The power of TETRA - Direct Mode Operation

1. The power of TETRA - Direct Mode Operation Andrea Festelli OTE

2. Agenda • Introduction & explanation of Direct Mode Operation (DMO) • Services & facilities • Benefits & Applications • 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’s multi-mode capability offers the best of both worlds in a single terminal. TRUNKING MODE DIRECT MODE Why Direct Mode in Trunking? BUT ...

4. What is TETRA Direct Mode ? There are 4 basic operational modes of TETRA DMO: • 1 “Back-to-back”(standard DMO terminal coverage) • 2 DMO Repeater(extended DMO terminal coverage) • 3 Dual Watch(periodic “scanning” of ‘other’ mode) • 4 DMO Gateway(relay between DMO and TMO)

5. For border or out of coverage area communications... TRUNKED TETRA TETRA DMO TETRA DMO: Back-to-back (1/2)

6. TRUNKED TETRA … and to provide communications within coverage at times of capacity limitations FAIL!! TETRA DMO TETRA DMO: Back-to-back (2/2)

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

8. TETRA DMO TETRA Dual Watch Terminal TETRA DMO: Dual watch Special radio terminal equipment can simultaneously get in touch with both TMO and DMO worlds TRUNKED TETRA

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

10. TETRA operation modes TETRA provides 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 As shown for “back-to-back”, also other DMO modes can be useful under the trunked network coverage

11. Timeslot 1 is used by the Master The Slave uses Timeslot 3 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 A B C P ‘Frequency Efficient’ mode can use timeslots 2 and 4 for another call

12. DMO Characteristics • Normal DMO enables 1 conversation per carrier(i.e. 1 per 4 timeslots) • Transmitting radio acts as ‘Master’ on a single timeslot • Receiving radio is ‘Slave’ on a single timeslot • In normal mode, two time slots are used, two are free • In Frequency Efficient Mode, all four timeslots are used (2x2) enabling two conversations per carrier

13. TYPE 1A DM1 MS RX MS TX • Single carrier (1A) • 1 conversation, 1 DM channel • Single carrier • Higher spectrum efficiency • Dual carrier (1B) • 1 conversation, 2 DM channels • Reduces potential for RF interference TYPE 1B DM1 DM2 MS RX MS TX DMO Repeater Type 1A & 1B • Only one call per repeater • Uses a 4 slot structure • 2 slot uplink • 2 slot downlink • Master/slave operation (3 slot delay)

14. DMO Master 1 1 1 2 2 2 3 3 3 4 4 4 Speech Slots A B 1 2 3 4 TDMA frame 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 Pre-emption request P TETRA DMO Repeater 1A DMO Slave DMO Repeater type 1A The Masterstill uses its Timeslot 1 and Timeslot 3 as in back-to-back Masternumbering 1 1 3 TETRA DMO A.I. Carrier X A A B B P P Slave numbering 1 1 3 The Slavestill uses its Timeslot 1 and Timeslot 3 as in back-to-back A B P

15. TYPE 2 DM1 DM2 RPT RX RPT TX DMO Repeater Type 2 • Two simultaneous calls per repeater • Uses a 4 slot structure • 4 slot uplink • 4 slot downlink • Master/slave operation (4 slot delay) • Dual carrier • More complex RF but supports multiple repeaters

16. 1 1 1 2 2 2 3 3 3 4 4 4 1 1 1 2 2 2 3 3 3 4 4 4 1 3 1 3 1 3 1 1 1 3 3 3 A TETRA DMO Repeater 2 P Speech Slots Pre-emption request DMO Master DMO Slave DMO Repeater type 2 B channel can use timeslot 2 and 4 Downlink Carrier A P Timeslot 1 is still used by the Master, the Slave still uses Timeslot 3 P A Uplink Carrier A P

17. Dual Watch • Radio is operational in one system mode (Direct or Trunked) and simultaneously monitors signalling on the other system. Mobile Unit whilst idle (Idle Dual Watch) or engaged in a call (Full Dual Watch) in Direct mode is alerted of a TMO call/request from a TMO terminal.

18. Frequency Usage TM1 TM2 DM1 Trunked Mode Air Interface GW RX GW TX DMO User DMO Gateway • Enables DMO terminals to communicate with the trunking system & vice versa • Uses ‘normal’ DMO air interface(single call) Uplink (TM1) Gateway Downlink (TM2) Direct Mode Channel DM1 • One DMO carrier per call Trunked Mode Cell

19. Benefits of DMO Gateway • Extends range of Trunking Mode Operation (e.g. radio cell fringes, tunnels, buildings, …) • Reduces Infrastructure costs • Enables remote ‘occasional users’ to have communication at cost effective rates • Gives Network Operators better coverage possibilities during early stages of network roll-out

20. DMO O.K. Managed Direct Mode - MDMO • MDMO terminal is restricted from transmitting unlessit receives an authorising signal • Generated by authorising device which is in permanent contact with system, or….. • …. generated by modified DMO Gateway device • Validity time encoded in authorising signal

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

22. DMO Services and Facilities • Simplex speech - Individual or Group Call • Circuit mode data up to 7.2 kbps, incl. point-to-point & point-to-multipoint • Status and short data service (SDS) • Late Entry • Emergency call • Talking Party Identification (TPI) , incl. suppression

23. DMO Security (Encryption) • Air-interface encryption - TEA1, TEA2, TEA3 and TEA4 incl. time stamping • Implicit authentication • End-to-end encryption mechanism

24. 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 • 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

25. Conclusions • TETRA is a multi-modestandard offering trunking and conventional operation in-one • DMO - a powerful feature in the total TETRA offering, as it comprises of several sub-modes of operation • Significant commonality with trunked V+D TETRA enables for multi-mode terminals (DMO & V+D) • DMO is a significant differentiator between TETRA and other cellular services