INTRODUCTION TO MOBILE COMMUNICATION

FDMA•Frequency Division Multiple Access•The frequency spectrum is divided into different frequency bands.•No precise coordination in time domain is necessary in FDMA system.•Used in GSM. k2 k3 k4 k5 k6k1

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TDMA• Time Division Multiple Access•Each channel is divided into timeslots, each conversation uses one timeslot.•Many conversations are multiplexed into a single channel. •Used in GSM

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Frequency Division Multiple Access

oWhen the subscriber enters another cell a unique frequency is assigned to him; used in analog systems.

Time Division Multiple Access

oEach subscriber is assigned a time slot to send/receive a data burst; is used in digital systems.

Code Division Multiple Access

oEach subscriber is assigned a code which is used to multiply the signal sent or received by the subscriber.

GSM

•Global System For Mobile Communication •GSM uses FDMA & TDMA technology.•GSM operate in frequency bands: 900MHz, 1800 MHz, 1900 MHz.•In INDIA we use GSM 900 and GSM 1800,GSM 1900 is used in America.

•GSM provides voice and data services.

• In GSM 900 and GSM 1800,the frequency ranges are divided into carrier frequencies spaced at 200kHz.

• In GSM 900 the duplex frequency is 25 MHz.• In GSM 1800 it is 75 MHz.• The total number of carriers in GSM 900 is 125,

whereas in GSM 1800 , the number of carriers is 375.

• The lowest and highest channels are not used to avoid interference(guard band).

• For Vodafone, the duplex freq. is divided into 22 channels i.e. ARFCN(Absolute Radio Frequency Channel Number) are sub-divided into 8 time subslot.

GSM uplink/downlink frequency bands used

GSM Frequency band

Uplink/BTS Transmit

Downlink/BTS Receive

900 MHz 935-960 MHz 890-915 MHz

1800 MHz 1805-1880 MHz 1710-1785 MHz

1900 MHz 1930-1990 MHz 1850-1910 MHz

Downlink

Uplink

• Uplink frequencyo It refers to a signal flow from Mobile Station (MS)

to Base Transceiver Station (BTS).

• Downlink frequencyo It refers to a signal flow from Base Transceiver

Station (BTS) to Mobile Station(MS).

• Duplex Frequencyo The radio carrier frequencies arranged in pairs

and it is the difference between these two frequencies.

• The simultaneous use of separate uplink and downlink frequencies enables transmission and receiving of signals.

GSM ARCHITECTURE

• A GSM network comprises of several elements.• Mobile Station• BTS(Base Transceiver Station)• BSC(Base Station Controller)• MSC(Mobile Services Switching Centre)• HLR(Home Location Register)• AUC(Authentication Centre)• VLR(Visitor Location Register)• GGSN(Gateway GPRS Support Node)• SGSN(Serving GPRS Support Node) • All these elements constitute a PLMN(Public Land

Mobile Network)

MOBILE STATION

•It is the combination of ME(Mobile Equipment) and SIM(Subscriber Identity Module)•ME is available in various styles and power.•SIM is a small chip,which contains the subscriber information.

G S M

Global GSM MobilityCardThe Smart Card to use

SIM Card BatteryHandset

Mobile Station

=

= =

SIM

•SUBSCRIBER IDENTITY MODULE•SIM cards are embedded with a microprocessor.•Stores customer identity information and is made to fit inside the cellular phone.• In addition, the SIM card contains tools needed for

authentication and coding and, depending on the type of the card, there is also storage space for messages such as phone numbers, etc.

• Memory capacity:- 1K, 3K, 8K, 16K,32K,64K

• GSM IDENTITIES

• GSM specifies few identities for its network and the network functions are based on these identities.

• GSM specifies 3 types of identities :-1-Subscriber Related2-Equipment Related3-Location Related

• Subscriber Related identities

o Mobile Station ISDN Number(MSISDN)

MSISDN=CC+NDC+SN CC=Country Code(+91) NDC=National Destination Code(9776/9583/7873 ) SN=Subscriber Number(018180)

The maximun length of MSISDN is of 15 digit.

o International Mobile Subscriber Identity(IMSI)

IMSI=MCC+MNC+MSINMCC=Mobile country code(405)MNC=Mobile Network Code(753)MSIN=Mobile Subscriber Identification Number(9 to 10 digit) All Network Related sub. Info is connected to the IMSI,Which is stored in SIM as well as in the HLR & in the serving VLR.

o Temporary Mobile Subscriber Identity(TMSI)

It is a temporary IMSI number allocated to an MS at registration.

