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Lte epc kp is and signalling (sf)


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LTE-EPC KPIs and Signalling (SF)

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Lte epc kp is and signalling (sf)

  1. 1. LEKS_SF_1 Multimedia over IP Based on SIP Response codes 1xx – Provisional response 2xx – Success 3xx – Redirection 4xx – Request failure 5xx – Server failure 6xx – Global failure PSTN SIP Proxy RTP Real-time Transport Protocol SDP Session Description Protocol SIP Session Initiation Protocol TCP Transmission Control Protocol UA User Agent UAC UA Client UAS UA Server UDP User Datagram Protocol UE User Equipment URI Uniform Resource Identifier VoIP Voice over IP Media Stream Alice Bob REGISTER sip: contact:<sip:> 200 OK INVITE sip: bob ? INVITE sip: bob@ bob@ ! 200 OK 200 OK ACK BYE Location Service SIP Registrar SIP URI: SIP proxy bob@ SIP proxy INVITE sip: SIP URI: 200 OK 200 OK 180 Ringing 180 Ringing 180 Ringing SIP Traffic Case 100 Trying 100 Trying DNS lookup Ringback Ringtone Bob answers Bob hangs up PSTN Breakout IP L2 / L1 TCP UDP AS Application Server DNS Domain Name System FQDN Fully Qualified Domain Name ISUP ISDN User Part Lx Layer x MG Media Gateway MGC Media Gateway Controller PCM Pulse Code Modulation PSTN Public Switched Telephone Network RFC Request for Comments RTCP Real-time Control Protocol SIP [RFC 3261] - Allows UAs to: register current IP address of the UA in the network set up, modify and release logical links - Can carry payload from other protocols (SDP, ISUP...) - Open to extensions (new methods, responses, headers, header values) SDP [RFC 2327, 3264] - Describes real-time multimedia sessions - Carried by e.g. SIP RTP [RFC 3550, 3267] - End-to-end transport of real-time data - Sequence numbers - Timestamps SIP User Agent Can act as: - Client (UAC), or - Server (UAS) SIP SIP SIP Any DNS SIP URI  IP addr. Stores IP address [or FQDN] per subscriberauthentication authorization service access implements policies routes requests Receives registrations Audio over RTP 5000 5001 RTCP 6544 6545 Video over RTP 7654 7655 RTCP 10002 10003 [RFC 3263] Session The media stream(s), Dialogue a peer-to-peer SIP relationship between two UAs RTCP [RFC 3550] - Reports quality on RTP session port port H.248 [RFC 3015] Used by MGCF to control resources in MGW DNS SIP Proxy Server SIP Proxy Server Location Service SIP Registrar S I P RTP RTCP Real-time app. SIP URI: SIP ISUP RTP PCM H.248SIP MGC MG Control plane (Signalling) User plane (Transmission) Any Eg. VoIP
  2. 2. LEKS_SF_2 IP-CAN PDN 1: IMS PCC Policy and Charging Control PCEF Policy and Charging Enforcement Function PCRF Policy and Charging Rules Function PGW Packet Data Network Gateway PDN Packet Data Network QoS Quality of Service RTSP Real Time Streaming Protocol SDF Service Data Flow SGSN Serving GPRS Support Node SGW Serving Gateway SIP Session Initiation Protocol SPR Subscriiption Profile Repository TDF Traffic Detection Function UDR User Data Repository VoIP Voice over IP AF AF Node that uses PCC, e.g.: • Media Server or CSCF For Operator Controlled Services GW PCEFAudio + Video over IP One IP-CAN Session Two IP-CAN Bearers Three SDFs: Signaling, Audio, Video) ADC Application detection and Control AF Application Function APN Access Point Name CSCF Call Session Control Function DPI Deep Packet Inspection eNB Evolved Node B EPS Evolved Packet System E-UTRAN Evolved UTRAN GGSN Gateway GPRS Support Node GW Gateway IP-CAN IP Connectivity Access Network LTE Long Term Evolution MMtel Multimedia