1. INTRODUCTION General Packet Radio Service (GPRS) is a new bearer service for GSM that greatly improves and simplifies wireless access to packet data networks It is a packet oriented mobile data service on the 2G and 3G cellular communication system's global system for mobile communications (GSM).

2. Characteristics GPRS uses packet switched resource allocation; resources allocated only when data is to be sent/received Flexible channel allocation a) one to eight time slots b) available resources shared by active users c) up and down link channels reserved separately d) GPRS and circuit switched GSM services can use same time slots alternatively Traffic characteristics suitable for GPRS a) Intermittent, burst data transmissions b) Frequent transmissions of small volumes of data c) Infrequent transmission of larger volumes of data

3. GPRS ARCHITECTURE

4. Architecture Entities The main entities are; SGSN- Serving GPRS Support Node GGSN-Gateway GPRS Support Node

5. SGSN – Serving GPRS Support Node Delivers data packets to mobile stations & vice- versa Detect and 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

6. GGSN – Gateway GPRS Support Node 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

7. GPRS Register GPRS Register is integrated with GSM-HLR. Maintains the GPRS subscriber data and Routing information. Stores current SGSN address

8. Other entities BG (Border Gateway) (Not defined within GPRS) Routes packets from SGSN/GGSN of one operator to a SGSN/GGSN of an other operator Provides protection against intruders from external networks DNS (Domain Name Server) Translates addresses from ggsn1.oper1.fi -format to 123.45.67.89 format (i.e. as used in Internet) Charging Gateway Collects charging information from SGSNs and GGSNs PTM-SC (Point to Multipoint -Service Center) PTM Multicast (PTM-M): Downlink broadcast; no subscription; no ciphering PTM Group call (PTM-G): Closed or open groups; Down/up -link; ciphered Geographical area limitation

9. Interfaces Gb – Connects BSC with SGSN Gn – SGSN – SGSN/GGSN (in the same network) Gp – SGSN –GGSN (in different networks) Gf – For equipment querying at registering time Gi – Connects PLMN with external Packet Data Networks (PDNs) Gr – To exchange User profile between HLR & SGSN Gs – To exchange Database between SGSN & MSC Gd – Interface between SMS & GPRS

10. GPRS mobile types Class A: Simultaneous GPRS and conventional GSM operation Supports simultaneous circuit switched and GPRS data transfer Class B: Can be attached to both GPRS and conventional GSM services simultaneously Can listen circuit switched and GPRS pages (via GPRS) Supports either circuit switched calls or GPRS data transfer but not simultaneous communication Class C: Alternatively attached in GPRS or conventional GSM No simultaneous operation ‘GPRS only’ mobiles also possible (e.g. for telemetric applications)

11. GPRS operations 1: Security; Based on GSM phase 2 Authentication SGSN uses same principle as MSC/VLR: Get triplet, send RAND to MS, wait for SRES from MS, use Kc MS can’t authenticate the network Key management in MS Kc generated same way from RAND using Ki as in GSM Ciphering Ciphering algorithm is optimized for GPRS traffic (‘GPRS - A5’) Ciphering is done between MS and SGSN User confidentiality IMSI is only used if a temporary identity is not available Temporary identity (TLLI) is exchanged over ciphered link

12. 2: GPRS Attach GPRS Attach function is similar to IMSI attach Authenticate the mobile Generate the ciphering key Enable the ciphering Allocate temporary identity (TLLI) Copy subscriber profile from HLR to SGSN After GPRS attach(detach) The location of the mobile is tracked Communication between MS and SGSN is secured Charging information is collected SGSN knows what the subscriber is allowed to do HLR knows the location of the MS in accuracy of SGSN

13. 3: Mobility management Instead of Location Area, GPRS uses Routing Areas to group cells. RA is a subset of LA. IDLE: MS is not known by the network (SGSN) STANDBY: MS’s location is known in accuracy of Routing Area MS can utilize DRX (to save battery) MS must inform its location after every Routing Area change (no need to inform if MS changes from one cell to another within same Routing Area) Before the network can perform MT data transfer MS must be paged within the Routing Area MS may initiate MO data transfer at any time

14. READY: MS’s location is known in accuracy of cell MS must inform its location after every cell change MS can initiate MO data transfer at any time SGSN does not need to page the MS before MT data transfer MS listens continuously GPRS PCCCH channel DRX in READY state is optional

15. 4 : Data transfer It involves two stages; Data call originating. Data call terminating.

16. GPRS channels Packet Data Channel (PDCH); The BSC assigns PDCHs to particular time slots, and there will be times when the PDCH is inactive, allowing the mobile to check for other base stations and monitor their signal strengths to enable the network to judge when handover is required.

17. Logical channels Packet Broadcast Central Channel (PBCCH); This is a downlink only channel that is used to broadcast information to mobiles and informs them of incoming calls Packet Paging Channel (PPCH): This is a downlink only channel and is used to alert the mobile to an incoming call and to alert it to be ready to receive data

18. Packet Access Grant Channel (PAGCH): This is also a downlink channel and it sends information telling the mobile which traffic channel has been assigned to it. Packet Notification Channel (PNCH): This is another downlink only channel that is used to alert mobiles that there is broadcast traffic intended for a large number of mobiles.

