basic of gsm

8/8/2019 Basic of Gsm

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Global System

for Mobiles

GSM


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TOPICS

GSM CONCEPTS

GSM SYSTEM ARCHITECTURE

IDENTITIES USED IN GSM

GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT

CALL MANAGEMENT

RADIO RESOURCE MANAGEMENT


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3

TOPICS

GSM CONCEPTS



GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT

CALL MANAGEMENT



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Telecom Basics

Communication

Voice and Data

Analog and Digital Circuit Switched and Packet Switched

Media - Copper Wire, Co-axial cable, Air, Optical

Fiber

Networks -PSTN, ISDN, PDN and Mobile Networks


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Background to GSM

1G : Advanced Mobile Phone Service (AMPS) Analog, Circuit Switched, FDMA, FDD

2G : Digital Advanced Mobile Phone Service (D-AMPS)

Digital, Circuit Switched, FDMA, FDD 2G : Global System for Mobile (GSM)

Digital, Circuit Switched, FDMA and TDMA, FDD

2G : Code Division Multiple Access (CDMA) Digital, Circuit Switched, FDMA, SS, FDD


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GSM History


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1982: Groupe Spcial Mobile (GSM)

created

1984: Description of GSM features

1985: List of recommendations settled

1987: Initial MoU (Memorandum ofUnderstanding) aside the drafting

of technical specifications was

signed by network operators of 13

countries:

1988: Validation and trials, of the radio

interface.

1991: First system trials are

demonstrated at the Telecom 91

exhibition.

1992: Official commercial launch of

GSM service in Europe. First

Launch in Finland

1993: The GSM-MoU has 62

signatories in 39 countries

worldwide.

1995: Specifications of GSM phase 2are frozen.

1999: GSM MoU joins 3GPP (UMTS)

GPRS Trials begins

2000: 480M GSM subscribersWorldwide

First GPRS Networks roll out

End 2002: 792M GSM subscribersWorldwide

Development of the GSM Standard


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12 SERIESOPERATION ANDMAINTENANCE

01 SERIES

GENERAL 02 SERIESSERVICE ASPECTS

03 SERIESNETWORK ASPECTS

04 SERIESMS-BSS INTERFACE AND

PROTOCOLS

05 SERIES

PHYSICAL LAYER ON THERADIO PATH.

06 SERIESSPEECH CODINGSPECIFICATIONS

07 SERIESTERMINAL ADAPTERS

FOR MOBILE STATIONS

11 SERIESEQUIPMENT AND TYPE

APPROVAL SPECIFICATIONS

10 SERIESSERVICE INTERWORKING

09 SERIES

NETWORKINTERWORKING

08 SERIESBSS TO MSC INTERFACES

GSM Specifications


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Increasing GSM Data Rates

Transmission Time GPRS = GeneralPacketRadioServiceHSCSD=HighSpeedCircuit SwitchedDataEDGE=Enhanced Data rate forGSM Evolution

UMTS = Universal Mobile Telecommunication System

10 sec 1 min 10 min 1 hour 0

UMTS

E/GPRS

ISDN

PSTN

GSM

webe-mail photo

web photoe-mail

web photo

video

clipreportphoto

web photoe-mail

videoclipreport

video

clipreport

videoclipreport

video

clipreport


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10

through

putkbps

10 k

100 k64 k

1 M

2 M

1 k 1998 1999 2000 2001 2002

Time frame

UMTSUMTS

GPRSGPRS

HSCSDHSCSD

9.69.614.414.4

pack

et

GPRS=GeneralPacketRadioService

HSCSD=HighSpeedCircuit SwitchedData

EDGE=Enhanced Data rate forGSM Evolution

UMTS = Universal Mobile Telecommunication System

EDGE

circu

it

Wireless Data Technology Options


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Circuit mode

Packet mode

AFDHCG

CG

CGCG

CG

DH

DH

AFDH

DH

AF

AF

AF

A

B

C

D

E

F

G

H

rcu t- w tc e or ac et-Switched


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Multiple Access Technique

Multiple Access Achieved by dividing the available radio

frequency spectrum, so that multiple users can be given access at

the same time.

FDMA - Frequency Division Multiple Access ( eg: GSM each Frequency channel is 200KHz)

TDMA - Time Division Multiple Access

( eg: GSM each frequency channel is divided into 8 timeslots)

CDMA - Code Division Multiple Access

(eg: IS95- Each User data is coded with a unique code)


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Duplex Technique

Duplex - How the up link and Down link of a user

is separated

FDD - Frequency Division Duplex

(eg: In GSM the up link and down link of a user is

separated by 45MHz )

TDD - Time Division Duplex

(the up link and down link of a user will be at the same

frequency but at different Time )


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Cellular

Networking technology

that breaks geographicarea into cells shaped

like honey comb

Cell

is the radio coveragearea of one base

transceiver station

1

23

4

56

7

6

72

1

5

GSM Concepts -

Cellular Structure


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What are the types in

GSM Network?

GSM-900 (Channels 125 operating band 900Mhz

carrier spacing 200khz spacing 45Mhz)

GSM -1800 (Channels 374 spacing 95Mhz)

GSM -1900(Used in USA)


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GSM Band Allocations (MHz)

Carrier frequency = ARFCN =Absolute Radio Frequency Channel Number

Frequencies are in MHz

GSM systems Uplink Downlink Band DuplexSpacing

Duplexchannels

GSM 450

GSM 480

GSM 850

450.4-457.6

478.8-486

824-849

460.4-467.6

488.8-496

869-894

2x7.2

2x7.2

2x25

10

10

45

35

35

124

GSM 900

E-GSM (900)R-GSM (900)

890-915

880-915876-880

935-960

925-960921-925

2x25

2x352x04

45

4541

124

17440

GSM 1800GSM 1900

1710-17851850-1910

1805-18801930-1990

2x752x60

9580

374299


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Frequency band

Uplink 890 - 915 MHz

Downlink 935 - 960MHz

Duplex Frequency Spacing 45MHz

Carrier separation 200KHzFrequency Channels 124

Time Slots /Frame(Full Rate) 8

Voice Coder Bit Rate 13Kbps

Modulation GMSKAir transmission rate 270.833333 Kbps

Access method FDMA/TDMA

Speech Coder RPE-LTP-LPC

GSM System specifications


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Functions of the Radio Interface

BTS-1 BTS-2

BTS

Speech and user's data

Signaling

Communication

modeIdle mode

GSM F il R di B d S t


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GSM Family Radio Band Spectrum

Uplink

Downlink

880 890 915 1710 1785

925 935 960 1805 1880

MHz

P-GSM

GSM 1800 GSM 1900

1850 1910

1930 1990

R-GSM

876

921

960

960

915

915

E-GSM

Uplink

Downlink

824 849

869 894 MHz

GSM 850

478.8 486

488.8 496

450.4 457.6

460.4 467.6

GSM 450 GSM 480


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GS


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GSM Time Division MultiplexFrame and Physical Channels

TS TS TS TS TS TS TS TS

0 1 2 3 4 5 6 7

Time4.615 ms

TDMA frame

Physical channel # 2 = recurrence of time-slot # 2

TDMA frame

0 9.23 ms

Time-slot

(frames repeat continuously)

TS TS TS TS TS TS TS TS

0 1 2 3 4 5 6 7


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Physical Channel

MS3

////ARFCN

1 2 124FDMA

BTS

Without FH

0

TDMAs

TS7

n

n-1

n+1

MS2

MS1

timeBTS

With FH


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Radio Link Aspects

From Speech to RF SignalBlah Blah Blah...Blah... Blah... Blah...

