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GPRS 介绍

GPRS 介绍. GPRS 业务与应用 GPRS 的无线子系统 GPRS 网络部分 GPRS 计费 引入 GPRS 业务对现有 GSM 网络的影响. GPRS 业务与应用. GPRS General Package Radio Servic 通用分组无线业务 提供用户端到端分组传输模式下发送和接收数据。 两类承载业务： 点对点（ PTP） 点对多点（ PTM）。. GPRS 提供应用业务的特点： 适用不连续的非周期性（突发）的数据传送，突发出现的时间间隔远大于突发数据的平均传输时延；

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GPRS 介绍

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  1. GPRS介绍

  2. GPRS业务与应用 • GPRS的无线子系统 • GPRS网络部分 • GPRS计费 • 引入GPRS业务对现有GSM网络的影响

  3. GPRS业务与应用 • GPRS General Package Radio Servic 通用分组无线业务 • 提供用户端到端分组传输模式下发送和接收数据。 • 两类承载业务： • 点对点（PTP） • 点对多点（PTM）。

  4. GPRS提供应用业务的特点： • 适用不连续的非周期性（突发）的数据传送，突发出现的时间间隔远大于突发数据的平均传输时延； • 适用小于500字节小数据量事务处理业务，允许每分钟出现几次，可以频繁传送； • 适用几千字节大数据量事务处理业务，允许每小时出现几次，可以频繁传送。 GPRS非常适合突发数据应用业务，能高效利用信道资源，但对大数据量应用业务GPRS网络要加以限制。

  5. GPRS应用业务概述 • 点对点PTP承载业务支持的横向（面向个人）应用业务： • 电子信箱E-mail业务 • Telnet远程登录业务 • FTP文件传输业务； • 交互式信息服务： • Web浏览业务 • 访问数据库 • 信息查询访问 • 电子号码薄（目录）服务，查找有关Internet用户信息服务（E-mai地址，电子号码）； • 检索服务

  6. 点对点PTP承载业务支持的纵向（面向集团用户小数据量事务处理）应用业务点对点PTP承载业务支持的纵向（面向集团用户小数据量事务处理）应用业务 • 信用卡确认（POS）； • 保安系统（电子监控）； • GPS自动定位跟踪业务（运钞车定位跟踪）； • 电子商务； • 电子银行； • 远程商务洽谈； • 石油、天然气管道监测系统； • 煤、水、电远程读表； • 彩票交易； • 仓库等监视系统等等。

  7. 点对多点PTM承载业务支持的纵向（面向集团用户小数据量事务处理）应用业务：点对多点PTM承载业务支持的纵向（面向集团用户小数据量事务处理）应用业务： • 点对多点PTM单向应用业务： • 新闻； • 股票金融信息； • 天气预报； • 业务报告； • 产品和业务广告； • 航班时刻表等等。 • 点对多点PTM双向（多向）应用业务： • 调度系统：外出流动工作人员任务分派调度管理； • 车队（出租车，邮政快递）调度管理； • 交通运输路由导引； • 集装箱码头船舶调度管理等等。

  8. Mobile Station (MS) • MS --- combination of TE and MT • TE --- Terminal Equipment Portable computers,PDA,Telemetry equipment • MT --- Mobile Terminal(card phone, mobile phone) GPRS终端（MT）有以下三类： A类：GPRS和GSM电路型业务可同时工作。 B类：可附着在GPRS和GSM电路型业务上， 但二者不能同时工作，可相互切换工作。 C类：只能附着在一种业务上。

  9. IP Network MS Base Transceiver System – BTS A’’ A MAP BSC MSC/VLR BTS HLR Gb Gs Gc Gr (MAP) Gi (IP) SGSN GGSN Gi (X.25) Gn Gn X.25 Network • Packet data for the radio interface • Slot and channel allocation • Existing A’’ interface is reused Backbone Network IP

  10. MS Base Station Controller – BSC A MAP BSC MSC/VLR HLR Gb Gs IP Network Gc Gr (MAP) Gi (IP) SGSN GGSN Gi (X.25) Gn Gn • GPRS Mobility Management • Gb –Frame Relay • Allocation of PDCH in cells • Handling of GPRS Paging • Broadcast GPRS information X.25 Network Backbone Network IP

  11. Mobile Switching Centre – MSC • Location info from SGSN • CS paging request to SGSN • Signalling coordination for class A/B mobile (Gs) • Suspend and resume function (A and Gb i/f) MAP MSC/VLR HLR IP Network Gs Gc Gr (MAP) Gi (IP) SGSN GGSN Gi (X.25) Gn Gn X.25 Network Backbone Network IP

  12. MS Home Location Register – HLR HLR IP Network Gc Gr (MAP) Gi (IP) SGSN GGSN Gi (X.25) Gn Gn X.25 Network • GPRS subscription androuting information • Maps subscriber to oneor more GGSNs • Update SGSN at attach and detach Backbone Network IP

  13. MS Serving GPRS Support Node – SGSN • Ciphering, authentication, and IMEI check • Mobility management • Logical link management towards the MS • Charging data • Packet routing & transfer • Connection - HLR, MSC, BSC and SMS-MSC IP Network Gi (IP) SGSN GGSN Gn Gi (X.25) X.25 Network

