29 Jan 201029 Jan 2010

ON

Modern Communication Network-TETRAModern Communication Network-TETRA

M. M A H E S H C H A N D R A,M. M A H E S H C H A N D R A,0 9 0 1 6 T 6 6 0 40 9 0 1 6 T 6 6 0 4

M.TECH (DIGITAL COMMUNICATION),M.TECH (DIGITAL COMMUNICATION),KAKATIYA INSTITUTE OF TECHNOLOGYKAKATIYA INSTITUTE OF TECHNOLOGY,,WARANGAL.WARANGAL.

ByBy

KEYWORDS

• PMR –PRIVATE MOBILE RADIO.

• PAMR- PUBLIC ACCESS MOBILE RADIO.

• DQPSK-DIFFERENTIAL QUARTERNARY PHASE SHIFT KEYING.

• DMO-DIRECT MODE OPERATION .

• TDMA-TIME DIVISION MULTIPLE ACCESS.

• FDMA-FREQUENCY DIVISION MULTIPLE ACCESS.

• ETSI – EUROPEAN TELECOMMUNICATION STANDADS INSTITUTE.

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I N D E X

• INTRODUCTION TO RADIO TRUNKING.

• TETRA –INTRODUCTION.

• TETRA FRAME STRUCTURE.

• TETRA CALL TYPES .

• DIFFERENCE BETWEEN GSM and TETRA SYSTEM .

• TETRA SUMMARY

• CONCLUSION.3

INTRODUCTION TO RADIO TRUNKING Digital Radio Trunking Systems – TETRADigital Radio Trunking Systems – TETRA

What is Radio Trunking ?? Trunking stands for “sharing”. Trunking stands for “sharing”. Whenever resources are in short supply, they will have to be Whenever resources are in short supply, they will have to be

shared. shared. In Radio Communications Trunking System a fixed number In Radio Communications Trunking System a fixed number

radio frequencies are used and are shared by large number of radio frequencies are used and are shared by large number of remote/ mobile subscribers. remote/ mobile subscribers.

The frequency spectrum is The frequency spectrum is a Scare resource. a Scare resource. This is commonly known as Radio Trunking System.This is commonly known as Radio Trunking System.

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INTRODUCTION TO RADIO TRUNKING Digital Radio Trunking Systems – TETRADigital Radio Trunking Systems – TETRA

Advantage of Digital Trunking System over Analogue

Trunking System: More More reliablereliable . . Flexible .Flexible . Low noise and Low noise and Provides internet connectivityProvides internet connectivity..

Disadvantages of Digital Trunking System over Analogue

Trunking System: Only the Only the low coverage range low coverage range as compared with Analogue as compared with Analogue

Trunking System. This can be overcome by more Trunking System. This can be overcome by more repeatersrepeaters..5

TETRA -INTRODUCTION

What is TETRA TETRA stands for “TETRA stands for “Terrestrial Trunked RadioTerrestrial Trunked Radio” initially it ” initially it

is is

called as “called as “Trans European Trunked RadioTrans European Trunked Radio”.”. TETRA –New standard from ETSI for digital trunked radio

system . TETRA is the TETRA is the first truly open digital PMR first truly open digital PMR standard.standard. TETRA standard contains TETRA standard contains high functionality for high functionality for

Emergency services.Emergency services.

Frequency Range: 380 - 400 MHz for public safety systems,380 - 400 MHz for public safety systems, 410 - 430 MHz & 870-876 MHz 915-921MHz for 410 - 430 MHz & 870-876 MHz 915-921MHz for

commercial applications commercial applications 6

TETRA -INTRODUCTION

Provides individual, Provides individual, groupgroup and and direct mode direct mode communications communications

between radios.between radios.

Packet data and Packet data and fast data transfer fast data transfer services .services .

Frequency economy.Frequency economy.

Fast call set-up Fast call set-up time (300 m sec) .time (300 m sec) .

Security features & Security features & EncryptionEncryption . .

TETRA provides Voice and Data Services .TETRA provides Voice and Data Services .