Digitizing and

Source Coding

Channel Coding

Interleaving

Ciphering

Burst Formatting

Modulating Demodulating

Burst De-formatting

Deciphering

De-interleaving

Channel Decoding

Source Decoding


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GSM Delays Uplink TDMA Frames

Downlink TDMA

T T T T T T T T

R TMS1

R TMS2

Downlink

Uplink

Fixed transmit

delay of three

time-slots

R R R R R R R R

0 1 2 3 4 5 6 7

The start of the uplink TDMA

is delayed of three time-slotsBTS side

MSs side

BTS

TDMA Frame (4.615 ms)


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Ti i Advance


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TX BTS CAN WHAT GSM HOW WHEN WHAT

RX BTS yes the ms-isdn

RX MS1 CAN

TX MS1 yes

RX MS2 WHAT

TX MS2 the

RX MS3 GSM

TX MS3 ms-isdn

RX MS4 HOW

TX MS4

RX MS5 WHEN

TX MS5

RX MS6 WHATTX MS6

RX MS7

TX MS7

RX MS8

TX MS8

PropagationDelay

DD

+3TS

TA

Timing Advance2 - Without Timing Advance: Collision

Ad


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CAN WHAT HOW WHEN WHAT

CAN

WHAT

HOW

WHEN

WHAT

TX BTS

RX BTS

RX MS1TX MS1

RX MS2TX MS2

RX MS3TX MS3

RX MS4TX MS4

RX MS5TX MS5

RX MS6TX MS6

RX MS7TX MS7

RX MS8TX MS8

yes

the

PropagationDelay

DD

+3TS - TA

yes the

Timing Advance = 2 * Propagation Delay

GSMms-isdn

ms-isdn

GSM

Timing Advance3 - With Timing Advance: No Collision


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Uplink 890 MHz to 915 MHz

Down Link 935 MHz to 960 MHz

25 MHz divided into 125 channels of 200 KHzbandwidth

890.0 890.2 890.4 914.8 915.0

935.0 935.2 935.4 959.8 960.0

UP

DOWN

Access Techniques


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Time Division Multiple Access

Each carrier frequency subdivided in time domain

into 8 time slots

Each mobile transmits data in a frequency, in itsparticular time slot - Burst period = 0.577 milli secs.

8 time slots called a TDMA frame. Period is .577 * 8

= 4.616 milli secs

0 1 2 3 4 5 6 7

4.616 ms

0.577 ms

Access Techniques ...


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GSM in comparison with other

Standards GSM gives mobility without any loss in Audio quality

Encryption techniques used gives high security in the air

Interface and also use of SIM.

Bit Interleaving for high efficiency in Transmission.

Variable Power (Power budgeting- extend battery life)

Minimum Interference.

Features-CCS7 Signaling

SMS (Short Message Services)

Emergency Calls

CELL Broadcast


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TOPICS

GSM CONCEPTS



GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT

CALL MANAGEMENT



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GSM Network

OMC

AUC

HLR

MSC

EIRVLR

BSC

BTS

MS

External

PSTN &

PDN N/W

SS

BSS

Switching

System

Base StationSystem

MS Mobile Station

BTS Base transceiver System

BSC Base Station Controller

MSC Mobile Switching CenterHLR Home Location Register

VLR Visitor Location Register

EIR Equipment Identity Register

AUC Authentication Center

OMC Operation And Maintenance Center


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Fundamentals


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GSM utilizes two bands of 25 MHz. 890-915MHz band is used for uplink while the 935-960 MHz is used for downlink.

The frequency bands are divided into 200KHz wide channels called ARFCNs (AbsoluteRadio Frequency Channel Numbers) i.e.there are 125 ARFCNs out of which only 124are used.

Each ARFCN supports 8 users with each usertransmitting / receiving on a particular time

slot (TS).

Fundamentals

124

123

.

2

1

124

123

.

2

1

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

Data burst = 156.25 bit periods = 576.9 s

960 MHz

959.8MHz

200KHz

935 MHz

935.2 Mhz

915 MHz

200KHz

45 MHz

Downlink (TDMA frame) = 8 TS

Uplink (TDMA frame)

Delay

TS: Time slot

914.8 MHz

890.2 MHz

890 MHz

DOWNLINK

UPLINK

ThereforeTherefore 1 TDMA1 TDMA frame = 156.25 x 8 = 1250 bitsframe = 156.25 x 8 = 1250 bits

and has a duration of 576.92and has a duration of 576.92 s x 8 = 4.615 mss x 8 = 4.615 msThe technology


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Channels : differentiating

between Physical and LogicalchannelsPhysical channels : The combination of an ARFCN

and a time slot defines a physical channel.

Logical channels : These are channels specified by

GSM which are mapped on physical channels.

Logical Channels on Air interface


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Logical Channels on Air interface

LOGICAL

CHANNELS

COMMON

CHANNELS

DEDICATED

CHANNELS

BROADCASTCHANNELS

COMMONCONTROL

CHANNELS

DEDICATEDCONTROL

CHANNELS

TRAFFICCHANNELS

FCCH BCCHSCH SDCCH SACCH FACCH

PCH AGCHRACH TCH/F TCH/EFRTCH/H


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FCCH

Logical channels

Logical channels

Control channels Traffic channels

BCH CCCHDCCH

Half

rate

Full

rate

SCH BCCH PCH AGCH RACH SDCCH SACCHFACCHCBCH

Frequency plan and importance of


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Frequency plan and importance of

BCCH

B3

B2

B9

B6 B4

B1

Sectored

antennas

MS ( monitoring the

broadcast radio B1 in idle

mode )

F S B B B B .. F S .. .. I

F0 F50F2 F3 F4 F5 F10 F11F1

F,S,B exist in time slot 0 of each frame

B7

B8

B5

B10

B11

B12

frequency plan:

dcast frequencies :

roadcast channels = 48-62

opping channels = 32-46


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What information does Broadcast Control channel

(BCCH) contain?

Serves as a Beacon for the Cell

Country Code (CC) and the Network Code (NC)

Location Area Identity (LAI)

List of neighboring cells which should be monitored by MS

List of frequencies used in the cell Cell identity

Back

Location Updates


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Location Updates

Location Updates can be classified into

two:

Periodic Location Updates:

This occurs as per the timer set by the network operator.If the MS does not perform this update the MSC marksthe MS as Detached on the VLR.

Location Update on a handover:This occurs if during a handover the MS is moved into anew Location Area Code (LAC).


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1. The MS is monitoring the BCCH and has all the decoded

information stored on the SIM ( including the LAC)2. As soon as the mobile is on a TCH it sends the signal

strength indication on the corresponding SACCH

3. The BSC monitors the signal strengths and on analysis

sends a handoff request on FACCH. The handoffprocess is completed on the FACCH.

4. After the completion of call, the MS starts monitoring the

BCCH again. On finding the LAC (stored on SIM) and that

decoded from the BCCH to be different , the MS requests

a Location Update through SDCCH.


