Seminar on Gsm 34

8/8/2019 Seminar on Gsm 34

http://slidepdf.com/reader/full/seminar-on-gsm-34 1/39

Summer TrainingSummer TrainingononSummer TrainingSummer Trainingonon



History of BSNL Bharat sanchar Nigam Ltd. Formed in

Oct 2000 is World·s largest

Telecommunication Company providingcomprehensive range of telecomservices in India : Wire line ,GSM

mobile, Internet, Broadband etc.



WHAT IS GSM

GLOBAL SYSTEM OF MOBILE(GSM) IS A SECOND GENERATION

CELLULAR ST ANDAREDDEVELOPEDTO CATER VOICESERVICES AND DAT A DELIVERY

USING DIGIT A

L MODULA

TION



EVOLUTION OF GSM

ST ANDARDS 1980s - Advance mobile phone services (AMPS),

in America. Early 1980s -European nations were developing

cellular solutions, but no common standardavailable. 1982 ² CEPT(Conference of European Posts and

Telegraph) formed a study group called theGroupe Special Mobile (GSM).

1989 ² GSM responsibility transferred to ETSI(European Telecommunications StandardsInstitute).

Global System for Mobile Communication. 1990 ² Phase I of GSM Specifications published. Mid 1991 - Commercial services started . 1997 ² Commercial services available in 110



GSM RadFrequSpectrum



GSM 900GSM-900

Uplink band 890-915MHZ

Downlink band 935-960MHZ

Channelspacing 200KHZ

Total#channel 124

Duplex spacing 45MHZ

#time slot 8



GSM radio frequency

spectrum In the frequency range specifed for (gsm -

900) 124 frequency channel with abandwidth of 200khz are available for

both uplink and downlink direction. The uplink (mobile station to BTS) use the

frequencies between 890-915mhz anddownlink (BTS to mobile station ) use thefrequencies between 935-960mhz .Theduplex spacing , the spacing between theuplink and downlink channel , is 45 mhz



Techniques used in GSM In the GSM system , TDMA in combination with

FDMA is used; the usage of each radio channel ispartitioned into multiple (eight) timeslots , and

each user is assigned a specific frequency/timeslot combination . Thus , only a single mobileis using a given frequency/ timeslot combinationat any particular time .



Cellular concept Cells are in hexagonal in shape . Radio channels are

allocated to these smaller areas to minimize theinterference and provide adequate performance,cater to traffic loads in these areas . Each of theseareas is called cell. Group of cells is called clusters.

The reason of clustering is that adjacent cellscannot use the same frequency spectrum because ofinterference.

The interference due using the same frequencies incells of different clusters is referred as cochannelinterference. The cells that use the same set offrequencies or channels are called cochannelcells.The interference from different frequencieschannels used within cluster is called adjacentchannel interference

The cellular concept can increase the number ofcustomers that can be supported in avaliablefrequency spectrum.



Frequency reuse in Cellular Telephony

Same frequency reused in the network

7 cell

cluster



Frequency Reuse Channel reuse is implemented by using the same channels within

cell located at different positions in the cellular network servicearea. Cell clusttering radio channel can be reused provided theseparation between cell containg the same set . Cell using the sameset are called co-channel cells. Within a service area (PLMN),

specific channel sets are reused at different location (anothercell). For eg. There are 7 channel set A to G . Neighboring cells are not

allowed to use same frequencies. PLMN can divided into clusterof7 cell each . The number of channel set is k is called reuse factor .In fig k=7 the equation is

k=i2+j2+ij

- cell are shaped ideally hexagonals- The distance between cells using the same channel set is always

the same .



MS BSCBTS MSC

HLR

VLR

EIR

AUC

SMS

OMC

GSM SYSTEM ARCHITECTURE



Network Element

MSC- Mobile ² services Switching CenterIt perform the switching function for all mobile stations

located in the geographic area covered by its assignedBSSs.

It also interface with the public switched telephone network(PSTN) as well as with other MSCs and also with HLR . Acting as a gateway MSC to interrogate the HLR.

MS(Mobile station)-Mobile station is made of two entities-

1- ME (Mobile equipment)is a piece of hardware thatcustomer purchase from dealer.2- SIM(Subscriber identity module that is a smart card.



Mobile equipment(ME) Portable and hand held devices Uniquely identify by an

IMEI(International mobile equipmentidentity. Voice and data transmission



SIM(Subscriber Identity

Module) Smart card contain the international

mobile subscriber identity

module(IMSI) Allow user to send and receive callsand received other subscribedservices.

