TETRA evolution for future needs

ETSI’s Terrestrial Trunked Radio (TETRA) is today the most successful digital trunked radio standard for professional users. The initial goal was to create a digital wireless communications technology meeting the specific requirements of emergency services, such as police, fire fighters and medical response units. The resulting specifications defined an exceptionally functional technology. By 2011, TETRA has been deployed in over 130 countries worldwide, of which half are outside Europe, with Asia Pacific and Africa being the fastest developing regions1. Nationwide government-operated mission critical TETRA networks have been in operation in Europe for many years and many other governments outside Europe are also basing their Government Radio Networks (GRN) on the TETRA standard. The largest market for TETRA continues to be national public safety organisations deploying TETRA for networks shared by its emergency services. However, the transport sector today present the second largest market segment.

In addition, TETRA also continues to be deployed in many other traditional PMR markets, such as utilities, industrial, as well as in the military sector for peace-keeping and other non-tactical activities.

Transportation is an ever-growing sector. TETRA finds application in this sector in a number of areas, for example with buses where alongside normal voice communications and broadcast traffic information, it can provide both real-time location information to its traffic control centre, and update passengers with arrival and departure information that is made available via intelligent roadside at-stop displays. Further - more the real-time location and capacity information can be used for intelligent traffic management allowing better passenger fluidity. This in turn reduces time spent and hence brings economic gains.

In airports, the group call facilities of TETRA are ideal for co-ordinating communications and work scheduling by flight number such that all the relevant teams servicing and dispatching a flight can communicate together.

For taxis, applications have been developed that allow traffic analysis and efficiency in deployment.

These aforementioned examples show the agility of the TETRA standard and suitability for innovative system integrators to provide customised operational solutions to meet communication challenges faced by modern public transport organisations. Data can, in a very reliable manner, be transferred via TETRA as status messages, Short Data Service (SDS) or IP packet data; in addition console display emula - tions can be built into computer applications to take full control of the radio for both voice and data. Centralised control is the key for system integrators to be able to build intelligent solutions – whether for management of pass - enger flows or vehicles.

With the move towards wideband TETRA and broadband solutions even a larger selection of services can be offered which in turn results in higher customer efficiency and satisfaction. These are important milestones at a time where data transmission capacity plays an ever greater role. The already existing wideband solutions are capable of transmitting data, images and basic moving video, while broadband solutions will be able to meet further demands for capacity – be it large amounts of data or streaming of high quality video like HD, 4K or 8K.

High quality video plays an important role when considering safety related applications like real-time surveillance video. These can often be found in the public transport, e.g. bus, metro and train and their passenger stations.

The technology

TETRA technology offers many advantages that include fast call set-up time, excellent group communication support, Direct Mode Operation (DMO) between radios, packet data and SDS, frequency economy, first-class voice quality and excellent security features. TETRA uses Time Division Multiple Access (TDMA) technology with four user channels on each 25 kHz of the allocated radio spectrum. This makes it inherently very efficient in the way that it uses the frequency spectrum.

The TETRA trunking facility provides a pooling of all radio channels which are then allocated on demand to individual users, in both voice and data modes. By the provision of national and multi-national networks, national and international roaming can be supported, the user being in constant seamless communications with his colleagues. The deployment of such systems i.e. TETRA ISI (Inter-System Interface) has already started.

TETRA supports point-to-point and point-tomulti- point communications both by the use of the TETRA infrastructure and by the use of DMO without infrastructure. TETRA is an inter - operability standard with support from many vendors; compared with proprietary solutions this gives users considerable advantages in the form of greater choice and lower price.

TETRA release 2 includes various improve - ments like TETRA Enhanced Data Service (TEDS). Bit rates that can be supported with TEDS range between 30 kbit/s and 400 kbit/s depending on channel widths of 25 kHz, 50 kHz, 100 kHz and 150 kHz. TEDS will hence have a major positive impact on the long-anticipated move to data intensive applications for mission critical users and others.

Other improvements in TETRA release 2 are the extension of the cell range from 58km to 83km and the inclusion of a common protocol format for positioning services, known as the Location Information Protocol (LIP).

Whilst many of the aforementioned enhancements are primarily a response to requirements of TETRA’s mission-critical users, they will of course benefit all the other demanding users as well.

