1) Mobile Int Gr B.

8/11/2019 1) Mobile Int Gr B.

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MOBILECOMMUNICATION

T15

PREPARED BY

VIVEK CHAKRAVERTY

APT


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EMERGENCY COMMUNICATION -

PRESENT STATUS


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Emergency Communication is provid

portable control phones (PCPs) using

following means:

a) Hooking on the overhead control ali

in non-RE area;

b) Provision of emergency sockets in RE a


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DISADVANTAGES(a) The Driver/Guard have to carry the cumbersome telescopi

masts and the PCP sets;

(b) Hooking up of the telescopic mast on the overhead alignme

procedure;

(c) In some cases, overhead alignment may be far away from th

track.

(d) In RE area, Driver and Guard have to walk about 50

establishing emergency communication.

(e) The emergency sockets and posts are prone to vandalism


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(f) Emergency communication is initiated only from the site of em

driver /guard of the affected train.

(g) The Section Controller/Emergency Controller is not able to

train crew in moving conditions.

(h) The emergency communication is initiated only in static co

the trains come to a halt and not in mobile conditions.

(i) All emergency calls are directed to the Control office and no

Station Master.

(j) SOS facility is not available.

(k) The weight of the Emergency Control phones is fairly heavy.


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PRESENT STATUS

After the GAISAL Accident in 1999, Board have taken a decision to

duplex Mobile Train Radio Communication on A, B & C route

Railways. It has also been decided to provide Universal Communication on D, D (Spl.), E & E (Spl.) routes.

The following factors should be considered so that deficiencies/sh

are taken care of :

a) Technology based on open/standard architecture should be sele

the system can be seamlessly extended and multi vendor sources a

b) Loco equipment should be made an integral part of the loco at

manufacturing itself


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c) The practice of loading and removal of loco equipment should b

d) Adequate number of mobile equipment should be catered fo

the communication requirements are catered for.

e) The backbone communication whether Radio or Optical Fibre b

be reliable and cover the entire run with no dark zones.

f) With the introduction of Radio based Signaling, the system shou

capability of integrating both the Signaling and Telecom

applications.

g) The system should be based on digital technology.

h) Communication to passengers on the trains should also be cat

system.


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Vide RB letter No.95/Tele/MW/5/ Pt. New De

10.09.1999, Board had decided that Mobile T

Communication (MTRC) system may be provided on

Croutes.

Proposal was during Works Programme 2000-2001.


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GSM based MTRC system is being introduced on A,B,C

IR for communication between train crew and

operating staff such as station masters, controllers, m

staff etc.

Work for over 3200 route kilometers have been san

Northern, North Central, Eastern , East Central and

Frontier Railways


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This system has been successfully commissioned o

Pradhankunta (260 RKMs) and Mathura-Jhansi (270 R

Installation of the system on Delhi-Ambala (198 RKM

completed and it is being commissioned.

Guwahati - New Bogaigaon - Katihar/Malda Town (68

Northeast Frontier Railway has been completed and

satisfactorily


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VERY HIGH FREQUENCY

COMMUNICATION


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The frequency band of VHF Communication

300 MHz. The frequency allotted by WPC

Planning and Coordination wing of m

communication) in VHF for Indian Railways band 146 to 174 MHz.

One spot frequency is used for each channe


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Communication during Maintenance andConstructional Blocks

Yard communicationCommunication in the train between Guard

Mobile Communication between moving trai

with fixed location (Station) or another movin

vehicle.Emergency Communication

ART equipped with hand held and base stat

VHF sets.


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Simplex--- One way radio communication

trans or receiveHalf-duplex---Both way radio communicatio

can trans and receive but one

(because the same frequency

for both trans and receive)

Full Duplex--- Both way radio communicatio

simultaneously. (Trans and re

frequencies are different)


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Modes of Propagation:

Line of sight waves,Reflection & scattering of waves

Channel capacity:

Single channel/Four channel/Sixteen chafor Voice or Low speed Data or both.


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. TYPES OF EQUIPMENT

Walkie -Talkie ( Hand Held) Set - 1W/2W/ 5W

Mobile Sets

Output power is 25 Watt,

Operates on 12V battery

Base Station

Installed at desired location,

Operating on AC Mains or by 12V battery


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External antenna with feeder cable connector moun

mast (Roof top) needed

Antennas used are

Whip Antenna for portable sets,

Ground Plane (GP) Antenna for base radio e

Feeder cable: 50 Ohms Unbalanced Coaxial cable

Antennas


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Depends upon terrain.

Average range of a

Walkie -Talkie (Hand Held set) - 1 to 2 km

Mobile Set- Upto 15 kmBase Station - upto 50 Kms. When antenn

are directional & fixed at the height of 15 t

COMMUNICATION RANGE

S.No. Frequency SM at Station to Driver & Shunting Engineering Electrical S&T deptt. Commercial RPF Mechanical


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in MHz all stns. LC gate Guard/Operating

deptt. deptt. deptt. deptt.