Protected by password or PIN.



BSS(Base StationSubsystem)

BSS is composed of two part thatcommunicate across the standardizedA

bis interface allowing operationbetween component made bydifferent suppliers

Base tranceiver station(BTS)

Base station controller(BSC)



BTS(Base Tranceiver

Station) BTS has a set of transceivers to communicate with mobiles

in its area. One BTS covers one or more than one cell The capacity of a cell depends upon number of tranceivers

in a cell. The BTS is connected to BSC through Abis interface . BTS transmit and receive voice at 13 kbps over air

interface to the mobile . BTS control the transmit power and commanding handovers

to the mobile stations.



BSC (Base Station

Controller ) Several BTS are connected to 1BSC. BSC connected to each BTS on an Abis

interface and to the MSC onA

interface . BSC control various functions of BTS andmobile ,like assigning a channel forcall,handover etc.



EIR(Equipment Identity

Register) EIR is the record of valid IMEIs. MSC ask mobile to send its IMEIs. MSC then checks the vailidity of IMEI with the EIR. All IMEI are store in EIR.

In the EIR , the IMEI are classified into three categories. White list:this contians the IMEI of type approved mobiles. Blacklist: list of IMEI which should barred because either

they are stolen are not functioning proprely. Greylist: list of IMEI who are to evaluated before they are

put in blacklist.



AUC(Authentication

centre ) Authentification is a process by which is

SIM is verified.

Secret data and the verification processalogorithm are stored atAUC.

AUC is associated with the HLR



HLR( Home Location

Register) HLR has all permanent subscriber

database. MSC communicates with HLR to get data

for subscribers on call .



VLR(Visting location

Register ) VLR has temporary data pertaining to

each subscriber .(TMSI) Temporary

mobile subscriber identity. Location area where the mobilestation is registered.

Copy of the subscriber data from theHLR



OMC(Operation &

Maintenance Centre) OMC is the centralized maintenance

and diagnostic heart of the BSS .

It allows the network provider tooperate , administer , and monitorthe functioning of the BSS.



SMSC(Short Messageservice Centre

Message is send to a particularmobile .

Message transfer takes placethrough SMSC.



Call Management

2.

. 3.

MS BSSMSC/VLR

RACH channel Request

SDCCH Assigh ACCH

Request for service SDCCH

Request for service

1.



quipment Va idation

IMEI request

4.

IMEI Answer

5.

6.

7.

MS MSC/VLRNEW

EIRBSS

IMEI Check

IMEI Check request



Call Set Up

Call set up request

10.

11.

12.

13.

MS BSSMSC/VLR

New

Call processing SDCCH

Assign trunk & radio

TCH assign

RR assigmentcompleted

RT assigncompleted

8.

9.



CALL SET UP

Network set up

MS BSSMSC/VLR New

PSTN

Network alertingAlerting(FACCH)

Connect billing start

connect

connect ack.

14.

15.

16.

17.

18.

19.



CALL SET UP

Release

Release complete

Clear

clear complete

MS BSS MSC/VLR New

PSTN

Disconnect

Network releaseStop billing

Channelrelease

20.

21.

22.

23.

24.

25.

26.



Location Updation



HANDOVER Between1&2interB

TS/intra BSC

Between 1&3interBSC/intraMSC

Between 1&4 inter

MSC



GSM services Tele-services

Bearer or data services

Supplementry services



Tele-services Telecommunication services that

enable voice communication via mobile

phone. Offered services

- Emergency call

- Short message services(SMS).



Bearer services

Include various data services for informationtransfer between GSM and other network likePSTN, ISDN etc at rate from 300to 9600 bps.

Short message services(SMS)- upto 160 charater alphanumeric data transmission

to/from the mobile terminal.- fax- Voice mail box- Electronic mail



Supplementry services Call related services:

Call waiting: Notification of incoming call while MS isengaged in an active.

Call hold: put a caller on hold to take another call.

Call forwarding : calls can be send to various numberdefined by the user.

Multi party call conferencing: link multiple calls together.



Characteristics of GSM

Standard Fully digital system using 900,1800 MHZ

frequency band.

Fully international roaming capability. Low service cost.

ISDN compatibility.

Support of short message services(SMS).

Good speech quality.



GSM Applications Mobile Telephony

Telemetry system

Automatic meter reading Toll collection



T HANKS!!!!!!!!!!!



Questions?

Seminar on Gsm 34

Documents

Transcript of Seminar on Gsm 34