Is used to protect the subscriber identity on air interface,by not disclosing the IMSI to unauthorized individuals.

TMSI is half the length(max 8 digit) of the IMSI,thus allowing twice as many MS’s to be paged in the same paging message.

o International Mobile Equipment Identity(IMEI)

• IMEI = TAC + FAC + SNR + Spare• TAC = Type Approval Code(6 digit)• FAC = Final Assembly Code(2 digit)• SNR = Serial Number(6 digit)• Spare = A spare bit for future use

o LOCATION RELATED IDENTITY

Mobile Station Roaming Number(MSRN)

MSRN=CC+NDC+SN CC=Country CodeNDC=National Destination Code(9776/9583/7873)SN=Subscriber Number(018380)

The mobile station roaming number(MSRN) is a temporary network identity which is assigned during the mobile terminating call.

oLocation Area Identity(LAI)

• The Location Area Identity(LAI) is a temporary network identity,which is also required for routing.

• The two main purposes of LAI are :oPaging , which is used to inform the MSC

of the LA in which the MS is currently situated.

oLocation updating of mobile subscribers. • The LAI contains the following:

oMCC(3 digits)oMNC(2-3 digits)oLAC(max 16bits)

• Base Station Identity Code(BSIC)• The Base Station Identity(BSIC) enables MS’s

to distinguish between different base stations sending on the same frequency.

• The BSIC consists of:oNCCoBCC

• NCC Network color code(3 bits) identifies the PLMN.It does not uniquely identify the operator.NCC is primarily used to distinguish between operators on each side of a border.

• BCC Base Station Color Code(3 bits) identifies the Base Station to help distinguish between BTS using the same control frequencies.

• Location Number(LN)

•The Location Number (LN) is a number related to a certain geographical area , which the network operator specifies by “tying” the location numbers to cells, location areas,or MSC/VLR service areas.The LN is used to implement features like regional/local subscription and geographical differentiated charging.•The LN consists of the following :

oCC(Country Code)oNDC(National Destination Code)oLSP(Locally Significant part)

GMSCPSTN

MSC

HLR

VLR

MSISDN

MSRNMSISDN

1

2

5

3

IMSI

4

MSR

N

6

BTS• Base Transceiver Station.• Responsible for communication to and from MS via

air interface.• BTS comprises radio transmission and reception

devices.• Including the antennae and signaling processing

specific to the radio interface.• BTS separates the speech and control signaling

associated with a MS and sends them to the BSC on separate channels.

• Vodafone uses two types of NOKIA BTS:--1.Ultra BTS2.Flexi BTS

ULTRA BTS FLEXI BTS

• Ultra BTS can support max. of 12 TRx (transcievers)

•Flexi BTS can support max. of 24 TRx.

•Ultra has drawback that it has all Pin connections on back side, if any of the Pin of a particular slot is damaged then that slot is useless

•Flexi BTS all connections are on front side so it is easy to install every equipment.

•Use to cover less area. •Use to cover maximum area.

BTS Structure:-• Transceiver (TRX):- It basically does transmission and

reception of signals. It also does sending and reception of signals to and from higher network entities (like the BSC in mobile telephony).

• Power amplifier (PA):-Amplifies the signal from TRX for transmission through antenna; may be integrated with TRX.

• Duplexer:-For separating sending and receiving signals to/from antenna. Does sending and receiving signals through the same antenna ports (cables to antenna).

• Antenna:-This is the structure that lies underneath the BTS; it can be installed as it is or disguised in some way (concealed cell sites).

