British Computer Society Presents

Mobile Telecommunication

By Nadine Mouali

Technical PresentationMonday 17 June, 2002

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Mobile TelecomAgenda

1. Overview of Cellular Systems

2. The Handset

3. The SIM Card

4. The Radio Interface and Microwave Transmission

5. The GSM Network

•The Base Station Subsystem

•The Network Subsystem

6. The Value Added Services on GSM

•Voice Mail

•SMS

•Fax and data

7. Coverage and Infrastructure Management

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Mobile TelecomIntroduction

Radio = 170 years old

Sender

Means

Reception

MassMedia

GSM = 20 years old

Telephone = 110 years old

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Mobile TelecomOverview of Cellular Systems

GSM

Group Special Mobile

Global System for Mobile Communication

DCS

Digital Cellular System

PCS

Personal Communications Services

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Mobile TelecomWhat’s a Cell ?

This is a cell

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Mobile TelecomCell Coverage

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Mobile TelecomCell Coverage in Belgium

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Mobile Telecom

Rationalized architecture - Easily maintainable by IT with significant resource savings

Quantum

IMS

SAP

DBGIS

DB

DB

Data

Base

GIS on MapGuideServer

TeleAtlas

Mapmaking

Tool

Web server

GIS clients

via web browser

background

Predicted coverage

Site, links, faults

Shops and Dealers

Geographical Information System for Coverage Management

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Mobile Telecom

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Mobile TelecomThe handset

• Handset is a transmitter and receiver (2 watt)

• Most important is the IMEI

• IMEI = International Mobile Equipment Identity

• This is a unique number

• Is the passport for the handset on the networkYou also need :

• MSISDN number (e.g. 0496/45.85.22)

• IMSI

• SIM

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Mobile TelecomWhat is a SIM Card ?

Credit card model

Plug-in model

SIM = Subscriber Identity Module

It’s the hart of all mobile communicationIt’s your personal passport on the network

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Mobile TelecomWhat is on a SIM Card ?

• SIM Serial• IMSI• Security Files :

• Secret Key (PIN1, PIN2, PUK)Secret Key (PIN1, PIN2, PUK)• Encrypting Key (ki)Encrypting Key (ki)

• User Information ---->

• Configuration Data

• Network Information• Channel Info Channel Info • Preferred NetworkPreferred Network• Location DataLocation Data• Prohibited NetworksProhibited Networks

• ADM = phonebook memory• 100 numbers of 14 digits100 numbers of 14 digits• 12 alphatags12 alphatags

• FDN = fixed phonebook memory• 20 numbers of 14 digits20 numbers of 14 digits• 12 alphatags12 alphatags

• SMS = short messages• 10 messages of 160 characters10 messages of 160 characters

• MSISDN = Mobile Subscription Integrated Service Digital Network

• 4 numbers of 12 digits ( memory help )4 numbers of 12 digits ( memory help )• they are your own mobile numbers ( voice, they are your own mobile numbers ( voice,

data, fax and 2nd line )data, fax and 2nd line )• SMSC = short messages service centre

number• +32486000005+32486000005

• SDN * = Service Dailling Numbers• 10 numbers of 14 digits10 numbers of 14 digits• 12 Alphatags ( fixed on the memory of the 12 Alphatags ( fixed on the memory of the

cardcard )

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Mobile TelecomWhat is a SIM Toolkit ?

• All GSM Services Can be updated or modified by OTA ( Over The Air programming. For this purpose, a SIM toolkit is provided in the Subscriber Identification Module.

• Simtoolkit is an application that is stored on your Simcard and offers you a 2-way communication between the network and the SIM

• It appears as an extra menu in the phone and offers intelligent value added services to the customer

• Examples:• Ordering pizza• Ordering a taxi• Paying your bills• etc...

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Mobile TelecomRadio Transmission

Radio Link

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Mobile Telecom

3 4 5 6 7 0 1 3 4 5 6 7 0 1

7 0 1 3 4 5 6 7 0 1 3 4 5 6 7

MS RX

MS TX

Monitoring

Operation of a mobile station in active speech or data communication using a single time slot.

