Members of our Presentation (Bsts09-08) Hafiz Umer Ejaz (Bsts09-09) Rai-Habib Ullah (Bsts09-31)...

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

Presentation

Why do we need cellular phones?

We can freely move and in contact with people at anytime.

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 System

Third Generation-IMT-2000

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 communication.

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 America.

It uses FDMA to separate channels in a link.

BAND

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 commercially.

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 fake

Poor data communication.

Bulky equipment.,

Do you remember 1G phones?

Do you remember 1G phones?

Basic technologies

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 (ETSI).

The first GSM network was launched in 1991 in Finland.

Main features of GSM

Compatibility with other systems

Flexibility and Increased Capacity

Improved Security and privacy

ISDN Compatibility

GSM Services

Speech Services

Bearer or Data Services

Supplementary services

Speech Services

Telephony

Emergency Calls

Dual Personal and Business Numbers

Bearer Data Services

Short Message Service (SMS).

Text files and fax.

Voice mail.

Supplementary Services

Number Identification

Call Forwarding

Call Waiting

Call Hold etc

GSM Specifications

GSM 900* Mobile to BTS (uplink): 890-915 MHz* BTS to Mobile (downlink):935-960 MHz EGSM900* Mobile to BTS (uplink): 880~915MHz * BTS to Mobile (downlink): 925~960MHz

EGSM 

880 890 915 925 935 960 MHz

GSM EGSM GSM

GSM Specifications

DCS (Digital Communication System) 1800

* Mobile to BTS (uplink): 1710-1785 MHz * BTS to Mobile (downlink) 1805-1880 MHz

Base Station Receive 

1710 1785 1805 1880MHz

Base Station Transmit

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)

Mobile Equipment

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)

General Architecture

*Radio Transceivers*Combiner*Duplexer*Antennas and feeder cables

Rack Structure

Signal Flow in BTS Rack

CSBCMB

DTRU（0~2）

B8018机柜

DTRU（3~5） DTRU（6~8）

LAYER 1 LAYER 2 LAYER 3

AEM AEM AEM

天馈

BSCEIB

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

The Transcoder

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 CancellerBilling

Mobile Switching Center (MSC)

Heart of the networkManages communication between GSM and

other networksCall setup function and basic switchingCall routing Billing information and collectionMobility management* Location Updating

Home Location Registers (HLR)

Permanent database about mobile users in a large service area

Database contains Subscriber ID Current subscriber VLR Subscriber status Authentication key

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 StatusLocation 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 provides security.

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 GMSC.

The GMSC routes calls out of the network and is the point of access for calls entering the network from outside.

Echo Canceller

An echo canceller models the voice signal passing through it

As the voice passes back through the canceller it applies signal to remove it dynamically.

Billing

The MSC/GMSC that originates a call generates a record (Call Detail Record which contains:

> Subscriber identity> Number called> Call length> Routing of the callThe record passes along the backbone to the

home networkBilling computer generates bills to be sent to

the user.