•Tranceiver Baseband unit(BB2A ): This unit is a digital signal processing board, consisting of two independent baseband units, functioning independently. It performs digital signal processing for speech and data channels. It uses software downloaded from the Base Operations and Interfaces (BOIx) unit sets its timing according to refer.•Base Operations & Interface unit(BOIx):This unit handles all the operations that are carried out in a BTS.The various functions of BOIx include:--

BTS initialization and self-testing

Configuration

O&M signaling

Software download

Main clock functions

Timing functions

Collection and management of external and internal alarms

Message delivery to the BSC (through the VXxx unit)

Cabinet control

• Combiner:-It Combines feeds from several TRXs so that they could be sent out through a single antenna. Allows for a reduction in the number of antenna used.

UNITS INSIDE A BTSUNITS INSIDE A BTS

POWER SUPPLY UNIT(PWSB)

BASE OPERATION & INTERFACES UNIT(BOIx)

TRANSCEIVER BASEBAND UNIT(BB2x)

TRANSMISSION UNIT(VXxx)

2-WAY RECEIVER MULTICOUPLER UNIT(M2xx)

COMBINER UNIT(WCxx)

TRANSCEIVER UNIT(TSXx)

DUPLEXER UNIT(DVxx)

STRUCTURE OF BTS TOWER STRUCTURE OF BTS TOWER

Base Station Controller (BSC)

• Monitor and Control several base stations• Frequency administration, control of

BTSs, exchange functions.• Channel allocation and release, handover

management.• BSC is the interface between MSC and

BTS• BSC is connected on one side to several

BTSs and on the other side to the MSC.

Mobile service SwitchingCenter (MSC)

•Responsible for all switching functions related to call processing•Coordinate the setting up of calls to and from GSM users.•MSC is the interface between GSM network & PSTN (Public Switched Telephone Network)

Gateway MSC (G-MSC)

•The MSC with an interface to other networks is called GMSC. •Network operator may equip all there MSCs with gateway function or only few. •MSC that don’t have gateway function has to route call from GMSC. •GMSC has some additional tasks like call from outer network enters in GMSC which queries HLR then forwarded the call to MSC where the called party is located.

Home Location Register (HLR)

• A database in charge of the management of mobile subscribers.

• Contains information of network subscribers• Information on teleservices and bearer

services subscription, service restrictions, and supplementary services.

• The data stored in HLR is of a semi permanent nature and does not usually change from call to call.

Visitor Location Register (VLR)

• Contains the relevant data of all MSs currently located in a serving MSC

• The permanent data is the same as data in the HLR.

• The temporary data includesTemporary Subscriber Identity (TMSI)Location Area Identity (LAI) of an MS• VLR allocates mobile subscriber roaming numbers (MSRNs) for the incoming call setup.

The relation between MSC and VLR

• Sum of MSC areas determine the geographical area of any PLMN.

• Each MSC has its own VLR so PLMN can also be described as the sum of all VLR areas.

• VLR can serve several MSC but one MSC always use only one VLR.

Authentication Center (AuC)

• 1st level security mechanism for a GSM cellular network.

• is a database that stores the list of authorized subscribers of a GSM network.

• it is linked to the MSC and checks the identity of each user trying to connect.

• also provides encryption parameters to secure a call made in the network.

CHANNELS

PHYSICAL LOGICAL

CONTROL CHANNEL

TRAFIC CHANNEL

CONTROLS CHANNEL

•Broadcast channels(BCH)(Downlink only)

oBroadcast controls channels(BCCH) Broadcasts cell specific information to

the MS.

oFrequency correction channel(FCCH) Used for frequency correction of MS.

oSynchronization channel(SCH) Carrier information about TDMA frame

number and the base station identity code(BSIC) of the BTS.

Common control channel(CCH)

oRandom access channel(RACH) Is used by the mobile when making its first access to

the system. By making that access, the MS is requesting a signalling. The reason for the access could be a page response or initiation. RACH is sent uplink,point to point.

oAccess Grant Channel (AGCH) It is used to assign dedicate resource to MS. It is sent

downlink, point to point and grandly access the network.

oPaging Channel (PCH) Used on the downlink to page the MS.

oCell Broadcast Channel (CBCH) It is used to transmit common message to the cell MS.

