Mobe Rado Network Pannng 1Genera Packet Rado Servce (GPRS) n Reease B6.2Expert tranngMobe Rado Network Pannng 2GPRS n Reease B6.2Agenda (1)IntroductonGenera archtecture and protoco ayersAcate GPRS archtectureAcate GPRS deveopment Software evouton Hardware evoutonMobe Rado Network Pannng 3GPRS n Reease B6.2Agenda (2)GPRS ar-nterface PDCH concept and channe codng Logca channes PDCH dynamc aocaton Tramc evauaton n the BSC UL/DL temporary bock ow estabshment TBF resource aocaton agorthm Mobe Rado Network Pannng 4GPRS n Reease B6.2Agenda (3)GPRS Network operaton MS capabtes Routng area Mobty management Attach procedure PDP context actvaton SI broadcastngMobe Rado Network Pannng 5GPRS n Reease B6.2Agenda (4)Rado nk contro agorthms UL/DL measurements Power contro Ce re-seecton and re-drecton nstead of handover Dynamc codng scheme adaptaton Frequency hoppng on PDCHMobe Rado Network Pannng 6GPRS n Reease B6.2Agenda (5)GPRS Desgn GPRS Desgn crteraMobe Rado Network Pannng 7IntroductonMobe Rado Network Pannng 8GPRS n Reease B6.2Why GPRS?Because of the nternet. There are bg expectatons on the potenta of nternet servces (nternet ncudng word wde web www, e-ma, ntranet and the ke) ohered to mobe subscrbersThe good od crcut swtched mode of data transmsson s not very we suted to the bursty way the data actuay ow between the end-user and the networkA packet mode transmsson aows to reuse the transmsson resources for other users whe you are readng the page |ust downoaded from the nternet. Ths even wthout urgng you to dsconnect, reconnect, dsconnect, ... GPRS s a rea "aways on" servceMobe Rado Network Pannng 9GPRS n Reease B6.2PrncpeGenera packet rado servce (GPRS) denes a network archtecture dedcated to packet transfer mode, wth rado access, whch aows servce subscrber to send and receve data n an end-to-end packet transfer mode, wthout utsng network resource n crcut-swtched modeA GPRS network can be nked to dherent xed data networks (e.G. IP, X25)GPRS uses the BSS archtecture, but denes a xed network (GPRS backbone) whch s dherent from the NSS, and whch nks the BSS to PDNs (packet data networks). The BSS s used for both crcut-swtched and GPRS servces.The BSS has 2 cents:The MSC, for crcut-swtched servces (A nterface)The GPRS backbone network, for GPRS (gb nterface)Mobe Rado Network Pannng 10Genera archtecture andprotoco ayersMobe Rado Network Pannng 11GPRS n Reease B6.2Genera archtecture (1)PDNe.g. X25 GPRSBackboneBSSMSC/VLR PSTNPDNe.g. IPAGbGiGiMobe Rado Network Pannng 12GPRS n Reease B6.2Genera archtecture (2)GPRS backbone archtecture :BSSPDNBSSSGSNIP based GPRS backboneSGSNGGSNPDN GGSNMobe Rado Network Pannng 13GPRS n Reease B6.2Genera archtecture (3)GPRS backbone s an IP network and s composed of routers: Servng GPRS Support Node (SGSN), at the same herarchca eve as the MSC, whch s nked to severa BSSs. It keeps track of the ndvdua MSs ocaton and performs securty functons and access contro Gateway GPRS Support Node (GGSN), whch s nked to one or severa data networks, provdes nterworkng wth externa packet-swtched networks and s connected wth SGSNs va an IP-based GPRS backbone networkMobe Rado Network Pannng 14GPRS n Reease B6.2Protoco ayers (1)Transmsson paneMACGSM-RFLLCRLCIP/X25SNDCPappcatonMSMACGSM-RFUmBSSRLCreayBSSGPNSL1bsNSL1bsBSSGPGbLLCSGSNSNDCP GTPL2L1IPUDP/TCPreayL2L1IPUDP/TCPGTPGGSNIP/X25GnMobe Rado Network Pannng 15GPRS n Reease B6.2Transmsson paneLayered protoco structure provdng user nformaton transfer and assocated contro procedures GSM-RF : physca ayer rado nk measurements, ce re/seecton,power contro, . RLC (Rado Lnk Contro) RLC denes the procedures for a seectve re-transmsson of unsuccessfuydevered RLC data bock and the procedures for segmentaton and re-assemby of LLC PDU MAC (Medum Access Contro) denes the procedures that enabe mutpe MSto share a common transmsson medum whch may consst of severa physca channesMS BSSMobe Rado Network Pannng 16GPRS n Reease B6.2Transmsson pane (2) LLC (Logca Lnk Contro) Ths ayer provdes a hghy reabe cphered ogca nk whch s ndependent of theunderyng rado nterface protocos SNDCP (SubNetwork Dependent Convergence Protoco) It maps network-eve characterstcs onto the characterstcs of the underyng network BSSGP (Base Staton System GPRS Protoco) Ths ayer conveys routeng and OoSreated nformaton between BSS and SGSN NS (Network Servce) It transports BSSGP PDUs and s based onframe reay connecton between BSS and SGSNMS SGSNBSS SGSNMobe Rado Network Pannng 17GPRS n Reease B6.2Transmsson pane (3) GTP (GPRS Tunneng protoco) Ths protoco tunnes user data and sgnangbetween GPRS support nodes, n the GPRS backbone network TCP (Transmsson Contro Protoco) It carres GTP PDUs n the GPRS backbone network for protocos that need a reabe data nk (e.g. X25) UDP (User Datagram Protoco) It carres GTP PDUs n the GPRS backbone network for protocos that do not need a reabe data nk (e.g. IP) IP (Internet Protoco) Ths s the GPRS backbone network used for routeng user data and contro sgnangGGSN SGSNMobe Rado Network Pannng 18GPRS n Reease B6.2Protoco ayers (2)Sgnang paneMACGSM-RFLLCRLCGMM/SMMSMACGSM-RFUmBSSRLCreayBSSGPNSL1bsNSL1bsBSSGPGbLLCSGSNGMM/SM GTPL2L1IPUDPreayL2L1IPUDPGTPGGSNGnMobe Rado Network Pannng 19GPRS n Reease B6.2Sgnang paneprovdes protocos for contro and support of the transmsson pane functons GMM/SM : GPRS Mobty Management/Sesson Management GPRS attach, GPRS detach,RA update, PDP context de/actvatonMS SGSNMobe Rado Network Pannng 20Acate GPRS archtectureMobe Rado Network Pannng 21GPRS n Reease B6.2Acate GPRS archtectureA Packet Contro Unt s dened by the GSM standard : contros the GPRS actvty n a ce handes