • LTE_5096a E-UTRAN S1 Initial Context Setup Failure Ratio per Cause OTH • LTE_5095a E-UTRAN S1 Initial Context Setup Failure Ratio per Cause RESOURC • LTE_5094a E-UTRAN S1 Initial Context Setup Failure Ratio per Cause TRPORT • LTE_5093a E-UTRAN For internal use S1 Initial Context Setup Failure Ratio per Cause RNL 26 Presentation / Author / Date ©2013 Nokia Solutions and Networks. . All rights reserved. . S1 Context Setup (RL30) Unsuccessful Case 2 eNB MME RRC Connection Setup 1 S1AP Init UE Message (NAS) M8000C12 M8000C12 UE_LOG_S1_SETUP UE_LOG_S1_SETUP eNB receives no response from MME for time period defined by tEstS1Con  S1 + SRB1 released • vendor file parameter <p name="tEstS1Con">16000</p> • unit: milliseconds Analysis: • No counter available for the number of S1 connection setup timer expirys (available after RL40) • Can compare M8000C12 UE_LOG_S1_SETUP and M8000C0 INI_CONT_STP_REQ • Need to analyze with Emil For internal use 27 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. . S1 Context Setup(RL30) Unsuccessful Case 3 eNB MME RRC Connection Setup 1 S1AP Init UE Message (NAS) M8000C12 M8000C12 UE_LOG_S1_SETUP UE_LOG_S1_SETUP NAS security Call drops at air interface Analysis: • No eNB counters available (available after RL40) • Can compare M8000C12 UE_LOG_S1_SETUP and M8000C0 INI_CONT_STP_REQ • Need to analyze with Emil For internal use 28 Presentation / Author / Date ©2013 Nokia Solutions and Networks. S1 Context Setup Unsuccessful Case: Emil example tEstS1Con tEstS1Con timer timer expires expires after after 16 16 sec sec For internal use  RRC Nokia RRC release release 29 Presentation / Author / Date ©2013 Solutions and Networks. . All rights reserved. . All rights reserved. S1 Context Setup (RL 40 onwards) Unsuccessful Procedure (No response from MME) For internal use 30 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. S1 Context Setup (RL 40 onwards) Unsuccessful Procedure (MME Failure) For internal use 31 Presentation / Author / Date ©2013 Nokia Solutions and Networks. . – Stop: Reception of RRCConnectionSetup or RRCConnectionReject message. / Author / Date ©2013 Nokia Solutions and Networks. cell re-selection and upon abortion of connection establishment by upper layers. All rights reserved. • UE L3 sends RRC Connection Request to lower layers (L2/L1) which are responsible for preamble sending and RA response monitoring and starts timer T300 which supervises the RRC connection establishment procedure. – Start: Transmission of RRCConnectionRequest. . RRC Connection Establishment Procedure T300 • The UE initiates the RRC connection establishment procedure when upper layers request establishment of an RRC connection while the UE is in RRC_IDLE state. – In case of T300 (200ms) expiry the UE will stop RRC Connection Establishment procedure and informs higher layer about failed procedure (T300 = preambTxMax*20ms+ harqMaxMsg3 *raContResoT). T300 : started when UE UE eNB RRC Connection Request L3 sends RRC Connection Request to RA Preamble L2/L1 and stopped in RA Response case of RRC Connection Setup or RRC Connection Reject is Contention Resolution received RRC Connection Setup For internal use 32 Dept. 321 and given by the prachConfIndex = 3 means preamble format 0 i. .PCMAX is the configured UE transmitted power. Random Access Procedure RA Preamble . . . .powerRampingStep is defined by parameter prachPwrRamp = 2 dB.In case of initial access the contention based RA procedure is used. UE eNB RA Preamble (msg1) RA Response (msg2) RRC Connection Request (msg3) For internal use 33 Dept. .e.PL is the downlink path loss estimate calculated by the UE.preambleInitialReceivedTargetPower is defined by parameter ulpcIniPrePw = -90 dBm. i.DELTA_PREAMBLE is as per 3GPP 36. Random Access preamble is selected by the UE from available PRACH contention based preamble signatures