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The power of TETRA - Direct Mode Operation. Francesco Pasquali OTE. Agenda. Introduction to Direct Mode Operation (DMO) Applications & related benefits Services & facilities Conclusions.

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Agenda
Agenda

  • Introduction to Direct Mode Operation (DMO)

  • Applications & related benefits

  • Services & facilities

  • Conclusions


Why direct mode in trunking

Legacy trunking offered many benefits over conventional communications and was a great success in the market

Automatic Operation

Spectral

Efficiency

It missed a key feature that conventional communications offered:

direct communication outside network coverage

?

DMO

Ease of

Data Services

Feature Rich

Service

TETRA offers the best of two worlds

TRUNKING MODE

DIRECT MODE

Why Direct Mode in Trunking?

BUT ...


What pmr users ask
What PMR users ask? communications and was a great success in the market

Users require to communicate everywhere at anytime, regardless of

  • lack of network coverage

  • lack of resources

  • any type of network failure

and always need

  • emergency communications

  • security

  • voice & data transmission, individual & group calls


Tetra operation modes
TETRA operation modes communications and was a great success in the market

TETRA terminals provide integrated digital trunked (TMO) and direct (DMO) modes of operation

DMO adds border or out of coverage area communications

DMO provides communications within coverage at times of capacity limitations or whenever connection with the infrastructure is not needed


What is tetra direct mode
What is TETRA Direct Mode ? communications and was a great success in the market

There are 4 basic operational modes of TETRA DMO:

  • “Back-to-back”

    • standard terminal to terminal communications

  • DM Repeater

    • extension of DMO terminal coverage

  • DM Gateway

    • relay between DMO and TMO

  • Dual Watch

    • periodic “scanning” of ‘other’ mode


Back to back scenario 1 3

For border or out of coverage area communications communications and was a great success in the market...

TRUNKED

TETRA

TETRA

DMO

Back-to-back scenario (1/3)


Back to back scenario 2 3

TRUNKED communications and was a great success in the market

TETRA

FAIL!!

Back-to-back scenario (2/3)

… for communications within coverage at times of capacity limitations (e.g. major incidents)

TETRA

DMO


Back to back scenario 3 3
Back-to-back scenario (3/3) communications and was a great success in the market

… for communications within coverage if connection to the infrastructure is not needed or wanted (localised activities or private communications)

Direct

communication


Dmo characteristics
DMO Characteristics communications and was a great success in the market

  • Normal mode DMO enables 1 communication per carrier (i.e. 1 per 4 timeslots, 2 slots used + 2 free)

  • Frequency Efficient Mode DMO enables 2 communications per carrier (i.e. all 4 slots used, 2 slots used per each call)

  • Transmitting radio acts as ‘Master’ on a single DMO channel (i.e. pair of alternated time slots)

  • Receiving radio is ‘Slave’ on a single DMO channel

  • Timeslot 1 is used as “traffic channel” for voice and data transmission by the Master radio

  • Timeslot 3 is used for signalling transmission by Master, slave and idle radios (e.g. for pre-emption and PTT request)


Back to back dmo channel usage

1 communications and was a great success in the market

1

1

2

2

2

3

3

3

4

4

4

TETRA DMO Air Interface TDMA frame

1

2

3

4

1

3

1

3

1

3

1

3

RX

RX

RX

TX

DMO

Master

TX

DMO

Slave

TX

TX

RX

A

B

C

Speech Slots

Pre-emption request

P

‘Back-to-back’ DMO channel usage

Master uses Timeslot 1 for voice/data TX

Slave (& Idle) use Timeslot 3 for pre-emption

A

B

C

P

‘Frequency Efficient’ mode can use timeslots 2 and 4 for another call


Benefits of back to back dmo
Benefits of “Back-to-back” DMO communications and was a great success in the market

  • Reliability

    • Local area communications always granted under any kind of fault of the network (disruption, congestion, interference)

  • Cost

    • Relaxed requirements for coverage in low-traffic areas and “enclosed” areas (e.g. buildings, tunnels, underground areas, etc.)

    • Relaxed requirements for base station channels provisioning

  • Special Applications

    • Local area operations (e.g. “strip-line”)

    • Covert operations


Tetra dmo repeater

TETRA communications and was a great success in the market

DMO

Repeater

TETRA

DMO

FAIL!!

TETRA DMO: Repeater

Special radio terminal equipment called DMO repeater, allows enlarging the DMO coverage when needed


Dm repeater type 1a 1b

Preferred Frequency Usage communications and was a great success in the market

  • Single carrier (1A) DM repeater

    • 1 communications

    • Single frequencyDM for Tx & Rx

    • Higher spectrum efficiency

DM

Trunked Mode

Air Interface

BS RX

BS TX

Preferred Frequency Usage

  • Dual carrier (1B) DM repeater

    • 1 communications

    • Two frequencies: DM1for Rx & DM2 Tx

    • Reduces potential RF interference to TMO

DM1

DM2

Trunked Mode

Air Interface

BS RX

BS TX

DM Repeater Type 1A & 1B

  • Based on usual 4 slot structure

    • 2 slots for Master  Repeater transmissions

    • 2 slots for Slave / Idle  Repeater transmissions

    • Master/slave operation (3 slot delay)