RLC/MAC functons may be ether n the BTS, the BSC or the SGSN Acate choce : PCU n a new network eement caed the MFS (Mut-BSS Fast Packet Server) smooth and cost ehectve ntroducton of the GPRSBTSBTSBSCBSCMFS SGSNGbAterMobe Rado Network Pannng 22GPRS n Reease B6.2Acate GPRS protoco ayers (1)Transmsson paneMACGSM-RFLLCRLCIP/X25SNDCPappcatonMSMACUmMFSRLCreayBSSGPNSL1bsNSL1bsBSSGPGbLLCSGSNSNDCP GTPL2L1IPUDP/TCPreayGSM-RFreayAbs/AterL1-GCHL2-GCHL1-GCHL2-GCHBTSMobe Rado Network Pannng 23GPRS n Reease B6.2Transmsson paneTwo propretary ayers are mpemented to extend the rado nterface to the MFS: L1-GCH s the physca ayer whch uses a synchronous mode of transmsson (16 kbt/s) L2-GCH conssts n a protoco between the MFS and the BTS for synchronsaton wth the rado nterface and channe actvaton.GCH nks go through the BSC transparentyMobe Rado Network Pannng 24GPRS n Reease B6.2Acate GPRS protoco ayers (2)Sgnang pane wth CCCH usageGSM-RFLLCGMM/SMMSBSCGPUmMFSRRMreayBSSGPNSL1bsGbGSM-RFreayAbsL1-GSLL2-GSLL1-RSLL2-RSLBTSL1-GSLL2-GSLAterL1-RSLL2-RSLreayRR BSCGPRR/RRMBSCMobe Rado Network Pannng 25GPRS n Reease B6.2Sgnang pane wth CCCH usageIn ths case, BSC sgnang ayers are concerned, n the connecton estabshment phase to access to CCCH, for GPRS common sgnang: L1-RSL s the physca ayer. It uses 64 or 16 kbt/s channes L2-RSL conssts of a LAP-D protoco L1-GSL uses 64 kbt/s channes L2-GSL conssts of a LAP-D protoco, doubed for redundancy reasons BSCGP (Base Staton Controer GPRS Protoco) conveys routng of GPRS reated messages (GPRS pagng messages, MS orgnated channe request, mmedate assgnment) when the CCCH s used for GPRS sgnang and handes channe aocaton for GPRS needsMobe Rado Network Pannng 26Acate GPRS deveopmentMobe Rado Network Pannng 27GPRS n Reease B6.2Software evoutonGPRS servces (and transmsson rates) w be ntroduced n two phases (accordng ETSI Spec.): Phase 1: Codng schemes CS1 and CS2 Phase 2: Codng schemes CS3 and CS4 The actua software Reease B6.2 ony supports GPRS phase 1 features (CS1 and CS2)B6.2 contans a mnma set of features absoutey needed for an operator to provde GPRS servce. Ths step s a short-term souton for a rst commerca ntroducton of GPRSMobe Rado Network Pannng 28GPRS n Reease B6.2B6.2 evouton stepsFor B6.2 reease step SMG 28, as ths reease s ony for test, nether G4 BTS step1 nor step 2 w be supported. Not compatbe wth SMG 29 (nc. Mobes)B6.2 step1 (former name B6.2 SMG29-1) s compant to SMG 30 and 30bs For B6.2 step 1, the rst verson w support G4 BTS Step 1. Ths verson w aow aso G3 BTS to support G4 modues (step 1). For mantenance reease ths w aow new TRE ntroducton n G3 and G4 BTSB6.2 step 2 (former name B6.2 SMG29-2) s compant wth SMG 30 and 30bs, 31 and 31bs For B6.2 step 2 (and foowng steps), G4 BTS step 1 & 2 w be supported, and G3 BTS w support G4 modues (step 1 & 2)Mobe Rado Network Pannng 29GPRS n Reease B6.2Hardware evoutonThe foowng hardware s supportng GPRS features No hardware retrot s necessary nsde the BTS for the GPRS functonaty BTS G1 MK2 wth DRFU BTS G2 wth FUMO (CS-1 ony and 8 bt access burst, nstead of 11) BTS G2 wth DRFU BTS Evoum(G3) BTS Evoum (G4 step1 and 2) Mcro M1M, M2M, M4M BSC G2 BSC TC TC G1 (Wth Gb nk drect MFS-SGSN) TC G2 (Wth Gb nk drect MFS-SGSN or Through MSC)Mobe Rado Network Pannng 30GPRS Ar-InterfaceMobe Rado Network Pannng 31GPRS n Reease B6.2PDCH concept (1)The access scheme s Tme Dvson Mutpe Access (TDMA) wth eght basc physca channes per carrer (TS 0 to 7)A GPRS tme-sot s named a "Packet Data CHanne" (PDCH)In mpementaton step 1 ony one TRX per ce can be dedcated to GPRS servce (max. 8 PDCH)PDCHs are mapped dynamcay on a 52-mutframe (PDCH dynamc aocaton), the resources eft are dedcated to CS The 52 mutframe conssts of 12 bocks of 4 consecutve frames, 2 de frames (frames 25 and 51) and 2 frames used for the PTCCH (frames 12 and 38)Mobe Rado Network Pannng 32GPRS n Reease B6.2PDCH concept (2)Master PDCH (MPDCH) vs Save PDCH (SPDCH) : MPDCH : A PDCH s caed GPRS Master Channe (MPDCH) when t carres a PBCCH and a PCCCH channe (not avaabe n B6.2) Advantages :Reduce CCCH and BSC oadImprove the access deay RsksHeavy to mpement SPDCH (Save PDCH): the BCCH and the CCCH of the crcut swtched desgn are used nstead of PBCCH and PCCCH (In B6.2, ets say PDCH = SPDCH)Mobe Rado Network Pannng 33GPRS n Reease B6.2PDCH concept (3)52-mutframe structuretme.......0 1 2 3 4 5 6 71 TDMA frame = 4.616 ms1 bock = 18.464 ms0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7B1 B3 B2 B4 B5 B6 B7 B8 B9 B10GPRSGSM tramcB11 B052-mutframe = 240 msPDCH1PDCH2PDCH3PDCH1PDCH2PDCH3PDCH1PDCH2PDCH3PDCH1PDCH2PDCH3FramesBocks0 8 4 13 17 21 26 30 34 39 43 47Frames 12, 38: PTCCHFrames 25, 51: Ide framesMobe Rado Network Pannng 34GPRS n Reease B6.2PDCH concept (4)1 bock ncudes 4 TDMA frames (=18.462ms)One PDCH n one bock s caed a RLC/MAC bock and occupes 4 tmesots wth 114 bts each (= 456 bts)Thus the brutto throughput rate s 456 bt/18.462ms = 24.7 kbt/s per tmesotHowever the ehectve data throughput rate s ower snce bts for USF, BSC and header are usedDependng on the codng scheme dherent ehectve data throughput rates per tmesot can be achevedMobe Rado Network Pannng 35GPRS n Reease B6.2Channe codng (1)On the rado nterface, data w be protected accordng to four dherent channe codng schemes for GPRS, CS1 to CS4The rst step of the channe codng procedure s to add a Bock Check Sequence (BCS) for error detectonFor CS-1 to CS-3, the second step conssts of addng four ta bts and a haf rate convoutona codng for error correcton that s punctured to gve the desred codng rateFor CS-4 there s no codng for error correctonThe most protected mode