on a cell (raNondedPreamb=40). / Author / Date ©2013 Nokia Solutions and Networks. DELTA_PREAMBLE = 0.e.A preamble transmission power is determined as follows: • PPRACH = min{PCMAX. preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER – 1) * powerRampingStep + PL} [dBm] . All rights reserved. . the UE monitors the PDCCH for Random Access Response(s) identified by the RA-RNTI. UE eNB RRC Connection Request RA Preamble 3TTI processing RA Response 5 TTI (5 ms) waiting time for delay by 3GPP the RA response from sending 36. / Author / Date ©2013 Nokia Solutions and Networks. and regardless of the possible occurrence of a measurement gap. • The UE may stop monitoring for Random Access Response(s) after successful reception of a Random Access Response containing Random Access Preamble identifiers that matches the transmitted Random Access Preamble. .321 the corresponding RA preamble defined by parameter raRespWinSize (3 internal value) For internal use 34 Dept. All rights reserved. Random Access Procedure RA Response (1/3) • Once the Random Access Preamble is transmitted. • The PDSCH message for RA Response is sent using QPSK modulation and default coding rate set by parameter maxCrRaDl = 0. – PDSCH HARQ is performed normally based on harqMaxTrDl = 4. / Author / Date ©2013 Nokia Solutions and Networks. . UE eNB RRC Connection Request RA Preamble RA Response 3TTI processing delay by 3GPP 5 TTI (5 ms) waiting time for 36.321 the RA response from sending the corresponding RA preamble defined by parameter raRespWinSize (3) For internal use 35 Dept. Random Access Procedure RA Response (2/3) • The RA Response is sent on PDSCH informed by PDCCH DCI 1A. • PDCCH aggregation level is set by parameter pdcchAggRaresp = 4 (default). All rights reserved.12 (default) – The 48bit RA response (+header = 7B = 56bit) has to use very low coding rate due to the very small amount of bits (turbo coding efficiency is greatly degraded). .213) = 12 TTI and with the prachConfIndex =3 this means after 20 ms from the first preamble.the UE shall transmit a RA Preamble (retransmission) new preamble sequence no later than in subframe n+4 (36. / Author / Date ©2013 Nokia Solutions and Networks.The entire preamble retransmission time (in case no response) is preambTxMax*20ms=10*20ms = 200ms UE eNB RRC Connection Request 5 TTI (5 ms) waiting time for the RA RA Preamble response from sending the 3TTI processing delay corresponding RA preamble defined RA Response by 3GPP 36.The single PRACH resource (1 subframe) per 10 ms radio frame prachConfIndex = 3. . All rights reserved. . Random Access Procedure RA Response (3/3) • In case the UE does not receive RA response within the specified window then the UE will reattempt and send the new RA preamble with a higher power. .321 by parameter raRespWinSize (3) If no random access response is received . • The new preamble can be transmitted earliest (from the last sent preamble) 3 TTI+ raRespWinSize (5TTI) + 4TTI (3GPP 36.213) For internal use 36 Dept.Random access response window size raRespWinSize = 5 TTI. PPUSCH Msg 3  min  PCMAX . a(j) = path loss compensation factor defined by ulpcAlpha (1). Random Access Procedure Message 3 • The RRC Connection Request (msg3) is the first message sent over the PUSCH and thus. .10 log  M PUSCH  i    ulpcIniPre Pwr   P REAMBLE_Msg3    j   PL   TF  i   preamble power ramp up   Msg 2  . UL power control settings need to be set appropriately in order to maximize Msg3 decoding reliability. RRC .e. . the total power ramping 3until canthe actually be a preamble is acknowledged by the RA response. The message Prampup is the total power ramp-up from the first to the last preamble i. ΔPREAMBLE_Msg3 allows for boosting of the UL power for Msg3 transmission by parameter deltaPreMsg3 (0 dB). All rights reserved. ΔTF(i) enables TB size impact to UE