GSM Network
Architecture
ELET 6302
Motivation
Outline
Introduction and history.
GSM architecture.
Implementation.
Technology and standards.
Summary
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
GSM Architecture
Home Location Register
BTS = Base Transceiver Station
AuC
Network
Management
Center
AuC = Authentication Center
OMC = Operation and Maintenance Center
Equipment ID
PSTN = Public Switched Telephone Network
ME = Mobile Equipment
Subscriber
Identity
Module
ME
B
T
S
Subscriber
Identity
Module
ME
B
T
S
Subscriber
Identity
Module
ME
B
T
S
Visitor Location
Register
Mobile
switching
center
Base station
controller
OMC
Data
communication
network
PSTN
Source: Stallings, 313
Source: Mehrotra, 27
GSM Architecture
MS Transmission
Band : 890 – 915
MHZ
BS Transmission
Band : 935 – 960
MHZ
45 MHz
F1 F2 F1' F2'
1
2
3
4
5
6
7
8
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
Frequency
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/
Implementation
Receiver
>Channel Decoding
Voice decoding
Deciphering
>De-Interleaving
Demodulation
>Re-formatting
>Channel encoding
Voice encoding
>Interleaving
Ciphering
Modulation
Amplifier
>Burst generation
Transmitter
Central processor, clock and tone, internal bus system, keyboard (HMI)
SIM = Subscriber Identity Module
Source: Heine, 14
Input filter
O&M Module
HF Transmitter
(HF-TX)
HF Receiver
(HF-RX)
TRX
Digital signal
processing (NF
functionality)
Transmission
system
Output filter
Slow frequency
hopping
Implementation
AbisInterface
Operation and maintenance functionality/clock distribution
Block Diagram of a BTS with one TRX
Source: Heine, 20
GSM Variants
Variant
Uplink
(MHz)
Downlink
(MHz)
Total
Bandwidth
DuplexChannels
frequency
GSM-400
451-458 and
479-486
461-468 and
489-496
Twice 14 MHz
10 MHz
Twice 72
GSM-900
(primary
band)
890-915
935-960
Twice 25 MHz
45 MHz
Twice 124
Extended
GSM-900
880-915
925-960
Twice 35 MHz
45 MHz
Twice 174
GSM-R
876-880
921-925
Twice 4 MHz
45 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
Summary
Network architecture
Implementation
Voice application
Data application
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.