s CS1, whch s therefore aways used for sgnangDependng on the rado condton CS1 or CS2 are used for tramc: ths choce s done by the MFS, accordng to the recepton quaty and eve measurements performed by the BTSMobe Rado Network Pannng 36GPRS n Reease B6.2Channe codng (2)Scheme ModuatonSchemeCodng schemes for RLCdata bocksCode rate Maxmum data rate pertmesot (RLC payoad)kbt/sCS-4 GMSK No codng 1.00 20.0CS-3 GMSK Haf rate convoutonacodng, punctured0.75 14.4CS-2 GMSK Haf rate convoutonacodng, punctured0.66 12.0CS-1 GMSK Haf rate convoutonacodng0.50 8.0Remarks: RLC payoad = throughput ohered to the LLC ayer RLC/MAC header, BCS, ta bts.are aready subtractedB 6.2Mobe Rado Network Pannng 37GPRS n Reease B6.2Channe types (1)Dherent GPRS ogca channes are carred by the PDCH whch are shared on a bock bass : PCCCH (Packet Common Contro CHanne): ths channe deas wth common contro (pagng, access grant, random access). The PCCCH supports the foowng sub-channes: PRACH (Packet Random Access CHanne) PPCH (Packet Pagng CHanne) PAGCH (Packet Access Grant CHanne) PBCCH (Packet Broadcast Contro CHanne): t broadcasts genera nformaton used by the MS to access the network for packet transmsson and nformaton (transmtted on BCCH) to aow CS operatonMobe Rado Network Pannng 38GPRS n Reease B6.2Channe types (2) PTCH (Packet Tramc CHanne) used for data transmsson and assocated sgnang PDTCH (Packet Data Tramc CHanne): ke TCH, but mapped on bocks of 4 bursts PACCH (Packet Assocated Contro CHanne): ke FACCH, used to transmt contro bocks. PACCH s mapped on one PDCH:f a snge PDTCH s aocated to an MS, the PACCH s aocated on the PDCH carryng the PDTCHf mutpe PDTCH are aocated to an MS, the PACCH s aocated on one of the PDCH carryng the PDTCHs (Acate BSS) PTCCH (Packet Tmng Advance Contro CHanne) used for contnuous tmng advance mechansm. It s mapped on one of the PDCH carryng the PACCH of that MS (Frames 12 and 38, used for the Tmng Advance + 2 de frames 25 and 51)Mobe Rado Network Pannng 39GPRS n Reease B6.2BSC MFSAocaton RequestDeaocaton RequestLoad IndcatonPDCH dynamc aocaton (1)The PDCH Dynamc aocaton s used for the co-ordnaton between crcut swtched and GPRS tramc wthn one TRX (PDCH group) for rado resource handngThs co-ordnaton s performed through the Acate BSCGP nterface between BSC and A935 MFSPDCH (de)-aocaton requests are sent from the MFS to the BSC and BSC crcut swtchedtramc oad s ndcated from the BSC to the MFSMobe Rado Network Pannng 40GPRS n Reease B6.2PDCH dynamc aocaton (2)Tmesots usabe for PDCH are grouped nto "PDCH groups" (ony one n B6.2 step 1) One PDCH group contans tme-sots beongng to the same TRX, havng the same frequency conguraton wthout hoes (=consecutve tmesots)Mobe Rado Network Pannng 41GPRS n Reease B6.2Parameter MAX_PDCH_GROUP (1)As the crcut swtched servces shoud be served wth prorty, the PDCH recourse contro parameters gve the possbty to reserve permanenty a certan amount of tmesots for CS, that w mt the number of tmesots used for GPRSThe parameter MAX_PDCH_GROUP set at the OMC-R denes the maxmum number of PDCH per PDCH group that may be actvated for GPRS tramcMobe Rado Network Pannng 42GPRS n Reease B6.2Parameter MAX_PDCH_GROUP (2)Ths parameter s an absoute maxmum that s not necessary reached a the tmeIt w not be reached n the three foowng cases: The GPRS oad s ow, The GPRS oad s hgh but a other tmesots are used for voce and therefore not avaabe for GPRS at that tme, The GPRS oad s hgh, a few TS are free but the ce s dened n hgh oad stateMAX_PDCH_GROUP: Range 1-8 (defaut vaue = 8)Mobe Rado Network Pannng 43GPRS n Reease B6.2Parameter MIN_PDCH_GROUPOn the other hand, a mnmum reservaton of tmesots for GPRS n a ce s recommended, to make sure some GPRS cas w be possbe at any tmeThe parameter MIN_PDCH_GROUP set at OMC-R denes the mnmum number of PDCH permanenty aocated to GPRS n a ceMIN_PDCH_GROUP: Range 1-8 (defaut vaue = 8)Mobe Rado Network Pannng 44GPRS n Reease B6.2Parameter MAX_PDCH_HIGH_LOADIn order to optmse resource, a second reservaton parameter for CS s ntroduced: MAX_PDCH_HIGH_LOADThs parameter takes precedence over the MAX_PDCH_GROUP n the ce whenever a hgh oad (voce tramc) stuaton s detected by the BSC for the ceMore TS are then dedcated to CS tramc but gves a ower maxmum number of GPRS tmesots per ceIn ths case, PDCHs must be de-aocatedMAX_PDCH_HIGH_LOAD: Range 1-8 (defaut vaue = 1)Mobe Rado Network Pannng 45GPRS n Reease B6.2PDCH de-aocaton (1)Two cases for the de-aocaton of a PDCH : hgh oad ndcaton sent by the BSC to the MFS : goba (crcut + packet) oad eevated n the ce GPRS ow oad : PDCH becomes emptyMobe Rado Network Pannng 46GPRS n Reease B6.2PDCH de-aocaton (2)GPRS ow oad : the MFS de-aocates nactve PDCH as ong as more than MIN_PDCH_GROUP PDCH are aocated nactve PDCH are de-aocated after a deay (T_PDCH_INACTIVITY, T_PDCH_INACTIVITY_LAST)Mobe Rado Network Pannng 47GPRS n Reease B6.2PDCH de-aocaton (3)Hgh oad stuaton : the MFS marks aocated PDCH exceedng the maxmum aowed number of PDCH (MAX_PDCH_HIGH_LOAD) as unavaabe for new requests when the PDCH becomes empty,the MFS de-aocates ths PDCH wthout deayMobe Rado Network Pannng 48GPRS n Reease B6.2timeMIN_PDCH_GROUPMAX_PDCH_HIGH_LOADMAX_PDCH_GROUPAllocated PDCHsCell is createdA GPRS MS requests4 timeslotsNormal BSC load Normal BSC load High BSC loadMaximum number ofPDCHs is reachedHigh BSC load the M!Sdeallocates PDCHs as soonas exceeding PDCHsbecome em"t#$Maximum number ofPDCHs in BSC high loadsituationPDCH resource controMobe Rado Network Pannng 49GPRS n Reease B6.2Tramc evauaton n the BSCLong term evauaton : 1-2 mnutesVarous uses : handover preparaton PDCH aocaton