ASSOCIATED CONTROLS CHANNELS (ACCH)oSlow Associated Controls Channel (SACCH)

It is used Measurement reports from the MS to BTS are sent on the uplink. On the downlink the MS receives information from the BTS on what transmitting power to use and also instruction on Timing advance (TA).It is also used for the transmission of short text message in call connected (busy) mode. Controls channel associated with a TCH.

oFast Associated control Channel (FACCH) Controls channel associated with a TCH.It is mainly used

handover information used on uplink and downlink.

oStandalone Dedicated Controls Channel (SDCCH) Used for system signaling during call setup or registration, uplink

and downlink, as well as the transmission of short message in idle mode.

• TRAFFIC CHANNELS (TCH)oHalf rate channels

Used for half rate speech at 11.4kbps or data up to 4.8kbps.

oFull rate channels Used for full rate speech at 22.8kbps or data up to

9.6kbps.

CONTROL CHANNELS

BROADCAST CHANNELS(CH)

COMMON CONTROL

CHANNELS(CCH)

ASSOCIATED CHSNNELS(ACH)

TRAFIC CHANNELS(TCH)

1. BCCH2. FCCH3. SCH

1. RACH2. AGCH3. PCH

4. CBCH

1. SACCH2. FACCH3. SDCCH

1. HALF RATE2. FULL RATE

The various departments of VODAFONE (ODISHA)

Here, Network Operation is divided into two basic departments:--

NSS(Network Switching Subsystem)• BSS(Base Station Subsystem) NSS comprises of two departments:--• IN(Intelligent Network)/VAS(Value Added Services)• SWITCH BSS comprises of four departments:--• OMCR(Operation & Maintenance Centre For Radio

Service)• RF(Radio Frequency)• TRANSMISSION• BSS O&M(Operation & Maintenance)

The various departments of VODAFONE (ODISHA)

Here, Network Operation is divided into two basic departments:--

NSS(Network Switching Subsystem)• BSS(Base Station Subsystem) NSS comprises of two departments:--• IN(Intelligent Network)/VAS(Value Added Services)• SWITCH BSS comprises of four departments:--• OMCR(Operation & Maintenance Centre For Radio

Service)• RF(Radio Frequency)• TRANSMISSION• BSS O&M(Operation & Maintenance)

NSS•NETWORK SWITCHING SUBSYSTEM•Does call switching process.•Consists of following branches:-

CALL PROCESS Authentication process: MS BSC MSC HLR

LU REQUEST LU REQUEST LU REQUEST

TRIPLET(Kc,RAND,SRES)GENERATED USING A3 ALGORITHTM

RAND SENT TO MS

TRIPLET GENERATED IN MS SENT TO MSC IF BOTH ARE SAME

AUTHENTICATION COMPLETED

LU RESPONSELU RESPONSE

Triple generated in MS using RAND sent from HLR

CALL SETUPCALLER SIDE:-IN:-INELLIGENCE NETWORK,STP-SIGNAL TRANSFER POINT,NPDB-NUMBER PORTABILITY DATABASE

STP

NPDB

IN

BSC MSCMS

A CALLING B

A PARTY AND B PARTY NUMBER

B PARTY NO

A PARTY NO

GMSC/MSC

A PARTY AND B PARTY NOANALYSED

CALL FORWADED TO REQUIRED MSC/GMSC

CALLING SIDE:-

IAM-INITIAL ADDRESS MESSAGE,SRI-SEND ROUTING INFORMATION,PRN-PROVIDE ROAMING NUMBER,ACM-ADDRESS COMPLETION MESSAGE

PSTN

GMSC HLR MSC/VLR BSC

IAM SRI PRN

MSRNMSRN

IAM

PAGING REQUEST

RESPONSEACMACM

MS

IN•INTELLIGENT NETWORK.•A branch of GSM architecture.•In prepaid service, the call goes to the MSC via the IN.•When a caller(prepaid customer) calls ,it checks available call time of the caller and sends this information to the MSC.•It informs the subscriber the facilities he is entitled and other information's such as available balance, free sms,etc.•The subscriber can get above information by using the USSD(Unstructured Supply Data) • It Deals with: 1.Billing 2.Recharge

Structure of IN:-

•STP:-Signal Transfor Point(It transfor the signal from MSC to SDP)•SGU:-Signalling Gateway Unit(It is a gateway to the SDP.It is used for trafic purpose)•SLU:-Service Logic Unit(Here the charging parametre is defined)•SDP:- It is a oracle based database.it contains information about suscribers MSDN,balance,plan.It also contains data of paper vouchers.