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Mobile Equipment(ME)

Frequency and Time Synchronization

Voice encoding and transmission

Voice encryption/decryption functions

Power measurements of adjacent cells

Display of short messages

International Mobile Equipment Identifier (IMEI)


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SIM Portable Smart Card with memory (ROM-6KB to 16KB-A3/A8

algorithm, RAM- 128KB TO 256KB, EEPROM- 3KB to 8KB ) Static Information

International Mobile Subscriber Identity(IMSI)

Personal Identification Number (PIN)

Authentication Key (Ki)

Dynamic Information

Temporary Mobile Subscriber Identity(TMSI)

Location Area Identity (LAI)

Phone memories, billing information

Ability to store Short Messages received

SIM C d d GSM M bil


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SIM-Card and GSM Mobile

Equipment

G S M

Global GSM MobilityCardThe Smart Card to use

+

SIM-Card

Contains:

- IMSI

=


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The SIM-Card Functions

Microchip with storeduser information

Credit Card Size

Permanent data:- Unique mobile subscriber identitythrough IMSI number and PIMSI

for Packet Mode

- Authentication parameter Ki,

- Authentication algorithm A3,

- Generating encryption key Kcalgorithm A8,

- PIN code.

Removable data:- Temporary Mobile Subscriber Number,- Location Area Identification- Routing Area Identification (Packet mode)

SIM-Card

G S M

Global GSM MobilityCardThe Smart Card to use

25 mm

15 mm


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Subscriber Identification

NatureInternational Mobile SubscriberIdentity

Conformity with E212

Mobile Station -Integrated Services DigitalNetwork Nb

Similar to ISDN,

Conformity with E164/E213

Nb. digits 3 2 max 10 1 to 3 2 to 4 total max 15

*This code does not identify a geographical area

but an operator

MS - ISDN

FormatMCC MNC MSIN

H1 H2 x x x ......... x x xCC NDC SN

M1 M2 x x x x x x x x

MeaningMobile

Country

Code

Mobile

Network

Code

Mobile Subscriber

Ident. Nb

H1 H2 = Identity of HLR

within the home PLMN

Country

Code

(where

subscription

has been made)

National

Destination

Code *

Mobile Subscriber

(national definition)

M1 M2 = nbr of logical HLR

IMSI

National Significant Mobile NumberIdentify a PLMN

worldwideIdentify the subscriber

of a PLMN


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Description Stored in SIM Card

MobileCountryCode

3 digits

MobileNetworkCode

2 digits

Mobile SubscriberIdentification Number (MSIN)

H1 H2 X X X X X X

10 digits max

Location Area Code

LAC

Temporary MobileSubscriberIdentity

4 octets

G S M

Global GSM MobilityCardThe Smart Card to useMCC

=

208 (France)

234 (G-B)

262 (Germany)

404,405(India)

MNC

=

71(APBSNL)

72(TNBSNL)

20 (Byte) IMSI = 15 digits max

NMSI

LAI

MobileCountryCode

3 digits

MobileNetworkCode

2 digits

Routing Area Code

RAC

RAI


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Country

Code

3 digits max

National

Destination

Code2 or 3 digits

SubscriberNumber (SN)

Roaming Number (RN)

HO-number

Must be dialed tomake a call to

mobile

subscriber

Is a PSTN-like

number to track the

MS that hands over

to another MSC

during call-in-state

Is a PSTN-likenumber used to

reach a roaming

MS

CC= 33 (France)

091(India)

001(US)

NDC = 9448(BSNL-karnataka)

9845,9880(Airtel)

9886(Hutch)

= 660, 661, 618 (Bytel)

M1 M2 X X X X X X X X X X X X X

10 digits max

Country

Code

National

Destination

Code

CountryCode

National

DestinationCode

MS-ISDN (15 digits max)

MSRN

Description Stored in the Network


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International Mobile EquipmentIdentity (IMEI)

Type Approval

Code

TAC FAC SNR SP

Final Assembly

Code

Serial number (SPare)

TYPE

APPR

OVED

IMEI: * # 0 6 #351475 60 926514 4


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MS Classmark

Revision level

RF power

Encryption algorithm

Frequency

Short message

LoCation Services

MS Positioning Method

8-PSK modulation

Multi-slot class

Multi-band

Classmark

Power classes

Class GSM400/850/900

1

2

3

45

8 W*

5 W

2 W**0.8 W

GSM1800

GSM1900

1 W**

0.25 W

4 W

1 W**

0.25 W

2 W

* Typical value for car mounted

** Typical value for handheld

Class

GSM

400/850/900

GSM

1800

GSM

1900

E1

E2

E3

2 W

0.5 W

0.2 W

1 W

0.4 W

0.16 W

1 W

0.4 W

0.16 W

For GMSK modulation

For 8-PSK modulation


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Base Transceiver Station

(BTS) Handles the radio interface to the mobile station.

Consists of one or more radio terminals for transmission

and reception

Each Radio terminal represents an RF Channel

TRX and MS communicates over Um interface

Received data transcoding

Voice encryption/decryption

Signal processing functions of the radio interface

Uplink Radio channel power measurements


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Home Location Register

(HLR) Stores user data of all Subscribers related to the

GMSC

International Mobile Subscriber Identity(IMSI)

Users telephone number (MS ISDN)

Subscription information and services

VLR address

Reference to Authentication center for key (Ki) Referred when call comes from public land network


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Visitor Location Register

(VLR) Database that contains Subscriber parameters andlocation information for all mobile subscribers

currently located in the geographical area controlled

by that VLR

Identity of Mobile Subscriber Copy of subscriber data from HLR

Generates and allocates a Temporary Mobile

Subscriber Identity(TMSI)

Location Area Code

Provides necessary data when mobile originates call


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Authentication Center (AuC)

Stores Subscriber authentication data called Ki, a

copy of which is also stored in in the SIM card

Generates security related parameters to authorize a

subscriber (SRES-Signed RESponse)

Generates unique data pattern called Cipher key (Kc)

for user data encryption

Provides triplets - RAND, SRES & Kc, to the HLR on

request.


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EIR (Equipment Identity

Register) EIR is a database that contains a list of all valid

mobile station equipment within the network, where

each mobile station is identified by its International

Mobile Equipment Identity(IMEI). EIR has three databases.,

White list - For all known,good IMEIs

Black list - For all bad or stolen handsets

Grey list - For handsets / IMEIs that areon observation


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GSM Entities and Signaling

Architecture


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GSM Protocols

CM - Connection Management

MM - Mobility Management

RR - Radio resource

LAPDm - LAPD for mobile

LAPD - Link Access Procedure for D channel

BTSM - BTS Management Part

BSSAP - BSS Application Part (BSC - MSC)

DTAP - Direct Transfer Application Part (MS - MSC)

MAP - Mobile Application Part

MTP - Message Transfer part of SS7

SCCP - Signaling Connection Control Part of SS7

TCAP - Transaction Capabilities Application Part ISUP - ISDN User Part


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Functional Plane of GSM

MS BTS BSC MSC/ HLR GMSC

VLR

MS BTS BSC MSC/VLR HLR GMSC

CC

MM

RR

Trans


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Subscriber Identity -MSISDN The MSISDN is a GSM directory number which

uniquely identifies a mobile subscription in the Public

Switched Telephone Network (PSTN).

Calls will be routed from the PSTN and other networks

based on the Mobile Subscribers MSISDN number.

MSISDN= CC + NDC + SN

CC= Country Code (91)

NDC= National Destination Code(98370)

SN= Subscriber Number (12345)


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International Mobile

Subscriber Identity [IMSI] Subscriber always identified within the GSM network

by the IMSI

This is used for all signaling in the PLMN stored in

SIM and HLR/VLR

The IMSI consists of three different parts

MCC = Mobile Country Code(3 Digits)

MNC = Mobile Network Code(2 Digits)

MSIN = Mobile Station Identification Number(Upto 10 digits)


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Temporary Mobile Subscriber

Identity [TMSI] The TMSI is used for the subscribers confidentiality.

