The power of TETRA - Direct Mode Operation Francesco Pasquali Selex Communications

Agenda Introduction to Direct Mode Operation (DMO) Applications & related benefits Services & facilities 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 offers the best of two worlds DMO ? It missed a key feature that conventional communications offered: direct communication outside network coverage TRUNKING MODE DIRECT MODE

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

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

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

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

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

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) communication Direct

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)

‘Back-to-back’ DMO channel usage Master uses Timeslot 1 for voice/data TX Slave (& Idle) use Timeslot 3 for pre-emption TETRA DMO Air Interface TDMA frame 1 2 3 4 1 3 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

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 xxx

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

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) Single carrier (1A) DM repeater 1 communications Single frequency DM for Tx & Rx Higher spectrum efficiency Trunked Mode Air Interface BS RX DM BS TX Preferred Frequency Usage Dual carrier (1B) DM repeater 1 communications Two frequencies: DM1 for Rx & DM2 Tx Reduces potential RF interference to TMO Trunked Mode Air Interface BS RX DM2 BS TX Preferred Frequency Usage DM1

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) Dual carrier 2 communications 2 frequencies: DM1 for Rx & DM2 Tx Need for RF full duplex Hw platform More complex and expensive than Type 1 Trunked Mode Air Interface BS RX DM1 BS TX Preferred Frequency Usage DM2

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

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

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

Benefits of DM Gateway Reliability: Cost: Special Applications: 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

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

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) in Direct mode receives TMO call, status and short messages from TMO users

Benefits of Dual Watch Cost: Special Applications: 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

Managed Direct Mode - MDMO MDMO terminal is restricted from transmitting unless it receives an authorising signal O.K. DMO 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

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 & 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)

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

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

Conclusions DMO is a key differentiator between TETRA and TETRA is a multi-mode standard 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

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