1 146.400 X Security D

2 147.975 ART Frequency Accident S

3 148.100 X Mechanica

4 149.750 X Engineeri

5 150.100 XC F1 for PL

6 150.150 XC F2 for PL

7 159.600 XC F3 for PL

8 159.650 X S&T Depar

9 159.700 XC XC Communic

10 160.400 X X X X X X X X Common F

11 160.550 XE XE Train Esco

12 161.150 X X Driver & G

13 161.425 X Electrical D

14 162.100 X X Shunting &

15 146.200 XC F4 for PL

16 148.050 XC F5 for PL

17 149.500 XC F6 for PL

18 149.550 XC F7 for PL

19 151.400 XC F8 for PL

20 151.450 XC F9 for PL

Note:

X - Channel programmed

XC - Channel programmed with CTCSS/MF coding.

XE - For Train duties only.

LIMITATIONS OF VHF COMMUNICATION


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LIMITATIONS OF VHF COMMUNICATION

-Short distance coverage

-Blank Zones occur due to terrain, high rise buildings & other

-Simplex/Half Duplex mode of working

-Maintenance of rechargeable batteries

-The set requires more than one battery set for continuous op

-Interference due to other user having adjacent frequencies.

-Effect of prevailing noise in the surrounding


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GSMHistory


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Compatibility

Noise Robust

Increased Capacity & Flexibility

Use of Standard Open Interfaces

Improved Security & Confidentiality

Cleaner Handovers

Subscriber Identification

ISDN Compatibility

Enhanced Range of Services

Development of the GSM Standar


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Development of the GSM Standar

1982: Groupe Spcial Mobile (GSM)

created

1984: Description of GSM features

1985: List of recommendations settled

1987: Initial MoU (Memorandum of

Understanding) aside the drafting of

technical specifications was signed by

network operators of 13 countries:

1988: Validation and trials, of the radiointerface.

1991: First system trials are demonstrated at

the Telecom 91 exhibition.

1992: Official commerc

service in Europ

Finland

1993: The GSM-MoU hin 39 countries w

1800

network launched

1995: Specifications of G

are frozen. First G

network launched

1999: GSM MoU joins 3GPRS Trials beg

2000: 480M GSM subsc

First GPRS Netw

End 2002: 792M GSM subWorldwide


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GSM-900 (Channels 125 operating band

carrier spacing 200khz spacing 45Mhz)

GSM -1800 (Channels 374 spacing 95Mhz)

GSM -1900(Used in USA)

What are the types in GSM Network?

Different Standards Worldwide


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GSM - 900

The term GSM-900 is used for any GSM system which operates in any 900 MHz band.

P-GSM - 900

P-GSM-900 band is the primary band for GSM-900 Frequency band for primary GSM-900 (P-GSM-900)

890 915 MHz for MS to BTS (uplink)

935 960 MHz for BTS to MS (downlink)

E-GSM - 900

In some countries, GSM-900 is allowed to operate in part or in all of the following extension band. E-G

900) band includes the primary band (P-GSM-900)andthe extension band :



R-GSM-900

R-GSM-900 (Railway GSM-900) band includes the primary band (P-GSM-900) and the following extens



Carrier frequency = ARFCN=Absolute Radio Frequency Channel Nu


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Ful(n) = 890.0 + (0.2) *n MHz

Fdl(n) = Ful + 45 MHz

where n =ARFCN ; 1 n 124


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RF CONCEPTS

F S


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Frequency Spectrum

Designation Abbreviation FrequenciesFree-spWavelen

Very Low Frequency VLF 9 kHz - 30 kHz 33 km -

Low Frequency LF 30 kHz - 300 kHz 10 km -

Medium Frequency MF 300 kHz - 3 MHz 1 km - 1

High Frequency HF 3 MHz - 30 MHz 100 m -

Very High Frequency VHF 30 MHz - 300 MHz 10 m - 1

Ultra High Frequency UHF 300 MHz - 3 GHz 1 m - 10

Super High Frequency SHF 3 GHz - 30 GHz 100 mm

Extremely High Frequency EHF 30 GHz - 300 GHz 10 mm -


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RADIO WAVES

Ground wavesSky wavesSpace waves

F t ff ti RF ti


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Factors affecting RF propagation

Free space loss

Multi path propagation

Building & vehicle penetration

Interference

Fading of signal


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A directional antenna

An Omni-directional antenna


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2

4

3

1

7

5

1

6 3

CELLULAR CON

WHY DO WE NEED CELLS?


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WHY DO WE NEED CELLS?

FREQUENCY (RESOURCE)SCARCITY

DEMAND FOR HIGHER

CAPACITY

COST EFFECTIVENESS

Base Sta

Base Station

Base Station

Base Stati


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Cellular Radio involves dividing a large servic

regions calledcells

.