VideoVideo application in future TETRA-TEDS . application in future TETRA-TEDS .7

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TETRA SPECIFICATIONSTETRA SPECIFICATIONS

P A R A M E T E R V A L U E

Channel spacing 25K Hz

Modulation π/4 DQPSK

Modulation rate 36 kbps

Bits per symbol 2

Voice coder rate ACELP (4.56 kbps )

Access format TDMA with 4 time slots/carrier

User data rate 7.2 kbps per time slot

Maximum data rate 28.8 kbps

Protected data rate Up to 19.2 kbps

TABLE 1TABLE 1

DATA RATES with DIFFERENT PROTECTION LEVELS

NO. TIME SLOTS

High Level Protection

Medium Level Protection

No Protection

1 2400 4800 7200

2 4800 9600 14400

3 7200 14400 21600

4 9600 19200 28800

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Data Throughput (bits/sec)Data Throughput (bits/sec)

TABLE 2TABLE 2

TETRA FRAME STRUCTURE.• Four time slot TDMA technology was adopted in TETRA .• One carrier with 25 KHz spacing provides 4 channels using TDMA (Time Division

Multiple Access) .

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FIG 1FIG 1

TETRA FRAME STRUCTURE.TDMA Structure of the voice + data system

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00 1111 2222 57575757 58585858 59595959............

hyperframehyperframe

0000 1111 2222 15151515 16161616 1717............multiframemultiframe

0000 1111 2222 3333

00 time slot time slot 50950900 time slot time slot 509509

frameframe

14.17 ms14.17 ms

56.67 ms56.67 ms

1.02 sec1.02 sec

61.2 sec61.2 sec

CFCF

Control FrameControl Frame

Speech calls use one channel Speech calls use one channel ..Data calls can use up to 4 channels Data calls can use up to 4 channels ( Data transfer rates up to( Data transfer rates up to 7.2 kbps per channel) .7.2 kbps per channel) .

FIG 2FIG 2

TETRA FRAME STRUCTURE.BIT RATE OF TETRA SYSTEM

• 1 Time Slot =510 modulating bits duration=255 symbols

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1 2 3 4 508 509 510 1 2 3 4 508 509 510

14.167 msec14.167 msec..

Bit duration =14.167 msec/510Bit duration =14.167 msec/510Bit rate =1/bit durationBit rate =1/bit durationBit rate =Bit rate =36000 bits/sec36000 bits/sec

Digital modulation, Digital modulation, π/4 π/4 --DQPSK DQPSK at Modulation rate 36 kbps at Modulation rate 36 kbps . .

FIG 3FIG 3

TETRA –SPECTRUM EFFICIENCYCOMPARISION WITH OTHER STANDARDS

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TETRA offers 32 communication TETRA offers 32 communication channels and channels and GSM offers 8 GSM offers 8 Channels per 200 K Hz bandwidth .Channels per 200 K Hz bandwidth .

FIG 4FIG 4

TETRA CALL TYPES

TETRA call typesTETRA call types Private call (individual call) .Private call (individual call) . Phone call (PSTN or PABX call).Phone call (PSTN or PABX call). Group call .Group call . Emergency call .Emergency call . Broadcast call .Broadcast call .

TETRA Traffic case - Trunking optionsTETRA Traffic case - Trunking options Trunking options only apply to simplex calls .Trunking options only apply to simplex calls . Applies to private simplex calls and group calls .Applies to private simplex calls and group calls . Trunking type is controlled by the Base Station.Trunking type is controlled by the Base Station. Message Trunking .Message Trunking . Transmission Trunking .Transmission Trunking .

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TETRA CALL TYPESTETRA CALL TYPESSimplex callsSimplex calls

Mobile is either transmitting or receiving .Mobile is either transmitting or receiving . Requires operation of Requires operation of PTTPTT switch (Push To Talk) . switch (Push To Talk) . Talk time is usually Talk time is usually limitedlimited, typically , typically one minute one minute

maximum.maximum. Group calls Group calls are always simplex .are always simplex .

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TETRA CALL TYPESTETRA CALL TYPESDuplex callsDuplex calls

Mobile is transmitting and receiving (like GSM phone call).Mobile is transmitting and receiving (like GSM phone call). Does not require holding PTT to continue transmission .Does not require holding PTT to continue transmission . Phone calls are usually but not always duplex .Phone calls are usually but not always duplex .

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TETRA CALL TYPESTETRA CALL TYPESPrivate callPrivate call

Private call (individual call)Private call (individual call) A call between two parties within the TETRA network .A call between two parties within the TETRA network . Simplex or duplex.Simplex or duplex.

