Introduction to mobile communication

SUBMITTED BY :-
PRAJNYADEEP SUBHASHIS PATRA
ALOK AHUTI ROUL
PRIYATOSH DAS
PAYAL PRIYA CHAND

INTRODUCTION TO MOBILE
COMMUNICATION

TECHNIQUES OF MOBILE COMMUNICATION
MULTIPLE ACCESS METHODOLOGY
o The technique of dynamically sharing the finite
limited radio spectrum by multiple users is
called multiple access technique.
o There are 3 types of multiple access
technique:-
 FDMA
 TDMA
 CDMA

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 k6 k1
c
f
t

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
f
t
k2 k3 k4 k5 k6 k1
c
t

CDMA
• Code Division Multiple Access
• All users share the same frequency all the time!
• To pick out the signal of specific user, this signal is
modulated with a unique code sequence.

Frequency Division
Multiple Access
o When the subscriber
enters another cell a
unique frequency is
assigned to him; used
in analog systems.
Time Division Multiple
Access
o Each subscriber is
assigned a time slot
to send/receive a
data burst; is used in
digital systems.
Code Division
Multiple Access
o Each 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
Downlink
Uplink
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

• Uplink frequency
o It refers to a signal flow from Mobile Station (MS) to Base
Transceiver Station (BTS).
• Downlink frequency
o It refers to a signal flow from Base Transceiver Station (BTS) to
Mobile Station(MS).
• Duplex Frequency
o 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.
Mobile Station
=
SIM Card Battery
Global GSM Mobility
Card
The Smart Card to use
G S M
Handset
= =

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 Related
2-Equipment Related
3-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+MSIN
 MCC=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.

oTemporary 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

oInternational Mobile Equipment Identity And
Softwre Version Number(IMEISV)
 IMEISV=TAC+FAC+SNR+SVN
 SVN=Software Version Number ,allows the mobile
equipment manufacture to identity differeft s/w version
of a given type approval mobile.
 The length of IMEISV is 16.

o LOCATION RELATED IDENTITY
 Mobile Station Roaming Number(MSRN)
 MSRN=CC+NDC+SN
 CC=Country Code
 NDC=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)

Introduction to mobile communication

• 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:
oNCC
oBCC
• 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)

• Regional Subscription Zone Identity(RSZI)
• For each regional subscription , zones/regions need to
be defined.
• This is achieved by using the Regional Subscription
Zone Identity (RSZI)
• The RSZI consist of the following:
oCC(Country Code)
oNDC(National Destination Code)
oZC(Zonal Code)

PSTN GMSC
MSC
HLR
VLR
MSISDN
1
2
5
3
4
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 BTS
2.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 BTS
POWER SUPPLY UNIT(PWSB)
BASE OPERATION & INTERFACES UNIT(BOIx)
TRANSCEIVER BASEBAND UNIT(BB2x)
TRANSMISSION UNIT(VXxx)
2-WAY RECEIVER MULTICOUPLER UNIT(M2xx)
TRANSCEIVER UNIT(TSXx)
COMBINER UNIT(WCxx)
DUPLEXER UNIT(DVxx)

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 Switching
Center (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 includes
Temporary 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.

Equipment identity register (EIR)
• The separation of subscriber identity from the identifier of MS
also bears a potential pitfall for GSM subscribers.
• It is possible to operate any GSM MS with any valid GSM
SIM. An opportunity exists for black market and stolen
equipment.
• To combat this problem EIR is introduced to identify and
track such equipment.
• Like HLR and VLR, the EIR is also a data base which maintain
three lists.
oWhite List
oBlack List
oGray List

• White List
Contains all approved types of mobile equipment.
• Black List
Contains all approved types of mobile equipment to
be barred.
• Gray List
Contains all approved types of mobile equipment to
be traced.