Each cell has the equipment to switch, transmit a

calls.

Cells - Reduce the need of High powered transmiss

Cells - Conventionally regarded as being hexagoreality they are irregularly shaped.

Cell shape is determined by the nature of the surro

e.g. Hills , tall building etc.

Hexagonal shaped cells are


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Hexagonal shaped cells are

artificial and cannot be generated

in the real world.

This shape is chosen to simplify planning and design of a ce

hexagons fit together without any overlap or gap in between them.

Another advantage of using hexagons is that it approaches a circula

the ideal power coverage area.

The real cell shape will keep changing due to prevailing conditions.

If the Point of Transmission is at the centre of a Cell, the maximum C

available from a Hexagonal Cell i.e., this layout needs minimum nu

cover a given Area, hence lesser number of Transmitting Sites are n


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Large Cells Small Cells

About 35 Km Nearly 1 KM

Remote Areas Urban Areas

High Transmission Power Low Transmission Po

Few subscribers Many Subscribers


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There are 124 carries in GSM Band. With each carriertimeslots, only 124 x 8 = 992 calls can be made !

Frequency Reuse is the solution

Using same frequency channel to serve more than

in the same given area

Interference problems caused by mobile units usingchannel in adjacent areas (cells) proved that all channot be reused in every cell.

Areas (cells) have to be skipped before the same freqreused


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The actual center to center distance of the

adjacent hexagon is

3R = (2R cos 300

),where R is the center to vertex distance.

The concept of number of cells per cluster is

important for locating co channel cell with in

the cellular structure.

It can be shown that co channel reuse ratio

D/R = 3Nwhere N is Cluster size

CELLULAR CONCEPTS


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N Q=D/R

1 1.733 3.004 3.467 4.589 5.2012 6.00

Q = D/R =

3N = 6 ( S/ I)

-

where is propagation constant

Much higher level of interference is tolerated if digital transmused.S / I 18 dB For Digital Cellular Mobile Systems.

Higher Q Less Interference.

Higher N

Larger Cluster Size.

Less Freq./ cell.

Lower Traffic Handling


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The same group of channels can be used in different cells that are f

away from each other so that their frequencies do not interf


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No similarly colored cells are adjacent, and therefore there are

adjacent cells using the same channel.

Performance/Capacity Trade Off


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Performance/Capacity Trade Off

Higher values of N Lower values of N

Reduce co channel interference Increase co channel inte

Leads to more cells/clusterLeads to few cells/cluste

Less no. of chls/cells More no. of chls/cell

Less traffic handling capacity More traffic handling cap

Principle Of Sectorizati


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A Directional Antenna is a

better solution for reducing the

Co-channel Interference

Each Cell is divided into 3 or 6

Sectors and uses 3 or 6

Directional Antennas at the

Base Stations.

In practice, Sectored Cells with

120Beam Antennas are used

Principle Of Sectorizati


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Omni Directional Cells

120 degree Sectors

60 Degree sectors

Each Sector in a Site has its own allocation of Radio Carr

Advantage By frequent reuse of frequency more capacity can be


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a1

a2

a3a3

a4a6

a5

OMNI CELL

1 ANTENNA

b1

b

120OC

3 ANTEN

60OCELLS

6 ANTENNAS

CELL TYPES


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Macro cells: Very Large Radius (more than 35 kms)

Micro cells: Medium Radius (upto 3 kms)

Pico cells: Extremely Small Radius cells (for Indoor coverage

Umbrella cells: for fast moving vehicles (to avoid frequent loading of the network)


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HANDOVER

HANDOVER


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A problem encountered in Cellular Communication is to provide con

Communication for a subscriber, who moves from one Cell to another

No two adjacent Cells in a Cluster have the same Radio Channels

So, Re-allocation of Radio channels must be fast and smooth.

This process is called Handover.

Processing Load per Subscriber on the system increases when Subsc

crosses Boundaries and cause frequent handoff of Calls between the

Practically, reduction of Cell Radius by 4 times increases Proc

approximately by a factor of 10.


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BS1

A B

RSL

Lev

Level w

HandoverMechanism


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Handovers

Hard Handoff

Analog, TDMA and GSM

Soft Hando

CDMA

Break before Make Make before Brea


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The mobile measures up to 32 adjacent cells for

Signal Strength (RxLevel)

Signal Quality (RxQual)

updated every 480 mS and sends to BTS

Handover is based on the following conditions:

RxLevel

Interference RxQual

Timing Advance

Power Budget

Interference- If signal level is high and still there is RXQUAL ph bl i b f i f


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the problem is because of interference.

RXQUAL - It is the receive quality. It ranges from 0 to 7 , 0 being7 the worst

RXLEV- It is the receive level. It varies from -47dBm to -110dBm

Timing Advance- Ranges from 0 to 63.

Power budget- It is used to save the power of the MS.


