The power of TETRA - Direct Mode Operation

1. The power of TETRA - Direct Mode Operation Francesco Pasquali OTE

2. Agenda • Introduction to Direct Mode Operation (DMO) • Applications & related benefits • Services & facilities • Conclusions

3. 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 ...

4. What PMR users ask? 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

5. TETRA operation modes 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

6. What is TETRA Direct Mode ? 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

7. For border or out of coverage area communications... TRUNKED TETRA TETRA DMO Back-to-back scenario (1/3)

8. TRUNKED TETRA FAIL!! Back-to-back scenario (2/3) … for communications within coverage at times of capacity limitations (e.g. major incidents) TETRA DMO

9. Back-to-back scenario (3/3) … for communications within coverage if connection to the infrastructure is not needed or wanted (localised activities or private communications) Direct communication

10. DMO Characteristics • 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)

11. 1 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

12. Benefits of “Back-to-back” DMO • 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

13. TETRA DMO Repeater TETRA DMO FAIL!! TETRA DMO: Repeater Special radio terminal equipment called DMO repeater, allows enlarging the DMO coverage when needed

14. Preferred Frequency Usage • 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)

15. Dual carrier • 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)

16. Benefits of DM Repeater • Same benefits as back-to-back DMO in terms of Reliability Cost Special Applications • BUT … on a wider area and with increased communication reliability

17. TETRA DMO Gateway TETRA DMO: Gateway Special radio terminal equipment can operate as a gateway between the two worlds TRUNKED TETRA TETRA DMO

18. Preferred Frequency Usage 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

19. Benefits of DM Gateway • 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

20. TETRA 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

21. Dual Watch • 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

22. Benefits of Dual Watch • 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

23. DMO 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

24. Benefits of MDMO • Network Operators maintain better control of their network resource/ revenues • Removes potential for interference • Manages roaming

25. DMO Services and Facilities • 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)

26. DMO Security (Encryption) • 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

27. DMO Benefits & Applications • 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

28. Conclusions • 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

29. The power of TETRA - Direct Mode Operation Francesco Pasquali OTE Thank you