GPRS - EDGE吴伟民电子与信息工程系wuwmhust.edu.cn2GPRS - EDGEOverviewGPRS ServicesNetwork ArchitectureUm Interface (MS-Bss)52- MultitrameLogical ChannelsPhysical ChannelGPRS Stack LayerSNDCPLLCGPRS en mode IdleGPRS Network modeClasses des mobilesMultislot ClassSession ManagementEvolution to EDGEModulations GPRS vs EDGEEDGE: RLC/MACRLC / MACTBF 3GPRS: OverviewWhat is GPRSGeneralBut only applicable to specific servicesPacketObviouslyRadioBut much moreServiceBut rather a transmission method4GPRS: OverviewCircuit vs. PacketCircuitPacket5GPRS: OverviewGPRS vs. non GPRSDifferences between GPRS and GSMWarranty on trafficWarranty on delay vs. Best effortCharging on time vs. charging on volumeRadio resource sharingDedicated channels vs. Shared channelsTransmission mode in the networkCircuit 64 kbps vs. IP networkUser rate up to 160 kbps6GPRS: OverviewCircuit vs. PacketService (point to point protocol)GSM allows both circuit and packet serviceGPRS allows only packet serviceSwitch mode in the networkIn MSC, circuit switch at 64 kbpsIn GPRS, datagram switchRadio path transmissionGSM use a resource during the complete call (circuit)But data are always in packet format (burst)7GPRS: OverviewShared ChannelsThe equivalent of a TCH is allocated to 16 (max)multiplexed flowsPossible to allocate several such resources to one user(multi-slot)Release through timerIndependent handling of directionWEB application traffic is not symmetricalLimitation through GSM symmetrical scheme8GPRS: Overview Location Area Code is relevant to LA (Location Area) inside a PLMN. Routing Area Code is relevant to RA (Routing Area) inside a LA.PLMN ALAC ACell CRAC ARAC BLAC BPLMN BCell ACell B9IPGPRS: OverviewTCP/IPIP: Internet ProtocolTo route datagram (32 bits address) throughinterconnected networksegmentationTCP: Transmission Control ProtocolPoint to point transportTCPUDPNumbering and acknowledge of datamultiplexingUDP: User Datagram ProtocolMore simple than TCPLocal networkprotocol(GPRS)No acknowledgementUsed for WAP 10GPRS Network ArchitectureGPRS network equipmentRadio sub-systemCCU: Channel Codec UnitPart of the BTS mainly handling the physical layerPCU: Packet Control UnitHandles RLC and MAC layersSwitchesSGSN: Serving GPRS Support NodeGGSN: Gateway GPRS Support Node11Um Interface (MS-BSS)MM Sub-LayerLLCRR-SAPGMMRR-SAPGRR-SAPRR ManagementNon -RRPDRRRRUpper Layer PDUsRLC/MACSAPI 0SAPI 3PBCCHPCCCHPACCHPDTCHBCCHRACH PCH SDCCHAGCHSACCHFACCHSDCCHSACCHData Link Layer (signalling L2)PDCHPHYSICAL LINK LAYER1252 Multi-TrameTDMA Frame: Same as GSM technologyNew format : Multi-frame 52 (PDCH : Packet Data Channel) 1 Block ( 4 frames in continue)B 0B 1B 2XB 3B 4B 5XB 6B 7B 8XB 9B 10B 11X52 multiframe (duration 240 ms)Bn : BlocksX : Idle frames13Logical ChannelsPBCCH : Packet Broadcast Common ChannelPCCCH : Packet Common Control ChannelPAGCH : Packet Access Grant ChannelPPCH :Packet Paging ChannelPRACH : Packet Random Access ChannelPDTCH : Packet Data Transfer ChannelPACCH : Packet Associated Control ChannelPTCCH : Packet Timing advance Control Channel 14Logical Channels PBCCH + PCCCH + PDTCH + PACCH + PTCCH + PRACH PCCCH + PDTCH + PACCH + PTCCH PDTCH + PACCH + PTCCH15Logical ChannelsShared Channels Logical channelsPDTCH (Packet Data Traffic