12-10-2012, 01:32 PM
Introduction to GSM
[attachment=36182]
Early 1980s there was analog
technologies:
Advanced Mobile Phone Services(AMPS)in
North America.
Total Access Communications System(TACS)
in the UK.
Nordic Mobile Telephone(NMT) in Nordic
countries.
Each country developed its own system,
which caused problems:
System worked only within the boundaries of
each country.
Mobile equipment manufacturers markets
were limited by the operating system.
Solution was GSM, which is digital
technology and was developed by
CEPT(Conference of European Posts and
Telecommunications)
The Goals of GSM
Improved spectrum efficiency
International roaming
Low-cost mobile sets and base stations
High-quality speech
Compatibility with ISDN and other telephone
company services.
Support for new services
QoS
GSM Cell Structure
The power level of a
transmitter within a
single cell must be
limited to reduce the
interference with the
neighboring cells.
GSM Architecture
Base Tranceiver Station
(BTS)
serves a single cell
usually placed in the center
of a cell
coding
crypting
multiplexing
modulating
synchronizing
Base Station Controller(BSC)
translates the 13-Kbps voice to the standard
64-Kbps channel (used by PSDN or ISDN)
frequency hopping
time and frequency synchronisation
power management
time delay measurements
The Registers Completing the
NSS
Home Location Register (HLR) contains all
information of each subscriber registered in the
corresponding GSM network
Visitor location Register (VLR) contains selected
information from the HLR, which is necessary for
call control and provision of the subscribed
services, for each mobile currently located in the
geographical area controlled by the VLR
NSS = HLR + VLR + MSC
Equipment Identity Register (EIR) contains
a list of all valid mobile equipment on the
network
Authentication Center (AUC) stores a copy
of the secret key stored in each subcribers
SIM card
EIR and AUC are used for security and
authentication purposes
[attachment=36182]
Early 1980s there was analog
technologies:
Advanced Mobile Phone Services(AMPS)in
North America.
Total Access Communications System(TACS)
in the UK.
Nordic Mobile Telephone(NMT) in Nordic
countries.
Each country developed its own system,
which caused problems:
System worked only within the boundaries of
each country.
Mobile equipment manufacturers markets
were limited by the operating system.
Solution was GSM, which is digital
technology and was developed by
CEPT(Conference of European Posts and
Telecommunications)
The Goals of GSM
Improved spectrum efficiency
International roaming
Low-cost mobile sets and base stations
High-quality speech
Compatibility with ISDN and other telephone
company services.
Support for new services
QoS
GSM Cell Structure
The power level of a
transmitter within a
single cell must be
limited to reduce the
interference with the
neighboring cells.
GSM Architecture
Base Tranceiver Station
(BTS)
serves a single cell
usually placed in the center
of a cell
coding
crypting
multiplexing
modulating
synchronizing
Base Station Controller(BSC)
translates the 13-Kbps voice to the standard
64-Kbps channel (used by PSDN or ISDN)
frequency hopping
time and frequency synchronisation
power management
time delay measurements
The Registers Completing the
NSS
Home Location Register (HLR) contains all
information of each subscriber registered in the
corresponding GSM network
Visitor location Register (VLR) contains selected
information from the HLR, which is necessary for
call control and provision of the subscribed
services, for each mobile currently located in the
geographical area controlled by the VLR
NSS = HLR + VLR + MSC
Equipment Identity Register (EIR) contains
a list of all valid mobile equipment on the
network
Authentication Center (AUC) stores a copy
of the secret key stored in each subcribers
SIM card
EIR and AUC are used for security and
authentication purposes