Frequency allocation

Wireless communication systems inevitably need the use of radio spectrum, a scarce and valuable resource. For emergency systems in Europe, the frequency bands 380-385 MHz and 390-395 MHz have been allocated for use by digital land mobile systems by the European Communication Office. For civil systems in Europe the frequency bands 410-430 MHz, 450-470 MHz have been allocated for TETRA.

Furthermore, the frequency band 380 MHz to 470 MHz has been allocated for wide band Public Protection and Disaster Relief (PPDR) radio applications. The decision on the harmonisation of frequency bands for the implementation of digital PPDR radio applications can be con - sidered as a clear indication of a commitment by the European national administrations to support broadband wide area Public Safety and Security PPDR radio applications – a decision of particular importance for TEDS.

Work is currently in progress to meet future needs for critical broadband systems. Last year the ECC (Electronic Communications Committee) published their Report 199 on User requirements and spectrum needs for future European broadband PPDR systems (Wide Area Networks). The report studies various PPDR scenarios and the corresponding envisaged spectrum needs. The report generally concludes that a 2 x 10 MHz bandwidth of spectrum will be needed in order to ensure the services availablity. The battle for dedicated frequencies for PPDR broadband services is however still far from being won.

TETRA and public safety standards development in ETSI

The production of the standards for TETRA and its further evolution is the task of ETSI’s TCCE (TETRA and Critical Communications Evolution) Technical Committee. The work is performed in close collaboration with the TETRA and Critical Communications Association, an industry organisation representing users, manu - facturers, application providers, integrators, operators, test houses and telecommunication agencies – in all, around 200 organisations from all corners of the world. This collaboration ensures that the standardised solutions meet the current and emerging expectations of all parts of the TETRA and critical communications community, thus helping to future-proof the TETRA technology and its users.

Within the ETSI technical committee, over 150 technical specialists from ETSI member companies participate in working groups that focus on specific topics, such as user requirements, air interface, network protocols, high-speed data, voice coding, security and off-network services.

The TETRA technology continues to evolve and it is the task of the ETSI TCCE committee to evolve the TETRA and related standards accordingly.

When it comes down to critical broadband data services, the TCCE committe has endorsed, as a working assumption, that the most likely solution will be based on using LTE as the bearer technology. The standardisation of LTE (often referred to as 4G mobile) is taking place in 3GPP, the Third Generation Partnership Project – a joint project between ETSI and five other regional standards bodies across the globe. As it stands, LTE as specified today is not capable of providing the vast range of functionality that we are used to in current TETRA systems. Therefore it has been natural for the TCCE committee, together with its partner organisation as experts of PMR specific requirements, to provide input to 3GPP to be used as a basis when developing functionality corresponding to that considered as funda - mental for PMR radio technology, such as efficient group call and direct mode operation. In 3GPP’s terminology these are called Proximitybased Services and Group Communication System Enablers for LTE. The standard development work on these features is underway and initial systems aspects may be publicly available during the latter part of 2014. However, it is generally believed that TETRA will be the principal technology for mission critical voice for decades to come.

The work of the TETRA and Critical Communi cations Evolution committee is complemented by other ETSI standards activities related to emergency response communications. ETSI’s EMTEL committee is responsible for identifying and co-ordinating the operational and technical requirements of those involved in the provision of emergency communications. As an example, the ‘EU Alert’ service can be mentioned – a specification of requirements for a European public warning system (PWS) where the alert is being sent in the local language. ‘Total Conversation’ provides for the handling of emergency calls placed by people with hearing or speaking disabilities by combining video, realtime text and audio in a conversational call.

ETSI’s Satellite Emergency Communication working group within the SES (Satellite Earth Stations and Systems) technical committe performs standardisation in the area of satellitebased emergency management including functional architectures, services for comm - unication and the supporting protocols. At this moment group is working on defining reference scenarios for emergency satelliteassisted telecommunication services in order to facilitate the evaluation of needed comm - unication resources. One of the scenarios being looked at in more details is the event of a mass casualty incident in public land transportation. This work can be expected to be published in early-2015.

All of this work relies on the involvement and feedback of users, operators, regulators and manufacturers who are invited to participate in the open standards process. ETSI produces globally-applicable standards for Information and Communications Technologies (ICT), including fixed, mobile, radio, converged, broadcast, vehicular, maritime, aeronautical and internet technologies, and is officially recognised by the European Union as a European Standards Organisation. ETSI is an independent, not-forprofit association whose over 750 members from 62 countries and across five continents determine its work programme and participate directly in its work.

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