Dm repeater type 2

  • Dual carrier communications and was a great success in the market

    • 2 communications

    • 2 frequencies: DM1for Rx &DM2Tx

    • Need for RF full duplex Hw platform

    • More complex and expensive than Type 1

Preferred Frequency Usage

DM2

DM1

Trunked Mode

Air Interface

BS RX

BS TX

DM Repeater Type 2

  • Two simultaneous calls per repeater

  • Based on usual 4 slot structure

    • Two alternated slots per call on each link

    • Master/slave operation (4 slot delay)


Benefits of dm repeater
Benefits of DM Repeater communications and was a great success in the market

  • Same benefits as back-to-back DMO in terms of

Reliability

Cost

Special Applications

  • BUT …

on a wider area and with increased

communication reliability


Tetra dmo gateway

TETRA communications and was a great success in the market

DMO Gateway

TETRA DMO: Gateway

Special radio terminal equipment can operate as a gateway between the two worlds

TRUNKED

TETRA

TETRA

DMO


Dm gateway

Preferred Frequency Usage communications and was a great success in the market

TM2

TM1

DM1

Trunked Mode

Air Interface

BS TX

BS RX

Uplink (TM1)

Gateway

Downlink (TM2)

Direct Mode

Channel

DM1

Trunked Mode

Cell

DMO User

DM Gateway

  • Enables DMO terminals to communicate with the trunking system & vice versa

  • Uses ‘normal’ DMO air interface (single call)

  • One DMO carrier per call


Benefits of dm gateway
Benefits of DM Gateway communications and was a great success in the market

  • Reliability:

    • Trunked communications through adjacent cells partially supported under fault of one radio base station

  • Cost:

    • More relaxed requirements for coverage in low-traffic areas and “enclosed” areas (incl. buildings, tunnels, underground areas, etc.)

    • Better coverage possibilities during early stages of network roll-out

  • Special Applications:

    • Enable “occasional and immediate coverage” at cost-effective rates


Tetra dmo dual watch

TETRA communications and was a great success in the market

DMO

TETRA

Dual Watch

Terminal

TETRA DMO: Dual watch

Special radio terminal equipment can get in touch with both TMO and DMO worlds simultaneously

TRUNKED

TETRA


Dual watch
Dual Watch communications and was a great success in the market

  • The Radio is operational in one mode (Direct or Trunked) and simultaneously monitors the other for incoming communications.

  • In particular the Radio Unit whilst idle (Idle Dual Watch) or engaged in a call (Full Dual Watch) inDirectmode

  • receives TMO call, status and short messages from TMO users


Benefits of dual watch
Benefits of Dual Watch communications and was a great success in the market

  • Cost:

    • Enlarge communication support in fringe areas: it allows further relaxing of coverage requirements

  • Special Applications:

    • Improve local area communications: terminals avoiding to waste resources can be contacted whenever needed


Managed direct mode mdmo

DMO communications and was a great success in the market

O.K.

Managed Direct Mode - MDMO

  • MDMO terminal is restricted from transmitting unless it receives an authorising signal

  • Authorisation can be received

    • directly from the SwMI (for Dual Mode or Dual Watch terminals)

    • from a DMO gateway and/or repeater device

    • from an authorising device permanently in contact with the system

  • Authorisation can be limited both in time and geographically


Benefits of mdmo
Benefits of MDMO communications and was a great success in the market

  • Network Operators maintain better control of their network resource/ revenues

  • Removes potential for interference

  • Manages roaming


Dmo services and facilities
DMO Services and Facilities communications and was a great success in the market

  • Simplex speech - Individual & Group Call

  • Late Entry

  • Transmitting Party Identification (TPI), incl. suppression

  • Emergency & pre-emptive calls

  • Status and Short Data Service (SDS)

  • Circuit mode data up to 7.2 kbps (P2P and P2MP)


Dmo security encryption
DMO Security (Encryption) communications and was a great success in the market

  • Air-interface encryption

    • Static Key Encryption

    • TEA1, TEA2, TEA3 and TEA4 incl. time stamping

  • Implicit authentication

    • Provided by Air Interface Encryption

  • End-to-end encryption


Dmo benefits applications
DMO Benefits & Applications communications and was a great success in the market

  • Operation outside the coverage of Trunking Infrastructure

  • Gives extra capacity when trunked network is highly loaded

  • Operations in poor signal strength areas (allows more relaxed coverage requirements and lower the related expenditure)

  • Fall-back operation when the Trunking Infrastructure system is inoperative

  • Covert Operations - cannot be monitored by Control

  • ‘Stripline’ applications (power, oil, water distribution lines) not requiring trunked network capacity


Conclusions
Conclusions communications and was a great success in the market

  • TETRA is a multi-modestandard offering trunking and direct communication in-one

  • DMO - a powerful feature thanks to exhaustive set of sub-modes of operation

  • Significant commonality with trunked V+D TETRA enables for dual-mode terminals actually available on the market

DMO is a key differentiator between TETRA and

other, public and private, cellular technologies


The power of tetra direct mode operation1

The power of TETRA - Direct Mode Operation communications and was a great success in the market

Francesco Pasquali

OTE

Thank you


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