Telephony OCS Online Charging System OFCS Offline Charging System SIP Default EPS Bearer eNB PGWSGW EPS IP-CAN Bearers ”Session Based Service” PCEF PDN 2: Internet Video Streaming Email File Transfer Example: • One IP-CAN Bearer • 3 Service Data Flows SDFs identified e.g. with DPI SDF Dedicated EPS Bearer IP-CAN Session PCRF SPR/ UDR TDF IP-TV MMtel APN X APN Y Gx Rx OFCS OCS IP-CAN Problems Ro GyGz MME HSS 1 11 1 12 1 13 1 14 1 15 HNW VNW 1 1 6 1 1 8 1 1 9 KPI: Session setup success rate RRC establishment S1 link establishment ERAB establishment System events and counters 1 1 7
  3. 3. LEKS_SF_3 E-UTRAN Key Performance Indicators, KPI PDN Packet Data Network IMS / Internet PCRF HPLMNVPLMN Provides QoS and charging rules • QoS aware packet routing • UP anchor:E-UTRAN  2G / 3G eNB SGW PGW • QoS aware packet routing • User IP-address allocation • Policy Enforcement Point MME HSS • Radio Base Station • Radio Resource Mgmt • Mobility • Security (e.g. Authentication) • Bearer Mgmt • Subscriber database Accessibility : The probability for an end-user to be provided with an E-RAB at request. (%) A1=InitialEPSBEstabSR= A2=AddedEPSBEstabSR= RRC.ConnEstabAtt.Cause RRC.ConnEstabSucc.Cause S1SIG.ConnEstabAtt S1SIG.ConnEstabSucc ERAB.EstabInitAttNbr.QCI ERAB.EstabInitSuccNbr.QCI ERAB.EstabAddAttNbr.QCI ERAB.EstabAddSuccNbr.QCI Retainability: How often an end-user abnormally looses an E-RAB during the time the E-RAB is used. (Release/time) R1QCI=x= R2= ERAB.RelActNbr.QCI ERAB.SessionTimeUE ERAB.SessionTimeQCI.QCI Integrity: The degree to which a service is provided without excessive impairments such as throughput, latency and packet loss. IP Throughput for a single QCI: (kbps) Downlink Uplink DRB.IPThpDl.QCI DRB.IPThpUl.QCI E-UTRAN IP Latency.(ms) Downlink DRB.IPLatDl.QCI Availability: E-UTRAN Cell Availability (%) CellAvailability= RRU.CellUnavailableTime.cause Mobility: E-UTRAN Mobility. (%) MobilitySuccessRateQCI=x= HO.ExeAtt HO.ExeSucc HO.PrepAtt.QCI HO.PrepSucc.QCI EPS Bearer = Radio Bearers + S1 Tunnel + S5/8 Tunnel P-GWS-GW Peer Entity UE eNB EPS Bearer Radio Bearer S1 Bearer End-to-end Service External Bearer Radio S5/S8 Internet S1 E-UTRAN EPC Gi E-RAB S5/S8 Bearer SRB DRB TS 32.450 SR Success Rate QCI Quality Cllass Indicator IP Internet Protocol QoS Quality of Service PDN Packet Data Network IMS Internet Multimedia Subsystem RRU Radio Remote Unit UP User Plane
  4. 4. LEKS_SF_4 E-UTRAN Key Performance Indicators, KPI Accessibility:         100 QCI.InitAttNbrERAB.Estab QCIr.InitSuccNbERAB.Estab EstabAttS1SIG.Conn EstabSuccS1SIG.Conn CausetabAtt.RRC.ConnEs CausetabSucc.RRC.ConnEs 1 QCI cause        QCI cause BEstabSRInitialEPSA     100 QCIAddAttNbr.ERAB.Estab QCI.AddSuccNbrERAB.Estab 2 QCI   QCI stabSRAddedEPSBEA Retanability: . . 1 . . QCI x QCI x QCI x ERAB RelActNbr QCI R ERAB SessionTimeQCI QCI      . . 2 . QCI ERAB RelActNbr QCI R ERAB SessionTimeUE   Integrity: xQCIxQCI IPThpDlDRBThpDownlink   . xQCIxQCI IPThpUlDRBThpUplink   . IP Throughput for a single QCI: xQCIxQCI IPLatDlDRBLatDownlink   . E-UTRAN IP Latency (ms) Availability: 100 _ ]ime.[causeavailableTRRU.CellUn-t_periodmeasuremen cause   periodtmeasuremen bilityCellAvaila Mobility:  %100 .QCIHO.PrepAtt c.QCIHO.PrepSuc HO.ExeAtt HO.ExeSucc RateSuccessMobility xQCI xQCI xQCI     TS 32.450