and de-aocaton : BSC LOAD INFORMATION message sent by the BSC to the MFS (Tramc_oad parameter)Mobe Rado Network Pannng 50GPRS n Reease B6.2Tramc evauaton n the BSC (2)Cacuaton of averages : non sdng average AV_TRAFFIC_LOAD representng the goba oad (crcut + packet) of the ce for A_TRAFFIC_LOAD sampes A_TRAFFIC_LOAD : 100 * (1 - Nb free TCH / Nb tot TCH) Nb tot TCH : tota number of TS n the ce for TCH and PDCH Nb free TCH : number of free TS not used by a TCH or a PDCH 1 sampe every TCH_INFO_PERIOD seconds (defaut vaue = 5s) Range: 1-16 Defaut vaue: 12 AV_TRAFFIC_LOAD s cacuated every 60s (12*5) when settng defaut vaues (ong term)Mobe Rado Network Pannng 51GPRS n Reease B6.2Tramc evauaton n the BSC (3)Decson process : corresponds to the cacuaton of the varabe Tramc_oad usng severa (N_TRAFFIC_LOAD) consecutve averages (AV_TRAFFIC_LOAD) compared to dherent threshods (HIGH_TRAFFIC_LOAD, LOW_TRAFFIC_LOAD, IND_TRAFFIC_LOAD) Defaut vaues:HIGH_TRAFFIC_LOAD IND_TRAFFIC_LOAD LOW_TRAFFIC_LOAD1-2 TRX 70% 45% 20%>2 TRX 80% 60% 50%N_TRAFFIC_LOAD1-2 TRX 63-4 TRX 35-6 TRX 2Mobe Rado Network Pannng 52GPRS n Reease B6.2Tramc evauaton n the BSC (4)Decson process, cacuaton of Tramc_oad : f Tramc_oad = ndente and: the ast N_TRAFFIC_LOAD averages AV_TRAFFIC_LOAD (ncudng the new one) verfy AV_TRAFFIC_LOAD > HIGH_TRAFFIC_LOAD then Tramc_oad = hgh the ast N_TRAFFIC_LOAD averages AV_TRAFFIC_LOAD (ncudng the new one) verfy AV_TRAFFIC_LOAD < LOW_TRAFFIC_LOAD then Tramc_oad = owMobe Rado Network Pannng 53GPRS n Reease B6.2Tramc evauaton n the BSC (5)Decson process, cacuaton of Tramc_oad : f Tramc_oad = ow and the new average AV_TRAFFIC_LOAD veres: IND_TRAFFIC_LOAD 0 and AV_TRAFFIC_LOAD > IND_TRAFFIC_LOAD or AV_TRAFFIC_LOAD> HIGH_TRAFFIC_LOAD then Tramc_oad = ndenteMobe Rado Network Pannng 54GPRS n Reease B6.2Tramc evauaton n the BSC (2)Decson process, cacuaton of Tramc_oad : f Tramc_oad = hgh and the new average AV_TRAFFIC_LOAD veres: IND_TRAFFIC_LOAD 0 and AV_TRAFFIC_LOAD < IND_TRAFFIC_LOAD or AV_TRAFFIC_LOAD< LOW_TRAFFIC_LOAD then Tramc_oad = ndenteMobe Rado Network Pannng 55GPRS n Reease B6.2Tramc evauaton n the BSC (2)Decson process, cacuaton of Tramc_oad_GPRS : same cacuaton than Tramc_oad wth : HIGH_TRAFFIC_LOAD -> HIGH_TRAFFIC_LOAD_GPRS LOW_TRAFFIC_LOAD -> LOW_TRAFFIC_LOAD_GPRS IND_TRAFFIC_LOAD -> 0 Defaut vaues:HIGH_TRAFFIC_LOAD_GPRS IND_TRAFFIC_LOAD LOW_TRAFFIC_LOAD_GPRS1 TRX 70% 0% 10%2 TRX 70 % 0% 20%3 TRX 70 % 0% 30% > 3 TRX 80% 0% 50%What is the real difference between raffic_l!ad_GPR" and raffic_l!ad when at the start !f the e#al$ati!n A_RA%%IC_LOAD is calc$lated &l!ball' f!r C" ( PD) Onl' the #al$es !f the thresh!lds) What is the real difference between raffic_l!ad_GPR" and raffic_l!ad when at the start !f the e#al$ati!n A_RA%%IC_LOAD is calc$lated &l!ball' f!r C" ( PD) Onl' the #al$es !f the thresh!lds) Mobe Rado Network Pannng 56GPRS n Reease B6.2Tramc evauaton n the BSC (2)Load Indcaton sent by the BSC to the MFS : Load Indcaton : Tramc_oad_GPRS = hgh -> Load Indcaton = hgh Tramc_oad_GPRS = ndente or ow -> Load Indcaton = norma Load Indcaton sent by the BSC to the MFS n case of change : norma hghL!ad indicati!n with raffic_l!ad *C"+ !r raffic_l!ad_GPR" *PD+)L!ad indicati!n with raffic_l!ad *C"+ !r raffic_l!ad_GPR" *PD+)Mobe Rado Network Pannng 57GPRS n Reease B6.2Tramc evauaton n the BSC (2)Recommended rues : HIGH_TRAFFIC_LOAD_GPRS > 100 * (MAX_PDCH_GROUP / Nb tot TCH) avod that the aocaton of MAX_PDCH_GROUP PDCH eads to a hgh oad ndcaton sent to the MFS and therefore trggers a de-aocaton procedureReference) HIGH_RA%%IC_LOAD_GPR" will ne#er be &reater beca$se there will ne#er be ,!re than MAX_PDCH_GROUP PDCH in the RX)Reference) HIGH_RA%%IC_LOAD_GPR" will ne#er be &reater beca$se there will ne#er be ,!re than MAX_PDCH_GROUP PDCH in the RX)Mobe Rado Network Pannng 58GPRS n Reease B6.2Tramc evauaton n the BSC (2)Recommended rues : HIGH_TRAFFIC_LOAD_GPRS - LOW_TRAFFIC_LOAD_GPRS > 100 * ((MAX_PDCH_GROUP - MAX_PDCH_HIGH_LOAD) / Nb tot TCH) avod a png-pong stuaton when the MFS de-aocates PDCH n case of hgh oad ndcaton receved from the BSC f ths rue s not vered there s not aways a png-pong stuaton dependng on the possbe tramc statesMobe Rado Network Pannng 59GPRS n Reease B6.2Tramc evauaton n the BSC (2)Recommended rues : exampe ce wth 2 TRX, 14 TS avaabe for tramc MAX_PDCH_GROUP = 6, MAX_PDCH_HIGH_LOAD = 1 HIGH_T_L_GPRS = 80%, LOW_T_L_GPRS = 50%TS PDCH / TS TCH 0 1 2 3 4 5 6 7 8 9 10 11 12 13 140 0 0.07 0.14 0.21 0.29 0.36 0.43 0.50 0.57 0.64 0.71 0.79 0.86 0.93 1.001 0.07 0.14 0.21 0.29 0.36 0.43 0.50 0.57 0.64 0.71 0.79 0.86 0.93 1.002 0.14 0.21 0.29 0.36 0.43 0.50 0.57 0.64 0.71 0.79 0.86 0.93 1.003 0.21 0.29 0.36 0.43 0.50 0.57 0.64 0.71 0.79 0.86 0.93 1.004 0.29 0.36 0.43 0.50 0.57 0.64 0.71 0.79 0.86 0.93 1.005 0.36 0.43 0.50 0.57 0.64 0.71 0.79 0.86 0.93 1.006 0.43 0.50 0.57 0.64 0.71 0.79 0.86 0.93 1.00Mobe Rado Network Pannng 60GPRS n Reease B6.2Temporary Bock Fow concept (1)A TBF s a physca connecton used by 2 RR enttes (one n the MS, the other n the MFS, both nvoved n a pont to pont daogue for packet connecton estabshment, .e one TBF per user) to support the undrectona transfer of LLC PDUs on packet data physca channesThe TBF s aocated rado resource on one or more PDCHs and comprses a number of RLC/MAC bocks carryng one or more LLC PDUsA TBF s temporary and s mantaned ony for the duraton of the data transferMobe Rado Network Pannng 61GPRS n Reease B6.2Temporary Bock Fow concept (2)A TBF s addressed by a Temporary Fow Identty (TFI), whch s unque n one ce, but may be used concurrenty for TBF's n opposte drectons (upnk and