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POWER CONTROL

POWER CONTROL

RF power control is employed to minimise the tra


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RF power control is employed to minimise the trarequired by MS or BS while maintaining the quality of th

By minimising the transmit power levels, interference tusers is reduced.

Power control is implemented in the MS as well as the B

Power control on the Uplink also helps to increase the b

Power received by the MS is continuously sent in the mreport.

Similarly uplink power received from the MS by the BTSby the BTS.

Complex algorithm evaluate this measurements and tasubsequently reducing or increasing the power in the downlink.


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DTX is a mechanism which allows the radio transmitter to be switch

DISCONTINUOUS TRANSMISSION (DTX)


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DTX is a mechanism which allows the radio transmitter to be switch

rate transmission (~ 500 bit/s) during silences )most of the time

pauses for the following purposes:

To save power in the MS

To reduce the overall interference level on the air

The DTX mechanism requires the following functions

A Voice Activity Detector on the transmit side

Evaluation of the background acoustic noise on the transmit side,

transmit characteristic parameters to the receive side

Generation on the receive side of a similar noise, called comfort n

periods where the radio transmission is cut


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Frequency Hopping

Multipath Fading results in variations in signal strength which is known

Frequency Hopping


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Multipath Fading results in variations in signal strength which is known

Fading.

Rayleigh Fading phenomenon is dependent on path difference and hen

of reception.

A fast moving mobile may not experience severe effect of this fading sin

difference is continuously changing.

A slow moving mobile ( or a halted mobile ) may experience severe dete

quality.

But, if the frequency of reception is changed when this problem occurs,

The fadingphenomenon is fast and almost continuous, this means the

changeshould also be continuous.

This process of continuously changing frequency is known as Frequenc

Frequency hopping is the technique of improving the S/N in a link by ad

frequency diversity.


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q y y

The base station commands the mobile station to activate frequency hop

mobile station moves towards the edge of a cell or into an area of high in

When frequency hopping is activated in the mobile station, the base stat

mobile station a set of RF channels, rather than a single RF channel.

A frequency hopping algorithm is also assigned to the mobile and is used

mobile of the pattern of the available frequencies it is to use.


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MULTIPLE ACCESS TECHNIQUES


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In order to several links to be in progress simultaneousame geographical area without mutual interference access techniques are deployed.

The commonly used multiple access techniques are

Frequency Divis ion Mult iple Access (FDM

Time Divis ion Mult iple Access (TDMA ) Code Divis ion Mult iple Access (CDMA )

FDMA F Di i i M l i l A FDMA


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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)

Power

TDMA

Power

FDMA

Power

CDMA


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Mobile Station

Base Station

SubsystemNetwork Subsystem

ARCHITECTURE OF A GSM NETWO


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SD

Mobile Station

BTS

MSC/

VLR

SIM ME

BSC

Subsystem

GMSC

y

AUCEIR HLR

Note: Interfaces have been omitted

+

Network Structure


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GSM Service AreaPLMN Service AreaMSC Service AreaLocation Area

Cells

Network Structure


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GSM SERVICE AREA

PLMN SERVICE AREA

MSC SERVICE AREA

LOCATIONAREA

CELLS

SYSTEM ENTITY FUNCTIONS


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Mobile station:

The mobile station represents the t

equipment used by cellular sub

supported by GSM system

Functions of Mobile Station


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Voice and data transmission

Frequency and time synchronization

Monitoring of power and signal quality of the surroucells

Provision of location updates even during inactive st

Equalization of multi path distortions


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The MS consists of two entities

Mobile Equipment (ME)

Subscriber Identity Module (SI

Mobile equipment (ME)It is the mobile handset.


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The major components of the Handset are Transmitter,

Receiver,Number Alignment Module,

Logic Unit,

Frequency Synthesizer,

Antenna and

the required software.

Identified by a unique International Mobile Equipmen(IMEI) (different from the phone number)

Class Power O/p


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p

1 20 W

2 8 W

3 5 W

4 2 W

5 0.8 W

Subscriber Identity Module (SIM)Contains subscriber-related information


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Contains subscriber related information

A smart card that holds information required to id

particular subscription to a mobile service

Can be used with any approved GSM handset

Identified by a unique International Mobile SubsIdentity (IMSI)

(different from the phone number)

COMPONENTS OF THE SIM CARD


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Central processing unit (CPU)

intelligence of the chip

performs all the mathematical functions

takes all the decisions required by the SIM.

Read Only Memory (ROM):

sufficient memory to store the operating system (s

commands that SIM understands)

contents of the ROM are permanent and it is not poto change them.

can be created as part of the manufacturing process

R d A M (RAM)


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Random Access Memory (RAM):

area of volatile memory

contents are lost each time the power is turned off

The memory can be at least 256 KB.

Buffers incoming data as a scratch pad for calculat

Electrically Erasable programmable Read Only Memory (EE

Stores all the application data such as the operatorparameters and the subscribers data.