  5. 5. LEKS_SF_5 EPC Key Performance Indicators, KPI PDN Packet Data Network IMS / Internet PCRF HPLMNVPLMN Provides QoS and charging rules • QoS aware packet routing • UP anchor:E-UTRAN  2G / 3G eNB SGW PGW • QoS aware packet routing • User IP-address allocation • Policy Enforcement Point MME HSS • Radio Base Station • Radio Resource Mgmt • Mobility • Security (e.g. Authentication) • Bearer Mgmt • Subscriber database Accessibility : EPS Attach Success Rate (%) The ratio of the number of successfully performed EPS attach procedures to the number of attempted. EASR= MM.EpsAttachAtt.Type MM.EpsAttachSucc.Type Dedicated EPS Bearer Creation Success Rate (%) The ratio of the number of successfully performed dedicated EPS bearer creation procedures by PGW to the number of attempted. DEBCSR= SM.CreationPGWInitBearerAtt SM.CreatationPGWInitBearerSucc Dedicated Bearer Set-up Time by MME (Mean) (Second) Describes the valid time per dedicated bearer set-up procedure by MME and is used to evaluate service accessibility. DBSTM= SM.EstabActDedicatedEpsBearer TimeMean Service Request Success Rate (%) Describes the ratio of the number of successfully performed service request procedures by UE to the number of attempted service request. SRSR= SM.EpsServiceReqAtt SM.EpsServiceReqSucc Mobility: Inter-RAT Outgoing Handover Success Rate (EPS->GSM) (%) Inter-RAT Outgoing Handover Success Rate (EPS->UMTS) (%) Inter-RAT Outgoing Handover Success Rate (EPS->CDMA2000) (%) Inter-RAT Incoming Handover Success Rate (GSM->EPS) (%) Inter-RAT Incoming Handover Success Rate (UMTS ->EPS) (%) Inter-RAT Incoming Handover Success Rate (CDMA2000->EPS) (%) Tracking Area Update Success Rate (%) Utilization KPI: Mean Active Dedicated EPS Bearer Utilization EPS Bearer = Radio Bearers + S1 Tunnel + S5/8 Tunnel P-GWS-GW Peer Entity UE eNB EPS Bearer Radio Bearer S1 Bearer End-to-end Service External Bearer Radio S5/S8 Internet S1 E-UTRAN EPC Gi E-RAB S5/S8 Bearer SRB DRB TS 132455
  6. 6. LEKS_SF_6 EPC Key Performance Indicators, KPI TS 132455
  7. 7. LEKS_SF_7 TAC Tracking Area Code PLMN Public Land Mobile Network TAI Tracking Area Identity ECM EPS Connection Managemen ID Identityt S1 Setup Used to take a new eNB into service. eNB already configured so the purpose is to inform the MME about the main parameters. S1 Setup & Initial Attach MME 1 Weight 100 1 1 S1AP Initiating Message S1 Setup (eNB ID, TAC (1..256) eNB ID = Global eNB ID + TAC (PLMN, TAI) + IP#. Can serve 1..6 PLMN S1AP Successful Outcome S1 Setup (MME, GUMMEI, relative MME Capacity) Relative MME Capacity (load balancing) 0 .. 255 Weight factor = probability to be choosen. 2 3 S1AP Unsuccessful Outcome S1 Setup (cause) = • Semantic error • CPU Overload • HW Failure • Unknown PLMN • Unspecified Example: Out of 3 UE attaches, eNB will forward 2 attaches to MME-1 and 1 attach to MME-2. If in case MME-1 is down, then all calls will be routed to MME-2. MME 2 Weight 50 MME Pool MME 1 wants to move Ue’s: RRC: Cause ”Load Balancing TAU”. ECM connected Ue’s. UE: RRC: TAU eNB: Choose MME 2 DNS UE: Attach (not initial) GUMMEI eNB: eNB: IP# GUMMEI If no answer select new MME …
  8. 8. LEKS_SF_8 TEID Tunneling Endpoint ID F-TEID MME IP + TEID Initial Attach HSSeNB MME Initial Attach The subscriber need to register to the network. NAS EMM Attach Request (IMSI/GUTI/S-TMSI, PDP ESM Request) Update Location (”Service Granted”, PDN IP#, QoS) Origin @ Realm Destination @ Realm Uu S1 MME S11 S5/S6 S6a (DIAMETER) SGW DNS Result Code: Successful or Failure. AMBR for Subscriber and APN (PGW). UL: 10 Mbps DL: 100 Mbps Charging Info. QoS defined by QCI eg. 9 = Best Effort. Default Bearer PGW Create Session Req. (F-TEID, EBI=x, ) Req./Resp. CP IP# UP IP# CP IP# UP IP#Create Session Resp..(S1-U, SGW F- TEID = xx + yy ) Allocate UE IP# if dynamic. 