Channel) and PACCH (PacketAssociated Control Channel)To convey user and signalling dataMultiplexed between 16 (or less) usersUnidirectional (UL or DL)PTCCH (Packet Timing advance Control Channel)To manage timing advanceDivided into 16 bi-directional channelsFixed allocation16Logical Channels Common Logical Channels (optional) PBCCH: trnasmits network description (PacketSystem Information Type x) PCCCH PPCH: equivalent to PCH PAGCH: equivalent to AGCH PRACH: equivalent to RACH (up to 11 bits)17Physical ChannelShared Channels Physical channelsPDCH (Packet Data Channel) is a physical channelPDCH is based on one frequency and one timeslotLogical channels are mapped onto physical channelsPDCH is organized into blocks of 4 consecutive bursts18TBF : Temporary Block Flow3GPP 44.060Definition:A Temporary Block Flow (TBF) is aconnection used by the two RR entities tosupport the unidirectionaltransfer of upper layer PDUs on packet dataphysical channels (PDCH)19GPRS Stack LayersUser Plane GPRS: ApplicationAppliControl Plane GPRS: Control L3IP-X25SNDCPLLCRLCMACL1PDTCHTBF-UserPDTCHTBF - ControlSM | GSMSGMMLLCRLCMACL1Control Plane GPRSGRRRLCMACL1PBCCH / PCCCHPRACHPACCH /PTCCHB 0B 1B 2XB 3B 4B 5XB 6B 7B 8XB 9B 10B 11X52 multiframe (duration 240 ms) 20GPRS User Plane21GPRS Control Plane22GPRS Control Plane23GPRS SNDCPOverviewMultiplexing of several PDPsBetween MS and SGSN: NSAPISequencing warranty for each PDPAccess to LLC through several QoS profilesSegmentation / Re-assemblyCompressionIP headerDataMS: SNDCPSGSN: SNDCP24GPRS MS IDENTITYMS identitiesIMSI: 8 bytesUnique identityStored in the SIM cardP-TMSI (Packet Temporary Mobile Subscriber Identity): 4 bytesSimilar to TMSIUsed to avoid sending IMSIAllocated within a RATLLI (Temporary Logical Link Identity): 4 bytesUsed by RLC/MAC layersDerived from P-TMSIP-TMSI signature: 3 bytesUsed to skip authentication procedure25GPRS MS IDENTITYTLLI: Temporary Logical Link IdentifierAllocated by SGSNUsing P-TMSITLLILLCLLE x: SAPIxLLE z: SAPI zLLCLLE x: SAPIxLLE z: SAPI zLLE y: SAPI yMSLLE y: SAPI ySGSNDLCIx (Data Link Connection Identifier)TLLI+SAPI26GPRS MS IDENTITYTLLI handlingGMM generates the TLLIGMM sends the TLLI to RLC/MAC, LLC and L3 RRRandom TLLIUsed in case no P-TMSI is availableIdentifier + Random bitsForeign TLLIUsed in case P-TMSI is available but assigned in a different RAIdentifier + Bits derived from the P-TMSILocal TLLIUsed in case P-TMSI is available and assigned in this RAIdentifier + Bits derived from the P-TMSI27GPRS LLCAddress FieldPD C/R XXSAPIPD: Protolcole Discriminator, LLC= 0, Other = InvalidC/R = Command / ResponseSAPI:0001: GPRS Mobility Mgt: LLGMM0010 : Tunnelling of Msg 2 :TOM20011 : User Data 3 : LL30101 : User Data 5 : LL50111 : SMS1000 : Tunnelling of Msg 8 : TOM81001 : User Data 9 : LL91011 : User Data 11: LL1128GPRS LLC3 Modes LLCProtected ModeCRC-24bitsHeader + DataUnprotected ModeCRC-24bitsHeaderAcknowledged ModeErr. FramesSGSNTOMSNDCPGMMSMSTOMSNDCPGMMSMSLLCLLCRLCMACGSM RFRLCMACGSM RFBSSGPNetw. Serv.L1BSSGPNetw. Serv. L1MSUmBSSGb29111101GPRS LLCControl FieldA Acknoledgement Request bitE Encryption function bit87654321Mn Unnumbured function bitI format(I+S)0A XN(S)XN(S)N(R)N(R) Transmitter receive sequence nbrN(S) Transmitter