Billing:-

MSC STP SGU SLU

SDP

Query sent Using Round Robing Algorithm

NOTIFMEDIATIONHLR

Query sent through XMLSOAP

Required charging is done.balance is updated

Charging Report is sent

Report is feched from SDP

Report sent to HLR

HLR is updated

Charging parameter sent to SDP

Paper Voucher:-*140*secrete code#(for vodafone)

RECHARGE

Easy Paper Web

HLR MSC SDP

Code is checked.balance updated

Easy Recharge(vodafone):-•Also known as E top up.Retailer sim

Prepaid Refill

MSISDN(2 times)

MRP

190 numberSMSC,

KOLKOTAETOP

SERVER LBA

SAPI

SDP

SMSC:-Short Message Service CentreLBA:-Load Balance Analyser(used for trafic)SAPI:-Hardware unit of IN

Number of user analysed

Web Recharge:-

Web

User number

Bank(balance deducted)

LBA SAPI SDPBalance Updated

OMCR(Operation & Maintenance Centre For Radio Service)

OMCR(Operation & Maintenance Centre For Radio Service)

This unit provides a logical connection between various BSCs,so that all the fault monitoring, performance and configuration management can be done by sitting in one particular place.Eg.:In Odisha,the OMCR manages all the 26 BSCs within the state.

So here we can log into several BSCs via X.25/IP(media),using OSS and can do fault & performance monitoring.

In ODISHA circle, Vodafone has 26 BSCs(like Cuttack, Puri, Khurda, Rourkela,etc.) which are controlled by OMCR(in Bhubaneswar).

If a fault occurs in any BTS(site) or BSC, due to which there is network problem in that area, then this department gets the alarm,i.e,the cause for failure.

Here there are two types of failure:--1. Active alarms(internal):These are which alarms which occur due

to any fault in the BTS units. They are:- BOI alarm. TRx alarm. Duplexer alarm. EB system alarm.

This unit provides a logical connection between various BSCs,so that all the fault monitoring, performance and configuration management can be done by sitting in one particular place.Eg.:In Odisha,the OMCR manages all the 26 BSCs within the state.

So here we can log into several BSCs via X.25/IP(media),using OSS and can do fault & performance monitoring.

In ODISHA circle, Vodafone has 26 BSCs(like Cuttack, Puri, Khurda, Rourkela,etc.) which are controlled by OMCR(in Bhubaneswar).

If a fault occurs in any BTS(site) or BSC, due to which there is network problem in that area, then this department gets the alarm,i.e,the cause for failure.

Here there are two types of failure:--1. Active alarms(internal):These are which alarms which occur due

to any fault in the BTS units. They are:- BOI alarm. TRx alarm. Duplexer alarm. EB system alarm.

2.Passive alarms(external):These are the alarms which occur due to the units present external to the BTS.

They are:--1.Mains fail. 2.One rectifier fail.3.Two rectifier fail.4.DG fail to start.5.DG fail to stop.6.DG on load.7.Low fuel.8.AC-1 fail. 9.AC-2 fail.10.High room temperature. 11.Smoke & Fire.12.Door open. If there is any upgradation,then this team logically creates

connection between server & upgraded BTS. It allocates cell ID,LAC,frequencies ,etc to a newly allocated

sites.

2.Passive alarms(external):These are the alarms which occur due to the units present external to the BTS.

They are:--1.Mains fail. 2.One rectifier fail.3.Two rectifier fail.4.DG fail to start.5.DG fail to stop.6.DG on load.7.Low fuel.8.AC-1 fail. 9.AC-2 fail.10.High room temperature. 11.Smoke & Fire.12.Door open. If there is any upgradation,then this team logically creates

connection between server & upgraded BTS. It allocates cell ID,LAC,frequencies ,etc to a newly allocated

sites.