PUSCH power calculation deltaTfEnabled (false) . ΔMsg2 is given by RA response TPC field according to the ulpcRarespTpc (0) Connection Reconfiguration UE eNB complete (HO) or RRC Connection RA Preamble Re-Establishment depending on the cause that initiated the RACH RA Response procedure RRC Connection Request For internal use 37 ©2013 Nokia Solutions and Networks. ulpcIniPrePwr (-90 dBm) is preamble initial received power. PL: pathloss [dB] = referenceSignalPower – higher layer filtered RSRP . . PCMAX is maximum allowed UE power (23 dBm for class 3). RRC Connection Request. . MPUSCH: number of scheduled RBs (UE Tx power increases proportionally to # of PRBs). . . All rights reserved. . – the maximum content resolution timer parameter defines the maximum amount of time allowed for contention resolution. / Author / Date ©2013 Nokia Solutions and Networks. the UE starts Contention Resolution Timer and restart timer at each HARQ retransmission. UE eNB RA Preamble 3TTI processing delay 7 TTI (7 ms) waiting time for RA Response by 3GPP 36. Random Access Procedure Contention Resolution (1/2) • Once RRC Connection Request (msg3) has been transmitted. the Contention Resolution UE starts Contention Resolution Timer raContResoT (32ms) For internal use 38 Dept. – harqMaxTrDl (4) indicates the maximum number of HARQ transmissions in DL. The HARQ delay is 8ms including some 0.6ms UE processing delay so 4 retransmissions equal 4*9ms=36 ms which covers the Contention Resolution timer 40 ms.321 the RA response RRC Connection Request Once RRC Connection Request (msg3 of RA Procedure) has been transmitted. raContResoT (32ms). 12) and the default has been changed from 0. • Used coding rate is defined by parameter maxCrRa4Dl. For internal use 39 Dept. . / Author / Date ©2013 Nokia Solutions and Networks.39. • Negative impact (1 PRB -> 3 PRBs reserved for CT) will be slight reduction in DL throughput (but net effect can be positive due to less resources reserved due to less overlapping reservations).12 to 0. • The maxCrRa4Dl could be reduced to the same value as maxCrRaDl = 0. All rights reserved. Random Access Procedure Contention Resolution (2/2) • The CQI reporting is started when measurements are configured in RRC Setup message and therefore the contention resolution message is sent in DL using default QPSK modulation and coding rate.39 recently in order to improve DL throughput. def 0.12 to improve the detection of Contention Resolution message. this default value is higher (less channel coding) compared to the same size RA response (maxCrRaDl = 0. Important KPIs/Counters .Possible failure causes with examples • Summary . . All rights reserved.Parameters Summary • Impact of different Features • Project examples • Links to further material For internal use 40 Presentation / Author / Date ©2013 Nokia Solutions and Networks. Content • Introduction .Target values and NSN and Project References • Optimization actions/analysis .Signalling flows and counter triggering .Call setup process and phases • KPIs: . Parameters related to call setup For internal use 41 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. . Parameters related to call setup For internal use 42 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. . All rights reserved. . Parameters related to call setup For internal use 43 Presentation / Author / Date ©2013 Nokia Solutions and Networks. Parameters related to call setup For internal use 44 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. . Important KPIs/Counters .Target values and NSN and Project References • Optimization actions/analysis .Call setup process and phases • KPIs: . . Content • Introduction . All rights reserved.Parameters Summary • Impact of different Features • Project examples • Links to further material For internal use 45 Presentation / Author / Date ©2013 