downnk). The TFI s managed by the MFSThe maxmum amount of PDCHs per TBF s mted by O&M or by the mobes mutsot capabty, whchever s ower. The maxmum amount of TBFs per PDCH s aso mted by O&M (user mutpexng)Mobe Rado Network Pannng 62GPRS n Reease B6.2Temporary Bock Fow concept (3)TBFUser 1TBFUser 2TBFUser 30 1 2PDCH1PDCH2PDCH3PDCH1PDCH2PDCH3PDCH1PDCH2PDCH3PDCH1PDCH2PDCH30 1 2 0 1 2 0 1 2 0 1 2PDCH1PDCH2PDCH3PDCH1PDCH2PDCH3PDCH1PDCH2PDCH3PDCH1PDCH20 1 2 0 1 2 0 1tmeB n B n+1 B n+6 B n+5 B n+4 B n+3 B n+2TFI = 5TFI = 9TFI = 13(no mutsotcapabty)(mutsotcapabty)(mutsotcapabty)3 RLC/MAC bocks (GPRS tramc)Mobe Rado Network Pannng 63GPRS n Reease B6.2Upnk State Fag (1)Each TBF s undrectonna: UpLnk TBF and DownLnk TBF for the same mobe are uncorreated For an UL TBF, the mobe receves one USF (Upnk State Fag) per PDCH to be used durng the TBFThe mobe decodes a the bocks on these PDCH : DL TBF : to dentfy the receved bocks (based on TFI) and to know when t must send DL ack (based on RRBP) UL TBF : to know when t can send one bock (based on USF) UL or DL TBF : to know when t must send a contro ack. (based on RRBP)The USF vaue n downnk bock Bn schedues the upnk bock Bn+1, .e. MS that has been aocated ths USF, can use Bn+1 ether as a PDTCH or a PACCHMobe Rado Network Pannng 64GPRS n Reease B6.2Upnk State Fag (2)Exampe of a Upnk Bock Fow schedungDownlink UplinkBock number TFI USF RRBPBn TFIa USF|Bn+1 TFIbUSFk PDTCH|Bn+2 TFIa USF| +3PDTCHkBn+3 TFIb USFk PDTCH|Bn+4 TFIb No Emsson PDTCHkBn+5 TFIb USF| PACCHaBn+6 TFIaUSFk PDTCH|RRBP : Reatve Reserved Bock Perod used to program packet contro on the UL PathMobe Rado Network Pannng 65GPRS n Reease B6.2UL/DL TBF estabshmentThe procedure may be entered ether when the MS s n packet de mode (access on PCCCH or CCCH) or when the MS s n packet transfer mode (.e. an UL TBF s aready estabshed, then the access s performed on the PACCH)Ony UL/DL TBF estabshment on the CCCH (case of B6.2) when the MS s de mode w be expanedMobe Rado Network Pannng 66GPRS n Reease B6.2UL TBF estabshment on CCCH, 1 phase access (1)MS BTS BSC MFSTA cacuatonRACHChanne request + TAChanne requestResourceaocatonAGCH or PCHImmedate assgnmentImmedate assgnmentTFI, USF, TAI, TAThe MS swtchson the assgnedPDCHPacket UL assgnment, pongTFI, USF, TAIPACCHPacket UL assgnmentPacket contro AckPACCHResourceactvatonRLC data bock (TLLI, TFI)PACCHPacket UL Ack/NackPDTCH123TLLI, TFIMobe Rado Network Pannng 67GPRS n Reease B6.2UL TBF estabshment on CCCH, 1 phase access (2)An Immedate assgnment s sent wth TFI, USF, TAI, TA and one PDCH (because the mutsot capabty s not known)A packet UL Assgnment message s sent wth the TFI, TAI, USF and PDCHs (addtona PDCHs may be aocated, snce ony one PDCH can be aocated when usng CCCH) n order to force the MS to send an acknowedgment (pong mechansm)The MS transmts UL bocks when aowed by the network. The MS sha provde ts TLLI n RLC data bocks, unt the end of the contenton resouton (.e. recepton of the Packet UL ack/Nack wth ts TLLI) Contenton resouton mechansm : two MS sends a Channe request at the same tme the MS sends ts TLLI the TLLI s present n the acknowegement from the MFS the MS wth the wrong TLLI s dscarded321Mobe Rado Network Pannng 68GPRS n Reease B6.2UL TBF estabshment on CCCH, 2 phases access (1)MS BTS BSC MFSTA cacuatonRACHChanne request + TAChanne requestResourceaocatonAGCH or PCHImmedate assgnmentImmedate assgnmentTBF startng tme, TAThe MS swtchson the assgnedPDCHsPACCHPacket resource requestResourceactvaton2Packet UL assgnmentPACCHPacket UL assgnment, pongPacket resource requestTFI, USFs, TAI, TLLIPACCHPacket contro AckPacket contro AckSnge bockaocatonTLLIRLC data bockPDTCH13Mobe Rado Network Pannng 69GPRS n Reease B6.2UL TBF estabshment on CCCH, 2 phases access (2)A 2 phases access s necessary when the MS wants ether to : use RLC unacknowedged mode gve ts mut sot cass gve OoS parameters (Peak_Throughput_Cass, Rado_Prorty)Immedate assgnment s sent to MS provdng the rado denton of 1 UL rado bockThe use of the TLLI aows contenton resoutonPacket Upnk assgnment s sent on PACCH, MS sends acknowedgment (pong) and data transfer begns321Mobe Rado Network Pannng 70GPRS n Reease B6.2DL TBF estabshment on CCCH (1)MS BTS BSC MFSLLC PDUResourceaocatonImmedate assgnmentTFI, TAIImmedate assgnmentPCH or AGCHPacket DL assgnment, pongTFI, TAIPACCHPacket DL assgnmentPACCHPacket contro AckPacket contro AckTA cacuatonTmng Advance / Power controPACCHTA / PCPDTCHRLC data bock1 PDCHaocated4 access burstsPDCH(s)aocated321Mobe Rado Network Pannng 71GPRS n Reease B6.2DL TBF estabshment on CCCH (2)An Immedate assgnment s sent wth a TFI, one PDCH and a Tmng Advance Index (no nta tmng advance vaue s provded). A tmer s actvated to gve tme to the MS to take nto account ths messageAt tmer expry, a packet DL Assgnment message s sent wth the TFI, PDCHs (addtona PDCHs may be aocated, snce ony one PDCH can be aocated when usng CCCH) and the tmng advance ndexThe network forces the MS to send an aknowedgment to be sure that the DL TBF has been successfuy estabshed and to be abe to compute an nta tmng advance vaue, the nta tmng advance vaue s sent to the MS and the data transfer begns321Mobe Rado Network Pannng 72GPRS n Reease B6.2TBF resource aocaton (1)GPRS s a packet servce that enabes to share the bandwdth dynamcay between severa mobes The TBF resource aocaton s used to co-ordnate the aocated amount of TBFs per PDCH, requestng addtona resources/TBFs (f avaabe n the PDCH group) n case of busy GPRS tramc Mobe Rado Network Pannng 73GPRS n Reease B6.2TBF resource aocaton (2)The TBF resource aocaton s controed by the packet swtched