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  1. 1. General Packet Radio Service 王詔丘
  2. 2. GPRS History <ul><li>Established by ETSI(European Telecommunications Standards Institute) </li></ul><ul><li>GSM phase 1 --- 1992 </li></ul><ul><li>GSM phase 2 --- 1996 </li></ul><ul><li>GPRS begin in 1994 and published at the end of 1997 </li></ul>
  3. 3. General Packet Radio Service <ul><li>Packet switching </li></ul><ul><li>GPRS is evolved from GSM by introducing two new core network nodes SGSN and GGSN </li></ul><ul><li>Existing GSM nodes(BSS,MSC/VLR and HLR) are upgraded </li></ul><ul><li>Concept foresees bit rates of nearly 170kb/s </li></ul><ul><li>QoS Support : service precedence 、 delay 、 reliability 、 mean throughput 、 peak throughput etc. QoS parameters </li></ul>
  4. 4. General Packet Radio Service <ul><li>Several users can use the same channel simultaneously </li></ul><ul><li>Always on line </li></ul><ul><li>Radio resource allocation </li></ul><ul><li>Charging is based on amount of transmitted data </li></ul><ul><li>No need to access HLR for every GPRS packet </li></ul><ul><li>Burst data transmission </li></ul>
  5. 5. GPRS Objectives <ul><li>GPRS uses packet switched resource allocation </li></ul><ul><li>Dynamic channel allocation </li></ul><ul><ul><li>1 to 8 time slots </li></ul></ul><ul><ul><li>Available resources shared by active users </li></ul></ul><ul><ul><li>Up and down link channels reserved separately </li></ul></ul><ul><ul><li>GPRS and circuit switched (GSM) services can use same time slots alternatively </li></ul></ul><ul><li>Efficient delivery of SMS over the GPRS air interface </li></ul><ul><li>Connections with data networks </li></ul><ul><ul><li>IP network,X.25,GPRS own protocols </li></ul></ul>
  6. 6. GPRS Development <ul><li>Phase </li></ul><ul><ul><li>Point-to-Point </li></ul></ul><ul><ul><li>Point-to-Multipoint </li></ul></ul><ul><li>Class </li></ul><ul><ul><li>Support GPRS and other GSM simultaneously </li></ul></ul><ul><ul><li>Support GPRS and GSM network parallel </li></ul></ul><ul><ul><li>Only GPRS </li></ul></ul><ul><li>Multi-slot Type </li></ul><ul><ul><li>Half-Duplex </li></ul></ul><ul><ul><li>Full-Duplex </li></ul></ul>
  7. 7. Service type of GPRS <ul><li>GPRS provides two types of services: </li></ul><ul><ul><li>PTP (Point-To-Point) </li></ul></ul><ul><ul><ul><li>Connectionless: IP </li></ul></ul></ul><ul><ul><ul><li>Connection-oriented: X.25 </li></ul></ul></ul><ul><ul><li>PTM (Point-To-Multipoint) </li></ul></ul><ul><ul><ul><li>Multicast Service (PTM-M) </li></ul></ul></ul><ul><ul><ul><li>Group Call Service (PTM-G) </li></ul></ul></ul>
  8. 8. GPRS Applications <ul><li>WWW </li></ul><ul><li>FTP </li></ul><ul><li>Telnet </li></ul><ul><li>Chat </li></ul><ul><li>E-mail </li></ul><ul><li>Image </li></ul><ul><li>Audio </li></ul><ul><li>Video </li></ul><ul><li>GPS(Global Positioning System) </li></ul>
  9. 9. GSM Architecture <ul><li>MS(Mobile Station) </li></ul><ul><li>BSS(Base Station Subsystem) </li></ul><ul><li>BTS(Base Transceiver Station) </li></ul><ul><li>BSC(Base Station Controller) </li></ul><ul><li>MSC(Mobile Switching Center) </li></ul><ul><li>PSTN(Public Switched Telephone Network) </li></ul><ul><li>HLR(Home Location Register) </li></ul><ul><li>VLR(Visitor Location Register) </li></ul><ul><li>AUC(Authentication Center) </li></ul>
  10. 10. GSM Architecture
  11. 11. GPRS Architecture
  12. 12. Comparison between GPRS & Circuit-switched
  13. 13. GPRS Architecture
  14. 14. GPRS Components <ul><li>GPRS support node(GSN) </li></ul><ul><ul><li>Packet routing and transfer within PLMN(Public Land Mobile Network) </li></ul></ul><ul><li>Gateway GPRS support node(GGSN) </li></ul><ul><ul><li>Acts as a logical interface to external PDN(Packet Data Network) </li></ul></ul><ul><ul><li>Maintains routing information used to tunnel the PDUs(Protocol Data Unit) to the SGSN currently serving the MS(Mobile Station) </li></ul></ul><ul><li>Serving GPRS support node(SGSN) </li></ul><ul><ul><li>Delivery of packets to the MSs within its service area </li></ul></ul>