Nokia Solutions and Networks.Possible failure causes with examples • Summary .Signalling flows and counter triggering . All rights reserved. . Features related to call setup • Any feature that improves link budget with/without interference will help  IRC for 2RX path (LTE979)-RL 40  IRC for 4RX path ( LTE 980) –RL50  Flexible UL bandwidth (LTE786) –RL50  DL adaptive CL MIMO (LTE568) –RL50  TTI Bundling (LTE907) –RL50  Supper Cell (LTE993) RL 35 • Physical RF optimization will always help. power control can be made less aggressive • Cell tracing provides also TA information to evaluate faraway attempts and overshooting cells For internal use 46 Presentation / Author / Date ©2013 Nokia Solutions and Networks. • To reduce uplink interference. Call setup process and phases • KPIs: . Content • Introduction . All rights reserved. .Signalling flows and counter triggering .Important KPIs/Counters .Target values and NSN and Project References • Optimization actions/analysis .Parameters Summary • Impact of different Features • Project examples • Links to further material For internal use 47 Presentation / Author / Date ©2013 Nokia Solutions and Networks.Possible failure causes with examples • Summary . • Analysis has done using different methods • Parameter changes has done as described in next slides • Managed to improve the RRC connection establishment SR. • The majority of RRC connection establishments are successful on PLMN level but there are still few failures due to no response to RRC setup message. Project Example – LTE Project in APAC 1/7 RRC Connection Establishment – Failure Rate • Project was carried out during main roll out phase. All rights reserved. . For internal use 48 Dept. around 200 sites are on air. / Author / Date ©2013 Nokia Solutions and Networks. 01 is taken into account during PDSCH scheduling. step 1 7 recommendation is to allow more transmissions of contention resolution message . The maximum amount of time allowed for contention resolution. . 6 Random Access Response Window Size parameter defines the raRespWinSize 5 (3) 7(5) (4).39 0.0. 2000ms (7) T300 = 600ms (4). The value 0.12 would be optimal and thus.6ms = 60. 200ms (1). 8ms (0). raContResoT 32ms (3) 32ms (3). 64ms (7) increased accordingly to 7*8. 400ms (3). 40ms (4). The maximum number of HARQ transmissions in DL that is configured for each UE at initial access to a specific cell. Timer T300 supervises the RRC connection establishment 300ms (2).. 24ms (2). 56ms (6). 10 (7) window size for the random access response in TTIs. 4 (2). step 0. T300 should be set according to preambTxMax*20ms T300 200ms (1) 600ms (4) 600ms (4). 8 (6). 48ms 64ms (7) in case harqMaxTrDl is increased 4->7 the raContResoT should be (5). The parameter defines the maximum code rate for random access procedure messages 4 (SRB0 message). Parameter Recommendations – DL 2/7 • The following parameter settings are recommended to reduce RRC setup failures due to DL issues.05. All rights reserved. 16ms (1). it should be tested in live network as well in order to further improve RRC setup success rate. 7 (5). + harqMaxMsg3*raContResoT = 10*20ms+5*64ms = 520ms -> 1500ms (6). For internal use 49 Dept. The HARQ delay is 8ms + 0.5.05 0. The harqMaxTrDl 4 1…16. 5 (3). 3 (1). procedure. This maximum code rate MaxCrRa4Dl 0. / Author / Date ©2013 Nokia Solutions and Networks. Parameters Current Range Description Recommendation 2 (0).2 ms => 64ms 100ms (0).. 1000ms (5).6ms for UE processing delay and thus. (11). step 1 used for message 3 of the contention-based random access 5 procedure. 