The document provides an overview of GSM and GPRS networks. It describes key components of the GSM access network including the BTS, BSC and MSC. It also explains the GSM core network elements such as the HLR, VLR, AuC and SMS centers. For GPRS, it outlines the new GPRS support nodes - SGSN and GGSN, and how they interface with existing GSM network elements.

1. GSM Overview Mr. G. Majhi SDE/ARTTC

3. Communication - Mobile Telephone Exchange Subscriber Line (2W) Inter-Exchange Junction Mobile Switching Centre (MSC) BSC BTS MS

5. A RADIO CELL Voice Channels Coverage area Forward path Reverse path Or control channels Lines to BSC MS

7. GSM Specifications Carrier Separation - 200 kHz No. of RF Carriers - 124 Access Method - TDMA/FDMA Modulation Method - GMSK Transmission Rate - 270.833 Kbps Speech Coding - Full rate 13 Kbps Half rate 6.5 Kbps Duplex Distance - 45 MHz

8. GSM FDMA ( F requency D ivision M ultiple A ccess 25 MHz 25 MHz Mobile to Base 0 1 2 890.2 890.4 890.6 ( MHz) Base to Mobile 0 1 2 935.2 935.4 935.6 200 kHz 45MHz Channel layout and frequency bands of operation 890 935 960 915 200 kHz

9. GSM TDMA ( T ime D ivision M ultiple A ccess) 45 MHz Frequency F2’ F1’ (Cell transmit) F2 F1 (Cell Rx) Amplitude Typical TDMA/ FDMA frame structure 8 7 6 5 4 3 2 1 8 7 6 5 4 3 2 1

10. FDMA/TDMA Scheme F R A M E BP1 BP2 BP3 BP4 BP5 BP6 BP7 BP8 BP1 BP2 TIME 890.0 890.2 890.4 890.6 890.8 891.0 891.2 915.8 FREQ MHz BURST

11. LOGICAL CHANNELS • USER INFORMATION( TRAFFIC) • SIGNALLING INFORMATION (CONTROL) GSM RF CHANNELS

13. Network Architecture HLR PSTN ISDN Data Networks  Air interface OSS BSC 1 MSC=16 BSC 1 BSC=1024 TRU A Interface A-bis interface B T S MSC VLR B T S B T S MSC VLR

15. LOCATION AREA : There are several LA in a MSC/VLR combination. A LA is a part of the MSC/VLR service area in which a MS may move freely without updating location information to the MSC/VLR exchange that control the LA. Within a LA a paging message is broadcast in order to find the called mobile subs. LA can be identified by system using the LAI . CELL : A cell is an identity served by one BTS. The MS distinguishes between cells using the BASE STATION IDENTIFICATION CODE(BSIC) that the cell site broadcast over the air. GSM Network Structure

16. GSM PLMN Service Area MSC/VLR MSC/VLR MSC/VLR MSC/VLR II I III IV

17. GSM MSC Service Area MSC/VLR LA 1 LA 2 LA 6 LA 3 LA 4 LA 5

18. LA 1 LA 2 LA 6 LA 3 LA 4 LA 5 C1 C5 C4 C7 C2 C3 C6 GSM Cells C = Cell MSC/VLR

19. GSM Relation between areas in GSM Location Area Cell Area served by a BTS Location Area MSC Service Area PLMN Service Area GSM Service Area

24. RSS RADIO SUB SYSTEM (RSS) n BTS n BTS BSC BSC BSC MSC/VLR

30. GSM MSC-BSS Configurations A-bis BSS Configuration -6 Multi - cell site = multi--BTS site Many single cell sites A A A Single - cell site Configuration -1 Multi - cell site (sector Cells Configuration -5 MCC: Mobile Switching Centre BSS: Base Station System BSC: Base Station Controller BTS: Base Transceiver Station A-bis BTS BTS BTS BSC BSS MSC BTS BTS BTS BTS

39. G eneral P acket R adio S ystem GPRS

40. Backbone Network Corporate Network ISP Network Gb Gs Gd Gr Gi Gn Gn SGSN GGSN P C U Network Evolution EDGE TRU MS BTS BSC MSC/VLR SMS-G/IW MSC AUC HLR MS U T R A N BTS BTS BTS R N C R N C MS UMTS Iu

41. Backbone Network Corporate Network ISP Network Gb Gs Gd Gr Gi Gn Gn SGSN GGSN P C U Network Evolution EDGE TRU MS BTS BSC MSC/VLR SMS-G/IW MSC AUC HLR MS

42. Backbone Network Corporate Network ISP Network Gb Gs Gd Gr Gi Gn Gn SGSN GGSN P C U Network Evolution EDGE TRU MS BTS BSC MSC/VLR SMS-G/IW MSC AUC HLR MS U T R A N BTS BTS BTS R N C R N C MS UMTS Iu

43. GPRS Architecture EIR SGSN HLR AUC GGSN ISDN / PSTN / PLMN Network IP-Backbone Network External IP Network External X.25 Network GMSC MSC/VLR A Gb Gs Gn Gf Gr Gi Gi Gn BTS BSC Abis BSS Um TE MT MS A GSM Interface Abis GSM Interface (Proprietary of M/s Ericsson) AUC Authentication Center BSC Base Station Center BSS Base Station System BTS Base Transceiver Station EIR Equipment Identity Register GGSN Gateway GPRS Support Node GMSC Gateway Mobile services Switching Center Gx GPRS Interfaces HLR Home Location Register MS Mobile Station MSC Mobile services Switching Center MT Mobile Terminal SGSN Serving GPRS Support Node TE Terminal Equipment Um Air Interface VLR Visitor Location Register GPRS Network Elements GSM Network Elements Traffic & Signaling Signaling