It should be combined with the LAI to uniquely

identify a MS.

Since the TMSI has only local significance (that is,

within the MSC/VLR area), the structure may be

chosen by each administration.

The TMSI should not consist of more than four

octets.


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Mobile Station Roaming

Number[MSRN] HLR knows in what Service area the subscriber is

located.

In order to provide a temporary number to be used

for routing, the HLR requests the current MSC/VLR toallocate a Mobile Station Roaming Number(MSRN) to

the called subscriber and to return it.

At reception of the MSRN, HLR sends it to the MSC,

which now can route the call to the VLR where thecalled subscriber is currently registered.


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International Mobile

Equipment Identity [IMEI] The IMEI is used for equipment identification. An IMEI uniquely identifies a mobile station as a piece or assembly of

equipment.

IMEI = TAC + FAC + SNR + sp

TAC= Type Approval Code (6 digits),determined by GSM body

FAC= Final Assembly Code (2 digits), identifies the manufacturer

SNR= Serial Number (6 digits), uniquely identifying all equipment within

each TAC and FAC

sp = Spare for future use (1 digit)


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Location Area Identity

LAI identifies a location area which is a group of cells.. It is transmitted in the BCCH.

When the MS moves into another LA (detected by monitoring

LAI transmitted on the BCCH) it must perform a LU.

LAI = MCC + MNC + LAC

MCC= Mobile Country Code(3 digits), identifies the country

MNC= Mobile Network Code(1-2 digits), identifies the GSM-PLMN

LAC= Location Area Code, identifies a location area within a GSM

PLMN network. The maximum length of LAC is 16 bits,enabling 65536

different location areas to be defined in one GSM PLMN.

TOPICS


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TOPICS

GSM CONCEPTS



GSM CHANNELS

GSM RADIO LINK

MOBILITY MANAGEMENT

CALL MANAGEMENT



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Physical channel:One timeslot of a TDMA-frame on one carrier

is referred to as a physical channel.

There are 8 physical channels per carrier in

GSM,channel 0-7(timeslot 0-7)

Logical channel:

A great variety of information must be

transmitted between BTS and the MS,for e.g.

user data and control signaling.Depending

on the kind of information transmitted we

refer to different logical channels.These logical

channels are mapped on physical

channel.

Channel concept

L i l h l


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FCCH

Logical channelsLogical channels

Control channels Traffic channels

BCH CCCHDCCH

Half

rate

Full

rate

SCH BCCH PCH AGCH RACH SDCCH SACCHFACCHCBCH


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Broadcast channels BCH Broadcast Channel-BCH

Allotted one ARFCN & is ON all the time in every cell. Present in TS0 and

other 7 TS used by TCH.

Frequency correction channel-FCCH

To make sure this is the BCCH carrier.

Allow the MS to synchronize to the frequency. Carries a 142 bit zero sequence and repeats once in every 10 frames on the

BCH.

Synchronization Channel-SCH

This is used by the MS to synchronize to the TDMA frame structure within the

particular cell.

Listening to the SCH the MS receives the TDMA frame number and also theBSIC ( in the coded part- 39 bits).

Repeats once in every 10 frames.


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Broadcast channels BCH ... BCH

The last information the MS must receive in order to receive calls or

make calls is some information concerning the cell. This is BCCH.

This include the information of Max power allowed in the cell.

List of channels in use in the cell.

BCCH carriers for the neighboring cells,Location Area Identity etc. BCCH occupies 4 frames (normal bursts) on BCH and repeats once

every Multiframe.

This is transmitted Downlink point to multipoint.

Cell Broadcast Channel - CBCH

Used for the Transmission of generally accessible information like ShortMessage Services(SMS)


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75

Common Control Channels

CCCH CCCH- Shares TS-0 with BCH on a Multiframe.

Random access channel-RACH:

Used by Mobile Station for requesting for a channel. When the mobile

realizes it is paged it answers by requesting a signaling channel(SDCCH) on RACH. RACH is also used by the MS if it wants to

originate a call.

Initially MS doesnt know the path delay (timing advance), hence

uses a short burst (with a large guard period = 68.25 bits).

MS sends normal burst only after getting the timing advance info on

the SACCH.

It is transmitted in Uplink point to point.


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76

Common Control Channels

CCCH .. Access Grant Channel-AGCH

On request for a signaling channel by MS the network

assigns a signaling channel(SDCCH) through AGCH. AGCH

is transmitted on the downlink point to point. Paging Channel-PCH

The information on this channel is a paging message

including the MSs identity(IMSI/TMSI).This is transmitted on

Downlink, point-to-multipoint.


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77

Dedicated Control Channels-

DCCH Stand alone dedicated control

channel(SDCCH)

AGCH assigns SDCCH as signaling channel on request byMS.The MS is informed about which frequency(ARFCN) &

timeslot to use for traffic.

Used for location update, subscriber authentication, ciphering

information, equipment validation and assignment of TCH.

This is used both sides, up and Downlink point-point.


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78

Dedicated Control Channels-

DCCH Slow associated control channel-SACCH

Transmission of radio link signal measurement, power control

etc.

Average signal strengths (RXLev) and quality of service(RXQual) of the serving base station and of the neighboring

cells is sent on SACCH (on uplink).

Mobile receives information like what TX power it has to

transmit and the timing advance. It is associated with TCH or

SDCCH

Fast associated control channel-FACCH

Used for Hand over commands and during call setup and

release. FACCH data is sent over TCH with stealing flag set


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79

Traffic Channels-TCH

TCH carries the voice data.

Two blocks of 57 bits contain voice data in the normal

burst.

One TCH is allocated for every active call.

Full rate traffic channel occupies one physical

channel(one TS on a carrier) and carries voice data at

13kbps

Two half rate (6.5kbps) TCHs can share one physicalchannel.

GSM Channels


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80

GSM Channels

Control ChannelsTraffic Channels(TCHs)

Full

rate

Half

rate

Dedicated Control

Channels

(DCCHs)

SlowFast

Downlink

Broadcast

Channels

(BCHs)

Common Control

Channels

(CCCHs)

Downlink Uplink

TCH /F TCH /H FCCH SCH BCCH PCH CBCH RACHAGCH SDCCH SACCHFACCH

Traffic Multiframing Signaling Multiframing Traffic Multiframing

(down uplink)

The Logical Channels on Radio Interface


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81FACCH

BTS

0 1 2 3 4 5 6 7TS

MS

FCCH

SCH

BCCH

PCH

AGCH

CBCH

SDCCH

SACCH

TCH

TCH

FACCH

SDCCHSACCH

FCCH

SCH

BCCH

RACH

PCH

AGCH

RACH

CBCH

Synchronization

Frequency correction

Broadcast control

Access request

Subscriber paging

Answer to Access request

Broadcast info

Dedicated Signaling

Sys Info 5, 6 + SMS

Traffic (speech data)

Associated Signaling

Associated Signaling

Traffic (speech-data)

Radio Measurement + SMS

Dedicated Signaling

Broadcast info

M.S. Pre-synchronization

Access request

Subscriber paging

Answer to Access request

e og ca C a e s o ad o e ace

Logical Channel Description (1/2)