1 1 MME get full control of UP routing and can change route due to mobility or load in core. Initial Ctx Setup Req.(E-RAB id, TEID, Attach Accept, Activate Default B. Req) Attach Accept, Default B. Req. EMM T3412=20dH for TAU. GUTI, QCI=9, UE IP#, DRB (SRB = 1) Attach Complete Modify Bearer Req. 2 2 Inform SGW about UP eNB IP# and TEID for S1-U RRC CONNECTION REQUEST Idle Mode Connected Mode RRC CONNECTION SETUP Config. of UE Protocols… RRC CONNECTION SETUP COMPLETE SRB 1 SRB 0 pmRrcConnEstabAtt + pmRrcConnEstabSucc + RRC Con. Setup logical S1 connection S1 Signalling Connection Establishment RRC CONNECTION SETUP COMPLETE NAS ’Attach Request’ INITIAL UE MESSAGE RRC S1AP DOWNLINK NAS TRANSPORT NAS UE identity Request’ DL INFORMATION TRANSFER pmS1SigConnEstabAtt + pmS1SigConnEstabSucc + MME E-RAB Establishment (Initial) RRC CON. RECONFIG. COMPLETE INITIAL CONTEXT SETUP REQUEST Includes a list of E-RABs to be setup RRC S1AP RRC CONNECTION RECONFIGURATION pmErabEstabAttInit + Stepped for each E-RAB received in the list of E- RABs to be setup INITIAL CONTEXT SETUP RESPONSE Authentication and security mode procedures pmErabEstabSuccInit + Stepped for each initial E-RAB that has been successfully established MME 3 3 4 4 Initial E-RAB Establishment Success Rate [%]: pmErabEstabAttInit pmErabEstabSuccInitpmS1SigConnEstabSucc pmRrcConnEstabAtt pmRrcConnEstabSucc = X X pmS1SigConnEstabAtt X 100 Added E-RAB Establishment Success Rate [%]: pmErabEstabAttAdded pmErabEstabSuccAdded = X 100
  9. 9. LEKS_SF_9 After successful Attach: UE ctx Release & Service Request MME HSS SGW PGW MME HSS SGW PGW UE ctx Release due to inactivity IP # GTP-U RRC MAC:C-RNTI (S-RNTI) GTP-U GTP-C IMSI MME IP# GTP-C CP # UP # CP # UP # TEID=1 TEID=xx TEID=0 TEID =yy UP # IP# IP # UE timer in eNB expires and buffer empty… t=10 .. 60 .. 120 s UE ctx Release Req. (cause=user inactivity) Modify Bearer Req.(Scope Indication=1, EBI=x) Scope => delete EBI + transport TEID (S1-U)Mod.B.Resp.( cause=req. accept, EBI=x) UE ctx Rel. Command (cause=normal release) 1 1 Normal for the MME even if radio conection with UE lost… UE ctx Release Complete2 2 RRC, C-RNTI, S1-U But Default Bearer and other ctx remains… CP IP# UP IP# CP IP# UP IP# pmErabRelMme + pmErabRelMmeAct + Normal release: pmErabRelNormalEnb + Abnormal release: pmErabRelAbnormalEnb + pmErabRelAbnormalEnbAct + MME Initiated ERAB Release ERAB Rel. Resp. ERAB Release COM. (ERAB’s) MME UL DL DRB and S1-U Releasad eNB Initiated ERAB Rel. Indication. DRB and S1-U Releasad pmErabRelMmeAct + pmUeCtxtRelMmeAct + pmErabRelMme + pmUeCtxtRelMme + Normal release: pmErabRelNormalEnb + pmUeCtxtRelNormalEnb + MME Initiated UE Ctx Release UE Ctx Rel. Com. MME eNB Initiated DRB and S1-U Releasad UE Ctx Rel. Complete pmErabRelAbnormalEnbAct + pmUeCtxtRelAbnormalEnbAct + Abnormal release: pmErabRelAbnormalEnb + pmUeCtxtRelAbnormalEnb + UE Ctx Rel. Req. (cause) UE Ctx Rel. Com. UE Ctx Rel. Complete E-RAB Release Rate [drops/s]: = pmSessionTimeUe pmErabRelRelAbnormalEnbAct + pmErabRelMmeAct UE Session Time Data Transfer Time In session Out of session In session 100 msec 100 msec pmSessionTimeUe +
  10. 10. LEKS_SF_10 UE ctx Release & Service Request UE Service Request After S1AP ctx release the UE remain attached… and by sending a ”Service Request” on NAS the con. Is resumed… HSSeNB MME Initial UE Message (S-TMSI, TAI, Service Req.(KASME) Uu S1 MME S6a (DIAMETER) Default Bearer PGW Initial Ctx Setup Req.(E-RAB id, TEID) Attach Accept, Default B. Req. SRB = 1 Attach Complete Opt. Auth. Info SGW Initial Ctx Setup Resp.(E-RAB id, TEID) Modify Bearer Req.(TEID, F-TEID, EBI=x, S1-U eNB F-TEID) Update Bearer Req(IMSI,EBI=x, QCI, Charging ID, AMBR) Update Bearer Response IP # GUTI GUTI Modify Bearer Resp.(cause=Req.Accept, PGW F-TEID, EBI) Create Bearer Req.(create new TFT) ERAB Mod.Req (ERAB ID, QoS, new TFT) (DRB = x) ERAB Mod. Resp.(ERAB ID, QoS) 2 2 ERAB modification on S1 1 1 SGW confirms S1-U can be used for payload… 3 3 Start UE activity timer… KASME Access Security Management PCRF IP-CAN Session Modification