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SIM

Most of the data contained within the SIM is protected against ror alterationsafter the SIM is issued.

Some of the parameters ( eg. LAI ) will be continuously updatecurrent location of the subscriber.

The SIM card can be protected by use of Personal Identity N

password.

The SIM is capable of storing additional information such as ac

charges.

MOBILE IDENTIFICATION NUMBERS


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i) MSISDN (Mobile subscribers ISDN number)

ii) IMSI (International mobile subscribers identity)

iii) TMSI (Temporary mobile subscribers identity)

iv) MSRN (Mobile subscribers roaming number)

v) IMEI ( International Mobile subscribers equipment

Human identity used to call a MS

MOBILE SUBSCRIBERS ISDN (MSISDN) NU


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The Mobile Subscriber ISDN (MSISDN) number is the telephthe MS.

This is the number a calling party dials to reach the subscri It is used by the land network to route calls toward the MSC

Mobile Subscriber No.

NDCNetwork destination code

SN--subscriber number

CC--country code(allotted internationally)

International mobile subscribers Identity


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The IMSI is an unique identity which

internationally and used within the network t

the mobile subscribers.

The IMSI is stored on the SIM, the HLR, VLR

database

IMSI finds its use in call routing.


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MCC--Mobile country code

MNC--Mobile network code

MSIN--Mobile subscriber identification number

-- identifies the country of domicile of the subsc

-- identifies the home GSM PLMN of the mobile s

-- identifies the MS within a G

TEMPORARY MOBILE SUBSCRIBERS IDENTITY

The GSM system can also assign a Temporary Mobil


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The GSM system can also assign a Temporary MobilIdentity (TMSI).

After the subscriber's IMSI has been initialized on theTMSI can be used for sending messages backwards aacross the network to identify the subscriber.

The system automatically changes the TMSI at reguthus protecting the subscriber from being identifiedattempting to monitor the radio channels.

The TMSI is a local number and is always allocated by

The TMSI is maximum of 4 octets.

MOBILE STATION ROAMING NUMBER (M

Suitable for the purpose of call processing when the custom


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Suitable for the purpose of call processing when the custom

in any other VLR area having connectivity with his home ne

The HLR of the roaming subscribers request the visited VLallotment of the temporary number.

Accordingly the visited VLR generates MSRN.

GMSC (gateway MSC) uses it for routing of calls to this cust

MSRN is stored in visited VLR, HLR.

INTERNATIONAL MOBILE EQUIPMENT IDENTIT

Provided to the mobile equipment through a unique


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Provided to the mobile equipment through a unique

its authentication and identification

The code is entered in SIM card of the user MS

Also recorded in the data base of the EIR of mobile s

sub system.

During the course of call processing, the IMEI entere

compared with the corresponding IMEI recorded in E

6 digits 2 digits 6 digits unit length


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TAC is 6 digits and approved by a national body.

FAC is 2 digits and is provided by the manufacturer.

SNR is 6 digits provided by manufacturer in serial sequence.

SP is spare digit of unit length.


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Base Transceiver Station (B

BTS is the equipment which facilitates the wireless

BTS


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BTS is the equipment which facilitates the wirelesscommunication between user equipments (UE) andnetwork.

BTS is a radio-end which determine a cell coverageprovide link with MS.

BTS include Transmitters and Receivers, antenna aprocessing unit as well as interface.

BTS communicate with MS via Um (air) interface

FUNCTION OF BTS


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Encodes, encrypts, multiplexes, modulates and feedRF signals to the antenna

Transcoding and rate adaption Functionality

Time and frequency synchronisation signals transmi

11 power classes from .01 watts (Micro cell) to 320 w(Umbrella cell)

A BTS has the following units

TRX : Transceiver--- Quite widely referred to as DRX (Drive


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TRX : Transceiver Quite widely referred to as DRX (Drive

Receiver). Basically does transmission and reception of signals

Power Amplifier : Amplifies the signal from DRX for transmthrough antenna. May be integrated with DRX

Combiner :- Combines feeds from several DRXs so that they

sent out through a single antenna. Used for reduction of numb

antenna

Duplexer : For separating sending and receiving signals to/

antenna. Does sending and receiving signals through the same

ports (cables to antenna)


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Antenna : Antenna is considered as part of BTS

Alarm Extension System : Collects working statu

alarms of various units in BTS and extends them to

Operations and Maintenance (O&M) monitoring sta


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A group of BTSs are connected to a particular BS

which manages the radio resources for them.


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The primary function of the BSC is call maintena

The mobile stations normally send a report of th

received signal strength to the BSC every 480 ms.

With this information the BSC decides to initiatehandovers to other cells, change the BTS transmitte

power, etc.