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82

FACCH MESSAGES Connection establishment from

SDCCH to TCH

End validation of a SDCCH-TCH

commutation

Characteristics of the future used BS

after handover

Connection establishment to BS after

handover

Validation of an handover

SACCH MESSAGES

Measures:

-power level of the communication-quality level of the communication

- level on the beacon frequency ofthe neighboring cells

Timing Advance

Power Control

SMS

TCH MESSAGES

Speech Data

Handover Access message (uplink)

SDCCH MESSAGES

Request for a SDCCH assignment

Request for the end of channelassignment

Order of commutation from SDCCH to

TCH

SMS

Logical Channel Description (2/2)


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83

FCCH MESSAGES

no message is sent (all bits 0)

BCCH MESSAGES

System Information type 1, 2, 2bis ,

2ter, 3, 4, 7, 8

(idle mode)

SCH MESSAGES

Frame Number

Base Station Identity Code (BSIC)

AGCH MESSAGES

For dedicated channel assignment:

- frequency number

-slot number- frequency hopping description-Timing Advance (1st estimation)-MS identification

PCH MESSAGES

messages containing a mobile

identity for a call, a short message

or an authentication

RACH MESSAGES

Service request:

-emergency call-answer to an incoming call-outgoing call-short message-call re-establishment- inscription

CBCH MESSAGES

Specific information

(weather, road information

g p


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System Information


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85

RACH Control parameters

- maxNumberRetransmission- numberOfSlotsSpreadTrans- cellBarred- callReestablishment- emergencyCallRestricted- notAllowedAccessClasses- AccessClassCongestion

BCCH allocation - Neighboring cells BCCHfrequencies in the same band

Extended BCCH allocation

- Neighboring cells BCCH frequencies inthe same band (complementary list)

- Neighboring cells BCCH frequencies inthe other band

- 2 ter indicator

- 5 ter indicator

LAI- Location Area Code- Mobile Country Code- Mobile Network Code

- cellIidentity

SYS INFO 1-4

SYS INFO 2/5

SYS INFO 2bis/5bi

SYS INFO 2ter/5te

SYS INFO 3-4/6

V10

System Information

SYS INFO: Parameters (1/2)

SYS INFO 3

SYS INFO 6

Cell Identity SYS INFO 3/6

System Information


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86

Control Channel description- IMSI Attach Detach- noOfBlocksForAccessGrant- No Of Multiframe Between Paging

Cell Options

- Uplink Power Control- Dtx Mode (UL)- CellDtx Downlink (DL)

- Radio Link Timeout

Cell Selection Parameters- cellReselectHysteresis- msTxPwrMaxCCH- rxLevAccessMin

Cell Reselection Parameters

- cellReselInd- cellBarQualify- cellReselectOffset- temporaryOffset- penaltyTime- earlyClassmarkSending- power offset

SYS INFO 3

SYS INFO 3-4

SYS INFO 3-4or 7-8

SYS INFO 3

System Information SYS INFO: Parameters (2/2)

V10

Traffic and Control Multiframing


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87

0 1 2 3 4 21 22 23 24 25 0 1 2 3 4 46 47 48 49 50

26 traffic frames = 120 ms

1 Hyperframe = 2,715,648 frames= 3h 28 min. 53 s 760 ms

0 1 2 3 5 2042 2043 2044 2045 2046 20474

1326

frames

0 1 2 3

46 47 48 49 500 1 3 42

22 23 2524

TS

0

TS

1

TS

2

TS

3

TS

5

TS

6

TS

7

TS

0

TS

1

TS

2

TS

3

TS

4

TS

5

TS

6

TS

7

TS

0

TS

1

TS

2

TS

3

TS

4

TS

5

TS

6

TS

7

TS

4

TS

0

TS

1

TS

2

TS

3

TS

4

TS

5

TS

6

TS

7

TS

0

TS

1

TS

2

TS

3

TS

4

TS

5

TS

6

TS

7

Frame

4.615 ms

Control channelTraffic channel

51 x 26 traffic frames = 6.12 s

26 x 51 control frames = 6.12 s


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88


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89


90/179


91/179


92/179


93/179


94/179

94


95/179

TOPICS


96/179

96

GSM CONCEPTS



GSM CHANNELS

GSM RADIO LINK MOBILITY MANAGEMENT

CALL MANAGEMENT


Speech

From Speech to Radio Transmission


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97

Speech

Source

decoding

Channeldecoding

De-interleaving

Burst de-formatting

Deciphering

Demodulation

equalization

Digitizing and

source coding

Channel

coding

Modulation

Ciphering

Burst formatting

Interleaving

Step 1

Step 2

Step 3

Step 4

Transmission

Step 5

Step 6 Diversity

GSM R di Li k


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98

GSM Radio Link

Speech Coding -Done at Transcoder of BSC and MS

The Linear Predictive Coder uses RPE-LTP(Regular Pulse

Excitation- Long Term Prediction)

Converts 64kbps voice to 13kbps(260 bits every 20ms) Channel Coding - Done at BTS and MS

Uses Convolution Coding and CRC (Cyclic Redundancy

Check)

Converts 13 kbps to 22.8 kbps (456 bits per 20ms)


99/179


100/179

Speech Quality Source Coding


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101

Codec Type Mean Opinion Score Rate (kb/s)

(MOS)

PCM A law 4.25 64

GSM EFR 4.2 12.2

CDMA 13 4.2 13

D-AMPS 4 8

GSM FR 3.8 13

CDMA 8 3.4 8

Quality MOS Listening Effort Required

Excellent 5 Complete relaxation possible, no effort.

Good 4 Attention necessary, no appreciable effort.

Fair 3 Moderate effort.

Poor 2 Considerable effort.

Bad 1 No meaning understood with feasible effort.


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Channel Processing in GSM


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103

C

20 ms20 ms

A

A8

A7

A6

A5

B4

B3

B2

B1

B8

B7

B6

B5

C4

C3

C2

C1

57 bits

Information

1 1

CRL CRL

3 3

Tail Tail

26 bits

Training

8 Bursts

8 Sub blocks

of 57 bits

Source coding

Channel coding

Interleaving

Normalburst

20 ms

B

456 bitsA 456 bitsB 456 bitsC

57 bits

Information

A8B4A7B3A6B2A5B1 B8C4B7C3B6C2B5C1

Speech blocks

Codec dependent Codec dependentCodec dependent

Overview for Full Rate


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104

Channel Processing in GSMO verview f or Half Rate


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105

C

20 ms20 ms

A

A4

A3

A2

A1

B2

B1

B4

B3

C4

C3

C2

C1

4 Bursts

4 Sub blocks

of 57 bits

Source coding

Channel coding

Interleaving

20 ms

B

228 bitsA 228 bitsB 228 bitsC

A4B2

A3B1

B4C2

B3C1

Speech blocks

Codec dependent Codec dependentCodec dependent

Normalburst 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

456

Interleaving: TCH Full Rate


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106

0 1 2 3 4 5 6 7 8 ... ... 452 453 454 455

0 1 2 3 4 5 6 78 9 10 11 12 13 14 15

448 449 450 451 452 453 454 455

57Rows

Divide 456 bits in 8 sub-blocks

765432107654 0 1 2 3

reordering&

partitioningout

diagonalinterleaving

456coded bits

burst

b0 b1 b56 b1 b56b0

bitinterleaving

Burst FormattingN l B


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107

1 frame:4.615 ms

0 1 2 3 4 5 6 7

Guard

157 126 57

DATA

156.25 bits duration

(0.577 ms)

