Introduction to RF

8/10/2019 Introduction to RF

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GSM Introduction and Overview to

Architecture

Presented by

Syed Intisar Haider

Compiled By: Syed Intisar Haider


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What is covered in this Presentation

Introduction to GSM

Channels on the Air Interface

Architecture of GSM

Some Basic call procedures


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Introduction to GSM

Section 1



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Before GSM: Mobile Telephony Milestones

Electric transmission(Graham Bell)

1st wirelesstransmissions

(Marconi)

1st analog cellularnetwork

1 0 1 0 1 0 1 0

Digital Technology

(1st digital switch)

1st public mobiletelephone

1st GSM communication(digital cellular network)

1 0 1 0 1 0 1 0



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1981 NMTThe Nordic Solution

Now 18 Millions Subscribers

450 MHz and 900 MHz

NORWAY, DENMARKFINLAND, SWEDEN,FRANCE (450 MHz)

1985 TACS in UK800 and 900 MHz

1979 AMPS800 MHz

Now 25 MillionsSubscribers

1985RADIOCOM 2000

FRANCE400 MHz900 MHz

Dedicated developments

Japan NTT cellular (1979) JTACS (1988)

1986C.450

GERMANY450 MHz

Analog Cellular Systems Around the World


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What is GSM

GSM stands for Global System For Mobile

Communication

It has been agreed upon and formulated by

European Telecommunication Standard Institute(ETSI).

Within ETSI ,special Workgroups called SMG are

responsible for maintaining this standard.



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Digital Advantages

Worldwide market

Open system

Technology low cost

High resistance

to interferences

Transmission data rate

Roaming

$

Transmission Security

Advantages of the GSM standard

GSM Benefits



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Architecture

Section 2


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Architecture of GSM

GSM/DCS system consists of 3 sub-sytems

1.Switching Subsystem

2.Radio Subsystem

3.Operation and Maintenance Subsystem.


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BSC MSC

BTS

OMC-R OMC-S

MS

BSS NSS

OSS

PSTN

Network Over view

BSS A hi


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TCU

BSCOMC-R

MSC RadioInterfaceA Interface

Ater Interface

Abis Interface

NSS

BSS

OMN Interface

Public Telephone Network

MS

MS

BTS

Sun

StorEdgeA5000

RadioInterface

BSS Architecture


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Traffic

Speech

Data Short messages

Transmission

Reception

A MESSAGES ISPENDING. PLEASECONTACT NBR452 587 65

Features at the radio interface

Signal processing

Coding Ciphering

D1

D2

D3

D4

D5

D6

D7

D8

D1

D2

D3

D4

D5

D6

D7

D8

Demodulation

1 2 3 4 5 6 7 8

Interleaving

Modulation

Coupling system

Frequencyhopping

PowerControl

Handover

L1M (Call sustaining)

Call clearing

GMSK

Q+ 90 10 - 90

I

002

104

017

113

002

104

017

113

Measurementpreprocessing

Capabilities of a BTS

BSC F ti


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RadioResources

Management

Routing

Radio Call Processing

MSC BTS

BTS

BTS

BTS

BSC Functions 1 - Basic Functions

Traffic Concentration


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Airinterface

Abisinterface

STARConnection

CHAINConnection

LOOPConnection

(single multi-drop)

MS (full multi-drop)

BSC

BTS Connection Modes

NSS A hit t


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NSS Architecture

MSC

MSC

BSC

BSC

AuC EIR

VLR HLR

PSTN


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Switching Subsystem

Also called Network Subsystem also referred asCORE

Responsible for end to end switching operation

between subscriber that might be of samePLMN,other PLMN or PSTN.

Modular Architecture


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Switching Subsystem Continued

Major Components

MSC-It acts like a normal switching node of the

PSTN or ISDN, and in addition provides all the

functionality needed to handle a mobilesubscriber, such as registration, authentication,

location updating, handovers, and call routing to a

roaming subscriber


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HLR: The HLR contains all the administrative informationof each subscriber registered in the corresponding GSM

network, along with the current location of the mobile.

VLR: Visitor Location Register contains selected

administrative information from the HLR, necessary forcall control and provision of the subscribed services, for

each mobile currently located in the geographical area

controlled by the VLR


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EIR: The Equipment Identity Register (EIR) is a databasethat contains a list of all valid mobile equipment on thenetwork, where each mobile station is identified by itsInternational Mobile Equipment Identity (IMEI)

AC: Authentication Centre provides information regarding

registration of a SIM card to a proper PLMN.Authentication Center is a protected database that storesa copy of the secret key stored in each subscriber's SIMcard, which is used for authentication and ciphering ofthe radio channel



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g y IN: IN stand for Intelligent network, An Intelligent Network (IN) is a technology that allows

network operators to provide unique services to their subscriber base. It is intended for fixedas well as mobile telecom networks. It allows operators to differentiate themselves byproviding value-added services in addition to the standard telecom services such as PSTN,ISDN and GSM services on mobile phones.

Televoting Call screening

Telephone number portability

Toll free calls / Free phone

Prepaid calling

Account card calling Virtual private networks (e.g. : Family group calling)

Centrex service (Virtual PBX)

Mass-calling service

Reverse charging

Home Area Discount

Premium Rate calls

Call distribution based on various criteria associated with the call

Location Based Routing

Time based routing

Call transfer



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A Signal Transfer Point(STP) is a router that relays SS7 messages between signalingend-points(SEPs) and other signaling transfer points (STPs).

Typical SEPs include service switching points(SSPs) - MSC and service control points

(SCPs) -IN.


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Core Architecture in Modern GSM networks


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Core Architecture in Modern GSM networks


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Basic Call Flows

Section 3


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GSM Basic Call Flows

MOC (Mobile to Landline)

Authentication


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Bibliography / References:

Introduction to GSM by Nortel

CP02 By Motorola

Celebrating 20 Years of GSM by NSN

Wikipedia

Documents

Introduction to RF