Base Station Controller (BSC)

responsible for radio interface manageme


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responsible for radio interface manageme

BTS and MS, i.e.channel management and

handovers

responsible for communication with the N

a single BSC typically manages 100-200 B

The functions of the base station are

1. Radio source control (Channels)


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a. Configuration of Radio channels

b. Selection, allocation and de-allocation of radio channels.

c. Monitoring of radio channel busy / idle.

d. Encryption of radio interface.

2. Frequency hopping and power control

a. Assignment of frequency hops sequence and start time.

b. Assignment of effective radiated power (ERP) values to mobile stat

3. Hand off management


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a.Collect signal quality data from adjacent BSSs.

b. Analyze signal quality and determine hand off need.

c. Keep MSC informed regarding hand off activity.

4. Digital signal processing

a. Trans coding and rate adoption.

b. Channel coding and decoding.

BSS functions are partitioned into a BSC and BTS( a single BSC generally controlling multiple BTS)

N k d


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Network and

Switching Subsystem

(NSS)

NSS performs the switching functions of GS

as well as databases for Subscriber and


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mobility management

Its main feature is to manage the communic

between the Mobile Station and other users

the Cellular Network.


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Mobile Service Switching Centre (MSC)The Switching part, is controlled by the MSC.


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Acts like a standard exchange in a fixed network and additionally prov

functionality needed to handle a mobile subscriber.

The main functions are

registration,

authentication,

location updating,

handovers and

call routing to a roaming subscriber.

Connections to external Networks like PSTN, PLMN and Intelligent Net

are also controlled by MSC.

An MSC, which provides connection to Networks

outside the area under the MSC is generally kno

GATEWAY MSC (GMSC)


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outside the area under the MSC, is generally kno

as Gateway MSC.

Gateway MSC (GMSC)

gateway to external networkincoming call is routed to GMSC, which the

determines MS locationGMSC function is often in the same machin

as the MSC


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IMSI, MSISDN and current VLR Address are also kepHLR.


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As soon as the Mobile Station crosses a Cell bounda

this information is updated in the HLR.

The HLR also maintains the services associated with

MS

One HLR can serve several MSCs

One PLMN may contain one or several HLR

Visitor Location Register (VLR) dynamically stores Subscriber

Information, when a Mobile Station is in the Location Area cove

VISITOR LOCATION REGISTER (VLR)


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,

the VLR

One VLR may be incharge of one or more LA.

A VLR is connected to one MSC and is normally integrated into

MSC's hardware

VLR is updated by HLR on entry of MS in its area.

VLR assigns TMSI which keeps on changing

Whenever a Roaming Subscriber enters in an area c

by an MSC, the information is passed to the VLR, whic


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by an MSC, the information is passed to the VLR, whic

recognizes the Subscriber as an outsider for the MSC.

If the Subscriber is allowed to Roam, VLR finds the

HLR of the Subscriber and downloads all relevant info

for the Subscriber from it.

VLR reduces the number of queries to HLR

IMSI & TMSI

MSISDN

DATA IN VLR


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MSISDN

MSRN.

Location Area

Supplementary service parameters

MS category

Authentication Key

The EIR is a database that stores IMEIfor all mobile equipments regis

particular MSC and is unique to every ME.

EQUIPMENT IDENTITY REGISTER (EIR


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Only one EIR per PLMN.

Any Cell Phone can be used fraudulently by inserting an authentic SIM

soon as a report is registered that a handset is stolen or misplaced, EIR D

updated to render the handset useless.

The EIR has three databases

White list: IMEI, assigned to valid ME. Black list: IMEI reported stolen

Gray list : IMEI having problems like faulty software, wro

of equipment etc.

AUC is a separate entity and physically included in HAUTHENTICATION CENTRE (AUC)


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It protects User Identity and allows a Secured Trans

i.e., Protect against intruders in air interface

Authentication (Ki) and ciphering(Kc) key are stored

data base.

Keys change randomly with each call

Keys are never transmitted to MS on air Only calcula

response are sent.

It monitors and controls all other components of GSM.

Operation and Maintenance Centre (O


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The OMC assists the network operator in Dynamic monitoring and main

satisfactory operation of the GSM network

The OMC is responsible for controlling and maintaining the MSC, BSC an

BTS.

It can be in charge of an entire PLMN or just some parts of the PLMN.

Its main functions are Traffic Monitoring,

Subscriber as well as Security Management and

Status report Generation.


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Mobile Train Radio Communication (MTRC) won GSM-R (Global System for Mobile

Communications for Railways) Technology.

