1. Overview of the GSM for Cellular System
Lecturer: srwa mohammad

2. GSM Overview
AGENDA • Background and Fundamentals • System Architecture Overview • Mobility Management • Radio Resource Management • Communication Management • Roaming

3. Background and Fundamentals
What is GSM?
GSM: Global System for Mobile Communications
Formerly: Group Special Mobile
When ?
• 1982: GSM created to set standard
• 1988: Industrial development started
• 1991: First Systems Deployed

4. Evolution of Cellular Networks
1G → 2G → 2.5G → 3G → 4G | Analog Digital | Circuit-switching Packet-switching

5. System Architecture Overview
Functional Architecture broadly divided into 4 parts:  Mobile Station (MS).  Base Station Subsystem (BSS).  Network Switching Subsystem (NSS).  Operation and Support Subsystem (OSS)

6. System Architecture-PLMN
PLMN: The GSM system is made up of sub-networks called: Public Land Mobile Network's (PLMN). Messaging system functions in GSM architecture: Mobile-services Switching Center (MSC) Home Location Register (HLR) Visitor Location Register (VLR) Equipment Identity Register (EIR) Authentication Center (AUC)

7. Mobile Station (MS)
Operation and Maintenance Center (OMC)
Base Station System (BSS)
Base Transceiver Station (BTS)
Base Station Controller (BSC).

8. GSM network with added elements

9. MS and SIM
Mobile Station (MS) enables generic radio and processing functions to access the network through the radio interface.
Each MS has a unique IMEI (Identity Mobile Equipment Identity)
Subscriber Identity Module (SIM) is basically a smart card, containing all the related information stored on the user’s side of the radio interface.
The SIM stores the IMSI

10. MS & SIM

11. What is an IMSI ? The International Mobile Subscriber Identity
consists of three parts
 The MCC identifying a country
 The MNC identifying a PLMN within this country
 The MSIN identifying a subscriber within the PLMN

12. IMSI

13. What is an IMEI Identity Mobile Equipment Identity
consists of three parts
The TAC is given by the GSM body
The FAC is given by the Mfg
The SNR is the serial no.

14. IMEI
SVN is software version

15. BTS

16. BTS
A BTS comprises radio transmission and reception devices (including antennas) , can be considered as complex radio modems. A BTS is virtually connected to the MS (Air interface) on one side and to the BSC on the other side. In general a BTS is represented with three cells. Each cell can have more than one TRX (i.e. Antennas).

17. BTS

18. BSC

19. BSC
A BSC is in charge of all the radio interface management through the remote command of the BTS and the MS, mainly the allocation and release of radio channels and the handover management.
A BSC is connected on one side to the MSC and on the other side to several BTSs.

20. BSC

21. MSC/VLR

22. MSC/VLR
A MSC co-ordinates the setting-up of calls to and from GSM users.
A VLR is a database in charge of temporarily storing subscription data (IMSI,MSISDN, TMSI) for subscribers currently situated in the service area of the corresponding MSC.
The MSC/VLR has interfaces with the BSC on one side and external networks on the other side

23. MSC/VLR