  11. 11. LEKS_SF_11 Dedicated Bearer Setup If required by the QoS parameters a dedicated bearer will be setup… Dedicated Bearer Setup SPReNB MME S1AP Init.Msg(ERAB Setup, ERAB ID=y) NAS Activate Dedicated EPS Beraer Context Req.(RAB=Y) Uu S1 MME Default Bearer RAB ID = x Active PGW Create Bearer Req.(EBI=Y, new TFT(PCC Rules)) SGW NAS Activate Ded.B. Ctx Req.(RAB=Y) S1AP Succ. Outcome ERAB Setup (ERAB ID=Y) APN-AMBR UE-AMBR TFT ARP L-EBI IP # GUTI GUTI PCRF SIP(SDP) Codec MPEG-4 SPR Subscriber Profile Respository SDP Session Description Protocol SIP Session Initiating Protocol APN Access Point Name TFT Tranport Format Template L-EBI Linked EPSBearerId Subscriber browsing on internet (default bearer). Finds streaming video. PCRF detects SDP=new codec and authorizes a dedicated bearer… PCC Rule QoS Default NGBR QCI 5 - 9 Dedicated NGBR GBR QCI 5 - 9 QCI 1 - 4 APN-AMBR UE-AMBR APN IP# ARP GBR MBR TFT ARP L-EBI NAS Activate Ded.B. CTx. Resp.(RAB=Y) NAS Activate Dedicated B. Ctx Resp(RAB ID = Y) Create Bearer Resp..(EBI=Y, new TFT ) Multimedia Session (Browsing Best Effort), Streaming Video (GBR) Dedicated Beraer (RAB ID=Y) and Default Bearer (RAB ID = X) active Example VoLTE: Two ”default” and one dedicated. Default 1: SIP signalling QCI = 5 (priority 1) IP# A with max 100 ms delay UE-PGW with max packet loss < 10 -6 Dedicated : VoIP QCI = 1 (priority 2) linked to Default 1 (L-EBI) GBR. ”Default 2”: smart phone traffic (video, chat, email, browser etc) QCI = ) (lowest priority) IP# B with max 300 ms delay UE-PGW with packet loss 10-6
  12. 12. LEKS_SF_12 Inter eNB HO over X2 When Ue changes its geographic position a HO is required – ideally over X2. • X2 HO prep X2AP to create tunnel • S1AP path switch to update MME for new S1-U • MME needs to inform SGW. Inter-eNB Handover over X2 & S1 HO MMEUu S1 MME PGW X2AP SN Status Transfer, eRAB, PDCP SN SGW X2AP Succ. Outcome ”HO prep” UL/DL TEID… GUTI X2AP Handover Prep. Target Cell ID, GUMMEI, eRAB, QoS Source Target S1AP ”DL NAS Trasnport” TAU Accept, new GUTI S1AP ”Path Switch Req.” CellID, TAC, RABID GTP-C Update UP Resp. UL GTP-U GTP-C Update UP Req. EBI, S1-U eNB TEID S1AP Succ. Outcome ”Path Swtich Req” X2AP X2AP ”UE ctx Release” S1AP ”UL NAS Transport”, Cell ID, TAU, old GUTI RSRP time sintrasearch Qmeas(n) R(n) R(s) Qmeas(s) qHyst(s) qoffset(s) tReselectionEutra Qrxlevmeas [dBm] = measured RSRP Qrxlevmin [dBm] = minimum required rx signal strength (SIB 3) (-140 to -44) pMaxServingCell [dBm]= max UL tx power (SIB 1 serving or SIB 3 inter freq neighbor) (-33 to 33 or 1000) (36.101) P [dBm] = UE max power capability (23 dBm) (36.101) RRC Meas. Report (Event A3) pmHoPrepAttLteIntraF + Handover Prep. HO Req. HO Ack. Source Target pmHoPrepSuccLteIntraF + RRC Con. Reconfig. pmHoExeAttLteIntraF + Handover Exec. RACH Procedure Source Target pmHoExeSuccLteIntraF + RRC Con. Reconfig. Complete Path Switch Req./ Resp. UE ctx Rel. T300 = Time UE waits for RRC Req.Resp (ms) T301= Time UE waits for RRC Re-estab.Req (ms) T310= Started after receiving N310 (”out of synch”) T311 = Started after initiating proc. (if expired and no suitable cell go to RRC IDLE) (sec.)
