GSM is a global standard for mobile communications that has over 500 million subscribers in 168 countries. It uses TDMA and FDMA to allow multiple users to access the network simultaneously. The GSM architecture includes the BTS, BSC, MSC, HLR, VLR, AuC and other components. It operates in frequency bands such as 900 MHz and 1800 MHz with channel bandwidth of 200 kHz. GSM supports voice calls and data transmission and uses technologies like encryption, authentication and SIM cards.
2. Outline
Introduction and history.
GSM architecture.
Implementation.
Technology and standards.
Summary
3. Introduction
Global System for Mobile Communication (GSM)
Anybody 500 million users (may 2001)
Anywhere 168 countries (may 2001)
Any media voice, messaging, data, multimedia
Source: Hillebrand, 1
7. FDMA/TDMA Scheme
TIME
BP2
BP1
BP8
BURST
BP7
F
BP6
BP5
R
BP4 A
BP3 M
BP2
E
BP1 FREQ
890.2 890.6 891.0
890.0 890.4 890.8 891.2 915.8 MHz
8. GSM Architecture
Home Location Register
Network
Management
BTS = Base Transceiver Station Center
AuC
AuC = Authentication Center
Equipment ID
OMC = Operation and Maintenance Center
PSTN = Public Switched Telephone Network
ME = Mobile Equipment Visitor Location OMC
Register
Subscriber B
Identity ME T Mobile
S
Module Data
switching
communication
center network
Subscriber B Base station
Identity ME T
Module
S
controller
Subscriber B
Identity ME T PSTN
S
Module
Source: Stallings, 313
Source: Mehrotra, 27
9. GSM Architecture
MS Transmission BS Transmission
Band : 890 915 Band : 935 960
MHZ MHZ
45 MHz
Year Introduced 1990
1 Access method TDMA
2
3 Channel Bandwidth 200 kHz
4
5
Number of duplex 125
6 channels
7
F1 F2 F1' F2' 8 Users per channel 8
Frequency
Speech coding bit 13 kbps
rate
Data coding bit rate 12 kbps
Frame size 4.6 ms
10. SIM (Subscriber Identity Module)
Billions of Calls
Millions of Subscribers
Thousand of Different Types of Telephones
Hundreds of Countries
Dozens of Manufacturers. Administrative data
And only one Card: The SIM Security data
Subscriber data
Roaming data
PLMN (Public Land Mobile Network
Source: Hillebrand, 369
http://ucables.com/products/simcards/
12. Implementation
Slow frequency
Transmission
HF Transmitter
Output filter TRX Abis-
(HF-TX) Interface
system
hopping
Digital signal
HF Receiver processing (NF
Input filter (HF-RX) functionality)
O&M Module Operation and maintenance functionality/clock distribution
Block Diagram of a BTS with one TRX
Source: Heine, 20
14. References
Bekkers, Rudi. Mobile Communications Standards: GSM, UMTS, TETRA, and ERMES.
Norwood, MA: Artech House, Inc., 2001.
Halonen, Romero, and Melero. GSM, GPRS, and EDGE Performance: Evolution Towards
3G/UMTS. England: John Wiley & Sons Ltd., 2003.
Hillebrand, Friedhelm. GSM and UMTS: The Creation of Global Mobile
Communications. England: John Wiley & Sons Ltd., 2002.
Heine, Gunnar. GSM Networks: Protocols, Terminology, and Implementation.
Norwood, MA: Artech House, Inc., 1999.
Mehrotra, Asha. GSM System Engineering. Norwood, MA: Artech House, Inc., 1997.
Harte, Levine, and Livingston. GSM Superphones. United States: APDG Publishing, Inc.
A Division of McGraw-Hill, 1999.