ZAC Technical Institute GSM Foundation Course Prepared by Syed Amir Abbas.

ZAC Technical Institute

GSM Foundation Course

Prepared by

Syed Amir Abbas


GSM Operator in Pakistan


14%

CDMA One

TDMA11%

GSM and Others

75%

GSM

Source: European Mobile Communications(EMC)


Vendor’s Of Operators

Core (MSC/BSC) RAN (BTS)

Mobilink Alcatel/Huawei/Siemens/Nokia Motrola/Alcatel Ufone Huawei/Nortel Huawei / Nortel

Telenore Siemens/Nokia Siemens / Nokia

Warid Ericsson Ericsson / Huawei Zong ZTE/Huawei

Ericsson/ZTE/Alcatel


Subscriber Data Base

Mobilink 31,958,597 Telenore 17,841,074 Ufone 17,800,424 Warid 15,114,678 Zong 3,662,099

Information received from PTA site survey on May 2008 (www.pta.com)


What is Telecommunication ? Telecommunication means to change

information into electronic signals for remote transmission and switching.

Fast Deployment

Saving Transmission cost.

Easy and Fast Access.


Frequency

“ The frequency of a radio wave is the number of times that the wave oscillates per second."

FM Radio : 100 MHz Approx. Television : 300 MHz Approx. Mobile Networks : 300 – 2000 MHz Approx.


Bandwidth In electronic communication, bandwidth is the

width of the range (or band) of frequencies that an electronic signal uses on a given transmission medium.

In this usage, bandwidth is expressed in terms of the difference between the highest-frequency signal component and the lowest-frequency signal component.

Bandwidth = Highest freq – Lowest Freq


Channels A Channel is a frequency or set of frequency which can be

allocated for the transmission and reception of information. Types Of Communication Channels.


What is Multiple Access

Simultaneous private use of a transmission medium by multiple independent users is called Multiple Access.

Advantages Of Multiple Access

• Increased capacity• Reduced capital requirement• Decreased per user expense


FDMA, TDMA & CDMA FDMA (Frequency Division Multiple Access) Each user on a different frequency A channel is a frequency TDMA (Time Division Multiple Access) Each user on a different window period in time slot. CDMA (Code Division Multiple Access) Each user uses the same frequency all the time but

mixed with different distinguished code patterns.


1st Generation Cellular System Widespread introduction in early 1980s.

Analogue modulation.

Frequency division multiple access.

Voice traffic only.

No inter-network roaming possible.

Insecure air interface.

Examples :

AMPS (Advance mobile Phone System, American based,800MHz)

TACS (Total Access Communications System, UK based,900MHz)

C-450 (German standard, 450MHz)

JTACS (Japanese Total Access Communications System,900MHz).


2nd Generation Cellular System Widespread introduction in 1990s.

Use digital modulation.

Variety of multiple access strategies.

More efficient use of radio spectrum.

International roaming capability.

Secure air interface.

Compatibility with ISDN.


GSM Architecture Overview A GSM system is made up of three subsystems:

The mobile station (MS) The Base station subsystem (BSS) The Network and switching subsystem (NSS)

The interfaces defined between each of these sub systems include:

“A” interface between NSS and BSS “Abis” interface between BSC and BTS (Within the BSS) “Um” air interface between the BSS and the MS


Abis Interface

Interface


GSM Frequency Concepts


GSM Call GSM Call SetupSetup


MS Mobile Station = phone + SIM card

BTS Base Transceiver Station BSC Base Station Controller HLR Home Location Register MSC Mobile services Switching

Centre VLR Visitor Location Register AUC Authentication Centre

Stand-alone or integrated in HLR

EIR Equipment Identity RegisterFor blacklisting stolen and

unwanted equipment SMSC Short Message Service

”Support” Centre VMS Voice Messaging System PrePaid Node Hosting prepaid service

system IN Intelligent Network services PSTN Public Switched Telephone

Network PABX Private Automatic Branch

Exchange

MSC/VLRWarid

Telenore

BSC

SMSC

EIR

INTERNET

MobilinkPSTN

BSC

PrePaidNode

VMS

HLR

MSCw

AUC


MSC SMSC

EIR

INTERNET

PABXPSTNInternational

PSTNFixed Network

BSC

IN

PrePaid

VMSVoicemail

HLR

MSC BSC


MSC SMSC

EIR

INTERNET

BSC

IN

PrePaid

VMSVoicemail

HLR

MSC BSC


PSTNFixed Network


BSCBSC

Base Station ControllerBase Station Controller

The call request reaches the BSC from the The call request reaches the BSC from the BTS and is forwarded to MSC.BTS and is forwarded to MSC.

After call is established, the BSC will perform After call is established, the BSC will perform decodingdecoding of the call (in typical config.) of the call (in typical config.)


BSC HLR

MSC SMSC

EIR

INTERNETIN

PrePaid

VMSVoicemail

MSC BSC


PSTNFixed Network


Checks A number.Checks A number. To whom is A subscriber calling?To whom is A subscriber calling?

(Checks B number)(Checks B number) Example : A subscriberExample : A subscriber has has

prepaid number.prepaid number.

MSC MSC

Mobile Switching CentreMobile Switching Centre


BSC HLR

MSC SMSC

EIR

INTERNETIN

PrePaid

VMSVoicemail

MSC BSC


PSTNFixed Network


BSC HLR

MSC SMSC

EIR

INTERNETIN

PrePaidPrePaid

VMSVoicemail

MSC BSC


PSTNFixed Network


Does the A subscriber have Does the A subscriber have money left on his/her account?money left on his/her account?

When the call is established When the call is established and on-going the subscriber’s and on-going the subscriber’s account is decremented account is decremented accordingly.accordingly.

PrePaid NodePrePaid Node


BSCHLR

MSC SMSC

EIR

INTERNETIN

PrePaid

VMSVoicemail

MSC BSC


PSTNFixed Network


BSCHLR

MSCMSC SMSC

EIR

INTERNETIN

PrePaid

VMSVoicemail

MSC BSC


PSTNFixed Network


Where is the B subscriber?Where is the B subscriber? MSC interrogates in HLR.MSC interrogates in HLR.

(HLR = Home Location (HLR = Home Location Register)Register)

MSCMSC Mobile Switching CentreMobile Switching Centre


BSCHLR

MSCMSC

IN

PrePaid

VMSVoicemail

MSC BSC


PSTNFixed Network

SMSC

EIR

INTERNET


BSCHLR

MSCMSC

MSC BSC


PSTNFixed Network

IN

PrePaid

VMSVoicemail

SMSC

EIR

INTERNET