The TDMA Frame

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Mobile Telecom

uplin

k

• From mobile phone to base station• Frequency 1710 MHz. / 1785 MHz.• Used for transmitting (Tx channel)• 374 up link-channels

The Radio Up Link

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Mobile Telecom

• From the base station to mobile phone• Frequency 1805 MHz / 1880 MHz• Used for receiving (Rx channel)• 374 down link-channels

downlin

k

The Radio Down Link

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Mobile TelecomRadio Transmission

Interfering Factors in Radio Link

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TREES

Radio Interference

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BUILDINGS

Radio Interference

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BUILDINGSInterference through reflection

Radio Interference

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WEATHER

Radio Interference

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Mobile Telecom

paper leadbrick

Radio Transmission Permeability

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Mobile TelecomMicrowave Transmission

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Mobile TelecomMicrowave transmission

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Mobile Telecom

5-10 km

Microwave transmission within a cell

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Mobile Telecom

Better coverage

here

Thanhere

BTS Site

Antennas (the BTS Sites) are on roofs of buildings or at elevated positions. It stands to reason that you will get better coverage, the higher up in the building you are.

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Mobile Telecom

Mobile Station

Base StationSub System

Network Switching Sub System

Public SwitchedTelephone Network

Operating Sub System

Basic Schedule of the GSM Network

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Mobile Telecom

Base StationController (BSC)

Star configuration

BS

BS BS

BS

The Base Station Sub System Configuration

BS

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Mobile Telecom

BSC

Closed loop

BS

BS

BS

BS

Daisy Chain Configuration

The Base Station Sub System Configuration

BS

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Mobile Telecom

Photo of base station high in the sky + microwave (source GIS)

Example of base station (microwave transmitter)

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Mobile Telecom

Motorway

Example of Base Station

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Mobile Telecom

Church

Example of Base Station

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Mobile Telecom

Rooftop ofBuilding

Example of Base Station

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Mobile Telecom

Top of lamppost

Example of Base Station

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Mobile Telecom

Base Station (BTS)

Base Station (BTS)

Base StationController (BSC)

Network Switching Sub System

(NSS)

Manhattan centre

The Functionality of a Base Station Sub System

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Mobile Telecom

BSC

BSC

BSC

BSC

BSC BSC

Base Subsystems and Network Subsystems

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Mobile Telecom

BSC

BSC

BSC

BSC

BSC BSC

MSC

Network Subsystems - The Switch

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Mobile TelecomBase Subsystems and Network Subsystems

Other telephone networks

Exchange

Base station

Base station

Telephone

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Mobile Telecom

Network Switching Sub System

Home LocationRegister (HLR)

Visitor LocationRegister (VLR)

Equipment IdentityRegister (EIR)

AuthenticationCentre

Echo Canceller

BTS

Public Switched Telephone Network

(PSTN)

Mobile SwitchingCenter (MSC)(controls HLR,VLRand EIR)

The Network Switching Sub System

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Mobile Telecom

PSTN

GATEWAYMSC

hlr vlr

Network Switching Sub System(NSS)

BSC

BTS

MSC

MS

A Call From a PSTN Phone to a Mobile Phone

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Mobile Telecom

MSCHLR

Network Switching Sub System (NSS)

VLR

MSC

BSC

RBS

RBS

MS

MS

A Call From Mobile to Mobile

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Mobile TelecomValue Added Services on the GSM network

• Voice Processing System (VPS)

• Short Message Service Centre (SMSC)

• Data and Fax facilities

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Mobile TelecomValue Added Services on the GSM network

Fax and Data Facilities :

• Separate Data and Fax number needed• PCMCIA card• Laptop and communication software

Advantages of FAX and Data on ISDN

• Digital system, does not recognize difference between speech, fax or data

• Standard sends on all 3 a speech signal

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Mobile Telecom

Examples of PCMCIA Cards :

Value Added Services on the GSM network

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Mobile TelecomSummary

1. Overview of Cellular Systems

2. The Handset

3. The SIM Card

4. The Radio Interface and Microwave Transmission

5. The GSM Network

•The Base Station Subsystem

•The Network Subsystem

6. The Value Added Services on GSM

•Voice Mail

•SMS

•Fax and data

7. Coverage and Infrastructure Management