  13. 13. LEKS_SF_13 Inter-eNB Handover over X2 & S1 HO S1 HO Whitout X2 we need S1HO. • eNB trigger HO based on measurements from UE • HO preparations • HO resource allocation and modification of S1-U KPI Handover Prep. = eNB ”outgoing leg” Relocation Proc. = ”MME ”incoming leg” (resource allocation) MMEUu S1 MME PGW S1AP Succ. Outcome HO Prep. (RRC Con. Reconfig. Info, Target PCI) SGW S1AP Handover Resource Alloc., ERAB ID, TEID GUTI S1AP Handover Prep. Target Cell ID, TAC Source Target S1AP ”UE ctx Release” cause = succ. HO” S1AP Succ. Outcome (RRC Con. Reconfig Info) S1AP ”MME status transfer” UL/DL PDCP SN (source forward info to target) GTP-C Modify B. Req. (MME switch the S1-U DL TEID, UL not changed) GTP-C Mod. B. Resp.(S1 SGW F-TEID, GTP-U TEID) S1AP ”HO Notification” CGI, TAI S1AP ”Source eNB sends HO command to UE” and ”Status Transfer Message to MME (PDCP SN) UE arrives… S1AP ”UE ctx Release” RRC Meas. Report (Event A3) pmHoPrepAttLteIntraF + Handover Prep. HO Req. HO Command Source pmHoPrepSuccLteIntraF + MME RRC Con. Reconfig. pmHoExeAttLteIntraF + Handover Exec. RACH Procedure Source pmHoExeSuccLteIntraF + RRC Con. Reconfig. Complete UE ctx Rel. MME Target SGW
  14. 14. LEKS_SF_14 Dedicated Bearer Release & Detach Dedicated Bearer Release Here, triggered by the NW e.g UE inactivity timer exp in SGW… Or UE by means of the Bearer Resource Modification or PDN Disconnect procedure. The DEACTIVATE EPS BEARER CONTEXT REQUEST message contains an ESM cause : #8: operator determined barring #36: regular deactivation #38: network failure #39: reactivation requested or #112: APN restriction value incompatible with active EPS bearer context MME SGW S1AP (ERAB Release ERAB ID) NAS Deact. D. B. ctx Rel. (RAB ID, ESM cause) Delete Bearer Req (EBI) ”No cause value” NAS Deact. D.B. ctx Rel Start the timer T3495 and wait for UE resp. If no resp. resend 5 times, then deactivate EPS locally… S1AP Succ. Outcome NAS Deact. D.B. ctx Resp. S1AP (ULNASTransport, NAS Deact. Dedicated EPS B. Resp (RAB ID) Delete Bearer Resp.(cause = Req. Accept, EBI) PGW Default Bearer RAB ID = x Active HSS eNB MMEUu S1 MME S11 S5/S6SGW PGW Delete B. Req. (TEID, EBI) Detach Normally triggered by the UE power off… Delete B. Req./Resp. Delete B. Resp.. (cause= Req. Accept) S1AP DL NAS Transport (Detach Request) S1AP UL NAS Transport (Detach Accept) UE ctx Release Req./Resp. DIAMETER Notification Req./Answer X CP IP# UP IP# CP IP# UP IP#X X IP #X + ppt ”Failure Cases…”
  15. 15. LEKS_SF_15 RRC Connection Problems CCCH SRB 0 RLC-SAP TM DCCH SRB 1 RLC-SAP AM BCCH : BCH : PBCH MIB (DL bandwidth/# RB) RS RSRP RSRQ PSS (0, 1, 2) 5 ms loop that gives slot synch To detect the 10 ms frame start SSS (0 .. 167) PDCCH CRC : for me? PDSCH : DL-SCH : BCCH SIBs (tell UE how to behave) PRACH : RACH preamble PCFICH Indicates the size of the DCI (1, 2, 3, or 4 OFDM symbols) PDCCH DCI UL Assignment: (UE ID, PRBs, MCS, HARQ id, TPC) PUSCH : UL:SCH : CCCH RRC Connection Request (cause …) CRC 24 TrBlk RNTI data Input data vector for a CRC, masked with RNTI If ERR ~= 0 then either an error has occurred or the input CRC has been masked. MAC-IDs UL : RA_RNTI DL : P-RNTI, SI-RNTI UL/DL : C-RNTI PCFICH PDCCH PDSCH : DL : SCH : CCCH RRC Connection Response (UE ID, DCCH, …) RACH: MAC Rand. Acc. Preamble (RA-RNTI, preamble index) Error Not sent/Not received UL-SCH/CCH: RRC Con. Req (temp C-RNTI, NAS UE ID=IMSI or TMSI 1 2Error RRC Con. Reject ( cause=?, wait time) RRC Security Mode Command 3Error RRC Security Mode Failure (cause ?) RRC Con. Reconfig. 