Gprs standards

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Gprs standards

  1. 1. GPRS Standards Overview By Mohan Palat GPRS Sales Training 1999 - Greater China Network Solutions Division
  2. 2. GPRS in a GSM Network PSTN MSC Voice GPRS Calls Packet Data BSC SGSN GGSN Network Packet Data BTS Calls GSM GPRS Sales Training 1999 - Greater China Network Solutions Division
  3. 3. Main Concepts  Packet-based transmission  1 to 8 timeslots can allocated on the air interface per carrier  Timeslots can be shared between active users  Interworking with external IP and X.25 networks  QoS - different QoS levels defined GPRS Sales Training 1999 - Greater China Network Solutions Division
  4. 4. Main Concepts - continued  No handovers in GPRS (on the RF interface)  only cell reselection  Uplink and Downlink timeslots allocated independently 1 2 3 4 1 2 GPRS Sales Training 1999 - Greater China Network Solutions Division
  5. 5. Types of Services Point to Point Point to MultiPoint (PTM) GPRS Network GPRS Network Service Service Requester Requester • Requires knowledge of the • Service Requester specifies location of receivers Receiver, Geographic Area (for PTM calls) GPRS Sales Training 1999 - Greater China Network Solutions Division
  6. 6. Types of MultiPoint (PTM) Service PTM - Multicast PTM - Group Call Cells Defined GPRS Geographic Area(s) Service Requester Service Requester Message may be targeted to specific group or Message transmitted to a specific receiver group - to all subscribers within a geographic area(s) messages are transmitted only to cells containing receiver group members NOTE: No subscription is required to receive a PTM-Multicast message GPRS Sales Training 1999 - Greater China Network Solutions Division
  7. 7. Types of PTM Services (cont.) PTM - IP Multicast GPRS Network IP Network Service Requester • IP messages are sent between participants • Group can be internal to PLMN or distributed across internet • Messages are compliant with Internet Protocols GPRS Sales Training 1999 - Greater China Network Solutions Division
  8. 8. GPRS Data Rates  GPRS Data Rates Channel Coding Scheme Code Rate Data Rate CS-1 1/2 9.05 Kbps CS-2 2/3 13.4 Kbps CS-3 3/4 15.6 Kbps CS-4 1 21.4 Kbps - Data Rates are per timeslot - Maximum of 8 timeslots per carrier (shared among multiple users) GPRS Sales Training 1999 - Greater China Network Solutions Division
  9. 9. Data Rate for Mobile Classes Rate Timeslots 1 2 3 4 5 6 7 8 9.05 9.05 18.1 27.15 36.2 45.25 54.3 63.35 72.4 13.4 13.4 26.8 40.2 53.6 67 80.4 93.8 107.2 15.6 15.6 31.2 46.8 62.4 78 93.6 109.2 124.8 21.4 21.4 42.8 64.2 85.6 107 128.4 149.8 171.2 GPRS Sales Training 1999 - Greater China Network Solutions Division
  10. 10. GPRS Backbone Networks Inter PLMN Backbone GGSN BG BG GGSN Intra PLMN PLMN PLMN Intra PLMN Backbone Backbone SGSN SGSN SGSN SGSN• Every intra-PLMN network is a private IP network• Inter-PLMN networks based on agreements between operators GPRS Sales Training 1999 - Greater China Network Solutions Division
  11. 11. GPRS Network Interfaces PSTN Current GSM interfaces MSC GPRS A Packet Data BSC SGSN GGSN Network Abis BTS GSM All the GPRS interfaces start with “G” GPRS Sales Training 1999 - Greater China Network Solutions Division
  12. 12. GPRS Network Interfaces - Gb PSTN Packet DataGSM GGSN SGSN Network MSC GPRS G A b BSC • Used for both signalling and user data exchange • Based on Frame Relay link protocol Abis • frame relay virtual circuits between BSS & SGSN BTS • data (PDU) field: 1-600 octets in size • Virtual circuits may be multi-hop • network of frame relay switching nodes • Users multiplexed over the Gb link • Access rates can vary over the Gb link GPRS Sales Training 1999 - Greater China Network Solutions Division
  13. 13. GPRS Network Interfaces - Gs PSTN Packet DataGSM GGSN SGSN Network MSC GPRS Gs A BSC • SS7 link between SGSN and MSC • Mainly for signalling (no data flow) Abis BTS GPRS Sales Training 1999 - Greater China Network Solutions Division
  14. 14. GPRS Network Interfaces - Gr/Gc PSTN Gc Packet DataGSM HLR GGSN SGSN Network MSC GPRS Gr A BSC • SS7 link between SGSN/GGSN and HLR • Signalling link, no user data transfer Abis • Primarily for BTS • lookup of GPRS subscriber info in HLR • GPRS mobile roaming (routing) information • GPRS Sales Training 1999 - Greater China Network Solutions Division
