Direct Mode - Introduction to TETRA
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The document presents an overview of TETRA Direct Mode Operations (DMO) and its key features compared to Trunked Mode Operations (TMO), highlighting benefits such as operation in out-of-coverage areas and reliability during network failures. It details communication methods, equipment types, and operational scenarios for DMO, emphasizing its unique capabilities in ensuring secure and fast communications without infrastructure dependencies. Overall, DMO serves as a critical differentiator for TETRA technology in various communication environments.
Direct Mode - Introduction to TETRA
- 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 2
- 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 3
- 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 4 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 5
- 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) 4 slots (up to 28.8 kbit/s)
- 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 9
- 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 11 • 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 13
- 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 15
- 16. Presentation on behalf of the TCCA Local area DMO operations 16 • 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 17
- 18. Presentation on behalf of the TCCA Rapid deployable system 18 • 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 19
- 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 20