  15. 15. Mobile Transmission <ul><li>SGSN(SGSN-S) encapsulates the packets transmitted by the MS and routes them to the appropriate GGSN(GGSN-S) </li></ul><ul><li>Based on the examination of the destination address, packets are then routed to the GGSN-D through the packet data network </li></ul><ul><li>The GGSN-D checks the routing context associated with the destination address and determines the SGSN-D and relevant tunneling information </li></ul><ul><li>Each packet is then encapsulated and forwarded to the SGSN-D, which delivers it to the destination mobile </li></ul>
  16. 16. Simple example of transmission
  17. 17. Packet Data Transmission Scenario <ul><li>Mobile-originated </li></ul><ul><ul><li>MS to some LAN host </li></ul></ul><ul><li>Mobile-terminated </li></ul><ul><ul><li>Receive packet from some host when MS is in Home Public Land Mobile Network ( PLMN ) </li></ul></ul><ul><li>Mobile-terminated </li></ul><ul><ul><li>Receive packet from some host when MS is roaming at some Visited Public Land Mobile Network ( PLMN ) </li></ul></ul>
  18. 18. Simple example of routing
  19. 19. GPRS Architecture
  20. 20. GPRS Coding Scheme <ul><li>Best reliability : CS-1 </li></ul><ul><li>No reliability : CS-4 </li></ul><ul><li>Maximum data rate : 171.2Kbps(21.4Kbps x 8) with eight time slots </li></ul>
  21. 21. FDMA & TDMA
  22. 22. Mobility Management <ul><li>Two encapsulation schemes: </li></ul><ul><ul><li>Between GSNs </li></ul></ul><ul><ul><li>Between MS and SGSN </li></ul></ul><ul><li>Before MS sends data, MS has to attach to GPRS using an attachment procedure </li></ul><ul><li>When moving to another SGSN(location update), GGSN and GR/HLR are informed about the new routing context </li></ul>
  23. 23. Mobility Management <ul><li>State Diagram </li></ul>
  24. 24. GPRS Protocols <ul><li>Sub-Network Dependent Convergence Protocol (SNDCP) </li></ul><ul><ul><li>maps a network-level protocol </li></ul></ul><ul><ul><li>provides compression, segmentation and multiplexing of network-layer messages to a single virtual connection </li></ul></ul><ul><li>Logical Link Control (LLC) </li></ul><ul><ul><li>assures the reliable transfer of user data across a wireless network </li></ul></ul><ul><li>Base Station System GPRS Protocol (BSSGP) </li></ul><ul><ul><li>processes routing and QoS information </li></ul></ul><ul><ul><li>uses the Frame Relay Q.922 core protocol </li></ul></ul><ul><li>GPRS Tunnel Protocol (GTP) </li></ul><ul><ul><li>tunnels the protocol data units between GSNs </li></ul></ul>
  25. 25. GPRS Protocols <ul><li>GPRS Mobility Management (GMM) </li></ul><ul><ul><li>handles roaming, authentication, and selection of encryption algorithms </li></ul></ul><ul><li>Network Service </li></ul><ul><ul><li>maps BSSGP's service requests to the Frame Relay Q.922 Core </li></ul></ul><ul><li>Radio Link Control(RLC)/MAC </li></ul><ul><ul><li>Enable multiple MSs to share a common transmission medium which consist of several physical channels </li></ul></ul><ul><li>Physical Link Sublayer(PLL) </li></ul><ul><ul><li>Data coding, detection and correction </li></ul></ul><ul><li>Physical RF Sublayer(RFL) </li></ul><ul><ul><li>Perform the modulation and demodulation of the physical waveforms </li></ul></ul>
  26. 26. Protocol Architecture
  27. 27. Air Interface – Physical Layer <ul><li>GPRS air interface protocol is concerned with communication between MS and BSS </li></ul><ul><li>Physical Channel divided into Packet Data Channel ( PDCH ) and Traffic Channel ( TCH ) , </li></ul><ul><li>PDCH --- Dedicated to Packet Data Traffic , </li></ul><ul><li>TCH --- GSM Voice or Data Traffic 。 </li></ul><ul><li>Allocation of TCHs and PDCHs is done dynamically according to the 「 Capacity-on-demand 」 principles </li></ul>
  28. 28. GPRS Architecture
  29. 29. GPRS Protocol Stack
  30. 30. GPRS Logical Channels <ul><li>Packet Broadcast Control Channel(PBCCH) </li></ul><ul><ul><li>Transmits system information to all GPRS terminals in a cell </li></ul></ul><ul><li>Packet Common Control Channel(PCCCH) </li></ul><ul><ul><li>Initiate packet transfers or respond to paging messages </li></ul></ul><ul><li>Packet Traffic Channels(PTCH) </li></ul><ul><ul><li>Channel resource allocation </li></ul></ul>
  31. 31. GPRS Logical Channels(cont.)
