wireless rollno-13 amit kumar 10803058

8/7/2019 wireless rollno-13 amit kumar 10803058

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Need to be wireless.where wire-line

is limitedHuman Connectivity ?

Remote control of instruments

Defense Forces


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Emergency

Rural


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Always Connected

Anytime, Anywhere, Anything


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Recent and Future Wireless Communications

SystemsRecent Systems


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What is GSM ?

Global System for Mobile (GSM) is a

second generation cellular standard

developed to cater voice services and

data delivery using digital modulation


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GSM: History

Developed by Group Spciale Mobile (founded 1982) which wasaninitiativeof CEPT ( Conferenceof European Postand

Telecommunication )

Aim : toreplacetheincompatibleanalogsystem

PresentlytheresponsibilityofGSMstandardizationresides with special

mobilegroupunderETSI ( Europeantelecommunication StandardsInstitute )

Fullsetofspecificationsphase-I becameavailablein 1990

UnderETSI, GSMisnamedas GlobalSystem forMobile

communication Todaymanyprovidersalloverthe worlduseGSM (morethan 135

countriesin Asia, Africa, Europe, Australia, America)

Morethan 1300 millionsubscribersin worldand 45 millionsubscriberin

India.


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GSM System Architecture

BSC

BSC

MSC

MS

MS

MS BTS

BTS

BTS

GMSC

PSTN

ISDNPDN

EIR

AUC

HLR

VLR


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GSM System Architecture-I

Mobile Station (MS)

Mobile Equipment (ME)

Subscriber Identity Module (SIM)

Base Station Subsystem (BSS)

Base Transceiver Station (BTS)

Base Station Controller (BSC)

Network Switching Subsystem(NSS)

Mobile Switching Center (MSC)

Home Location Register (HLR)

Visitor Location Register (VLR)

Authentication Center (AUC)

Equipment Identity Register (EIR)


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System Architecture

Mobile Station (MS)

Mobile Equipment

Portable, vehicle mounted, hand held device

Uniquely identified by an IMEI (International MobileEquipment Identity)

Voice and data transmission

Monitoring power and signal quality of surrounding cellsfor optimum handover

Power level : 0.8W 20 W

160 character long SMS.


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System Architecture

Mobile Station (MS) contd.

Subscriber Identity Module (SIM)

Smart card contains the International Mobile Subscriber

Identity (IM

SI

) Allows user to send and receive calls and receive other

subscribed services

Encoded network identification details

- Key Ki,Kc and A3,A5 and A8 algorithms

Protected by a password or PIN

Can be moved from phone to phone contains keyinformation to activate the phone


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System Architecture


Base Station Subsystem is composed of two parts that

communicate across the standardized Abis interface allowing

operation between components made by different suppliers

1. Base Transceiver Station (BTS)

2. Base Station Controller (BSC)


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System Architecture


Base Transceiver Station (BTS):

Encodes,encrypts,multiplexes,modulates and feeds the

RF signals to the antenna.

Communicates with Mobile station and BSC Consists ofTransceivers (TRX) units


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System Architecture


Base Station Controller (BSC)

Manages Radio resources for BTS Assigns Frequency and time slots for all MSs in its area Handles call set up Transcoding and rate adaptation functionality Handover for each MS Radio Power control

It communicates with MSC and BTS


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System Architecture

Network Switching Subsystem(NSS)

Mobile Switching Center (MSC)

Heart of the network

Manages communication between GSM and other networks Call setup function and basic switching

Call routing

Billing information and collection

Mobility management

- Registration

- Location Updating

- Inter BSS and inter MSC call handoff

MSC does gateway function while its customer roams to othernetwork by using HLR/VLR.


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System Architecture

Network Switching Subsystem

Home Location Registers (HLR)

- permanent database about mobile subscribers in a large servicearea(generally one per GSM network operator)

- database contains IMSI,MSISDN,prepaid/postpaid,roamingrestrictions,supplementary services.

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 ofqueries to HLR

- Database contains IMSI,TMSI,MSISDN,MSRN,LocationArea,authentication key


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System Architecture

Network Switching Subsystem

Authentication Center (AUC)- Protects against intruders in air interface

- Maintains authentication keys and algorithms and providessecurity triplets ( RAND,SRES,Kc)

- Generally associated with HLR

Equipment Identity Register (EIR)- Database that is used to track handsets using the IMEI

(International Mobile Equipment Identity)

- Made up of three sub-classes: The White List, The BlackList and the Gray List

- Only one EIR per PLMN


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Call Routing

Mobile startup

Call Originating from MS

Call termination to MS


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GSM uses paired radio channels

0 124 0 124

890MHz 915MHz 935MHz 960MHz


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CELLULAR PHONE SWITCHED ON

It first scans the group of forward controlchannels, to determine the one with thestrongest signal and than monitors the control

channel until the signal drops below a efficientlevel.

In this case it again scan for control channelwith strong base station signal

5% are control channels and rest 95% are forvoice and data channels.


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INCOMINGCALL

MSC dispatches the request to all base stations in the cellularsystem.

MIN(subscribers telephone number),is broadcasted as apaging message over all forward control channels.

The mobile receives the paging message and responds byidentifying itself over the reverse control channel.

The base station relays the acknowledgement sent by mobile

and informs MSC of handshake. MSC instructs the Base Station to move the call in unused

voice channel within the cell.

Base Station signals the mobile to change frequency tounused forward and reverse voice channels


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At this point another data message(alert) is

transmitted over the forward voice channel to

instruct the mobile telephone to ring.


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OUTGOING CALL

A call initiation request is sent on the reverse

control channel.

This includes MIN,ESN,and the telephone no.of the called party

Also includes SCM(Station Class

Mark),maximum transmitter power level of

the user.

BTS forward the request to MSC.


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Handoff Strategies

When a mobile moves into a different cell while a

conversation is in

progress, the MSC automatically transfers the call to a

new channel

belonging to the new base station.

Handoff operation

identifying a new base station

re-allocating the voice and control channels with the

new base station.


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MSC validates the request, make connection

to the called party through PSTN.

Instructs the BTS and mobile user to move toan unused forward and reverse voice channel

to begin conversation.

Case for roamers(FCC renewed for

unregistered ,HLR-billing status, VLR)


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Sectoring

Decrease the co-channel

interference and keep the cell

radius R

unchanged

Replacing single omni-

directional antenna by several

directional antennas Radiating within a specified

sector


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An illustration of a cellular system.

The Towers represents the Base Stations which

provides the radio access between mobile users

and the Mobile Switching Center(MSC)


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The Cellular Concept


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Frequency Reuse


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Future OfGSM

2ndGeneration

GSM -9.6 Kbps (data rate)

2.5Generation ( Future ofGSM)

HSCSD (High Speed ckt Switched data)Data rate : 76.8 Kbps (9.6 x 8 kbps)

GPRS (General Packet Radio service)

Data rate: 14.4 - 115.2 Kbps

EDGE (Enhanced data rate for GSM Evolution)

Data rate: 547.2 Kbps (max)

3 Generation

WCDMA(Wide band CDMA)

Data rate : 0.348 2.0 Mbps


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Documents

wireless rollno-13 amit kumar 10803058