send sequence numberN(R)S1S2N(U) Transmitter unconfirmed sequenceS format10AXN(R)XN(R)S1S2numberP/F Poll Bit when issued as CommandFinal Bit when issued as ResponseUI formatU formatX X N(U)N(U) E PMP/F M4 M3 M2 M1PM Protected Mode BitSn Supervisory function bitX Spare Bit30GPRS LLCControl Field807A6X543N(S)211N(S)XN(R)2N(R)113XXXK4I frameR(1) R(2) R(3) R(4) R(5)R(6) R(7) R(8)SACK formatR(9) R(10)R(11)R(12)R(13) . R(16).R(253) R(254) R(255)X 36(max)10AXXN(R)1N(R)112S frameSACK formatR(1) R(2) R(3) R(4) R(5)R(6) R(7) R(8)R(9) R(10)R(11)R(12)R(13) . . R(16).R(253) R(254) R(255)X 34 (max)31GPRS RLC/MACManagement of TBFs (Temporary Blocks Flows)Management of Logical ChannelsTBF has oneTFI,Unidirectionnal Identity allocated by networkCoding Scheme: CS 1 CS 2 CS 3 CS 4Block Size : 22 octets, 9 kbit/sBlock Size : 32 octets, 13.4 kbits/sBlock Size : 38 octets, 15.6 kbits/sBlock Size : 52 octets, 21.4 kbits/sCS1User dataProtectionCS2CS3CS4 32GPRS RLC/MACTBFStands for Temporary Block Flow“Channel” allocated between the MS and the BSS to conveydataUnidirectional (Uplink or Downlink)Release through timerMSTBF1TBF1TBF2TBF2BSS33GPRS RLC/MAC: Uplink TBF3 Modes for TBF Uplink AllocationStatic Allocation: a bitmap is sent to MS duringTBF establishment (1TS1USF)Dynamic Allocation: MS sends 1 to 4Blocks on reception USF Flag from NetworkExtended Dynamic Allocation: MS sends 1 to 4Blocks on reception USF Flag from Network,But from 1 to N PDCHs, mandatory in MultiSlot2 Types of TBF Uplink Establishment1 phase access2 phases access: mandatory for multi slot uplink transfer34GPRS RLC/MAC: Header of Uplink Data BlockPayload Type: 00 RLC/MAC Data Block 01 RLC/MAC Control BlockCountdown ValueTFI: Temporary Flow IdentityBSN: Block Sequence Number, could be acknowledged by networkIn sending Packet Uplink Ack/Nack message (including BSN(s) ACK-NACK)TLLI (optional)35GPRS RLC/MAC: Header of Uplink Data BlockCountdown ProcedureUsed by the MS to announce the end of the TBFBS_CV_MAX (See SI13) indicates when the Countdown Procedure shallbe startedWhile remaining RLC/MAC blocks BS_CV_MAXCV = 15If remaining RLC/MAC blocks BS_CV_MAXCV = remaining RLC/MAC blocks - 1Last RLC/MAC block sent with CV=0Two RLC/MAC blocks sent with same CV if two UL timeslots areallocated to the MSResource request is not possible during Countdown ProcedureNew RLC/MAC blocks New TBF36GPRS RLC/MAC: Header of Downlink Data BlockPayload TypeS/P and RRBP: NW requires to MS for sendingPacket Control Acknowledgement control messageTFI: Temporary Flow IdentityBSN: Block Sequence Number, could be acknowledged by mobileIn sending Packet Downlink Ack/Nack message (including BSN(s) ACK-NACK)USF: Uplink State Flag37GPRS RLC/MAC: Header of Downlink Data BlockUplink State FlagUsed to multiplex several users on the same PDCHUSF assigned to the MS during the assignment procedureUSF present in each DL RLC/MAC blockUSF of the MS present within DL RLC/MAC blockThe MS can send an UL RLC/MAC block at next occurrenceThe MS sends one or four UL RLC/MAC block dependingon USF GRANULARITYUSF is allocated on a timeslot basisThe MS needs to monitor every allocated timeslotUSF=7 reserved for PRACH38GPRS RLC/MAC: Header of Downlink Data BlockUplink State FlagMS1 is