GPRS - EDGE,吴伟民 电子与信息工程系 wuwmhust.edu.cn,2,GPRS - EDGE Overview GPRS Services,Network Architecture Um Interface (MS-Bss) 52- Multitrame Logical Channels Physical Channel GPRS Stack Layer SNDCP LLC,GPRS en mode Idle GPRS Network mode Classes des mobiles Multislot Class Session Management Evolution to EDGE Modulations GPRS vs EDGE EDGE: RLC/MAC,RLC / MAC TBF,3,GPRS: Overview,What is GPRS,General,But only applicable to specific services,Packet,Obviously,Radio,But much more,Service,But rather a transmission method,4,GPRS: Overview,Circuit vs. Packet,Circuit,Packet,5,GPRS: Overview,GPRS vs. non GPRS,Differences between GPRS and GSM,Warranty on traffic,Warranty on delay vs. Best effort,Charging on time vs. charging on volume,Radio resource sharing,Dedicated channels vs. Shared channels,Transmission mode in the network,Circuit 64 kbps vs. IP network User rate up to 160 kbps,6,GPRS: Overview,Circuit vs. Packet,Service (point to point protocol),GSM allows both circuit and packet service GPRS allows only packet service,Switch mode in the network,In MSC, circuit switch at 64 kbps In GPRS, datagram switch,Radio path transmission,GSM use a resource during the complete call (circuit) But data are always in packet format (burst),7,GPRS: Overview,Shared Channels,The equivalent of a TCH is allocated to 16 (max) multiplexed flows,Possible to allocate several such resources to one user (multi-slot),Release through timer,Independent handling of direction,WEB application traffic is not symmetrical Limitation through GSM symmetrical scheme,8,GPRS: 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 A LAC A Cell C RAC A,RAC B,LAC B,PLMN B,Cell A,Cell B,9,IP,GPRS: Overview TCP/IP IP: Internet Protocol,To route datagram (32 bits address) through interconnected network segmentation TCP: Transmission Control Protocol Point to point transport,TCP,UDP,Numbering and acknowledge of data multiplexing UDP: User Datagram Protocol More simple than TCP,Local network protocol (GPRS),No acknowledgement Used for WAP,10,GPRS Network Architecture,GPRS network equipment,Radio sub-system,CCU: Channel Codec Unit,Part of the BTS mainly handling the physical layer,PCU: Packet Control Unit,Handles RLC and MAC layers,Switches,SGSN: Serving GPRS Support Node GGSN: Gateway GPRS Support Node,11,Um Interface (MS-BSS) MM Sub-Layer LLC,RR-SAP,GMMRR-SAP,GRR-SAP RR Management,Non -RR,PD,RR,RR,Upper Layer PDUs RLC/MAC,SAPI 0,SAPI 3,PBCCH,PCCCH,PACCH,PDTCH,BCCH,RACH PCH SDCCH AGCH,SACCH,FACCH,SDCCH,SACCH,Data Link Layer (signalling L2) PDCH PHYSICAL LINK LAYER,12,52 Multi-Trame TDMA Frame: Same as GSM technology New format : Multi-frame 52 (PDCH : Packet Data Channel) 1 Block ( 4 frames in continue),B 0,B 1,B 2,X,B 3,B 4,B 5,X,B 6,B 7,B 8,X,B 9,B 10,B 11,X,52 multiframe (duration 240 ms) Bn : Blocks X : Idle frames,13,Logical Channels PBCCH : Packet Broadcast Common Channel PCCCH : Packet Common Control Channel PAGCH : Packet Access Grant Channel,PPCH :,Packet Paging Channel,PRACH : Packet Random Access Channel PDTCH : Packet Data Transfer Channel PACCH : Packet Associated Control Channel PTCCH : Packet Timing advance Control Channel,14,Logical Channels, PBCCH + PCCCH + PDTCH + PACCH + PTCCH + PRACH, PCCCH + PDTCH + PACCH + PTCCH, PDTCH + PACCH + PTCCH,15,Logical Channels,Shared Channels Logical channels,PDTCH (Packet Data Traffic Channel) and PACCH (Packet Associated Control Channel),To convey user and signalling data,Multiplexed between 16 (or less) users Unidirectional (UL or DL),PTCCH (Packet Timing advance Control Channel),To manage timing advance,Divided into 16 bi-directional channels Fixed allocation,16,Logical Channels, Common Logical Channels (optional), PBCCH: trnasmits network description (Packet,System Information Type x), PCCCH, PPCH: equivalent to PCH, PAGCH: equivalent to AGCH, PRACH: equivalent to RACH (up to 11 bits),17,Physical Channel,Shared Channels Physical channels,PDCH (Packet Data Channel) is a physical channel PDCH is based on one frequency and one timeslot Logical channels are mapped onto physical channels PDCH is organized into blocks of 4 consecutive bursts,18,TBF : Temporary Block Flow,3GPP 44.060 Definition:,A Temporary Block Flow (TBF) is a connection used by the two RR entities to,support the unidirectional,transfer of upper layer PDUs on packet data,physical channels (PDCH),19,GPRS Stack Layers User Plane GPRS: Application,Appli,Control Plane GPRS: Control L3,IP-X25 SNDCP LLC RLC MAC L1 PDTCH TBF-User,PDTCH TBF - Control,SM | GSMS GMM LLC RLC MAC L1,Control Plane GPRS GRR RLC MAC L1 PBCCH / PCCCH PRACH PACCH /PTCCH,B 0,B 1,B 2,X,B 3,B 4,B 5,X,B 6,B 7,B 8,X,B 9,B 10,B 11,X,52 multiframe (duration 240 ms),20,GPRS User Plane,21,GPRS Control Plane,22,GPRS Control Plane,23,GPRS SNDCP Overview Multiplexing of several PDPs Between MS and SGSN: NSAPI Sequencing warranty for each PDP Access to LLC throu