2dB (1). -116 dBm (2). -90 dBm (15) The power ramping step size parameter defines the power increment step size for Random Access preamble prachPwrRamp 2 dB (1) 0dB (0). -96 dBm (12). The maximum number of HARQ transmissions in UL that is configured for each UE at initial access to a harqMaxTrUl 5 1…7 7 specific cell. -100 dBm (10). The maximum number of HARQ transmissions harqMaxMsg3 3 1…8. / Author / Date ©2013 Nokia Solutions and Networks. The rachPwrRamp from 2dB to 4dB is 4 dB (2) recommended to have faster rampup due to decreased PRACH initial power. -94 dBm (13). -90 dBm preamble transmission. -104 dBm (8). The recommendation is to reduce the ulpcIniPrePwr -106 dBm (7). Used for the calculation of P0_NOMINAL_PUSCH (j=2) = last deltaPreMsg3 0 dB (1) -1…6. Parameter Recommendations – UL 3/7 • The following parameter settings are recommended to reduce RRC setup failures due to UL issues. The parameter defines the initial power for Random Access -110 dBm (5). For internal use 50 Dept. -112 dBm (4). -92 dBm (14). -118 dBm (1). . 4dB (2). The parameter is aligned with DL HARQ transmissions. -102 -110 dBm (5) (15) PRACH interference generation by reducing the PRACH initial dBm (9). -108 dBm (6). All rights reserved. Parameters Current Range Description Recommendation -120 dBm (0). 6dB (3) transmission. -114 dBm (3). step 1 (1 corresponds 0 dB) preamble power + deltaPreMsg3 for PUSCH (re)transmission 4 dB (2) corresponding to the random access response grant. -98 dBm power . Parameters Current Range Description Recommendation nCqiRb 1 1.. i. 10ms (1).e. All rights reserved. deltapucchshift 2 1…3 Maximum number of cyclic shifts allowed for Formats 1/1a/1b 2 5ms (0).x 1 2ms (0). For internal use 51 ©2013 Nokia Solutions and Networks. PUCCH Configuration 4/7 •The following parameters are recommended for PUCCH configuration..94.2047 associated DL scheduling PDCCH. 20ms cellSrPeriod 20 ms (2) Scheduling Request periodicity in the cell. . step 1 3 frequency band.98 Number of PRBs dedicated to Formats 2.. 10ms cqiperNp 20 ms (3) Periodicity of periodic CQI / PMI feedback on PUCCH or PUSCH 20 ms (2).. 5ms (1). 80ms (4) First physical resource block available for PRACH in the UL system prachFreqOff 3 0. Roundup [PUCCH resources/2] The parameter defines how many OFDM symbols are used for PDCCH channel transmission.. 20 ms (2). 20ms (3) AckNack index offset relative to the lowest CCE index of the n1pucchAn 36 10. In RL20 eNB maxNrSymPdcch 3 1…3 3 uses fixed value for each TTI but in RL30 the PDCCH allocation is dynamic depending on the load. 40ms (3). offset to decide the number 18 of resources reserved for SRI .. maxNumQci1Drb 100 0…200 100 maxNumQci1Drb must be equal or less than maxNumActUE. addAUeTcHo] <= maxNumRrc. The number of 100 active UEs in the cell cannot exceed: maxNumActUE + max[addAUeRrHo (15). Maximum number of 120 RRC connections (maxNumRrc) is to be set to a higher value (or equal) than maximum number of active UEs in the cell: maxNumActUE + max [addAUeRrHo. addAUeTcHo (20)] Threshold for the maximum number of established QCI1-GBR-DRBs in the cell. Radio Admission Control 5/7 •RAC thresholds for the maximum number of RRC connected users and the active (DRB) users in a cell can be aligned with the configured PUCCH capacity.. Parameters Current Range Description Recommendation The number of RRC-connections established in the cell cannot exceed maxNumRrc. The RAC will check this condition for the admission of the single non-GBR DRB at S1AP: Initial Context Setup. .840 SRB1 has been admitted and successfully configured. Threshold for the maximum number of established DRBs in the cell.. A UE is termed active if at least one single non- maxNumActUE 80 0. maxNumActDrb 360 0. RAC shall always be invoked for the admission of SRB1 at RRC Connection Setup..4200 360 maxNumActDrb must be equal or greater than maxNumActUE. For internal use 52 ©2013 Nokia Solutions and Networks. An RRC connection is considered as established if the maxNumRrc 240 0.840 GBR data radio bearer has been successfully configured for it.. All rights reserved... data region (PDSCH) is varying accordingly. All rights reserved. • The feature adjusts the number of PDCCH symbols per subframe (TTI). . For internal use 53 ©2013 Nokia Solutions and Networks.e. • This will improve the end user DL throughput during small PDCCH load condition (few UEs to be scheduled). i. Usage Based PDCCH Adaptation 6/7 • The number of PDCCH symbols is adaptively adjusted based on the current load condition. Parameters Current Range Description Recommendation The parameter defines how many OFDM symbols can be used for PDCCH channel transmission. If phichDur is set to Extended i.The actual OFDM symbol amount used for PDCCH in a TTI is selected from values between the minimum actLdPdcch False (0) false (0). true (1) true (1) reasonable amount of symbols for the selected DL bandwidth and maximum allowed number of PDCCH symbols (maxNrSymPdcch). For internal use 54 ©2013 Nokia Solutions and Networks.e. PHICH is transmitted in the first 3 symbols of each TTI then. eNB selects based on usage the actual value for each TTI. All rights reserved.. Activate or deactivate the load adaptive number of PDCCH symbols in a cell . .. PDCCH Configuration 7/7 •The following parameter are recommended for dynamic PDCCH adaptation functionality.3 3 UEs in PCFICH. which and value is signaled to the maxNrSymPdcch 3 1. maxNrSymPdcch must be set to 3. [other possible examples] For internal use 55 Presentation / Author / Date ©2013 Nokia Solutions and Networks. All rights reserved. . RRC Performance RRC completion success degraded due to initial context setup failures For internal use 56 / ©2013 Nokia Solutions and Networks. All rights reserved. . For internal use 57 / ©2013 Nokia Solutions and Networks. RRC Connection Release Failures Most of RRC release failures due to EPC with ‘other’ reason caused by the initial context setup failure (see scenario). . All rights reserved. E-RAB Performance E-RAB setup success degraded due to initial context setup failures. For internal use 58 / ©2013 Nokia Solutions and Networks. . All rights reserved. All rights reserved. E-RAB Setup Failures Most of E-RAB setup failures due to ‘other’ reasons (see scenario) For internal use 59 / ©2013 Nokia Solutions and Networks. . . For internal use 60 / ©2013 Nokia Solutions and Networks. EPC initiates UE context release (RRC release) with cause “Semantic Error”. Initial Context Setup Failure – Scenario • The initial context setup failure due to incorrect UE-AMBR = 0 setting. • The eNB rejects the S1AP: INITIAL CONTEXT SETUP REQUEST message because the both UE-AMBR in UL and UE-AMBR in DL have been set to 0 and thus. All rights reserved. Parameters Summary • Impact of different Features • Project examples • Links to further material For internal use 61 Presentation / Author / Date ©2013 Nokia Solutions and Networks. .Target values and NSN and Project References • Optimization actions/analysis .Important KPIs/Counters . Content • Introduction . All rights reserved.Call setup process and phases • KPIs: .Possible failure causes with examples • Summary .Signalling flows and counter triggering . http://nop-i.nokiasiemensnetworks.php?dst=L2xuYnRzX2ZwLnBocA • IMS link to this material: .net/Alpaca/Account/Login?ReturnUrl=/Alpaca/ • LTE Project Uploads: .nokiasiemensnetworks. .https://alpaca.inside.aspx • JUMP: .emea.nokiasiemensnetworks.inside. Links to relevant material • MBB PL KPI Bench marking tool (for KPI target values): .net/sites/nporadio/Radio%20Wiki/Home.https://sharenet-ims.https://sharenet-ims.nokiasiemensnetworks.com/Open/383538041 • LTE feature Testing Materials in IMS: .emea.nsn-net.nsn-net.inside.https://workspaces.com/Overview/D505370850 For internal use 62 Presentation / Author / Date ©2013 Nokia Solutions and Networks.https://sharenet-ims.com/pl_login.com/Open/505235702 • Radio wiki for more details: . All rights reserved.