  14. MS Gateway GPRS Support Node – GGSN • External interfaces • Access functionality • ‘Traditional’ gateway functionality • Subscriber addresses publish • Routing IP Network Gi (IP) GGSN Gi (X.25) X.25 Network

  15. Local ISP ISP 1 ISP 2 Interworks with External Networks Internet GPRS Mobile Network Corporate Network

  16. MS Backbone Network IP Network Gi (IP) SGSN GGSN Gi (X.25) Gn Gn X.25 Network • Links GSN nodes • Standardised to be IP Backbone Network IP

  17. SMS-G/IW MSC HLR AUC BTS SOG SGSN MS BGw Traffic & Signalling Signalling New HW OLD SW Ericsson GPRS Solution Gd (MAP) A’’ A BSC MSC/VLR Gr (MAP) (BSSAP+) Gs Gb ISP Network Gi (IP) GGSN Gi (IP) Gn Gn CorporateNetwork Backbone Network IP PTM-SC

  18. What is GPRS? • General Packet Radio Service • GPRS is a GSM service for end-to-end packet switching • Reuse of existing infrastructure • Interworks with existing circuit-switched services • Based on standardised open interfaces

  19. GPRS – traffic casesContent • GPRS Attach • PDP Context Activation • Access Point Name, DNS • Authentication, RADIUS • Packet Routing & Packet Tunnelling • Location Update

  20. BTS BSC MSC/VLR HLR Corporate Network IP Network SGSN GGSN MS DHCP DNS RADIUS FW Router Router Other GPRS Operator Backbone Network IP BG PTM-SC GPRSNetwork Model ISP Network DNS Internet

  21. GPRS User Data Communication Procedure • IMSI attach • GPRS attach • PDP context activation • Receiving or Transmitting data

  22. GPRS – traffic casesContent • GPRS Attach • PDP Context Activation • Access Point Name, DNS • Authentication, RADIUS • Packet Routing & Packet Tunnelling • Location Update

  23. GPRS Attach (1) and PDP Context Activation(2)

  24. GPRS – traffic casesContent • GPRS Attach • PDP Context Activation • Access Point Name, DNS • Authentication, RADIUS • Packet Routing & Packet Tunnelling • Location Update

  25. 1. MS sends PDP context activation request to SGSN.2. Security functions may be executed between MS and SGSN.3. SGSN validates request.4. SGSN will find the correct GGSN and create a GTP.5. GGSN contacts an external network and ask for IP-number.6. The server in the external network executes security function.7. The sever in the external network sends IP-number to GGSN.8. GGSN sends IP-number back to MS.

  26. GPRS – traffic casesContent • GPRS Attach • PDP Context Activation • Access Point Name, DNS • Authentication, RADIUS • Packet Routing & Packet Tunnelling • Location Update

  27. Location update procedures • Cell Update • Routing Area Update • Combined routing area and location area update

  28. Cell Update • Used by mobiles in READY state • PCU detects when a new cell has been entered and includes the new cell ID in the next uplink BSSGP PDU sent to SGSN. • An RA update takes place instead of the cell update if the RA is also changed.

  29. Routing Area Update • Used by mobiles in READY and STANDY state • The MS sends a Routing Area Update Request to SGSN when • the MS has entered a new RA • the periodic RA update timers has expired • a suspended MS is not resumed by the BSS • Can be intra or inter SGSN RA Update

  30. Inter SGSN RA Update • MS sends RA Update Request to the new SGSN. • The new SGSN gets the MS information from the old SGSN. • The old SGSN forwards all buffered and unacknowledged packets to the new SGSN. • The new SGSN executes security check between MS and HLR. • Update the GGSN, the new SGSN creates a GTP tunnel to the GGSN. • Update the HLR(new SGSN address, Tid,Qos,etc) • Update the MSC/VLR if the Gs interface exists. • The old SGSN removes the MM and PDP-context. • RA Update is completed.

  31. GPRS Air Interface • Protocol Stack • Radio Blocks • Logical Channels • GPRS MS States and Modes • Network Operation Mode • Paging and Packet Transfer • Cell Selection and Reselection

  32. GPRS SNDCP Protocol SNDCP (Subnetwork Dependent Convergence Protocol) • Multiplexing of data packets from one or several applications onto one logic link. • Compression of redundant protocol information and user data. • Segmentation and reassemble.

  33. GPRS Air Interface • Protocol Stack • Radio Blocks • Logical Channels • GPRS MS States and Modes • Network Operation Mode • Paging and Packet Transfer • Cell Selection and Reselection

  34. GPRS Air Interface • Protocol Stack • Radio Blocks • Logical Channels • GPRS MS States and Modes • Network Operation Mode • Paging and Packet Transfer • Cell Selection and Reselection

  35. Logical Channel in GSM

  36. PDCH Allocation • All PDCH are allocated to the PCU. • One PSET( PDCH set) can consist maximum 4 consecutive TS. • MS can only be assigned PDCH from one PSET. • Dedicated and/or On-demand PDCH • 0-8 dedicated GPRS channels / cell • unlimited number of on-demand (dynamic) GPRS channels /cell • CS can pre-empt dynamic GPRS channels • First dedicated PDCH carries PCCCH

  37. GPRS Air Interface • Protocol Stack • Radio Blocks • Logical Channels • GPRS MS States and Modes • Network Operation Mode • Paging and Packet Transfer • Cell Selection and Reselection

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