Members of our Presentation
(Bsts09-08) Hafiz Umer Ejaz
(Bsts09-09) Rai-Habib Ullah
(Bsts09-31) M.Arsalan Qureshi
(Bsts09-32) Shoaib Ansari
(Bsts09-34) Talal Rashid
Why do we need cellular phones?
We can freely move and in contact with people at
It helps to organize our life.
If someone lost, it can give you directions.
Advantages of cellular phone
Advantages to Mobile User
Advantages to Network Provider
Different technologies of Cellular phones
First Generation -Analog Mobile Telephone System
Second Generation-Digital Mobile Communication
Cellular technologies overview
First Generation Cellular Systems
The predominant technology of first generation was
Advanced Mobile Phone System or AMPS.
First generation cellular systems made its entrance
in 1979, work in 1980’s were based on analog
On October 12, 1983 the regional Bell operating
company began the first United States commercial
cellular service in Chicago.
Advanced Mobile Phone System (AMPS) is
one of the leading analog cellular systems in North
It uses FDMA to separate channels in a link.
AMPS was released in 1983 using the 800-MHz to
900-MHz frequency band
The System uses two separate analog channels
The band between 824 and 849 MHZ carries reverse
communication and the band between 869 and 894
MHZ carries forward communications
Total Access Communications Service
The original European 900 MHz analog system
launched in 1985 by Vodafone.
Still used in Austria, Bahrain, China, Japan etc
Uses a protocol known as Frequency Division
Multiple Access (FDMA).
Nordic mobile telephony (NMT)
It uses 450 and 900 MHz band.
Still used in parts of Europe and Asia, including
Algeria, Andorra, Bangladesh etc.
It was the first cellular system to be used
Problems in First Generation
As 1G was based on (FDMA) for transfer between
cells, it was very vague and had a low capacity.
It has a low degree of safety, Low security, easy to
Poor data communication.
Do you remember 1G phones?
Do you remember 1G phones?
CDMA (Code division multiple access)
TDMA (Time division multiple access)
History & Introduction of GSM
In 1982, the European Conference of Postal and
Telecommunications Administrations (CEPT)
created the GSM.
In 1989, GSM responsibility was transferred to the
European Telecommunications Standards Institute
The first GSM network was launched in 1991 in
Main features of GSM
Compatibility with other systems
Flexibility and Increased Capacity
Improved Security and privacy
Bearer or Data Services
Dual Personal and Business Numbers
Bearer Data Services
Short Message Service (SMS).
Text files and fax.
Call Hold etc
* Mobile to BTS (uplink): 890-915 MHz
* BTS to Mobile (downlink):935-960 MHz
* Mobile to BTS (uplink): 880~915MHz
* BTS to Mobile (downlink): 925~960MHz
EGSM GSM EGSM GSM
880 890 915 925 935
DCS (Digital Communication System) 1800
* Mobile to BTS (uplink): 1710-1785 MHz
* BTS to Mobile (downlink) 1805-1880 MHz
Base Station Receive Base Station Transmit
1710 1785 1805 1880MHz
GSM System Architecture Overview
(MS) Mobile Station
(BSS) Base Station Sub-system
(NSS) Network and Switching Sub-system
The GSM Mobile Station (MS)
Mobile Equipment (ME)
Subscriber Identity Module (SIM)
International Mobile Equipment Identifier (IMEI)
160 character long SMS
The IMEI may be used to block stolen equipment
Subscriber Identity Module (SIM)
International mobile subscriber identifier (IMSI)
Allows user to send and receive calls and receive
other subscribed services
SIM is Protected by 4-8 digit PIN
PUK – Personal/Pin Unlocking Key
Base Station Subsystem (BSS)
(BTS) Base Transceiver Station
(BSC) Base Station Controller
(XCDR) The Transcoder
Base Transceiver Station (BTS)
*Antennas and feeder cables
Signal Flow in BTS Rack
DTRU（0~2） DTRU（3~5） DTRU（6~8）
AEM AEM AEM
LAYER1 LAYER 2 LAYER3
Base Station Controller (BSC)
Main functions of BSC
* Allocates a channel for the duration of a call
* Handles call set up
* Maintains the call
* Monitoring quality
* It communicates with MSC ,BTS & NSS.
*Controls one or more BTSs
Network and Switching Sub-system
(MSC) Mobile Switching Center
(HLR) Home Location Register
(VLR) Visitor Location Register
(EIR) Equipment Identity Register
(AUC) Authentication Center
(GMSC) Gateway Mobile Switching Centre
(EC) Echo Canceller
Mobile Switching Center (MSC)
Heart of the network
Manages communication between GSM and other
Call setup function and basic switching
Billing information and collection
* Location Updating
Home Location Registers (HLR)
Permanent database about mobile users in a large
Database contains Subscriber ID
Current subscriber VLR
Visitor Location Registers (VLR)
Temporary database which updates whenever new
MS enters its area, by HLR database
Controls those mobiles roaming in its area
Reduces number of queries to HLR
Database contains Mobile Status
Location Area Identity(LAI)
Equipment Identity Register (EIR)
Database that is used to track handsets using the
IMEI (International Mobile Equipment Identity)
Made up of three sub-classes:
* White List
* Black List
* Gray List
Authentication Center (AUC)
Protects against intruders in air interface
Maintains authentication keys and algorithms and
Generally associated with HLR
Gateway Mobile Switching Centre
The GMSC is a device which routes traffic entering a
mobile network to the correct destination.
The GMSC accesses the network’s HLR to find the
location of the required mobile user.
A particular MSC can be assigned to act as a GMSC.
The operator may decide to assign more than one
The GMSC routes calls out of the network and is the
point of access for calls entering the network from
An echo canceller models the voice signal passing
As the voice passes back through the canceller it
applies signal to remove it dynamically.
The MSC/GMSC that originates a call generates a
record (Call Detail Record which contains:
> Subscriber identity
> Number called
> Call length
> Routing of the call
The record passes along the backbone to the home
Billing computer generates bills to be sent to the