BTS RUNNING

SMOKE & FIRE

DOOR OPEN

2 RECTIFIERFAIL

DG ON LOAD

AC-2 FAIL

MAINS FAIL

BATTERY ON LOAD

DG FAIL TO START

DG FAIL TO STOP

LOW FUEL

AC-1 FAIL

HIGH ROOMTEMPERATURE

DECI-ISON

IF MAINSRETURN

YES

YES

NO

BACK-UP PLAN FOR A BTS: SEQUENCE OF ALARMS THAT COME TO THE OMCR,IF MAINS TO THE BTS FAIL.

1 RECTIFIER FAIL

This team maintains a 24 hour report,known as KPI(Key Performance Indicator) report.

The KPI includes various measurements:--1.Total calls.2.Call drop rate(%).3.Call set-up success rate(%).4.HOSR(Handover Success Rate)(%).5.Peak Traffic(Erl*).*1Erl(Erlang) is an unit of telecommunications

traffic measurement.An Erlang represents the continuous use of one voice path.It is used to describe the total traffic volume of one hour.

6.Traffic alarm.7.Call Block.8.Network Availability.

This team maintains a 24 hour report,known as KPI(Key Performance Indicator) report.

The KPI includes various measurements:--1.Total calls.2.Call drop rate(%).3.Call set-up success rate(%).4.HOSR(Handover Success Rate)(%).5.Peak Traffic(Erl*).*1Erl(Erlang) is an unit of telecommunications

traffic measurement.An Erlang represents the continuous use of one voice path.It is used to describe the total traffic volume of one hour.

6.Traffic alarm.7.Call Block.8.Network Availability.

DIFFERENT BSCs CONTROLLED BY OMCR(VIA OSS:OPERATING SUPPORT SYSTEM)

DIFFERENT BSCs CONTROLLED BY OMCR(VIA OSS:OPERATING SUPPORT SYSTEM)

RF(Radio Frequency)RF(Radio Frequency) This team makes plan for installation of BTS,such as tower

height, antenna position, proper handover,etc. They allocate the frequencies to the BTS. The cell LAC(Location Area Code) is also planned by this

team. If there is any upgradation,then this team allocates the

frequencies & cell LAC. Drive testing is performed by this team,i.e. maintaining the

continuity of services and call, when there is a call drop. This team keeps an account of Rx level,Rx quality of a

particular site. Depending upon the population, physical topography,etc.

the RF team analyses the whole cell to get optimum coverage in that cell.

This team makes plan for installation of BTS,such as tower height, antenna position, proper handover,etc.

They allocate the frequencies to the BTS. The cell LAC(Location Area Code) is also planned by this

team. If there is any upgradation,then this team allocates the

frequencies & cell LAC. Drive testing is performed by this team,i.e. maintaining the

continuity of services and call, when there is a call drop. This team keeps an account of Rx level,Rx quality of a

particular site. Depending upon the population, physical topography,etc.

the RF team analyses the whole cell to get optimum coverage in that cell.

BSS O&M(Operation & Maintenance)

BSS O&M(Operation & Maintenance)

This team does the site related work.After the OMCR gets the alarm, they inform to

this team & they go to the site & rectify the fault.

If their is any upgradation,they go to the site & install the equipments.

This team does the site related work.After the OMCR gets the alarm, they inform to

this team & they go to the site & rectify the fault.

If their is any upgradation,they go to the site & install the equipments.

TRANSMISSIONTRANSMISSION

The main work of this team is to provide a transmission media between various BSCs.

The transmission media between various BSCs is done either by X.25 or IP.

This team manages all the MUX which connects the optical fibers.

If there is any fault(power related) in the MUX,they get alarm & inform the related team.

If the fibers get cut at any region, they come to know about the fault from their servers.

This team provides a media for all the network elements.

The main work of this team is to provide a transmission media between various BSCs.

The transmission media between various BSCs is done either by X.25 or IP.

This team manages all the MUX which connects the optical fibers.

If there is any fault(power related) in the MUX,they get alarm & inform the related team.

If the fibers get cut at any region, they come to know about the fault from their servers.