Developed requirement

common communicatio

for the railway

UIC

GSM-R Spcification


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Railway communicationbody selected GSM as th

standardEIRENE

Development & testing

system based on EIRENspecifications

MORANE

ETSI

INDUSTRIALPARTNERS

UIC = Union Internationale des Chemins de fer

EIRENE = European Integrated Railway radio Enhanced NEtwo

MORANE = Mobile radio for RAilway Network in Europe

ETSI = European

Telecommunications

Standards Institute

GSM-R : In operatio

GSM-R Requir ements :


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Sl

No

GSM GSM-R

1 Honey-comb network Linear network

2 th th

GSM and GSM-RA Comparison


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2 Repetition of frequency at the 4thCell Repetition of frequency at the 5thC

3 360D coverage 33D coverage (Directive antennas a

4 Only one type of Handset is used Different types of Mobile sets are u

the type of use)

5 No priority, group call or broadcast call Priority, group call or broadcast cal

6 No functional addressing or locationdependent addressing

Both functional & location dependeused

7 Power output of Handset


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Frequency bands for use by GSM-railway may differ i


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Frequency bands for use by GSM railway may differ i

individual countries (especially in non UIC countries)

national regulations and have to be agreed.

If the frequencies are outside GSM-R band, GSM-R

applications are still possible but border crossing tra

be not functional due to different frequency ranges.

CHANNEL-WISE ALLOCATION OF FREQUE(ON THE BASIS OF 4-CELL REUSE/ 5TH CELL REPETITION PATTERN

SL NO SL NOFrequencies(MHz)

CHL CHLFrequen


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UP LINK DN LINK UP LINK

1 1 907.8 952.8 7 8 909.2

2 2 908 953 8 9 909.4

3 3 908.2 953.2 9 *10 f10

4 4 908.4 953.4 10 *11 f11

5 6 908.8 953.8 11 *13 f13

6 7 909 954

Frequencies(MHz)NO. NO.

Frequen

* To be allotted by WPC in addition to 8-pair already allotted for the R


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ARCHITECTURE OF GSM-R NETWORK

The MTRC system consist of following sub-system:-


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Mobile Station(MS)

Base Station Sub-System(BSS) Switch sub- System(SSS)

Operation & Maintenance Subsystem

MS consist of two parts :-i) Subscriber identity module(SIM)

ii) Mobile equipment(ME)/Handset

The functionality of the above systems are same adescribed in GSM networks except some ratings li

powers of MS and BTS.


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There are different types of mobile equipments, distinprincipally by their power and application.

The fixed terminals (8W)are the ones installed in driv

Hand held sets are of 2W power.

RF power of BTS will be 20-25 W.


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enhanced MULTILEVEL PRECEDENCE AND PREEMPTION


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If a handover to neighbouring Cells is unsuccessful due to conge

radio channel, a preemption service is necessary to allow imme

to a traffic channel occupied by a low priority application

enhanced MULTILEVEL PRECEDENCE ANDPREEMPTION (eMLPP)


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to a traffic channel occupied by a low priority application.

A preemption service will release ongoing low priority calls t

channels for emergency call setup.

These calls shall be set up in 2 second or less.

Up to 7 different eMLPP levels (2 network and 5 subscriber leintroduced.

One or more priority levels can be assigned to a mobile subscrib

Network Level 1 is reserved for Railway Emergency C

Network Level 2 for ETCS.


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Maximum allowed and default priority will be stored

HLR with the related subscriber data.

When an eMLPP priority call is build up, the MSC / VL

insert the priority into the call set-up message to the B

The BSC will evaluate the Priority and give access to t

appropriation channel for either call set-up or hand-o

Two subscribers are involved in a point to point call

Train controller initiates a REC in the Group Area

The subscribers are notified

GSM-R Indian Railways

eMLPP


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The subscribers are notified

The ongoing ptp is terminated and the REC is connected

Point to point callOKOK

Emergency...Emergency...


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FUNCTIONAL ADDRESSIN

To call Driver of train :

Driver of particular train keeps changing.

Functional Addressing


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Without Functional Addressing: Controller must always know the changing

number (MSISDN) of the specific Train Driver of

train 2423

With Functional Addressing : Controller dials the Unique Number and is

connected to the driver currently on duty. No

Need to remember the mobile no of each Driver.Train Driver o

USSD string for MSC IN

Functionalnumber

(Train nr. +f ti d )

Basicsregistration/deregistration


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USSD string for

RegistrationDeregistrationInterrogation

MSC INfunction code)

Registration com

Association betw

Number and MSI

Train Driver now

OK

REGISTRATIONA Train Driver or employees on the Train, registers to the respective func

by establishing an USSD dialogue via MSC / VLR to the HLR, where their M

stored (HLRmobile).


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This HLR is establishing a dialogue to the HLRfunctional regarding the callin

The HLRfunctional, in turn, establishes a Call Forwarding from the required

Number to the MSISDN.

After completion, the registering Subscriber will get an acknowledgemen

Only one MSISDN can register under one functional number. Users tryingfunctional number already in use will be rejected.

Same way, a Functional Number is unique inside the HLR functional and cann

duplicated

DEREGISTRATIONMSISDN registered to a Functional Number will be de-registered b

establishing an USSD dialogue via MSC / VLR to the HLR, where th

stored (HLR bil ).


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stored (HLRmobile).