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TETRA CALL TYPESTETRA CALL TYPESPhone callPhone call

Phone call (PSTN or PABX call)Phone call (PSTN or PABX call) A call between a TETRA user and a fixed or mobile A call between a TETRA user and a fixed or mobile

phone.phone. Call is set up via the TETRA network’s PSTN Gateway.Call is set up via the TETRA network’s PSTN Gateway. Call is normally duplex, hook signalling.Call is normally duplex, hook signalling.

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TETRA CALL TYPES-TETRA CALL TYPES-Group callGroup call

Group callGroup call A call between more than two parties.A call between more than two parties. Call is always simplex, direct set-up.Call is always simplex, direct set-up. Only possible if one or more groups have been Only possible if one or more groups have been

attached.attached.

What about commercial digital networks?What about commercial digital networks?GSM / CDMA 2000GSM / CDMA 2000

Public mobile networks do not fulfil all public safety requirements.

Public mobile networks are developed to meet the demands of consumers, which are very different from those of public safety organisations.

It cannot guarantee service during emergencies and disasters.

It cannot provide FAST call set-up time(<300 m sec).

It cannot provide special terminal functionality .20

Difference between GSM and TETRA System

T E T R A G S M•Designed for professional mobile radio applications.

•Designed for public cellular telephony.

•Based on TDMA – Economy on frequency spectrum.

•Based on FDMA and TDMA.

•Suitable for emergency services due to very fast call set up time (<300 ms).

•Not suitable for emergency services (Call set up time ~ a few seconds).

•Maintain privacy and mutual security.

•Do not maintain privacy and mutual security.

•Direct Mode Operation(DMO) is possible, which supports voice and data transmission without a Base Station between Radio Terminals.

•Direct Mode Operation(DMO) is not possible.

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Divisions in INDIA using TETRA radio Divisions in INDIA using TETRA radio systemsystem

The DELHI Metro project.

The HYDERABAD police .

The Delhi Airport.

INDIAN Parliament.

Digital Radio Trunking Systems – TETRA Digital Radio Trunking Systems – TETRA SummarySummary

In order to tackle In order to tackle terrorismterrorism, all the user agencies of Govt. , all the user agencies of Govt. and Private Organizations need to upgrade and integrate and Private Organizations need to upgrade and integrate their communication infrastructure for secure, faster & their communication infrastructure for secure, faster & reliable communications. reliable communications.

This integrated network should be capable of providing This integrated network should be capable of providing unified command and control channels for voice, data and unified command and control channels for voice, data and video applications video applications in future.in future.

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Digital Radio Trunking Systems – Digital Radio Trunking Systems – TETRA TETRA SummarySummary

• Disasters – both natural and man-made .

• Major Incidents/ fires .

• Incidents .

• RTA (Road Traffic Accidents) .

• Routine policing .

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Digital Radio Trunking Systems – TETRA Digital Radio Trunking Systems – TETRA SummarySummary

Four-channel TDMA gives excellentFour-channel TDMA gives excellent

spectrum economy spectrum economy - 4 channels- 4 channels

in one 25 kHz carrier .in one 25 kHz carrier .

Trunking technology supports Trunking technology supports controlled use of controlled use of shared shared

networks networks ..

Three Carriers- Three Carriers- 12 Channels12 Channels

FIREFIRE POLICEPOLICE

MEDICALMEDICAL

FIG 5FIG 5

CONCLUSION

TETRA is emergent digital PMR technology. Characteristics like consistent voice quality, greater call

privacy , fast call set-up ,high speed data transfer and outstanding spectral efficiency etc .reflects the dominance of TETRA over other PMR and PAMR systems.

It is modern technology for police ,fire service ,military ,etc.

Future success of TETRA depends on network operators to deliver benefits of TETRA services cost effectively to end users.

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REFERENCES

• Mikulic, M.; Modlic, B” General system architecture of

TETRA network for public safety services”

ELMAR, 2008. 50th International Symposium Volume 1,  10-

12 Sept. 2008 Page(s):207 - 210 .

• Laakso Nokia,  ” Overview of TETRA and it’s services

facilites   ”  Presentation on www.tetramou.com

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THANK YOUTHANK YOU

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