  32. 32. Uplink
  33. 33. Downlink
  34. 34. HSCSD and EDGE <ul><li>High-Speed Circuit-Switched Data ( HSCSD ) </li></ul><ul><ul><li>Multi-timeslot </li></ul></ul><ul><ul><li>Using V42bis coding scheme can achieve 14.4Kbps </li></ul></ul><ul><ul><li>Maximum data rate : 115.2Kbps(14.4Kbps * 8) </li></ul></ul><ul><ul><li>Circuit switching </li></ul></ul><ul><li>Enhanced Data for GSM Evolution ( EDGE ) </li></ul><ul><ul><li>Maximum data rate : 384kbps </li></ul></ul><ul><ul><li>EDGE use the new Modulation Technique --- eight-phase-shift ( 8PSK ) </li></ul></ul><ul><ul><li>Support Packet switching and Circuit switching simultaneously </li></ul></ul>
  35. 35. GPRS Glossary <ul><li>ETSI(European Telecommunications Standards Institute) </li></ul><ul><li>MS(Mobile Station) </li></ul><ul><li>BSS(Base Station Subsystem) </li></ul><ul><li>BTS(Base Transceiver Station) </li></ul><ul><li>BSC(Base Station Controller) </li></ul><ul><li>MSC(Mobile Switching Center) </li></ul><ul><li>PSTN(Public Switched Telephone Network) </li></ul><ul><li>HLR(Home Location Register) </li></ul><ul><li>VLR(Visitor Location Register) </li></ul><ul><li>AUC(Authentication Center) </li></ul><ul><li>GPRS support node(GSN) </li></ul><ul><li>Gateway GPRS support node(GGSN) </li></ul><ul><li>Serving GPRS support node(SGSN) </li></ul><ul><li>packet data network(PDN) </li></ul><ul><li>Public Land Mobile Network ( PLMN ) </li></ul><ul><li>Sub-Network Dependent Convergence Protocol (SNDCP) </li></ul><ul><li>Logical Link Control (LLC) </li></ul><ul><li>Base Station System GPRS Protocol (BSSGP) </li></ul><ul><li>GPRS Tunnel Protocol (GTP) </li></ul><ul><li>GPRS Mobility Management (GMM) </li></ul><ul><li>Packet Data Channel ( PDCH ) </li></ul><ul><li>Traffic Channel ( TCH ) </li></ul><ul><li>Packet Broadcast Control Channel(PBCCH) </li></ul><ul><li>Packet Common Control Channel(PCCCH) </li></ul><ul><li>Packet Traffic Channels(PTCH) </li></ul><ul><li>High-Speed Circuit-Switched Data ( HSCSD ) </li></ul><ul><li>Enhanced Data for GSM Evolution ( EDGE ) </li></ul>
  36. 36. Reference <ul><li>J. Cai and DJ Goodman, General Packet Radio Service in GSM , IEEE Communications, vol. 35, no. 10, pp. 122-131, October 1997 </li></ul><ul><li>G. Brasche and B. Walke, Concepts , Services , and Protocols of the New GSM Phase 2+ General Packet Radio Service, IEEE Communications, vol. 35, no. 8, pp. 94-104, Aug 1997 </li></ul><ul><li>C. Bettstetter, GSM PHASE 2+ GENERAL PACKET RADIO SERVICE GPRS:ARCHITECTURE, PROTOCOLS AND AIR INTERFACE, IEEE Communications,1997 </li></ul>