This team provides a media for all the network elements.

TRANSMISSION UNIT:CONNECTION OF SEVERAL BTS TO A SINGLE BSC

TRANSMISSION UNIT:CONNECTION OF SEVERAL BTS TO A SINGLE BSC

GSM Speech And Voice Coding

Process:-

• Sampling• Quantization• Vocoder• Channel Coding• Interleaving

Sampling:-• The human voice is sampled in accordance to a formula

fs >=2fm(maximum frequency of human voice)• Generally the human voice maximum range is 4000HZ• Hence the sampling rate(fs) is 8000hz.Quantization:-• Each sample is quantised to 13 bit rate and converted to

104kbps.• It is then converted to 50 blocks of 2080bit/20ms

Vocoder:-•Each block of 2080 bit/20ms is compressed to 260 bit/20 ms by vocoder.Encoder:-

Encoder260 bit/20ms

50 132 78

Ia Ib 2a

53 136 78

378 78

2bit multipier

456bit/20ms(22.8kbps)

Interleaving:-• The 456 bit is divided into 8 packets each having 57 bits.

19...

08...

210...

311...

412...

513...

614...

715...

Upto 57 bit

1 way leaving from MS to BTS

2 way leaving from MS to BTS

Burst:-•The information carried in a logical channel is called burst.Different type of burst:-•Frequency Correction Burst•Synchronisation burst•Normal burst•Access burst•Dummy burst

GPRS

GPRS NETWORK ARCHITECTURE

•GGSN•SGSN•BORDER GATEWAY•DOMAIN NAME SERVER•CHARGING GATEWAY

GGSN:-

• Gateway GPRS Support Node• Main functions:-

Interface to external data networks Resembles to a data network router Forwards end user data to right SGSN Routes mobile originated packets to right

destination. Collects charging information for data network

usage. Data packets are not sent unless the user has

activated the PDP address.

SGSN:-

•Serving GPRS Support Node•One for few BSCs or one (or few) per every BSC•Main functions:-

Authenticates GPRS mobiles.Handles mobile’s registration in GPRS network.Handles mobile’s mobility management.Interaction with HLR,VLR.

BG (Border Gateway):-

•Interconnects different GPRS operators' backbones.

•Enables GPRS roaming.DNS (Domain Name Server) :-•Translates IP host names to IP addresses (DNS Resolution).•Makes IP network configuration easier.•In GPRS backbone SGSN uses DNS to get GGSN and SGSN IP addresses.Charging Gateway:-•Collects charging information from SGSNs and GGSNs and forward them to billing centre.

Interfaces•Gb – Connects BSC with SGSN•Gn – SGSN – SGSN/GGSN (in the same network)•Gp – SGSN –GGSN (in different networks)•Gi – Connects PLMN with external Packet Data Networks (PDNs)•Gr – To exchange User profile between HLR & SGSN•Gs – To exchange Database between SGSN & MSC•Gd – Interface between SMS & GPRS

GPRS mobile types

Class A:• Simultaneous GPRS and conventional GSM operation• Supports simultaneous circuit switched and GPRS data

transferClass B:

• Can be attached to both GPRS and conventional GSM services simultaneously

• Supports either circuit switched calls or GPRS data transfer but not simultaneous communication

Class C:• Alternatively attached in GPRS or conventional GSM• No simultaneous operation.

GPRS NETWORKGPRS NETWORK•

GPRS Data Rates

Coding Scheme Data Rate (kbps) Interface

CS-1 9.05 Abis

CS-2 13.4 Abis

CS-3 15.6 Dynamic Abis Pool

CS-4 21.4 Dynamic Abis Pool

GPRS implementation• GPRS/EGPRS capable terminals are required• GPRS territory is required in BTS• Packet Control Units (PCUs) need to be implemented in

BSCs• Gb interface dimensioning• GPRS packet core network dimensioning

• If CS3&CS4 will be implemented following units/items are required PCU2 with S11.5 BSC SW Dynamic Abis Pool (DAP) EDGE capable TRXs UltraSite and MetroSite BTS SW support

EGPRS Implementation

• Can be introduced incrementally to the network where the demand is

EGPRS capable MS

Network HW readiness/upgrade (BTS and TRX)