This HLR is establishing a dialogue to the HLRfunctional regarding t

MSISDN.

The HLRfunctionalin turn cancels the call forwarding from the requir

number to the MSISDN.

After completion, the registering subscriber gets an acknowledge

registered).

EXPIRATION DATEAll functional numbers contain a programmablevalidity p

hours).


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During the registration process, the Expiration Date of the s

member inside this functional number will be computed anAfter exceeding the expiration date, the service ignores the

owner.

In case the value of the validity period is set to 0, the featur

switched off for this functional number. That means a regis

any member for this functional number has no time limit.


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LOCATION DEPENDENT ADDRES

To call Controller :

Without LDA


Location Dependent Addressing


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Driver wishes to communicate emergency to controller.

Driver is not aware of who is Controller of that area.

Driver must know the no of each controller on route.

With LDA

Driver dials the short code i.e 1200 and is connected to c

charge of that area.

Short Code is common throughout journey.

LOCATION DEPENDENT ADDRESSIt provides the Automatic Routing of Mobile Originated Cal

pre-defined destinations relative to the geographic area wh

subscriber is roaming.


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Train driver dials a short number as defined in the EIRENE

plan. This short number will be automatically converted int

corresponding long number(s) of the train controller(s) res

the area the train is actually moving through.

If a train is passing between two controller areas the conne

made to both controllers.

IN MSC


Location Dependent Addressing ( LDA)


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Controller B

Cont


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VOICE BROADCAST SERVICE (VBS)

A VBS is characterized by following key points

One Broadcast Call Number combines all members of a certai

VOICE BROADCAST SERVICE (VBS)


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For each Broadcast Call, a Service Area composed out of a ncells is assigned

Dialing the broadcast call number initialises the parallel set-upconnections into all Cells of the assigned service area. All memb

group being in the service area will be paged to receive a notifi

ongoing voice broadcast call

Dependent on the call ID a priority members of the group call join the call

The MSC retrieves all necessary information from the co-located Group

(GCR), which stores Tables having

The Group ID (1 to 7 digit depending on the length of the group call ar

The Group Call Area ID (MCC + MNC + LAC + CI)


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The Group Call Reference (27 bit binary encoded field with Group IDArea ID)

The Cell List corresponding to the Group Call Area ID (max. 50 cells)

The Dispatcher List corresponding to the group call references (up to

per group call reference )

An information whether the call is active or not

Security Information

MSC connects the so called Dispatcherwith a duplex connectio

Each cell of the required group call area is setup with half-dupl

connections.

M b ll i hi ill b d d


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Membersactually present in this area will be paged and connec

common channel down-link (can only listen)

If a member of the group enters the Cell after beginning of the vo

he will just join the ongoing voice broadcast at his time of entry.

If a member of the group leaves the voice broadcast area, he willdisconnected.

The setup of a VBS is possible with eMLPP or as a normal cal

priority and preemption.

The Group Area is predefined

Train controller initiates a VBS call in a Group Area

The speech is broadcasted to all users in the area


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TraTrain is

Train is

Train is

(One way communication)


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VOICE GROUP CALL SERVICE(VGCS)

VGCS is characterised by the key point that the actual spea

change during a call.

G b ill ll li t t th i V i G

(VGCS)


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Group members will normally listen to the ongoing Voice G

As soon as the initiator of the VGCS stops speaking, he indic

he releases the up-link.

All group members will be notified that they can now requ

linkto become the next talker by using their Push-To-Tal

A dedicated duplex channel will be allocated in the respecti

Initial talker releases the up-link (and changes to the common

this cell, if he is a mobile subscriber)

Possible new talker sends an up-link request

The BSC serving this area selects the first Uplink Request and p


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The BSC serving this area selects the first Uplink Request and p

the MSC

The MSC serves the first UPLINK_REQUEST of all BSC in the Gr

The new talker confirms his up-link request

The other group member get an up-link seized or up-link rejec

The duplex channel for the new talker is switched through

The Group Area is predefined

Train controller initiates a VGCS call in a Group Area

The speech is broadcasted to all users

The user can confirm by using Push To Talk, PTT

The Call can be initiated by any group Member

Group group call - group Id

- priority (n

- call setup


Voice Group Call - VGCS


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Train

acknoh

The Call can be initiated by any group Member.Train is

Train is

Train is

OK

OK

OK

HANDSETs USEd IN MTRC, NFR

OPH HAND SET

PROVIDED

To Loco Pilots


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GPH HAND SET

PROVIDED

To Station Master

To Guards

To Lobby & Officers

To S&T Maintenance staff, P WAY staff

Operational Handheld

(OPH 940)


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Emergency Button Robust Design IP 54 resistant housing Push to talk button

GSM-R Cab Radio Front Pan


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GSM-R Controllers Termin


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Thank You

1) Mobile Int Gr B.

Documents

Transcript of 1) Mobile Int Gr B.