The power of TETRA - Direct Mode Operation Andrea Festelli OTE

Introduction & explanation of Direct Mode Operation (DMO) Agenda Introduction & explanation of Direct Mode Operation (DMO) Services & facilities Benefits & Applications Conclusions

Why Direct Mode in Trunking? Spectral Efficiency Automatic Operation Feature Rich Service Ease of Data Services Legacy trunking offered many benefits over conventional communications and was a great success in the market BUT ... TETRA’s multi-mode capability offers the best of both worlds in a single terminal. DMO ? It missed a key feature that conventional communications offered: direct communication outside network coverage TRUNKING MODE DIRECT MODE

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)

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

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

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

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

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

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

‘Back-to-back’ DMO A B C P A B C P DMO Master DMO Slave RX RX RX TX TX Timeslot 1 is used by the Master 1 The Slave uses Timeslot 3 3 TETRA DMO Air Interface TDMA frame 1 2 3 4 A B C P TX TX RX TX RX RX RX TX DMO Master DMO Slave ‘Frequency Efficient’ mode can use timeslots 2 and 4 for another call Speech Slots A B C Pre-emption request P

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

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

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

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 RPT RX DM1 RPT TX TYPE 2 DM2

DMO Repeater type 2 A P P A A P A P DMO Slave DMO Master 1 2 3 4 1 3 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 TETRA DMO Repeater 2 A Uplink Carrier A 1 2 3 4 P 1 3 DMO Slave DMO Master Speech Slots A Pre-emption request P

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.

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

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

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

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

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

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

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

Conclusions TETRA is a multi-mode standard 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