Training

sequence

33

DATA

8.25

S SGuard

Band

Burst

148 bits

Normal Burst

Burst Formats


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108

Synchronization Burst

(SCH)

Tail Data Extended Training Sequence Data Tail


(0.577 ms)

3 bits 39 encrypted bits 64 synchronization bits 39 bits 3 bits 8.25 bits

Guard

Period

Frequency Correction Burst

(FCCH)

Tail Data Tail


(0.577 ms)

3 bits 142 fixed bits (0) 3 bits 8.25 bits

Guard

Period

Normal Burst

Burst Formats


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109

Access Burst

Tail TrainingSequence Guard PeriodTail

156.25 bits (0.577 ms)

8 bits 36 encrypted bits 68.25 bits3 bits41 synch bits

Data

Dummy Burst

Tail Dummy Sequence Training Sequence Dummy Sequence Tail

3 bits 58 mixed bits 26 midamble bits 58 mixed bits 3 bits 8.25 bits

Guard

Period

156.25 bits (0.577 ms)

156.25 bits (0.577 ms)

13 bits 57 encrypted bits 1 26 bits 57 encrypted bits 3 bits 8.25 bits

Tail Data Training Sequence Data Tail Guard

Period

Normal Burst


110/179


111/179


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112

Burst The information format transmitted during one

timeslot in the TDMA frame is called a burst.

Different Types of Bursts

Normal Burst

Random Access Burst Frequency Correction Burst



113/179

T Training Sequence Coded Data T GP

156.25 bits 0.577 ms


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114

T

3

Training Sequence

41

Coded Data

36

T

3

GP

68.25

Random Access Burst

T

3

Fixed Bit Sequence

142

T

3

GP

8.25

T

3

Coded Data

39

Training Sequence

64

Coded

Data 39

T

3

GP

8.25

Freq. Correc. Burst


156.25 bits 0.577 ms

156.25 bits 0.577 ms

Transmission on the

di h l


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115

radio channels A timeslot has a duration of .577 m seconds (148 Bits) 8 timeslots(8 x 0.577 = 4.62 ms) form a TDMA frame If a mobile is assigned one TS it transmits only in this time

slot and stays idle for the other 7 with its transmitter off, called

bursting

The start on the uplink is delayed from downlink by 3 TSperiods One TS = duration of 156.25 bits, and its physical contents is called a burst

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

DownlinkBTS > MS

UplinkMS > BTS

Offset


116/179

Frames Types On Um


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117

Interface TDMA Frame

8 Time slots (Burst Period)

Length is 4.62 ms(8 * 0.577ms)

26-TDMA Multiframe

26 TDMA Frames (24 TCH, SACCH, Idle)

120 ms (26 * 4.62ms)

51-TDMA Multiframe

26 TDMA Frames (FCCH, SCH, BCCH, SDCCH, CCCH)

235.6 ms (51 * 4.62ms)

Frames Types On Um


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118

Frames Types On Um

Interface Super Frame 51* 26 TDMA Frames

6.12 S

Hyper Frame 2048 * 51* 26 TDMA Frames

3 Hours, 28 Minutes, 53 Secs and 760 ms


119/179

M bilit M t


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120

Mobility Management

Mobility Management (MM)

Location updating- normal,periodic, IMSI attach

Paging

Security Management Preventing unauthorized users- authentication

Maintaining Privacy of users- ciphering

Providing roaming facility

MM functionality mainly handled by MS, HLR,MSC/VLR.

Network Attachment


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121

Cell Identification MS scans complete GSM frequency band for

highest power

Tunes to highest powered frequency and looks

for FCCH. Synchronizes in frequency domain

Get training sequence from SCH which followsFCCH. Synchronizes in time domain.

Accesses BCCH for network id, location area and

frequencies of the neighboring cells.

Stores a list of 30 BCCH channels

N t k Att h t


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122

Network Attachment.. PLMN Selection

Get the operator information from SIM.

Cell Selection

Selected cell should be a cell of the selected PLMN

Signal strength should be above the threshold. Cell should not be barred

Location Update

Register with the network by means of location

updating procedures.

S it A th ti ti


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123

Security - Authentication

Authentication center

provides RAND to Mobile

AuC generates SRES using

Ki of subscriber and RANDMobile generates SRES

using Ki and RAND

Mobile transmits SRES to

BTS

BTS compares receivedSRES with one generated

by AuC

MSKi RAND

A3

SRES

RAND

SRES

SRES

Auth Result

AuCBTSMS

S it Ci h i


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124

Security - Ciphering

Data sent on air

interface ciphered

for securityA5 and A8

algorithms used to

cipher data

Ciphering Key isnever transmitted

on air

MSKi RAND

A8

Kc

MS Network

Um interface

A5 A5

Kc Kc

Data DataCipheredData

TOPICS


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125

GSM CONCEPTS

GSM SYSTEM ARCHITECTURE IDENTITIES USED IN GSM

GSM CHANNELS


CALL MANAGEMENT


Communication Management


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126

Co u cat o a age e t

(CM) Setup of calls between users on request Routing function i.e. Choice of transmission

segments linking users

Point to Point Short message services


127/179

PLMN Selection


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128

No

automaticmode

The MS selects the firstPLMN from the preferredPLMNs list (if it is not in

the forbidden PLMNs list)

The user selects aPLMN from the

displayed PLMNs

manualmode

YesYes

Creation of a foundPLMN list

Is there an up to datefound PLMNs list?

End of PLMNselection

YesNo (automatic)

Cell Selectionsucceed?

Selection of thenext preferredpossible PLMN

No (manual)

PLMN Selection Constitution of the "Found PLMN list"


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129

Listen to all the

frequencies of the GSMspectrum:power level measurement

and average on thesemeasurements

Select the best

frequenciesaccording to the

power level

(124 channels in GSM900, 374 in GSM 1800and 299 in GSM 1900

(30 in GSM 900 and 40 in GSM 1800)

Memorize thebeacon

frequencies in the

precedentselection

=> Create theFound PLMN list

Constitution of the Found PLMN list

List of the

Initial Cell Selection


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130

Suitable cell:

- cell of the selected PLMN- cell not barred- C1 > 0

Eligible cell

List of thefrequencies of the

selected PLMN

IMSI Attach

Look for the cell with the bestC1 in the suitable cells list

Eligible cell?

Yes

Selection ofanother PLMN

No

C1 Computation for

eligible cells

Suitable cell?

Yes

No

Rejected?

Yes

PLMN set in theforbiddenPLMN list

End of Cell Selection

No

Cell Selection


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131

BTS-2

BTS-1

This cell

BTS-3

BTS-4

BTS-5

1

1

1

1

2

3

45

Purpose: get synchronization

with the GSM network

prior establishing any communication.

FCCH

SCH

BCCH

1

Immediate AssignmentMS BSC MSC

BTS


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132

MS BSC MSC

CM SERVICE REQUEST

SDCCH or TCH6

CHANNEL REQUEST

RACH

1

BTS

CHANNEL REQUIRED2

CHANNEL ACTIVATION3

IMMEDIATE ASSIGNMENTAGCH

5IMMEDIATE ASSIGNMENTCOMMAND5

CHANNEL ACTIVATION

ACK.4

Immediate

Assignment

LOCATION UPDAT. REQU.

