On May 16 Angelo Benvenuto took part at the opening masterclass of Critical Communications World 2017, speaking about Direct Mode

1. Presentation on behalf of the TCCA
Introduction to TETRA
Direct Mode
Angelo Benvenuto
Leonardo
Critical Communications World, Hong Kong, 16 May 2017
1v1

2. Presentation on behalf of the TCCA
Agenda
• DMO Modes, Services and facilities
• DMO key differences with TMO
• Equipment types: Repeaters, Gateways
• Benefits and Applications
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3. Presentation on behalf of the TCCA
TETRA operation modes
Trunked Mode Operations
• requires a well deployed network infrastructure
• provides a wide set of features
Direct Mode Operations
• doesn’t require an infrastructure
• provides services in “out of coverage” areas
• ensures services in case of main infrastructure faults
• supports a well defined subset of TMO features
• “simplex” voice communications only
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4. Presentation on behalf of the TCCA
DMO a key differentiator
TETRA DMO provide an answer for
• Fast
• Reliable
• Secure
Regardless lack of network coverage, resources
and failures
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Communications services

5. Presentation on behalf of the TCCA
DMO Operational modes
• 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
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6. Presentation on behalf of the TCCA
Key differences between DMO/TMO (1/2)
Individual call (point-to-point)
Group call (point-to-multipoint)
Circuit mode data transfer
Short data service (type 1, 2, 3, 4)
Status messages
Late entry
Emergency and pre-emptive calls
OTAR (over the air re-keying)
TMO DMO
 (Simplex)

1 slot
(up to 7.2 kbit/s)



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4 slots
(up to 28.8 kbit/s)
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




7. Presentation on behalf of the TCCA
Key differences between DMO/TMO (2/2)
TMO DMO





 (gateway)










Air interface encryption
End to end encryption
IP packet data
Call authorized by dispatcher
Ambience listening
Network based features
Call forwarding
Call recording

8. Presentation on behalf of the TCCA
Protocol details
TMO protocol stack DMO protocol stack
DMO
Frame structure

9. Presentation on behalf of the TCCA
DMO back-to-back
• Normal handheld and mobile terminals
• Capability so support DMO
• May need separate license
• GUI to select DM functionalities
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10. Presentation on behalf of the TCCA
DMO Characteristics
• Normal mode
Frequency Efficient mode
DMO enables 2 communications per carrier
(i.e. all 4 slots used, 2 slots used per each call)

11. Presentation on behalf of the TCCA
DMO repeater
• Special radio terminal equipment
• Functionalities embedded in mobile or handheld
terminals
• widen the DMO coverage when needed
reaching an MS out of the coverage
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• Based on usual 4 slot structure
• there are different type of Repeater:
 DM Repeater 1A For Normal Mode
 DM Repeater 1B For Normal Mode
 DM Repeater 2 For Freq Efficient Mode (Obsolete)

12. Presentation on behalf of the TCCA
DM Repeater Type 1A & 1B
• Single carrier (1A) DM repeater
 1 communications
 Single frequency DM for Repeater Tx & Rx
 Higher spectrum efficiency
• Dual carrier (1B) DM repeater
 1 communications
 Two different frequencies:
DM1 for Rx & DM2 for Tx
 Reduces potential RF interference
Trunked Mode
Air Interface
RP RX
DM2
RP TX
Type 1B
DM1
Trunked Mode
Air Interface
MS RX
DM
MS TX
Type 1A

13. Presentation on behalf of the TCCA
DMO gateway
• Enables DMO terminals to communicate with the
trunking system & vice versa
• Functionality embedded in mobile terminals
• Additional license may be required
• Gateway uses the ‘normal’ Back2Back DMO mode
(single call)
• One DMO carrier per call
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14. Presentation on behalf of the TCCA
DM Gateway
• Enables DMO terminals to communicate with the trunking system & vice versa
• Gateway uses the ‘normal’ Back2Back DMO mode (single call)
• One DMO carrier per call
Trunked Mode
Air Interface
GW RX
DM1
GW TX
TM1 TM2
Frequency Usage

15. Presentation on behalf of the TCCA
Typical applications
• Local area DMO communications
– Outside TMO coverage
– Strip line operations
• TMO network range extension
– Poor signal strength areas
– Uncertain coverage
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16. Presentation on behalf of the TCCA
Local area DMO operations
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• Localized activities outside TMO coverage
• No need of central coordination
• TMO signal lost
• No need to load TMO with additional traffic
• Avoid contention with other TMO users
• Example: rural area power line
maintenance
• Typical required coverage: 250 m

17. Presentation on behalf of the TCCA
TMO network extension
• Police officers when operating on foot after
leaving a vehicle
• First responders in building/in tunnel
operations
• Fire crews using the appliance as a gateway
or repeater on the fire ground
• Ambulance Crews leaving the vehicle to
attend to patients
• Transportation users when parked in
depots use Gateway for communications
to Trunked mode users
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18. Presentation on behalf of the TCCA
Rapid deployable system
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• An Emergency outside the Network
Coverage
• Needs of a fast network deployment
• Helicopter provides hot spot like
functions to operators working in
outside area
• Connection with remote control
center provided via gateway function

19. Presentation on behalf of the TCCA
DMO Benefits
• Operation outside of the coverage of a TETRA Infrastructure
• Predictable operation in poor signal strength areas
• Covert use (no monitoring from the network can take place)
• Communications when there are capacity limitations on a network
• Communication when a network fails
• Extension of the operational reach of a network
• Economic solution to coverage at edge of network or rural areas
• Enhanced coverage during network roll-out
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20. Presentation on behalf of the TCCA
Summary
• TETRA is a multi mode standard offering trunking & direct
mode communications
• DMO is a powerful feature thanks to its wide set of sub-mode
operations
• DMO provides a complementary service to trunked mode
communications
DMO: a key differentiator between TETRA and other public and
private cellular technologies
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