  15. 15. GPRS Network Interfaces - Gn PSTN Packet DataGSM SGSN GGSN Network MSC G GPRS n A BSC • IP network protocol (UDP/IP, TCP/IP) • Used for signalling and data transfer Abis • GPRS Tunnelling Protocol (GTP) operates over IP BTS • User data encapsulated with GTP • May be multi-hop GPRS Sales Training 1999 - Greater China Network Solutions Division
  16. 16. GPRS Network Interfaces - Gi PSTN Packet DataGSM SGSN GGSN Network MSC Gi GPRS A BSC • IP or X.25 network protocol • Used for both signalling and data transfer Abis • Main interconnection point between GPRS network BTS and external packet data network GPRS Sales Training 1999 - Greater China Network Solutions Division
  17. 17. GPRS Network Interfaces - Gp PSTN GPRS PacketGSM GGSN Data SGSN Network MSC G p A GGSN BSC External PLMN Abis BTS • IP network protocol • Can be an Inter-PLMN backbone (internet, leased line) • Provides Gn interface + security • Connects to an external GPRS network GPRS Sales Training 1999 - Greater China Network Solutions Division
  18. 18. GPRS Interfaces - Summary Other Networks Voice Gp GPRS on a different PLMN Gi Echo MSC GGSN Gs Gn VLR HLR A SGSN Gr XCDR Gb BSC BTS BTS BTS GPRS Sales Training 1999 - Greater China Network Solutions Division
  19. 19. Packet Control Unit (PCU) BTS BSC GSN PCU (1) BTS BSC GSN (2) PCU BTS BSC GSN PCU (3)• Provides GPRS radio channel control functions Circuit switched GPRS Sales Training 1999 - Greater China Packet Solutions Division Network switched
  20. 20. GPRS Mobile Identification  IMSI - same as GSM  (Packet) TMSI -  local to an SGSN  assigned both by MSC/VLR and SGSN  MSC/VLR uses 00, 01, 10 & SGSN 11 as the two most significant bits  MS can be allocated 2 TMSIs simultaneously  PDP Address  GPRS Mobile has one or more network layer addresses  can be temporary or permanent (eg, IP address) GPRS Sales Training 1999 - Greater China Network Solutions Division
  21. 21. GPRS Subsystem Identities  GSN Address  each SGSN and GGSN has an IP Address  GSN Number  SGSN has a number for communication with HLR, etc.  TLLI (Temporary Logical Link Identity)  identifies the logical link between MS and SGSN  used for network layer routing GPRS Sales Training 1999 - Greater China Network Solutions Division
  22. 22. PTM Group Identification  IMGI (International Group Mobile Identity)  defines 2 levels of identification Service provider Application Level  IMGI can be stored on SIM Card or on the ME  2 types of IMGIs: HPLMN IMGI or IMGIs that can be used in multiple PLMNs  IMSI used for authentication  Subscriber Profile:  subscribed services (PTP, PTM-G etc)  subscriber profile (priority, throughput, etc) GPRS Sales Training 1999 - Greater China Network Solutions Division
  23. 23. GPRS Mobile Classes  Class A:  supports both GPRS and Circuit-Switched (including SMS)  user can make/receive calls on both services simultaneously  mimimum of 1 timeslot available to each type of service  Class B:  supports both GPRS and Circuit-Switched  only one type of service at a time  can be attached to both services  Class C:  can be only attached to one service at a time  can receive/make calls from default/manually selected service GPRS Sales Training 1999 - Greater China Network Solutions Division
  24. 24. GPRS Mobile Types  Type 1:  Classes 1 through 12  Class 12: 4 consecutive ts receive, transmit on 3rd. ts OR 2 consecutive ts receive and transmit  Type 2:  Classes 13 through 18  Can simultaneously transmit and receive on timeslots  Classes 13 = 3 ts, Class 14 = 4 ts ….. Class 18 = 8 ts  Type 3:  Half Duplex, power efficient mode  Classes 19 through 28  Class 19-23 supports ts from 3-8 Difference is the spacing of PACCH  Classes 24-28 supports ts from 3-8 GPRS Sales Training 1999 - Greater China Network Solutions Division
  25. 25. GPRS Network Interworking GPRS must interwork with the following external data networks:  X.25 networks  IP networks a. user’s IP address is allocated from a pool of unused IP addresses upon activation of access to IP network b. user’s IP address is permanently allocated  other GPRS PLMNs GPRS Sales Training 1999 - Greater China Network Solutions Division
  26. 26. GPRS Support in Cells  A cell may or may not support GPRS Non-GPRS Cells GPRS Cells GPRS Sales Training 1999 - Greater China Network Solutions Division
  27. 27. Tunnelling in GPRS  GPRS Tunnelling Protocol (GTP) PLMN 1 IP PLMN 2 Backbone SGSN GGSN  Point to Point path through one or more intermediate nodes  Data Packet  add GPRS Tunnelling Protocol header • contains endpoint identifiers  insert this in a TCP or UDP packet data unit  insert this in an IP packet data unit GPRS Sales Training 1999 - Greater China Network Solutions Division