SDCCH or TCH6

OR

Registration: the Very FirstLocation Update


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133

LAI HLR

IMSI

VLR id

TMSI

IMSI

TMSI

Release

VLR

IMSI

TMSI

LAI

MSC

BTS

BSS

BSC

2

4

5

2

6

1

2

4

5

6

3

4TMSI

5


134/179


135/179

IMSI Attach


136/179

136

MSCBTS

BSS

BSC

VLR

3

4

5

4

6

1 CHANNELREQUEST

2IMMEDIATEASSIGNMENT

LOCATION UPDATING

REQUEST (IMSI Attach)3

5LOCATION UPDATING

ACCEPT (LAC, TMSI)

4Authentication

Procedure


137/179

Great Britain France Germany

Outgoing Call


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138

FT

y

Telephone

network

Terminating

MSCBSC

BTS

BSS

VLR

Gateway

MSC

HLR

MS BSS MSC

PSTN

Mobile Originating Call


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139

ACM = Address Complete Message

ANM = ANswerMessage

IAM = Initial Address Message

MS SC

CHANNEL REQUEST1

CM SERVICE REQUEST2 CM SERVICE REQUEST2

CALL PROCEEDING7CALL PROCEEDING

7

Assignmentprocedure7

IAM6

IMMEDIATE ASSIGNMENT2

ACM8

VLR

Ring

ANM10

ALERTING9

SETUP (basic) orEMERGENCY

4 SETUP4

CONNECT11

CONNECT ACKnowledge11

Authentication procedure3

Cipheringprocedure3

5

Dialing

RingingPath

Established

Ringing

SendingNumber

Mobile Terminating Call1 - Paging Principle


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140

PSTN

LA1

LA2

BTS11

BTS21

BTS22

BTS31

BTS12

BTS23

HLR

4

3

5

1

2

5

6

6

BSC1

BSC2

BSC3

MSC/

VLRGMSC

Mobile Terminating Call2 - Detailed Procedure


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141

VMSCBSS

VLR

Visitor PLMN

GMSC

HLR

Home PLMN

RoutingInformation

(MSRN)

6

IAM : Initial Address Message

MSISDN : Mobile Station Integrated Services Digital

network Number

MSRN : Mobile Station Roaming Number

IMSI : International Mobile SubscriberIdentity

GMSC : Gateway MSC

VMSC : VisitorMSC

TMSI : Temporary Mobile SubscriberIdentity

PN

InternationalSS7

ISDNIAM (MSRN)

7IAM

(MSISDN)2

Send

RoutingInformation

(MSISDN)

3

Provide Roaming Number

(IMSI)4

PAGE

(TMSI + LA)

9

Send infoto I/C

(MSRN)

8

Roaming Number

(MSRN)5

PAGINGREQUEST

(TMSI + LA)10

PAGING

REQUEST

(TMSI)

11

MSISDN

1

Mobile Terminating Call3 - End to End Procedure


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142

MS BSS VMSC

CHANNEL REQUEST(LAC, Cell ID)

5

PSTN

IMMEDIATE ASSIGNMENT

(SDCCH or TCH)

6

PAGING REQUEST4

PAGING REQUEST

(TMSI or IMSI, LA)3

GMSC

IAM(MSISDN)

1IAM

(MSRN)2

CM SERVICE REQUEST

(Paging Response)7 PAGING RESPONSE

(TMSI or IMSI, LA)7

Authentication procedure8

Cipheringprocedure9

Address Complete Message11

ANswer Message12

Setup, Assignment, Alerting10

CONNECT12

Dialing

Ringing

PathEstablished

Call Release1 - Mobile Initiated


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143

MS BSS MSC

Call in progress1

RELEASE COMPLETE4

PSTN

DISCONNECT2 DISCONNECT

2

RELEASE3RELEASE

3

RF Channel Releaseprocedure 8

Release5

RELEASE INDICATION7

CHANNEL RELEASE6

Releasetone

9

Call Release2 - PSTN Initiated


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144

PSTN

On hook

Purpose:

informs the mobile

then releases radio

and network resources.

REL

RLC

MSC

BTS

BSS

BSC

1

1 1

12

33

4

55

4

6

2

Mobile Originated Call


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145

Mobile Originated Call

Request for Service

Authentication

Ciphering

Equipment Validation

Call Setup

Handovers

Call Release


146/179


147/179

TOPICS

GSM CONCEPTS


148/179

148

GSM CONCEPTS

GSM SYSTEM ARCHITECTURE IDENTITIES USED IN GSM

GSM CHANNELS


CALL MANAGEMENT


Radio Resource Management


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149


Establish maintain and release stable connections

between MS and MSC

Manage Limited Radio and Terrestrial resources

Handover process is the sole responsibility of the RRLayer

Functions of RR layer are performed by MS and BSC

and partly by MSC



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150


Power Control

Hand over Control

Discontinuous Transmission

Frequency Hopping

P C t l


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151

BTS commands MS at different

distances to use different power levels

so that the power arriving at the BTSs Rx is

approximately the same for each TS

- Reduce interference

- Longer battery life

Power Control

Handover


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152

Handover

Means to continue a call even a mobile crossesthe border of one cell to another

Procedure which made the mobile station really

roam

Handover causesRxLev (Signal strength , uplink or downlink)

RxQual (BER on data)

O & M intervention

Timing AdvanceTraffic or Load balancing

Handover Types


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153

Handover Types

Internal Handover (Intra-BSS)

Within same base station - intra cell

Between different base stations - inter cell

External Handover (Inter-BSS)

Within same MSC -intra MSC

Between different MSCs - inter-MSC

Handover Types

MSCGMSC


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154

BSC

BSC

BSC

BSC

MSC

MSC

C-1 C-2

C-3

C-4


155/179


156/179

Frequency Hopping


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157

Frequency Hopping Frequency Hopping permits the dynamic switching of radio links from

one carrier frequency to another.

Base Band Hopping

At the BTS each the timeslot is shifted to another transceiver, which

is transmitting at the hop frequency. User will be connected to

different Transceivers depending on hop sequence.

Synthesis Hopping

At the BTS transceiver changes the frequencies used. The user will

be connected to only one transceiver.

Decreases the probability of interference

Suppresses the effect of Rayleigh fading

Wireless Data

Add-on to GSM network :

PCU; Packet Segmentation/re-assembly and scheduling Radio channel access control and management Transmission error detection and retransmission. Power control

S rf the Internet hile on the mo e

Enhanced Data rate for GSM Evolution EDGE is an enhancement of GPRS and CSD technologies. Based on the current GSM technology - same TDMA frame

structure, same bandwidth (200 kHz). Uses 8-PSK modulation instead of GMSK

Universal Mobile Telecommunication Standards Innovative Service Architecture : VHE Concept - providing the us

the same look and feel of its personalized services independent of


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158

Wireless Data

98 99 2000 2001

GSM

DATAGSM

DATA

HSCSDHSCSD

GPRSGPRS

EDGEEDGE

UMTSUMTS

SIM

ToolkitSIM

Toolkit

WAPWAP

Data Application

Time

Circuit Switched technology

Packet Switched technology

Technology for Applications

SMS Data: 160 -numeric charactersUser Data Rate : 9.6kbps

One time slot over the air interface

High Speed Circuit Switched Data

User Data Rate:14.5kbps

Use multiple timeslots (max=8),hence max rate = 115.2kbps.