assigned USF1MS2 is assigned USF2DOWNLINKUSF7USF7USF1USF2USF1USF7USF1USF2USF7UPLINKMS1MS2BSNBSNBSNBSNBSN39GPRS RLC/MAC: Header of Control BlockUplinkPayload TypeDownlinkPayload TypeS/P and RRBP: NW requires to MS for sendingPacket Control Acknowledgement control messageTFI (Optional): Temporary Flow IdentityUSF: Uplink State Flag40GPRS Network ModeNetwork Mode of Operation (NMO broadcasted within SI13)NMO2: no co-ordinationDouble registrationLocation Updating AND Attach or RAUIMSI Detach AND GPRS DetachNo Paging co-ordinationImpossible to receive a CS Paging during a GPRS transferNMO1: co-ordinationSingle registrationCombined proceduresPaging co-ordinationCS Paging are sent on PACCH during a GPRS transfer41Classes the MobilesMS classClass AMobile registered in both modesAble to perform both operations simultaneously (GSM call + Retrievean email)Technically very difficult (2 radios needed)Class BMobile registered in both modesOnly one service at one time (either call OR email)Priority for GSMClass CMobile registered in one mode (GSM or GPRS)42GPRS: MultiSlot Class43Session ManagementOverviewUsed to manage PDP contextsActivationDeactivationModificationPDP context: logical association between a MS and PDN (Public DataNetwork) running across a GPRS networkThe PDP context defines aspects such as:RoutingQoSSecurityPDP1 / APN1PDP1 / APN1BillingPDP2 / APN2PDP2 / APN2Etc 44EDGEEnhanced Data rates for GSM EvolutionAppeared in Release 99Increase data rate on air interface Rate can be multiplied by 3IR HARQAMCImportant modification related to signal processingFew modifications within RLC/MAC(Increase ARQ window size, Compressed ACK)LLC and SNDCP: same as GPRS45Modulation GPRS vs EDGEGMSK Vs. 8PSKGMSK: Gaussian Minimum Shift Keying1 bit onto one symbol8PSK: 8 Phase Shift Keying3 bits onto one symbol Transfer rate * 346Modulation GPRS vs EDGEReduced decision interval and therefore more affected by noiseNeed robust radio link47Modulation GPRS vs EDGEMore complicated signal processing to differentiate the constellation48EDGE: RLC/MACModulation and Coding SchemesGPRS: 4 Coding Schemes (CS1 to CS4)8PSK: 9 Modulation and Coding Schemes (MCS)49EDGE: RLC/MACEGPRS block structureEGPRS uses the GSM Normal Burst for data transfer4 Normal Bursts used to form a Radio BlockStealing bitsIn GSM, used to indicate FACCHIn GPRS and EGPRS, used to indicate coding schemeStealing bits are combined with the encrypted bitsTable gives the MCS used and header typeCS1 always used for RLC/MAC Control Blocks50EDGE: RLC/MACDownlink RLC/MAC Header Type 1Used for MCS7, MCS8 and MCS9Two RLC blocks per radio blockEGPRSSupplementaryPolling (requestsAck/Nack and itstype)Temporary FlowIdentifierUplink State Flag(which TBF isallowed to sendon next block)Block SequenceNumber 1Block SequenceNumber 2Coding andPuncturing Scheme(channel coding andpuncturing used forthe data part)51EDGE: RLC/MACDownlink RLC/MAC Header Type 2Used for MCS5 and MCS6Downlink RLC/MAC Header Type 3Used for MCS1, MCS2, MCS3 and MCS4Split Block indicator(indicates if some userdata is retransmittedusing 2 blocksresegmentation)52EDGE: RLC/MACUplink RLC/MAC HeaderType 1Rtransimit Block (indicates whetherany of the RLC data blocks havebeen sent previously)Type 2Type 3