  28. 28. “Anonymous Acess” concept  MS does not identify itself (IMSI)  Authentication not required for Anonymous Access  Temporary TLLI assigned to MS  Regular GPRS call: all GPRS activities can be traced to a GPRS subscriber  Anonymous GPRS call: all GPRS activities can be traced only to an auxiliary TLLI.  Mobile requests Anonymous Access, and a logical link to SGSN (TLLI) is established  Examples:  Services where Service Provider pays for the call  Services where user confidentiality is required GPRS Sales Training 1999 - Greater China Network Solutions Division
  29. 29. Half Duplex Mode  Fixed vs Dynamic Allocation  Dynamic: MS must continuously monitor downlink (USF bits)  Fixed: MS is given specific time to start and stop transmitting  Fixed Allocation Mode is the Half Duplex Mode of operation GPRS Sales Training 1999 - Greater China Network Solutions Division
  30. 30. GPRS Standards  GPRS Standards being done in phases PHASE 1: PHASE 2: • PTP  • PTM-Multicast (TCP/IP, connectionless) • PTM-Group Call • X.25 Support • Supplementary Services • Network Interfaces • Additional External Network (Gn, Gb, Gr, Gp, Gs, Gi) Interfaces • Security • Charging Issues (information to be collected) • SMS over GPRS • anonymous access GPRS Sales Training 1999 - Greater China Network Solutions Division
  31. 31. GPRS Standards Breakdown STAGE 1 02.60 General GPRS Overview 03.60 03.64 03.61 03.62 General System Radio Arch. Point to MultiPoint Point to MultiPoint STAGE 2 Desc. & Network Description Multicast Group Call Architecture 02.60 04.65 09.60 04.61 04.62 LLC SNDCP Gb Interface PTM-M Services PTM-G Services STAGE 3 08.64 07.60 09.60 04.60 BSSGP User External Network Gb Interface Interworking Interworking • Plus modifications to existing standards (Stage 3) Read 03.60 if you have time to read only one document ! GPRS Sales Training 1999 - Greater China Network Solutions Division
  32. 32. Air Interface - New Channels  PDTCH - Packet Data Traffic Channel Uplink &  PACCH - Packet Associated Control Channel Downlink  PBCCH - Packet Broadcast Control Channel Downlink Only  PCCCH  PAGCH - Packet Access Grant Channel Downlink Only  PPCH - Packet Paging Channel  PNCH - Packet Notification Channel  PRACH - Packet Random Access Channel Uplink Only GPRS Sales Training 1999 - Greater China Network Solutions Division
  33. 33. Air Interface Timeslot Allocation  Upto 8 timeslots can be allocated for GPRS  maximum one GPRS carrier per cell (initial release)  Air interface timeslot configuration:  GPRS only timeslots  GPRS and Circuit Switched timeslots  Circuit Switched (GSM voice) timeslots 0 0 0 Switchable . . . TCH . . . BCCH/CCCH with GPRS msg 7 7 7 GPRS only BCCH Second BCCH Second BCCH Second Carrier Carrier Carrier Carrier Carrier Carrier GPRS Sales Training 1999 - Greater China Network Solutions Division
  34. 34. Mobile States and Transitions IDLE:  - not attached to GPRS IDLE - MS, SGSN has no valid location routing informationSTANDBYtimer GPRS Attach GPRS Detach - MS can only receive PTM-M  STANDBYexpiry - MS attached to GPRS network READY - MS can receive pages for incoming data READY timer expiry or Packet Data - MS can receive CS pages Force to STANDBY Transmission READY  - MS sends and receives packet STANDBY data - MS remains in this state until it times out GPRS Sales Training 1999 - Greater China Network Solutions Division
  35. 35. Basic Call Processing MS turns on. MS initiates LOGON procedure with SGSN GGSN gets location update of MS. HLR assigns IP address to MS from its static pool of IP addresses MS goes into standby mode GPRS Sales Training 1999 - Greater China Network Solutions Division
  36. 36. Mobile Originated Call Channel Request on PRACH or RACH BSS assigns initial resources to MS (Timing Advance, Timeslots) Data Blocks Packet Data Channel Packet Acknowledge PACCH Channel MS goes into STANDBY Mode GPRS Sales Training 1999 - Greater China Network Solutions Division
  37. 37. Mobile Terminated Call Paging Request from BSS Channel Request on PRACH or RACH BSS assigns initial resources to MS (Timing Advance, Timeslots) Data Blocks Packet Data Channel Packet Acknowledge PACCH Channel MS goes into STANDBY Mode GPRS Sales Training 1999 - Greater China Network Solutions Division

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