TETRA - Direct Mode Operation Doug Gray Motorola

AGENDA Introduction & explanation of Direct Mode Operation (DMO) Services & Facilities Benefits & Applications Conclusions

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

WHAT IS TETRA DIRECT MODE ? There are 4 basic operational modes of TETRA DMO, viz. 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 (continuous relay between modes) Communication between Direct Mode terminals Communication between trunked and DMO terminals Further permutations are possible, e.g. Gateway/Repeater

TETRA DMO - BACK-TO-BACK TRUNKED TETRA C TETRA DMO A1 TETRA DMO B1 A3 A2 B2 B3

TETRA DMO REPEATER TRUNKED TETRA TETRA DMO A1 C A3 DMO Repeater B1

TETRA DMO-DUAL WATCH TRUNKED TETRA TETRA DMO TETRA DMO A2 B2 A1 C A3

TETRA DMO - GATEWAY TRUNKED TETRA TETRA DMO TETRA DMO A1 C A3 Gateway B1 Gateway B3

‘Frequency Efficient’ mode can use these timeslots for another call ‘BACK-TO-BACK’ DMO 1 2 3 4 DMO Air Interface ‘Frequency Efficient’ mode can use these timeslots for another call 1 2 3 4 Speech Slot Slot Structure Pre-emption DMO DMO Master Slave

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 Slide shows a list of characteristics

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) Simple RF 1 conversation, 1 DM channel Single carrier MS RX DM1 MS TX TYPE 1A Dual carrier (1B) More complex RF 1 conversation, 2 DM channels Supports multiple repeaters Reduces potential for RF interference MS RX DM1 MS TX TYPE 1B DM2

DMO REPEATER TYPE 1A DMO DMO Master Slave Frequency Usage DM1 MS RX 2 3 4 Master Slot Slave Slot DMO Air Interface DM1 Frequency Usage MS RX SPEECH UPSLOT Direct Mode Channel DM1 Direct Mode Channel DM1 SPEECH DOWNSLOT Pre-Emption Upslot (Slave slot pattern moved for diagram clarity) Type 1A Repeater DMO Slave DMO Master

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 Uses power control and addressing RPT RX DM1 RPT TX TYPE 2 DM2

DMO REPEATER TYPE 2 ‘B’ channel can use other slots DMO DMO Master 1 2 3 4 DMO Air Interface ‘B’ channel can use other slots 1 2 3 4 Uplink Carrier Pre-Emption Upslot (Slave slot pattern omitted for diagram clarity) 1 2 3 4 Downlink Carrier SPEECH UPSLOT Direct Mode Channel DM1 SPEECH DOWNSLOT Direct Mode Channel DM2 Type 2 Repeater DMO Master DMO Slave

DUAL WATCH Radio is operational in one system mode (Direct or Trunked) and simultaneously monitors signalling on the other system. Mobile Unit whilst engaged in a call in Trunking mode is alerted of a DMO call/request from a DMO terminal.

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

DMO REPEATER/GATEWAY Combines the functionality of a repeater and a gateway (similar to a VHF-UHF talk-through repeater) Interconnects direct mode to trunked mode Uses ‘normal’ DMO air interface (single call) Can be manned or stand alone (i.e. free running or manned by an operator) Trunked Mode Air Interface GW RX DM1 GW TX TM1 TM2 Frequency Usage

BENEFITS of DMO GATEWAY Extends range of Trunking Mode Operation 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 or Repeater/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. concealment

DMO SECURITY (ENCRYPTION) Air-interface encryption - TEA1, TEA2 & TEA3, incl. time stamping Implicit authentication Key management incl. Over The Air Rekeying (OTAR) “Zapping” (enabling/ disabling) terminals 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 Contol ‘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

TETRA - Direct Mode Operation Thank You Doug Gray Motorola