1. GSM – GLOBAL SYSTEM FOR MOBILE COMMUNICATION
Debby Nahl
Fall 2004

2. DISCUSSION TOPICS History Building Blocks System Architecture
Features (Basic and Advanced)
Advantages of GSM
Future – what’s next

3. HISTORY
Early 80’s Europe was experiencing rapid growth in the analog cellular telephone systems
1982 Conference of European Posts and Telegraphs (CEPT) GSM (Groupe Special Mobile) group was formed to study and develop a pan-European public land mobile system
GSM mandate was to develop a standard to be common for the countries that created it – provide service to the entire European continent

4. HISTORY contd. GSM criteria – Good subjective speech quality
Low terminal and service cost
Support for international roaming – one system for all of Europe
Ability to support handheld terminals
Support for range of new services and facilities
Enhanced Features
ISDN compatibility
Enhance privacy
Security against fraud

5. HISTORY contd.
Late 1980’s GSM work was transferred to the European Telecommunication Standards Institute (ETSI) and SGM (Special Mobile Group) was created
Document the functionality and interaction of every aspect of the GSM network
1987 ETSI oversees the creation of GSM MoU (Memorandum of Understanding) Association

6. HISTORY contd.
Formal objective of the GSM MoU Association is the promotion and evolution of the GSM systems and GSM platforms
Concepts of a published international standard and a constantly evolving common standard are unique to GSM
Work groups throughout the world specifically designed to allow interested parties to meet and work on finding solutions to systems enhancements that will fit into existing programs of GSM operators

7. HISTORY contd. Phase I of GSM specifications was published in 1990
International demand was so great that the system name was changed from Groupe Special Mobile to Global Systems for Mobile Communications (still GSM)
Commercial service started in mid-1991
1992 first paying customers were signed up for service
By 1993 there were 36 GSM networks in 22 countries
Early 1994 there were 1.3 million subscribers worldwide
By 1996 there were more than 25 million subscribers worldwide
By October 1997 it had grown to more than 55 million subscribers worldwide

8. Building Blocks AMPS – Advanced Mobile Phone System
TACS – Total Access Communication System
NMT – Nordic Mobile Telephone System

9. Building Blocks contd. AMPS – Advanced Mobile Phone System
analog technology
used in North and South America and approximately 35 other countries
operates in the 800 MHz band using FDMA technology

10. Building Blocks contd. TACS – Total Access Communication System
variant of AMPS
deployed in a number of countries
primarily in the UK

11. Building Blocks contd. NMT – Nordic Mobile Telephone System
analog technology
deployed in the Benelux countries and Russia
operates in the 450 and 900 MHz band
first technology to offer international roaming – only within the Nordic countries

12. System Architecture Mobile Station (MS) Base Station Subsystem (BBS)
Mobile Equipment (ME)
Subscriber Identity Module (SIM)
Base Station Subsystem (BBS)
Base Transceiver Station (BTS)
Base Station Controller (BSC)
Network Subsystem
Mobile Switching Center (MSC)
Home Location Register (HLR)
Visitor Location Register (VLR)
Authentication Center (AUC)
Equipment Identity Register (EIR)

13. System Architecture Mobile Station (MS)
The Mobile Station is made up of two entities:
Mobile Equipment (ME)
2. Subscriber Identity Module (SIM)

14. System Architecture Mobile Station (MS) contd.
Mobile Equipment
Produced by many different manufacturers
Must obtain approval from the standardization body
Uniquely identified by an IMEI (International Mobile Equipment Identity)

15. System Architecture Mobile Station (MS) contd.
Subscriber Identity Module (SIM)
Smart card containing the International Mobile Subscriber Identity (IMSI)
Allows user to send and receive calls and receive other subscribed services
Encoded network identification details
Protected by a password or PIN
Can be moved from phone to phone – contains key information to activate the phone

16. System Architecture Base Station Subsystem (BSS)
Base Station Subsystem is composed of two parts that communicate across the standardized Abis interface allowing operation between components made by different suppliers
Base Transceiver Station (BTS)
Base Station Controller (BSC)

17. System Architecture Base Station Subsystem (BSS) contd.
Base Transceiver Station (BTS)
Houses the radio transceivers that define a cell
Handles radio-link protocols with the Mobile Station
Speech and data transmissions from the MS are recoded
Requirements for BTS:
ruggedness
reliability
portability
minimum costs

18. System Architecture Base Station Subsystem (BSS) contd.
Base Station Controller (BSC)
Manages Resources for BTS
Handles call set up
Location update
Handover for each MS

19. System Architecture Network Subsystem
Mobile Switching Center (MSC)
Switch speech and data connections between:
Base Station Controllers
Mobile Switching Centers
GSM-networks
Other external networks
Heart of the network
Three main jobs:
1) connects calls from sender to receiver
2) collects details of the calls made and received
3) supervises operation of the rest of the network components

20. System Architecture Network Subsystem contd.
Home Location Registers (HLR)
- contains administrative information of each subscriber
- current location of the mobile
Visitor Location Registers (VLR)
- contains selected administrative information from the HLR
authenticates the user
tracks which customers have the phone on and ready to receive a call
periodically updates the database on which phones are turned on and ready to receive calls

21. System Architecture Network Subsystem contd.
Authentication Center (AUC)
mainly used for security
data storage location and functional part of the network
Ki is the primary element
Equipment Identity Register (EIR)
- Database that is used to track handsets using the IMEI (International Mobile Equipment Identity)
Made up of three sub-classes: The White List, The Black List and the Gray List
Optional database

22. System Architecture

23. Basic Features Provided by GSM
Call Waiting
- Notification of an incoming call while on the handset
Call Hold
- Put a caller on hold to take another call
Call Barring
- All calls, outgoing calls, or incoming calls
Call Forwarding
- Calls can be sent to various numbers defined by the user
Multi Party Call Conferencing
- Link multiple calls together

24. Advanced Features Provided by GSM
Calling Line ID
- incoming telephone number displayed
Alternate Line Service
- one for personal calls
- one for business calls
Closed User Group
- call by dialing last for numbers
Advice of Charge
- tally of actual costs of phone calls
Fax & Data
- Virtual Office / Professional Office
Roaming
- services and features can follow customer from market to market

25. Future -- UMTS (Universal Mobile Telephone System
Reasons for innovations
new service requirements
availability of new radio bands
User demands
seamless Internet-Intranet access
wide range of available services
compact, lightweight and affordable terminals
simple terminal operation
open, understandable pricing structures for the whole spectrum of available services

26. Advantages of GSM Crisper, cleaner quieter calls
Security against fraud and eavesdropping
International roaming capability in over 100 countries
Improved battery life
Efficient network design for less expensive system expansion
Efficient use of spectrum
Advanced features such as short messaging and caller ID
A wide variety of handsets and accessories
High stability mobile fax and data at up to 9600 baud
Ease of use with over the air activation, and all account information is held in a smart card which can be moved from handset to handset