TRS capacity upgrade (Abis and Gb)

Dynamic Abis

(E)GPRS Logical Channels

GPRS Air Interface Logical Channels

CCCHCommon Control Channels

DCHDedicated Channels

PCHPaging CH

AGCHAccess Grant CH

RACHRandom Access CH

Existing GSM Channels(Shared with GPRS Signaling in GPRS Release 1)

PACCHPacket Associated

Control CHPDTCHPacket Data TCH

NEW GPRS Channels

Radio Resource (RR) Management Procedures

• Takes care of the allocation and maintenance of radio communication paths

• Paging:- The paging procedure moves the MS to ”Ready” state

to allow the SGSN to forward downlink data to the BSS

• TBF Establishment/Release:- A TBF is temporary and is maintained only for the

duration of the data transfer.

Physical connection where multiple mobile stations can share one or more traffic channels – each MS has own TFI

The traffic channel is dedicated to one mobile station at a time (one mobile station is transmitting or receiving at a time)

Is a one-way session for packet data transfer between MS and BSC (PCU)

Uses either uplink or downlink but not both (except for associated signaling)

Can use one or more TSLs

SESSION MANAGEMENT IN GPRS

GPRS attach•User is registered in SGSN, after authentication check from HLR

•SGSN assigns P-TMSI to MS

GPRS detach

•Disconnection of MS from GPRS network is called GPRS detach

•It can be initiated by MS or by network(SGSN or HLR)

Session Management• PDP Context (Packet Data Protocol): Network level

information which is used to bind a mobile station (MS) to various PDP addresses and to unbind the mobile station from these addresses after use

• PDP Context Activation– Gets an IP address from the network– Initiated by the MS– Contains QoS and routing information enabling data

transfer between MS and GGSN– PDP Context Activation and Deactivation should

occur within 2 seconds

PDP Context Activation

SITE CREATION

ET CREATION•ET selected.

•ET status check(working or not)ZUSI:ET,598:;

•Configuration checkZWUP:598::ALL;

•If it isn’t configured to ABIS,to configureZWUC:598:ETS2,0:IF=ABIS:BCSU,6:;

OMU CREATION

• ET -598• BCF-500• BTS-1498,1499,1500• LAC-ID-2302• CELL ID-34211(For 1st sector)

34212(For 2nd sector)34213(For 3rd sector)

ZDSE:OM500:BCSU,4:62,1:32,598-31,0::;

BCF CREATION

•BCF500 connected with OMUZEFC:ID 500,E:DNAME=OM500,:

•BCF Status checkedZEEI:BCF-500

SECTOR CREATION• FOR 1ST SECTOR ZEQC:BCF=500,BTS=1498,NAME=ALOK,SEGNAME=ALOK,REF=1001:CI=3421

1,BAND=1800,: NCC=2,BCC=3,MCC=405,MNC=753,LAC=2302:HSN1=25,:GENA=Y,RAC=232;

• FOR 2ND SECTOR ZEQC:BCF=500,BTS=1499,NAME=HAPPY,SEGNAME=HAPPY,REF=1001:CI=34

212,BAND=1800,: NCC=3,BCC=5,MCC=405,MNC=753,LAC=2302:HSN1=28,:GENA=Y,RAC=232;

• FOR 3RD SECTOR ZEQC:BCF=500,BTS=1500,NAME=PG,SEGNAME=PG,REF=1001:CI=34213,BA

ND=1800,: NCC=4,BCC=6,MCC=405,MNC=753,LAC=2302:HSN1=30,:GENA=Y,RAC=232;

DAP CREATION

• ZESE:ID=500,CRCT=598-27&&-30,BCSU=3,PCU=4:;

TRX CREATION

• ZERC:BTS=1498,TRX=1:PREF=P,GTRX=Y,DAP=500,FREQ=833,TSC=3,PCMTSL=598-1,:DNAME=T5001:CH0=MBCCH,CH1=SDCCB,CH2=TCHD,CH3=TCHD,CH4=TCHD,CH5=TCHD,CH6=TCHD,CH7=TCHD,;