Needs a duplexor in MS for

simultaneous Tx and Rx

SGSN: GPRS mobility Encryption

ChargingGGSN : Interface to the PDN, Internet

Max user data rate : 21.4 kbps

Dynamic rate adaptation to suit the radio conditions at

that time ( 9.05 kbps, 13.4 kbps, 15.6 kbps 21.4 kbps)

W@P Gateway W@P ServiceW

@

P

F

o

n

e

InternetMobile Network

Surf the Internet while on the move

W@P Gateway : Adaptation of the information to the mobile Compression of the data Buffering of the information

Uses 8 PSK modulation instead of GMSK. Requires good propagation conditions. Allows upto 48 kbps (EGPRS) and upto 28.8 kbps (ECSD) on every

radio channel EDGE helps GSM-Only operators to compete with UMTS.

p p

network and terminal. Global Convergence : Fixed/Mobile, Telecom/Datacom, public/private

Mobile Multimedia driven market. Wideband bearers - 2GHz band ( 5 MHz per carrier), -max. 2Mbps

References


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159

References

Wireless and Personal Communication Systems.Vijay.K.Garg and Wilkes

Overview of the GSM System and Protocol

Architecture, IEEE Comm. Magazine, Moe Rahnema.

The GSM System for Mobile Communications- Michel

Mouly & Marie-Bernadette Pautet

Overview of the GSM Comm- John Scourias.

Coverage or Traffic LimitationsTRAFFIC-

LIMITED

AREA COVERAGE-


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AREA

(10000

subscribersper km2)

COVERAGE-

LIMITED

AREA

(-75 dBmat cell edge)

COVERAGE-LIMITED

AREA

(-70 dBm

at cell edge)


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Different Types of CellsEXTENDED-CELL:

macro cell with system coverage

CONCENTRIC-CELL:

macro cell with system coverage


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High sensitivity tointerference

Requires "secured"Frequency reuse pattern

High isolation frominterferences

A few Frequenciesintensively reused

MACRO-CELL:antenna radiating above roofs

---> Wide Coverage ( 35 km)

MICRO-CELL:

Antenna below the roofs

---> small coverage

PICO-CELL:

Antenna inside building

---> Very small coverage

extension ( 120 km) for coasts... limitation inside another macro


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Cell Sectorization


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TRI OMNI BI

Omni directional Site Antennas


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165

Bi and Trisectorial Site Antennas


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Link Budgeting


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Calculation of the maximum coverage range of each cell in a specific environment.

Definition of planning tools parameters.

Based on the path loss calculation between the MS and the BS in both ways.

This calculation considers:

RF parameters of MS and BS,

system parameters (diversity gains...),

propagation parameters (shadowing), physical installation parameters (antenna height),

environment classification.


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- What is the maximum EIRP?

- What are the losses intransmission and reception?

- Is diversity used? - What is the minimumequivalent sensitivity?

- What is the maximumequivalent output power?

- What are the body losses?

- Beyond which distance the

communication will cut off?- Is indoor coverage

guaranteed?

- Is frequency hopping used?

EIRP:Equivalent Isotropic Radiated Power

Link Budget Parameters Overview


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Duplexer

Combiner

Power Amplifier

DLNA:Diversity Low Noise Amplifier

Specific Tx Cable

Losses

Tx PA Output

Power

Combiner losses

Rx Sensitivity

Rx Diversity Gain

DLNA conf.Standard conf.

Base Station

Tx PA Output Power

Other factors for MSBody LossesCommon cable losses

Propagation Parameters:

- Incar, Indoor penetration factors- Frequency 900, 1800, 1900 MHz

- Antenna Height

- Environment

Design Parameters:

Overlapping margin

Rx Sensitivity

Antenna Gain

MS

Rx Sensitivity

Common cable Losses

Antenna Gain

Radio Link

Link Budget Parameters BTS TX Power Amplifier


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2.5W PA 25W PA 35W PA 20W PA 30W PA

GSM 900 S2000LS2000E

S4000 Indoor

S4000 Outdoor

S4000 Indoor S2000HS8000 Indoor

S8000 Outdoor

DCS 1800 S2000L S4000 IndoorS2000E

S2000H

S4000 Outdoor

S4000 Indoor

S8000 Indoor

S8000 Outdoor

PCS 1900 S2000L

S2000E

S2000H

S4000 Indoor

S4000 Outdoor

S8000 Outdoor

Link Budget Parameters Combiners


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D

H2D

Hy/2

2-Way Hybrid Combiner with Duplexer2-Way Hybrid Combiner with Duplexer

4.5 dB Loss4.5 dB Loss

allows Synthesized Frequency Hopping

4-Way Cavity Combiner with

Duplexer

4-Way Cavity Combiner withDuplexer

allows Baseband Frequency Hopping

4.9 dB Loss4.9 dB Loss

C C C C

D

TX TX TX TXTXTX

Link Budget Parameters Cable Losses


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At the BS, for a 7/8 foam dielectric coaxial cable:

4 dB/100 m (900 MHz),

6 dB/100 m (1800 MHz),

Common cable losses for 40 meters: 2.5 dB (900 MHz) and 3.5 dB (1800 MHz).

Jumpers (up and down the feeder)

0.5 dB (800 MHz),

1 dB (1800 MHz).

Link Budget Parameters BTS Antenna Gain


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Omnidirectional antenna

Default 6.5 V with 11 dBi gain

Directional antenna for trisectorial site

Default 65 H / 6.5 V with 18 dBi gain

Link Budget Parameters Mobile Station Parameters


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900 MHz 1800/1900 MHz

TX PA Output

Power33 dBm (2W) 30 dBm (1W)

RX Sensitivity -102 dBm

-2 dBi for Handheld

2 dBi for Car Kit

Body Loss

Antenna Gain

Common CableLoss

-100 dBm

0 dB for Handheld2 dB for Car Kit

3 dB for Handheld

0 dB for Car Kit

Link Budget PresentationParameters

Frequency 1800 MHzAntenna Gain (65 )

18 dBi


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Base Height 40.0 m

Mobile Height 1.5 m

Environment Urban

RX TX

Mobile

Antenna Gain-2 dB

Cable Loss0 dB

Output Power

Sensitivity

-100 dBm

30 dBm

Jumper Loss

Feeder Loss

Sensitivity

-110 dBm

3 dB

Options

Rx Diversity Gain: 5 dB

Overlapping Margin: 0 dB

Penetration Factor

Body Loss 3 dB

15 dB

Outdoor Minimum Field

95%: -80 dBm

Coverage Range

95%: 810 m

0.5 dB

Base Station

Max TX Output Power

RXm RXd

44.8 dBm

Coupling system

TX loss4.5 dB

Link Budget Calculation

Exercise 1 : S8000 INDOOR: OPERATING FREQUENCY 1800 MHz


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BTS M STX OUTPUT POWER 30.00 W (44.8

dBm)

1.00 W (30.0 dBm)

COMBINER LOSSES 5.0 dB None

RX SENSITIVITY -110.0 dBm -102.0 dBm

RX SENSITIVITY +

DIVERSITY

-115.0 dBm None

COMMON CABLE LOSSES 3.0 dB 0.0 dB

ANTENNA GAIN 18.0 dBm -2.0 dBm

BODY LOSSES 3.0 dB

OVERLAPPING MARGIN 0.0 dB

INDOOR PENETRATION

FACTOR

18.0 dB

FadingExample of Field Strength Variation for GSM 1800


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-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Distance (m)

FieldStrength

(dBm)

Measurement

Free Space

Zoom on

Short Term Fading

Long Term Fading

2 m

/2

Clutters


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basic of gsm

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