tramc occurrence per PDCHThe foowng states are dstngushed: Empty, Actve, Busy and FuEmpty Actve Busy FuMAX_UL/DL_TBF_PDCHN_TBF_PER_PDCHTmeMobe Rado Network Pannng 74GPRS n Reease B6.2Parameter MAX_UL_TBF_PDCHA mnmum bt rate can be acheved by denton the parameter MAX_UL_TBF_PDCH, denng the maxmum number of users that share a PDCH n the upnk drecton between 1 and 7The same parameter MAX_DL_TBF_SPDCH can be dened at OMC-R for the downnk drecton between 1 and 9For exampe, f MAX_UL_TBF_PDCH s set to 5, when CS-2 s used, the ehectve mnmum raw bt rate per user on ths PDCH w be about 2.4 kbts/s (12/5). When a PDCH reaches ths sharng eve, t s decared fu and w dentey not accept a sxth shared userRange: |1;7| for UL, Defaut vaue: 7Range: |1;9| for DL, Defaut vaue: 9 Mobe Rado Network Pannng 75GPRS n Reease B6.2Parameter N_TBF_PER_PDCH (1)The parameter N_TBF_PER_PDCH denes for each PDCH the number of shared TBF (users) served by the SystemThs number, comprsed between 1 and MAX_UL/DL_TFB_PDCH, enabes to ensure a good bt rate as ong as GPRS oad s norma For exampe, f the N_TBF_PER_PDCH=2 and codng scheme 2s used, the preferred raw bt rate per user w be 6.0 kbts/s (12/2)When the number of users on the PDCH reachesN_TBF_PER_PDCH, the PDCH s decared "busy" nstead of "actve" and w preferaby not accept a thrd userMobe Rado Network Pannng 76GPRS n Reease B6.2Parameter N_TBF_PER_PDCH (2)The BSS w try as much as possbe to respect N_TBF_PER_PDCH as preferred vaueThs one can however be exceeded when GPRS oad s such that a current PDCHs are busy and no more new PDCH can beaocated to GPRS n the ce In ths case, the sharng can be ncreased up to the dened absoute maxmum MAX_UL_TBF_PDCH or MAX_DL_TBF_PDCH vaueRange: |1;16|, Defaut vaue : 2Mobe Rado Network Pannng 77GPRS n Reease B6.2Parameter MAX_PDCH_PER_TBFHowever to prevent one mutsot MS to use too many PDCHs each tme t wants to transmt data (detrment of other users), the parameter MAX_PDCH_PER_TBF mts the number of PDCH aocated to a snge TBF (e.g. one mobe)Range: |1;5|, Defaut vaue: 5 Theoretca max. btrate (MAX_UL/DL_TBF_PDCH = 1) per MS n Acate step 1 mpementaton (CS-2): 5*12kbt/s = 60kbt/s/user. However the bt rate per user s aso mted by the mutsot capacty of the mobes Mobe Rado Network Pannng 78GPRS n Reease B6.2TBF resource aocaton agorthmThe TBF resource aocaton agorthm s performed n 4 stepswthn the MFS and s trggered by a TBF estabshment request STEP 1:Selection of MSsupported multi-slot conf.MAXPDC!PERTB"TBF requestMS !ulti"slot #l$ss%STEP 2:Analysis ofconcurrent TBFconstraintsSTEP #:PDCHselectionS$e% &:PDCHcoicePDCH re-!uest to BSCPDCH al-located by BSCAlready al-located PDCHscan be usedMobe Rado Network Pannng 79GPRS n Reease B6.2Step1 & 2Step 1 : At the end of ths step, the maxmum number of PDCHs, t s possbe to aocate to the MS, s determned (accordng to the MS mut-sot cass and the O&M parameter MAX_PDCH_PER_TBF)Step 2 : No resource reaocaton s foreseen n B6.2. Consequenty TBF estabshment on one drecton sha compy wth constrants mposed by potenta concurrent TBF on the other drecton As a consequence: MS supported mutsot conguratons may be reduced (n_MS_requested) The tmesots not usabe due to concurrent TBF constrants are marqued as "unusabeMobe Rado Network Pannng 80GPRS n Reease B6.2Step 3 (1)At the begnnng of ths step: the maxmum number of PDCHs whch can be aocated s known (n_MS_requested) some postons may be unusabe due to concurrent TBF constrants n_aocated_pdch s the tota number of aocated PDCHs The am of ths step s to compute n_consecutve_pdch whch s the maxmum number of consecutve PDCHs whch state s equa to "actve" or "empty" and not "unusabe", .e. not marqued as descrbed n step2Mobe Rado Network Pannng 81GPRS n Reease B6.2Step 3 (2)n_consecutve_pdch >= n_MS_req ?yes non_aocated_pdch < MAX_PDCH_GROUP ?n_aocated_pdch < MAX_PDCH_HIGH_LOAD ?yesnoAocaton request3 21Mobe Rado Network Pannng 82GPRS n Reease B6.2TCH 0 1 2 3 4 5 6 7MAX_UL/DL_TBF_PDCHN_TBF_PER_PDCHn_consecutve_pdch = 2 (TS 3, TS 4)n_aocated_pdch = 6 (TS 1, TS 2, TS 3, TS 4, TS 5, TS 6)Step 3 P$r$!eters e&$!pleStep 3 (3)If n_consecutve_pdch n_MS_requested then step 4 s done (the GPRS request s served on the n_consecutve_pdch PDCHs)1Mobe Rado Network Pannng 83GPRS n Reease B6.2Step 3 (4)If n_consecutve_pdch < n_MS_requested and n_aocated_pdch < MAX_PDCH_GROUP/MAX_PDCH_HIGH_LOAD then an ALLOCATION REOUEST s sent to the BSC wth the foowng parameters: n_MS_requested, MAX_PDCH_GROUP or MAX_PDCH_HIGH_LOAD, btmap gvng the exstng GPRS channes wth ther status:Bit!$p e&$!pleTS0 and TS1 are unusabe due to TBF concurrent constrantsTS4 s n the "fu state", T2 s n the busy stateTCH 0 1 2 3 4 5 6 7N_TBF_PER_PDCHbm2MAX_UL/DL_TBF_PDCHunusabe2Mobe Rado Network Pannng 84GPRS n Reease B6.2Step 3 (5)the BSC tres to aocate free tmesots (see ref. |18|) and sends an ALLOCATION CONFIRM to the MFS ndcatng the new conguraton of the PDCH group.At ALLOCATION CONFIRM recepton, n_consecutve_pdch and n_aocated_pdch are updated, and the processng descrbed n step 4 s doneIf n_consecutve_pdch < n_MS_requested and n_aocated_pdch = MAX_PDCH_GROUP/MAX_PDCH_HIGH_LOAD, then the processng descrbed n the step 4 s done wthout any aocaton request towards the BSC3Mobe Rado Network Pannng 85GPRS n Reease B6.2Step 4If n_consecutve_pdch = n_MS_requested the request s served on the n_consecutve_pdchIf n_consecutve_pdch > 0 AND n_consecutve_pdch < n_MS_requested then the request s served on n_consecutve_pdch and the MFS tres to extend the seected combnaton by usng ad|acent PDCHs n the busy stateIf n_consecutve_pdch = 0 and at east one PDCH wth ess than MAX_UL/DL_TBF_PDCH