4Error RRC Con. Re-est. Req. (cause =”reconfig. failure” RRC Con. Re-establ. (new SRB 1, new security ctx). RRC Con. Re-establ. Compl. OK! Error RRC Con. Re- establ. Reject (cause ?) 5 or ... Failure! 1 2 3 4 5 Error on Uu: interference on DL-SCH, coverage? High TA? Solution: partial freq. Reuse! eNB CPU overload? Typically cell congested, no radio resources. ? = • ”reconfig. Failure” • ”HO failure” • ”other reason” - wait time second before new request (1 .. 16) Typically due to problem in handset during ciph/integr. Procedure…. Sent instead of ”RRC Con. Reconfig. Complete”. eNB must take decision what to do… RLC AM used for RRC sign. but ACK never received (not sent or interference?). If repeated eNB drops the con. And release UE… If S1AP cause = ”failure in Uu procedure” or ”release due to EUTRAN” possible caused by AM errordue to interference or problem in UE power control… freq (power)
  16. 16. LEKS_SF_16 SCH Shared Channell QoS Quality of Service TTI Transmission Time Interval VoIP Voice over IP RRC Radio Resource Control PRB Physical Resource Block MCS Modulation and Coding Scheme RI Rank Indicator PMI Precoding Matrix Indicator MIMO Multiple Input Multiple Output PAPR Peak to Average Power MAC-Scheduler Purpose: • Efficient SCH(Data) Resources Assignments Consideration • Traffic Volume, QoS (Buffer Status, Priority…) • Channel Condition Scheduling Interval • Dynamic Scheduling by MAC : One TTI (1ms : One Sub- frame) • Semi-Persistent for VoIP : Multiple TTIs by RRC Resource Assignment : • PRBs & MCS MIMO • RI and PMI Freq. Time. DL OFDMA: High Throughput High PAPR UL SC-FDMA: Fair Throughput Low PAPR saves battery… RE MappingCell Specific Scrambling Layer Mapping (symbols mapped on 1,2,3,4 layers) Modulation (QPSK, xQAM) Precoding (mapping to 1, 2or 4antenna ports) RE Mapping OFDM (IFFT) OFDM (IFFT) Code word, qo Pseudo Random bit sequence Depends on selected tx mode: •Single antenna tx • tx diversity • spatial multiplexing (MIMO) • beamforming X i . . . . Y i . . . . Code word, q1 (if MIMO) 1 modulation Symbol -> RE antenna ports . . . CRC 24 Code Block Segmentati on FEC Turbo Coding R = 1/3To detect bit errors If input > 6144 bits Bit error correction Sub block Interleaving Rate Matching Code Block Concatenati on To achieve high throuput and error correct coding by HARQ Add segmentet blocks... 1 TB PDU S P1 P2 ”Code Word” MAC PHY Output Assignment (DL) Grant (UL) Scheduler Data related inputs •HARQ retransmissions •Data buffer (DL) User related inputs •UE capabilities •UE measurement gaps •Sync status QoS translation •UE prioritization •Resource Allocation •PDCCH resources •Buffer estimation (UL) •RB and symbols •DL Power Power Control CQI (DL) PMI(DL) RI(DL) MCS (DL) QCI table •Priorities •LCGs SINR(UL) RRC Connection Request (UL) • UL interference based on i.e eNB sharing of load over X2 with max 20ms • 3G quality can be measured DL/UL with ded. Ch’s. LTE user are distributed in time x freq. Test mobiles can never measure UL quality. • Satisfy latency and packet error loss characteristics of each QCI class • Satisfy