GPRS EDGE 1.1.pptx

General Packet Radio Service (GPRS) Constraints with GSM network • • • • • Data Rates too slow – about 9.6 kbps Connection setup time too long Inefficient resource utilization for bursty traffic Proves expensive for bursty traffic utilization No efficient method for packet transfers Comparison...

General Packet Radio Service (GPRS) Constraints with GSM network • • • • • Data Rates too slow – about 9.6 kbps Connection setup time too long Inefficient resource utilization for bursty traffic Proves expensive for bursty traffic utilization No efficient method for packet transfers Comparison of GSM & GPRS Data Rates Modulation Technique Billing Type of Connection GSM 9.6 Kbps GMSK Duration of connection Circuit – Switched Technology GPRS 14.4 to 115.2 Kbps GMSK Amount of data transferred Packet Switched Technology What is GPRS ? • General Packet Radio Service (GPRS) is a bearer service for GSM that greatly improves and simplifies wireless access to packet data networks • GPRS applies packet radio principal to transfer user data packets in an efficient way b/w MS & external packet data network • GPRS features: – True packet radio system sharing network and air interface resources – Volume based charging – TCP/ IP (Internet &Intranet) interworking, MMS over GPRS – Peak data rate from 9.05 kbps ..171.2 kbps – Protocols designed for evolution of radio – EDGE new GSM modulation – Migration into 3rd Generation Benefits of GPRS • Efficient use of radio bandwith (Statistical Multiplexing) • Constant connectivity Statistical Multiplexing High Data Rate • GPRS uses radio channel i.e. 200 kHz wide • Radio channel carries digital data stream of 271 kbps • This rate is divided into 8 time slots each carrying 34 kbps per time slot • Data rate 14 kbps per time slot achieved after corrections • GPRS can combine upto 8 time slots giving data rate of 114 kbps GPRS Network Elements GPRS Architecture is same as GSM except few hardware modifications :  GPRS includes GSNs  SGSN : Serving GPRS Support Node  GGSN : Gateway GPRS Support Node  GPRS Register GPRS Architectural Detail 2G MS (voice only) NSS BSS E Abis PSTN A PSTN B BSC MS C MSC BTS Gs VLR GMSC D SS7 H Gb 2G+ MS (voice & data) Gr HLR AuC Gc Gn SGSN BSS — Base Station System BTS — Base Transceiver Station BSC — Base Station Controller Gi IP NSS — Network Sub-System MSC — Mobile-service Switching Controller VLR — Visitor Location Register HLR — Home Location Register AuC — Authentication Server GMSC — Gateway MSC PSDN GGSN SGSN — Serving GPRS Support Node GGSN — Gateway GPRS Support Node GPRS — General Packet Radio Service SGSN: Node Serving GPRS Support • Delivers data packets to mobile stations & vice-versa • Detect & Register new GPRS MS in its serving area • Packet Routing, Transfer & Mobility Management • Authentication, Maintaining user profiles • Its location register stores location info. & user profiles GGSN: Node Gateway GPRS Support • Interfaces GPRS backbone network & external packet data networks • Converts the GPRS packets from SGSN to the PDP format • Converts PDP addresses change to GSM addresses of the destination user • Stores the current SGSN address and profile of the user in its location register • Performs authentication • Many-to- many relations among SGSNs & GGSNs GPRS Register • GPRS Register is integrated with GSM-HLR. • Maintains the GPRS subscriber data and Routing information. • Stores current SGSN address GPRS Backbone Network • GSNs are connected through IP based backbone • Two Backbones: • Intra PLMN backbone networks that connects GSNs of the same PLMN & private IP networks • Inter PLMN backbone networks that connects GSNs of the different PLMN. Roaming agreement is necessary • GPRS Tunneling protocol (GTP) • PLMN- Inter PLMN interconnect are called Border gateways (performs security functions to protect Intra- PLMN backbone against unauthorized users and attacks). GTP – GPRS Tunneling Protocol • GTP tunnels user data packets and related signaling information between GSNs • Signaling is used to create, modify and delete tunnels • Defined both at Gn and Gp interface • Below GTP, TCP or UDP are employed to transport the GTP Packets within backbone network Inter working with IP networks • GPRS n/w can be interconnected with an IPbased packet data network • GPRS supports both IPv4 and IPv6 • GPRS n/w