TBFs the request s served on the usabe PDCHsIf n_consecutve_pdch = 0 and no other usabe PDCHs the UL request s re|ected and the DL request s queuedMobe Rado Network Pannng 86GPRS Network operatonMobe Rado Network Pannng 87GPRS n Reease B6.2MS capabtes (1)In order to evauate btrates per user, the resource aocaton has aso to be consdered from the MS pont of vewThree MS casses and types are dened for GPRS: Cass-A: MS can operate GPRS and other GSM servces smutaneousy Cass-B: Supports smutaneous attach, smutaneous actvaton and smutaneous montor. Smutaneous tramc s not supported. The mobe user can make and/or receve cas on either of the two servces sequentay but not smutaneousy. There s an automatca swtchbetween GPRS and GSM servces Cass-C: Supports ony non-smutaneous attach. Aternate use ony. If both servces (GPRS and Crcut Swtched) are supported then a Cass C MS can make and/or receve cas only from ether GPRS or Crcut Swtched servce (manua swtch)Mobe Rado Network Pannng 88GPRS n Reease B6.2MS capabtes (2)The maxmum number of PDCHs granted to an MS depends n ts mut-sot cassThe MS constrants determnng the maxmum capacty per user are the foowng: MS type type 1: smpex MS (ether transmt or receve) type 2: dupex MS (receve and transmt smutaneousy) Max. number of receve/transmt tmesots per TDMA frame:Re B6.2 supports 2 UL sots / 4 DL sots for Type 1 MS and 5+5 for Type 2 MS Mn. tme (n tmesots) between receve, transmt and measurementsMobe Rado Network Pannng 89GPRS n Reease B6.2Routeng AreaFor GPRS, as pagng s more frequent than n GSM, RA were dened whch may be smaer than LAA RA s a subset of one and ony one LAA RAI (RA Identty) dentes severa cesThe MS ocaton n Standby state s known n the SGSN at the RA eveThe MS s paged n ts RA when MT tramc arrves at the SGSNA RA s served by ony one SGSNMobe Rado Network Pannng 90GPRS n Reease B6.2Locaton managementMS enters n a new ceNew ce nsde the current RAMS n Ready stateCe updateNew ce beongs to a new RARA updateNew ce beongs to a new LARA/LA updateOny n NMO IMobe Rado Network Pannng 91GPRS n Reease B6.2MS mobty management states (1) Ide : the MS s not attached to the network : pagng s not possbeStandby : the MS s attached to the network : pagng s possbe the MS ocaton s known wth the RA accuracyReady : the MS ocaton s known wth the ce accuracyMobe Rado Network Pannng 92GPRS n Reease B6.2MS mobty management states (2)IdeReadyStandbyGPRSattachGPRSdetachPDU transmssonTmerexpryTmerexpryMobe Rado Network Pannng 93GPRS n Reease B6.2Attach procedure (1)Am : to access to GPRS servces, an MS must rst make ts presence known to the network by performng a GPRS attach to the SGSNResuts : a ogca nk between the MS and the SGSN s created the MS s n Standby state and may actvate a PDP context the MS ocaton s known (RA accuracy) the MS s avaabe for pagng va the SGSNCombned GPRS and IMSI attach s possbe for cass A/B MSMobe Rado Network Pannng 94GPRS n Reease B6.2Attach procedure (2)MS BSS SGSNUL TBF estabshmentUL TBFATTACH REOUESTATTACH ACKNOWLEDGEDL TBF estabshmentDL TBFUL TBF estabshmentUL TBFATTACH COMPLETEMobe Rado Network Pannng 95GPRS n Reease B6.2PDP context actvatonAm : n order to send and receve GPRS data, the MS must actvate the PDP (Packet Data Protoco) address t wants to useResuts : the MS s known n the correspondng GGSN (the GGSN knows the SGSN where the MS s ocated) and data transmsson wth externa data network can begnMobe Rado Network Pannng 96GPRS n Reease B6.2System nformaton broadcastng (1)The BCCH ndcates f GPRS s supported n the ce : SI 3 : RA_COLOUR ed present f GPRS supportedIf GPRS s supported : SI13 s broadcasted on the BCCH SI13 broadcast nstead of retransmsson of SI 1Wthout PBCCH, t s not possbe to ndcate to the MS : a GPRS neghbourng ces st GPRS re-seecton parameters (C31 and C32 crtera)Mobe Rado Network Pannng 97GPRS n Reease B6.2System nformaton broadcastng (2) SI 3 and SI 4 content : RA_COLOUR : routeng area coour SI13_PBCCH_LOCATION : gves SI 13 schedue or PBCCH ocatonMobe Rado Network Pannng 98GPRS n Reease B6.2System nformaton broadcastng (3)SI 13 content (not exhaustve) : RA : routeng area code NMO : network mode of operaton PAN_DEC, PAN_INC, PAN_MAX : rado nk supervson ALPHA : upnk power contro T_AVG_T, T_AVG_W : cacuaton of average eves PC_MEAS_CHAN : eve measurements on BCCH / PDCH NETWORK_CONTROL_ORDER : set to NC0 = MS controed ce re-seecton , no measurement reportngMobe Rado Network Pannng 99Rado Lnk Contro AgorthmsMobe Rado Network Pannng 100GPRS n Reease B6.2DL measurementsMS measurement reports are transmtted from the MS to the MFS n each DL(N) Acknowedge command contanng the averaged eve C of the servng ce (C_VALUE) and RXOUAL averaged over the receved bocksThe reportng perod depends on the parameters DL_ACK_PERIOD (Range: 1 to 64, Defaut=16) or DL_NACK_PERIOD (Range: 1 to 64, Defaut=32) These perods (counted n number of RLC data bocks) are used by the BSS durng a DL (un)acknowedged TBF to request MS acknowedgmentSo ony when the MS receves data, the measurement report s sentThus the reportng perod s not tuneabe and t vares sgncantyMobe Rado Network Pannng 101GPRS n Reease B6.2UL measurements (1)At each receved bock, eve and quaty are computed (over 4 TDMA frames) and sent to the MFSThe measurements are averaged, the averagng agorthms are qute compexThe reevant parameters for UL and DL are:LEVEL OUALITYDOWNLINK T_AVG_T, T_AVG_W DL_(N)ACK_PERIODUPLINK K_AVG_L K_AVG_OMobe Rado Network Pannng 102GPRS n Reease B6.2UL measurements (2)The parameter PC_MEAS_CHAN determnes on whch channe the MS sha measure the receved power eve on the DL for the purpose of the UL