Guaranteed Bit Rate (GBR), Minimum Bit Rate (MBR) • Enforce downlink maximum bit rate for sum of downlink bearers • new users are admitted only when QoS requirements of existing and newly added users/bearers can be met. • perform frequency selective and frequency diverse scheduling (localized and distributed virtual resource blocks) depending upon channel conditions, QoS requirements etc. • Adapt TB size, MIMO and rank depending on CQI, PMI and RI from UEs plus data buffers • Higher priority to HARQ re-tx versus new tx… RSRQ = NRB x RSRP RSSI
  17. 17. LEKS_SF_17 Radio Quality Downlink UL Scheduling Req. • Power Headroom • Buffer Status Reporting (long and Short) The three most important tasks in LTE prelaunch radio parameter planning are: 1 Physical Cell Identity (PCI) allocation 2 Physical Random Access Channel (PRACH) parameter planning, and 3 Uplink reference signal (RS) sequence planning During/after launch are: 4: UL Power control 5: Handover thresholds 6: Paging (MME/eNB paging capacity) 7: Control Channel planning Also SI-time-to-release and DRX-cycle should be configured… MIMO MIMO PCI PCI PCI PRACH Attach Request Connected Mode UE UL RS Handover thresholds UL PC MME P a g i n g UL Path Loss DL Path Loss Uplink Budget, 64 kbps, 2 RB’s, 3- sector macro-cell Downlink Budget, 1 Mbps, Antenna Diversity, 10 MHz, 46 dBm ”When needed” ~ 100 Hz UMTS CPICH GSM RSSI dB/dBm t RSRQ RSRP RSRQ bad while RSRP stable = increasing DL interference Both RSRQ and RSRP bad = path loss… t1 t1 + t Timing Advance, TA To synch tx/rx of UL radio (UE/eNB) in time domain eNB sends TA value in RACH responce. TA = 0 .. 1287 = UE sent RACH at max 200 km distance = cell range of 100 km. TA = 0,52 μs = 156 m MAC timing advance command values between 0 and 63. Using the 64 index values, a distance of 64 x 156m = 10 km so ± 5km at 3600km/h. PRACH Planning 839 preamble sequences available Paging (MME/eNB paging capacity) The process of TA dimensioning contains two main tasks: • TA dimensioning for the MME • TA dimensioning for the RBS Number of ZC sequences required per cell, for a given random access radius. A cell requires five ZC sequences per cell for up to 7.3km radius, which is typically sufficient for urban and suburban macro cells. This results in sequence reuse factor of at least 839/5 ≈ 167 cells, hence allows for easy planning process. Paging Failures • defective handsets; • insufficient coverage; • wrong settings for broadcast cell (re)selection parameters like S0 criteria.
  18. 18. LEKS_SF_18 Performance • ”Call Drops” due to Uu MME Opt: RRC Con. Release (cause=”unspecified”) UE ctx Rel. Request (”failure due to EUTRAN”) UE ctx Rel. Command (cause=”normal release”) UE ctx Rel. Complete May not be seen as dropped from for the user… since UE moves in/out from IDLE. Takes 1 – 2 seconds to setup RRC… Makes sence to distinguis between subscriber level (QoE) and service level (NW). • Should we aggregate per QCI? • Aggregate per handset? ”Uu failure or radio connection lwith UE lost” Coverage? Interference? Handset? Permanent interference due to ext. Source? MAC Scheduler Algorithm? Buildings, tunnels? Parameter errors e.g. missing neighbours? Protocol? Measurements? QoE 2000 2010 2020 User-paid revenues Traffic growth Non user-paid revenues Voice-centric pay-per minute X 100%