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. BCCH
2. FCCH
3. SCH
1. RACH
2. AGCH
3. PCH
4. CBCH
1. SACCH
2. FACCH
3. SDCCH
1. HALF RATE
2. 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)

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 RESPONSE LU RESPONSE
Triple
generated
in MS using
RAND sent
from HLR

CALL SETUP
CALLER SIDE:-
IN:-INELLIGENCE NETWORK,STP-SIGNAL TRANSFER POINT,NPDB-NUMBER PORTABILITY DATABASE
STP
NPDB
IN
MS BSC MSC
A CALLING B
A PARTY
AND B
PARTY
NUMBER
B PARTY NO
A PARTY
NO
GMSC/MSC
A PARTY
AND B
PARTY NO
ANALYSED
CALL FORWADED TO REQUIRED MSC/GMSC

CALLING SIDE:-
PSTN
GMSC HLR MSC/VLR BSC
IAM SRI PRN
MSRN MSRN
IAM
PAGING
REQUEST
ACM ACM RESPONSE
MS
IAM-INITIAL ADDRESS MESSAGE,SRI-SEND ROUTING INFORMATION,PRN-PROVIDE
ROAMING NUMBER,ACM-ADDRESS COMPLETION MESSAGE

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
MEDIATION NOTIF
HLR
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

RECHARGE
Easy Paper Web
Paper Voucher:-
*140*secrete code#(for vodafone)
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 number SMSC,
KOLKOTA
SDP
SAPI
Number of
user
analysed
ETOP
SERVER LBA
SMSC:-Short Message Service Centre
LBA:-Load Balance Analyser(used for trafic)
SAPI:-Hardware unit of IN

Web Recharge:-
Web
User number
Bank(balance deducted)
LBA SAPI SDP
Balance Updated

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.

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 RECTIFIER
FAIL
DG ON LOAD
AC-2 FAIL
MAINS FAIL
BATTERY ON
LOAD
DG FAIL TO
START
LOW FUEL
DG FAIL TO
STOP
AC-1 FAIL
HIGH ROOM
TEMPERATURE
DECI-ISON
IF MAINS
RETURN
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.

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

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.

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.

TRANSMISSION
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

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:-
260 Encoder
bit/20ms
Ia Ib 2a
50 132 78
53 136 78
2bit multipier
378 78
456bit/20ms(22.8kbps)

Interleaving:-
• The 456 bit is divided into 8 packets each having 57 bits.
1
9
.
.
.
0
8
.
.
.
2
10
.
.
.
3
11
.
.
.
4
12
.
.
.
5
13
.
.
.
6
14
.
.
.
7
15
.
.
.
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 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
transfer
Class 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 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
CCCH
Common Control Channels
DCH
Dedicated Channels
PCH
Paging CH
AGCH
Access Grant CH
RACH
Random Access CH
Existing GSM Channels
(Shared with GPRS Signaling in GPRS Release 1)
PACCH
Packet Associated
Control CH
PDTCH
Packet 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

MS sends "Activate PDP
Context Request" to
SGSN
SGSN checks against HLR
SGSN gets the GGSN IP
address from DNS
SGSN sends "Create PDP
Context Request" to
GGSN.User (dynamic) IP
address allocated
SGSN sends “Activate
PDP Context Accept“ to
the MS
GGSN sends "Create PDP
Context Response" back
to SGSN

SITE CREATION
ET CREATION
•ET selected.
•ET status check(working or not)
ZUSI:ET,598:;
•Configuration check
ZWUP:598::ALL;
•If it isn’t configured to ABIS,to configure
ZWUC: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 OMU
ZEFC:ID 500,E:DNAME=OM500,:
•BCF Status checked
ZEEI: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,:
• FOR 3RD SECTOR
 ZEQC:BCF=500,BTS=1500,NAME=PG,SEGNAME=PG,REF=1001:CI=34213,BA
ND=1800,:

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,FR
EQ=833,TSC=3,PCMTSL=598-
1,:DNAME=T5001:CH0=MBCCH,CH1=SDCCB,CH2=T
CHD,CH3=TCHD,CH4=TCHD,CH5=TCHD,CH6=TCHD,C
H7=TCHD,;

Introduction to mobile communication

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Introduction to mobile communication