power controThe codng rues are: If the Parameter PC_MEAS_CHAN = 0 the measurements are performed on the BCCH-TS If PC_MEAS_CHAN =1, the measurements are performed on ALL bocks on one of the used PDCHsMobe Rado Network Pannng 103GPRS n Reease B6.2UL measurements (3)The Tmng advance procedure s used to derve the correct vaue for tmng advance that the MS has to use for the UL transmsson of rado bocksIt comprses two parts: Inta tmng advance estmaton Contnuous tmng advance updateThe evauaton s smar to the CS approach and s updated every 0.96 secMobe Rado Network Pannng 104GPRS n Reease B6.2UL Power contro (1)In step 1 power contro s ony mpemented on the UL n an open oop conguraton whch s descrbed n the 05.08 GSM recommendatonDurng open oop power contro the MS adapts ts output power n UL per bock (.e. 4 tmesots) based on the receved average sgna strength n DL assumng the same path oss n UL and DLThe open oop s due to the fact, that there s no ndcaton by the BTS whether the output power PCHwas sumcenty ow or hgh: the same path oss n UL and DL s assumed.Mobe Rado Network Pannng 105GPRS n Reease B6.2UL Power contro (2)When accessng the network on the (P)RACH the MS uses the output power dened by (GPRS_)MS_TXPWR_MAX_CCH, whch s broadcasted by the (P)BCCHIn case of cosed oop power contro (not avaabe n step 1) the output power s commanded by the BS ste as for CS tramc Mobe Rado Network Pannng 106GPRS n Reease B6.2( ) ( ) PMAX C PCH CH" #$ % min&+ = &CHUL Power contro (3)Each PDCH bock s transmtted wth the output power PCH: : s the maxmum cassmark power n GSM 900 or 1800 (= 39 dBm for GSM 900 and 36 dBm for GSM 1800) : s send to the MS. Ths parameter s used for gradng the power contro to a target receved eve at the BTS sde Mn:0, Max: 62, Defaut: 20 dB for GSM 900 and 24 dB for GSM 1800 : s send to the MS. Ths parameter can be descrbed as a reactvty factor. The 05.08 GSM recommendaton suggest to use = 1 n order to have an open oop power contro C : s the DL eve average cacuated by the MS PMAX : the power s mted to MS_TXPWR_MAX_CCH (43 dBm for GSM 900)Mobe Rado Network Pannng 107GPRS n Reease B6.2UL Power contro (4)By comparson of the GPRS power contro behavour and the GSM power contro behavour the foowng resuts are reevant: By appyng the defaut parameter (for apha and gamma) GPRS power contro s more reactve than the GSM power contro because of the dherent weghtng factor for the dherent power contro agorthms Under use of the defaut parameter the Mobe stays onger n hgher output power than for norma GSM appcatons. To acheve the same behavour for GPRS and GSM power contro has to be decreased, by ncreasng . Ths s not recommended, because of causng more often re-transmssons due to sgna fadngCHMobe Rado Network Pannng 108GPRS n Reease B6.2Ce seecton and re-seecton (1)There are no handovers for the packet mode of GPRS mobesIf a roamng to another ce s to be done, ths w happen through ce (re)-seecton n packet de modeWhen a mobe n packet transfer mode eaves the coverage range of a BTS or suhers from nterference, the nk quaty w degrade and retransmsson w be actvatedIn ths case the GPRS mobes reman connected to ther servng ce unt the ca s dropped or the TBF transmsson s nshed (whch s more probabe, due to the short duraton of the data transfer per bock ow) Mobe Rado Network Pannng 109GPRS n Reease B6.2Ce seecton and re-seecton (2)In case of a ca drop ce reseecton n packet de mode s performed and the data package s resent on a new ceIf the data transmsson s nshed wthout ca drop, reseecton (f necessary) n packet de mode s performed and the next data package w be send to a new ceFurthermore for GPRS MS the quaty of the rado nk s addtonay dependng from the retransmsson rateTherefore the RXOUAL/RXLEV based power contro and handover agorthms as mpemented for CS tramc are no onger appcabeThe ce seecton (or roamng) n packet mode, s performed by the MS n an autonomous way by a ce reseecton n packet de modeMobe Rado Network Pannng 110GPRS n Reease B6.2Ce seecton and re-seecton (3)As for CS tramc, the MS contnuousy montores the receved sgna strength on the BCCH frequences (MPDCH f avaabe) of the servng ce and the 6 strongest neghbour ces (out of the neghbource st for CS) and cacuates the receved eve average of each frequency Mobes wth GPRS functonaty are abe to appy two ce reseecton agorthms: no MPDCH or GPRS reseecton parameters n the ce : the common C1 and C2 crtera wth MPDCH n a ce: the crtera C31 and C32 Note: C31 and C32 not avaabe n B6.2.Mobe Rado Network Pannng 111GPRS n Reease B6.2Dynamc CS adaptaton (1)The Acate GPRS souton contans a dynamc codng scheme adaptaton for CS1 to CS4 (aso for a E-GPRS codng schemes)In the actua software reease B6.2, the dynamc codng scheme adaptatons s mpemented for CS1 and CS2Dependng on the average receved eve (RX_LEV) and the transmsson quaty (RX_OUAL), the approprate codng scheme (ether CS-1 or CS-2) s determned dynamcay, both n the UL and n the DLAn O&M ag (EN_CS_ADAPTATION) ndcates whether ths dynamc adaptaton s actvated n the ce or not (defaut vaue: enabed)Mobe Rado Network Pannng 112GPRS n Reease B6.2Dynamc CS adaptaton (2)The foowng threshods determne the dynamc codng scheme adaptatonThe quaty s thereby the domnant (ma|or) crteron for a codng scheme change: Change from CS-1 to CS-2 f AV_RXOUAL < CS_OUAL_1_2 and AV_RX_LEV>=CS_LEV (quaty = good, eve = good) CS_OUAL_1_2 consttutes the RX_OUAL threshod used n rado nk supervson, to change from CS1 to CS2 Range: 0 to 7 Defaut vaue: 3.5Mobe Rado Network Pannng 113GPRS n Reease B6.2Dynamc CS adaptaton (3)Change from CS-2 to CS-1 f AV_RXOUAL >= CS_OUAL_2_1 or AV_RX_LEV