1. Lectured By: Vivek Dimri Assistant Professor, CSE Dept. SET, Sharda University, Gr. Noida

2. General Packet Radio Service (GPRS) The General Packet Radio Service (GPRS) is a new non voice value added service that allows information to be sent and received across a mobile telephone network. It supplements today's Circuit Switched Data and Short Message Service. GPRS involves overlaying a packet based air interface on the existing circuit switched GSM network. This gives the user an option to use a packet-based data service.

3. General Packet Radio Service (GPRS) Architecture GPRS is a data network that overlays a second- generation GSM network. This data overlay network provides packet data transport at rates from 9.6 to 171 kbps. Additionally, multiple users can share the same air- interface resources simultaneously. GPRS attempts to reuse the existing GSM network elements as much as possible, but to effectively build a packet-based mobile cellular network, some new network elements, interfaces, and protocols for handling packet traffic are required.

4. General Packet Radio Service (GPRS) Architecture

5. Therefore, GPRS requires modifications to numerous GSM network elements as summarized below: Mobile Station (MS) New Mobile Station is required to access GPRS services. These new terminals will be backward compatible with GSM for voice calls. BTS A software upgrade is required in the existing base transceiver site.

6. General Packet Radio Service (GPRS) Architecture Therefore, GPRS requires modifications to numerous GSM network elements as summarized below: BSC The base station controller (BSC) requires a software upgrade and the installation of new hardware called the packet control unit (PCU). The PCU directs the data traffic to the GPRS network and can be a separate hardware element associated with the BSC. Databases (HLR, VLR, etc.) All the databases involved in the network will require software upgrades to handle the new call models and functions introduced by GPRS.

7. General Packet Radio Service (GPRS) Architecture Therefore, GPRS requires modifications to numerous GSM network elements as summarized below: GPRS Support Nodes (GSNs) The deployment of GPRS requires the installation of new core network elements called the Serving GPRS Support Node (SGSN) and Gateway GPRS support node (GGSN)

8. General Packet Radio Service (GPRS) Architecture GPRS Support Nodes: Serving GPRS Support Node (SGSN): The Serving GPRS Support Node is responsible for- Authentication of GPRS mobiles, Registration of mobiles in the network, mobility management, and Collecting information for charging for the use of the air interface.

9. General Packet Radio Service (GPRS) Architecture GPRS Support Nodes: Gateway GPRS Support Node (GGSN): The Gateway GPRS Support Node acts as an interface and a router to external networks. The GGSN contains routing information for GPRS mobiles, which is used to tunnel packets through the IP based internal backbone to the correct Serving GPRS Support Node. The GGSN also collects charging information connected to the use of the external data networks and can act as a packet filter for incoming traffic Therefore, GPRS requires modifications to numerous GSM network elements.

10. GPRS Functional Groups Network Access Packet Routing and Transfer Mobility Management Logical Link Management Radio Resource Management Network Management

11. GPRS Functional Groups Network Access Registration Authentication, and authorization Packet terminal adaption Admission control Message screening Charging information collection for transmission in GPRS & external networks

12. GPRS Functional Groups Packet Routing and Transfer Relay function Routing Address translation and mapping Encapsulation and Tunneling Domain Name Service functions Compression and ciphering

13. GPRS Functional Groups Mobility Management Cell update Routing area update Combine routing area and location area update Logical Link Management Logical link establishment Logical link maintenance Logical link release

14. GPRS Functional Groups Radio Resource Management Um interface management Cell selection Um-tranx- Packet data transfer capability, medium access control, packet multiplexing, packet discrimination, error detection and correction and flow control Path management Network Management Functions Support Operational, Authentication and Maintenance (OA&M) related functions

15. Coding scheme in GPRS GPRS offers coding scheme with different levels of error detection and correction These are used depending upon the radio frequency signal conditions and the requirements Given labels for coding schemes are CS-1 CS-2 CS-3 CS-4

16. Coding scheme in GPRS CS-1 Applies highest level of error detection and correction Used when interface levels are high and signal levels are low This prevent the data re-sent too often This level of detection and coding results in a half code rate, i.e. for every 12 bit that enter the coder, 24 bits result It results in an actual throughput of 9.05kbps data rate

17. Coding scheme in GPRS CS-2 This error detection and coding scheme is for better channels It effectively uses a 2/3 encoder Results in a real data throughput of 13.4kpbs CS-3 This effectively uses a ¾ coder Result in a data throughput of 15.6 kbps

18. Coding scheme in GPRS CS-4 This scheme is used when signal is high and interference levels are low No correction is applied to the signal Allowing maximum throughput of 21.4kbps

19. Channels in GPRS GPRS uses the same modulation and frame structure that is employed by GSM. Slots can be assigned dynamically by the BSC to GPRS calls depending upon the demand, remaining use for GSM traffic New data channel called Packet Data Channel (PDCH) is used for GPRS. GPRS slots may also be used by base station to judge the time delay using logical channel Packet Timing Advance Control Channel(PTACCH)

20. Channels in GPRS GPRS uses the following various channel groups Broad Cast Channel Packet Broadcast Central Channel (PBCCH) This is a downlink channel Used for broadcast information to Mobiles and informs them of incoming calls, etc. It broadcast general information required to setup call like- power control parameters, access method and operational modes, network parameters, etc.

21. Channels in GPRS Common Control Channel Packet Paging Channel(PPCH) This is a downlink channel It is used for control signaling prior to the call set up. Used to alert the mobile to an incoming call and be ready to get data. Packet Random Access Channel (PRACH) This is an uplink channel It enables the mobile to initiate a burst of data in the uplink There are two types of PRACH burst, standard 8bits and an 11 bits burst added to allow for priority setting

22. Channels in GPRS Common Control Channel Packet Access Grant Channel(PAGCH) This is a downlink channel It is used to send information to mobile about traffic channel assigned. It occurs after the PPCH has informed the MS. Packet Notification Channel (PNCH) This is a downlink channel It use to alert MS that there is a broadcast traffic intended for a large no of mobiles It is typically used in point to point multicasting

23. Channels in GPRS Dedicated Control Channel Packet Associate Control Channel(PACCH) This is both uplink and downlink channel It is used for control signaling while a call is in progress. It takes over from the PPCH once the call is set up. It carries information like- power control message, channel assignment, and ACK of received data Packet Timing Common Control Channel (PTCCCH) This is both uplink and downlink channel It use to adjust timing advance. It ensure that message arrive at correct time from MS to BS regardless distance in between.

24. Channels in GPRS Dedicated Traffic Channel Packet Data Traffic Channel(PDTCH) This is both uplink and downlink channel It is used to send the traffic Up to eight(8) PDTCHs can be allocated to a MS to provide high speed data.

25. Applications for GPRS Chat Text and Visual Information Still Images Moving Images Web Browsing Document Sharing / Collaborative working Audio Push to Talk (PTT) Internet E-mail