looks like IP sub network and GGSN looks like a IP router • DHCP, DNS servers are installed GPRS –Internet Connection GPRS SESSION MANAGEMENT GPRS Procedures • Attach & Detach • • • • • MS sends Attach Request to SGSN New SGSN requests IMSI from Old SGSN If not successful, New SGSN requests IMSI from MS RA/LA Update if needed Attach Accept • The PDP context activation • allows data transmission between MS and external data network • RA update procedure • tracks the location of the MS and re-establishes the logical link between MS & SGSN 20 21 22 23 PDP Context Activation • Mobile Station applies for PDP address • For each session PDP context is created & it contains •PDP type •PDP addressed assigned to MS •Address of GGSN that servers access point to PDN • With active PDP context MS able to send or receive data packets • Allocation of PDP address can be static or dynamic PDP Context Activation Session Management(Contd.) Quality of Service attributes : 1. Priority Class:  2. Delay Class :  3. 5 classes Peak Throughput:  5. 4 delay levels 0.5,5,50 sec, best effort Reliability Class:  4. 3 levels 9 classes 8-2048 Kbps Mean Throughput:  19 classes best effort-111Kbps GPRS Mobile State and Location Management GPRS mobile state Mobile station can be in 1 of the 3 states depending on traffic amount • Idle : MS is not using GPRS service • Ready : Performing GPRS Attach, into READY State MS gets • Standby : When MS does not send any packets for longer period of time, Ready timer Expires State Model of GPRS MS Routing Area Update • GSM coverage Area is divided into several Routing Areas(RA) • RA consists of several cells • SGSN is informed when MS moves to a new RA • MS sends a “Routing Area Update Request” to its assigned SGSN • Types of Routing Area Update • Intra SGSN Routing Area Update • Inter SGSN Routing Area Update Routing Area Update Mobility Management Consists of two levels: • Micro mobility management : - • Tracks the current RA or cell of MS It is performed by SGSN Macro mobility management : - Keep tracks of MS’s current SGSN Stores it in HLR, VLR, and GGSN GPRS Logical Channels Packet Data Channel(PDCH) • Physical Channel for GPRS Traffic • PDCH are taken from all channels available in the cell • Depending on current traffic load and priority of service, the physical channel are allocated to either GPRS or GSM services. • Physical channels not currently used by GSM can be allocated as PDCH to increase the QOS for GPRS GPRS Logical Channels Group Channel Packet data Traffic channel PDTCH Packet broadcast control channel PBCCH Packet common Control Channel (PCCCH) Packet Dedicated Control Channels Function MS BSS Broadcast Control MS BSS PRACH Random Access MS BSS PAGCH Access Grant MS BSS PPCH Paging MS BSS PNCH Notification MS BSS MS BSS Timing Advance Control MS BSS PACCH PTCCH Data Traffic Direction Associated Control GPRS Logical Channels • • • • The physical data channel is called Packet Data Channel Several logical data channels can occur on the same PDCH These logical data channels are : Packet data traffic channel (PDTCH) • For data transfer • Time slot sharing • Packet dedicated control channels (PDCCH) • Packet associated control channel (PACCH) • Conveys signaling info • Packet timing control channel (PTCCH) Uplink/Down link • Sending bursts/timing info • Packet common control channels (PCCCH) • Packet random access channel (PRACH) • Uplink from MS to BS to initiate transfer • Packet paging channel • Packet access grant channel (PAGCH) • Downlink for resource assignment • Packet notification channel • Point-to-multipoint multicast notification • Packet broadcast control channel (PBCCH) • Broadcasts system information Summary GPRS — 2.5G • General packet radio service • First introduction of packet technology • Aggregate radio channels • Support higher data rates (115 kbps) • Subject to channel availability • Share aggregate channels among multiple users • All new IP-based data infrastructure • No changes to voice network GSM Evolution for Data Access 2 Mbps UMTS 384 kbps 115 kbps EDGE GPRS 9.6 kbps GSM 1997 2000 GSM evolution 2003 2003+ 3G EDGE • Enhanced Data rates for Global Evolution • Increased data rates with GSM compatibility • Still 200 KHz bands; still TDMA • 8-PSK modulation: 3 bits/symbol give 3X data rate • Shorter range (more sensitive to noise/interference)