1. GSM Network Architecture
ELET 6302

2. Motivation

3. Outline Introduction and history. GSM architecture. Implementation.
Technology and standards.
Summary

4. 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

5. GSM Architecture Mobile switching center Base station controller
Network Management Center
Home Location Register
BTS = Base Transceiver Station
AuC = Authentication Center
OMC = Operation and Maintenance Center
PSTN = Public Switched Telephone Network
ME = Mobile Equipment
AuC
Equipment ID
OMC
Visitor Location Register
Subscriber Identity Module
BTS
Mobile switching center ME
Data communication network
Subscriber Identity Module
Base station controller
BTS ME
Subscriber Identity Module
BTS ME
PSTN
Source: Stallings, 313
Source: Mehrotra, 27

6. GSM Architecture MS Transmission Band : 890 – 915 MHZ
BS Transmission Band : 935 – 960 MHZ
45 MHz
Year Introduced
1990
Access method
TDMA
Channel Bandwidth
200 kHz
Number of duplex channels
125
Users per channel 8
Speech coding bit rate
13 kbps
Data coding bit rate
12 kbps
Frame size
4.6 ms

7. SIM (Subscriber Identity Module)
Billions of Calls
Millions of Subscribers
Thousand of Different Types of Telephones
Hundreds of Countries
Dozens of Manufacturers….
And only one Card: The SIM
Administrative data
Security data
Subscriber data
Roaming data
PLMN (Public Land Mobile Network
Source: Hillebrand, 369

8. Implementation Receiver Transmitter SIM = Subscriber Identity Module
>Channel Decoding
>De-Interleaving
>Re-formatting
Voice decoding
Deciphering
Demodulation
>Channel encoding
>Interleaving
>Burst generation
Voice encoding
Ciphering
Modulation
Amplifier
Transmitter
Central processor, clock and tone, internal bus system, keyboard (HMI)
SIM = Subscriber Identity Module
Source: Heine, 14

9. Implementation Block Diagram of a BTS with one TRX Source: Heine, 20
HF Transmitter (HF-TX)
Output filter
TRX
Abis-Interface
Slow frequency hopping
Transmission system
Digital signal processing (NF functionality)
HF Receiver (HF-RX)
Input filter
O&M Module
Operation and maintenance functionality/clock distribution
Block Diagram of a BTS with one TRX
Source: Heine, 20

10. GSM Variants Variant Uplink (MHz) Downlink (MHz) Total Bandwidth
Duplex-frequency
Channels
GSM-400
and
and
Twice 14 MHz
10 MHz
Twice 72
GSM-900 (primary band)
Twice 25 MHz
45 MHz
Twice 124
Extended GSM-900
Twice 35 MHz
Twice 174
GSM-R
Twice 4 MHz
Twice 19
DCS-1800
1,710-1,785
1,805-1,880
Twice 75 MHz
95 MHz
Twice 373
PCS-1900
1,850-1,910
1,930-1,990
Twice 60 MHz
80 MHz
Twice 300
Source: Bekkers, 299

11. Summary Network architecture Implementation Voice application
Data application

12. 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.