GSM is a mobile communication system that was developed to provide standardized cellular communication across Europe. Key aspects of GSM include supporting international roaming, good speech quality, and compatibility with ISDN. The core components of GSM are the mobile station (MS), base station subsystem (BSS), and network subsystem. The MS contains the mobile equipment (ME) and subscriber identity module (SIM). The BSS includes base transceiver stations (BTS) and base station controllers (BSC). The network subsystem comprises mobile switching centers (MSC), home location registers (HLR), visitor location registers (VLR), and other registers. GSM supports calling features and provides secure, efficient cellular communication across multiple countries.

1. GSM – GLOBAL SYSTEM FOR
MOBILE COMMUNICATION
Raman sanoria

2. HISTORY
• 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

3. System Architecture
• Mobile Station (MS)
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)

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

5. 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)

6. 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

7. 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
3. Base Transceiver Station (BTS)
5. Base Station Controller (BSC)

8. 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

9. 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

10. 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

11. 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

12. 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

13. System Architecture

14. 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

15. 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

16. 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

17. 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