19. Packet Random Access Channel (PRACH): This is an uplink channel that enables the mobile to initiate a burst of data in the uplink. There are two types of PRACH burst, one is an 8 bit standard burst, and a second one using an 11 bit burst has added data to allow for priority setting. Packet Associated Control Channel (PACCH): This channel is present in both uplink and downlink directions and it is used for control signaling while a call is in progress.

20. Packet Timing Advance Common Control Channel (PTCCH): This channel, which is present in both the uplink and downlink directions is used to adjust the timing advance. This is required to ensure that messages arrive at the correct time at the base station regardless of the distance of the mobile from the base station. Packet Data Traffic Channel (PDTCH): This channel is used to send the traffic and it is present in both the uplink and downlink directions. Up to eight PDTCHs can be allocated to a mobile to provide high speed data.

22. Interworking with GSM services GPRS can interwork with GSM services through Gs- interface If no Gs interface exists: Type of the location update procedure is indicated by the network in the response message to MS

23. Effects on different MS classes if Gs does not exist: A-class mobiles must use conventional GSM services via normal GSM channels B-class mobiles won’t get simultaneous support from the network. Depending on MS design MS can try listen both paging channels simultaneously by themselves MS does IMSI detach and use only GPRS service No effect on C-class mobiles as simultaneous services are not supported

24. GPRS extends the GSM Packet circuit switched data capabilities and makes the following services possible: SMS messaging and broadcasting "Always on" internet access Multimedia messaging service (MMS) Push to talk over cellular (PoC) Instant messaging and presence—wireless village Internet applications for smart devices through wireless application protocol (WAP) Point-to-point (P2P) service: inter-networking with the Internet (IP) Point-to-Multipoint (P2M) service[citation needed]: point- to-multipoint multicast and point-to-multipoint group calls Services offered

25. Classes of GPRS services There are 4 types of class: Precedence Class An application can be assigned a Precedence Class 1, 2 or 3. If an application has a higher precedence (1) than another (3) then its traffic will be given a higher priority. Delay Class Applications can request predictive delay classes which guarantee an average and 95-percentile delay. There are 4 classes, 1 being the fastest.

26. Reliability class Applications can request differing levels of reliability for its data depending on its tolerance to data loss. Throughput Class Applications can choose different profiles for throughput. There are 2 distinctions in class, peak and mean. Peak throughput class is used mainly for burst transmissions with a variable in octets per second describing the throughput required for burst of specified size.

27. Benefits of GPRS New Data Services High Speed (Data Rate 14.4 – 115 kbps) Efficient use of radio bandwidth (Statistical Multiplexing) Circuit switching & Packet Switching can be used in parallel Constant connectivity

28. Applications of GPRS Web browsing Corporate & Internet Email Vehicle Positioning Remote LAN Access Home Automation Document Sharing/Collaborative working

29. EDGE Technology EDGE Enhanced Data Rates for Global Evolution. EDGE is the radio technology that allows operators to increase both data speeds and throughout capacity 3-4 times over GPRS. A major benefit of EDGE is that it enables existing TDMA carriers as well as GSM carriers to offer 3G services while still realizing lower costs due to higher efficiency and higher data rates.

30. EDGE was formerly called GSM384, because it allows data transmission speeds of 384 Kbps. Edge Technology which is an enhancement of GSM enables full global roaming(600 M subscribers of GSM in over 170 countries get to communicate). Example of EDGE tech is AT&T It’s designed to deliver multimedia applications like streaming TV, audio and videos to mobile phones

31. The idea behind EDGE is to obtain even higher data rates on the current 200KHz GSM carrier by changing the type of modulation used. EDGE is based on 8PSK(phase shift keying) which allows a much higher bit rate across the air interface.

32. EDGE uses the same TDMA frame structure, logic channel and 200kHz carrier bandwidth as today’s GSM networks. With EDGE, operators can offer more wireless data application including wireless multimedia, e-mail, web infotainment and videoconferencing

33. Comparison btn GPRS and EDGE

34. W-CDMA W-CDMA is Wideband Code-Division Multiple Access. W-CDMA is a third-generation (3G) mobile wireless technology that offers much higher data speeds to mobile and portable wireless devices.

35. W-CDMA can support mobile/portable voice, images, data, and video communications at up to 2 Mbps (local area access) or 384 Kbps (wide area access). The input signals are digitized and transmitted in coded, spread- spectrum mode over a broad range of frequencies. A 5 MHz-wide carrier is used, compared with 200 KHz-wide carrier for narrowband CDMA.

36. As well as supporting conventional voice, text and MMS services, WCDMA (Wideband Code Division Multiple Access) can carry data at high speeds, enabling mobile operators to deliver richer mobile multimedia services such as music-on-demand, TV and video streaming and broadband Internet access. It is a 3G technology that increases data transmission rates in GSM systems by using the CDMA air interface instead of TDMA.

37. Parameters of WCDMA Channel bandwidth; 5MHz Duplex mode; FDD( frequency division duplexing and TDD time division duplexing Spread Spectrum technigue; Direct spread Chip rate; 3.84 MHz.

38. HSDPA (High Speed Downlink Packet Access) For personal reading

39. References Telecommunication system engineering 3 rd edition Roger L. Freeman S. Buckingham, Data on GPRS, mobile Lifestreams limited, 1999.