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Wireless Networks

Chris Lord (cil103) An Overview of General Packet Radio Service (GPRS). Wireless Networks. Based on information from http://www.comsoc.org/livepubs/surveys/public/3q99issue/bettstetter.html. What is GPRS?. Bearer service for GSM Packet-switched

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Wireless Networks

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  1. Chris Lord (cil103) An Overview of General Packet Radio Service (GPRS) Wireless Networks Based on information from http://www.comsoc.org/livepubs/surveys/public/3q99issue/bettstetter.html

  2. What is GPRS? • Bearer service for GSM • Packet-switched • Can inter-operate with other packet-switched networks (e.g. IP, X.25) • Higher data-rates and lower connection times than conventional GSM

  3. GPRS Integration (1) • Addition of GPRS Support Nodes (GSN) • All GSNs connected by IP-based GPRS backbone network • Intra-PLMN (Public Land Mobile Network) – Connect GSNs on same network, private IP-based networks of the provider • Inter-PLMN – Connect GSNs on different PLMNs; requires a roaming agreement to be installed

  4. GPRS Integration (2) • Serving GSN: • Authentication/charging • Visited Location Registry (VLR) • User profiles • Gateway GSN • Packet delivery between mobile stations and external packet data networks (PDN), e.g. IP, X.25 • Authentication/charging

  5. GSM Network Interfaces (1) • Gb interface: Connects the BSC with the SGSN • Gn/Gp interfaces: Transmits user data and signalling data between GSNs • Gn for transmissions on same PLMN • Gp for transmissions on external PLMNs • Gf interface: IMEI queries • Gi interface: Connect to external PDNs

  6. GSM Network Interfaces (2) • Gr interface: Exchange of user information between HLR and SGSN • Gc interface: Exchange of location information between GGSN and HLR • Gs interface: Connects databases of SGSN and MSC/VLR to coordinate between GPRS and conventional GSM networks • Gd interface: Connects SGSN with SMS Gateway MSC (SMS-GMSC)

  7. BTS BTS BTS EIR AUC HLR VLR GSM System Architecture GMSC BSC MSC BSC

  8. BTS GGSN SGSN BTS BTS GGSN User/Signalling data Signalling data GPRS System Architecture SMS-GMSC SMS-IWMSC Other GPRS PLMN Gd Gp BSC BSC Gb Gs Gr EIR MSC/ VLR HLR Gn Gf D Gc PDN Gi

  9. Services • Bearer services for GPRS offer end-to-end packet-switched data transfer. Two types: • Point-to-point (PTP) • Internet access • SMS messages • Point-to-multipoint (PTM) • Unidirectional distribution of information (e.g. weather, news) • Conferencing services between multiple users

  10. Quality of Service (1) • QoS profiles can be defined using parameters derived from service precedence, reliability, delay and throughput. • QoS profiles can be negotiated between the mobile user and the network, per session, depending on current resources, and can affect billing

  11. Quality of Service (2) • Three priorities: High, Medium, Low • Three reliability classes that guarantee maximum values of loss, duplication, mis-sequencing and corruption of packets • Delay defines maximum mean delay and 95-percentile delay • Throughput specifies peak and mean bit-rate

  12. GPRS and Conventional GSM • GSM/GPRS services can be used in parallel. Three classes of mobile station: • Class A – Simultaneous use of GSM and GPRS • Class B – Can register for both GSM and GPRS, but only use one at a time • Class C – Can attach for only either GSM or GPRS (with the exception of SMS messages)

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