Thirty years have now passed since the completion of the first set of TETRA standards by ETSI. It is important to remember that TETRA brought the critical communications world into a new ‘digital age’ at almost the same time as our perhaps more famous, commercial, mass-market ETSI sibling, GSM.

NATO’s important decision to give European public safety organisations access to up to 2 x 5MHz in the key 380-400MHz UHF band, meanwhile, provided further fuel and momentum to efforts to develop a unified communications solution for first-responders. 

Other key developments during the mid-1990s included the creation of TETRA MoU – still thriving today as TCCA – in late 1994 by the main drivers of the emerging standard. And also strong competition from a French FDMA alternative (TETRA uses the TDMA channel access method), the publicly available specification Tetrapol, which is still in use today in countries such as France, Spain and Switzerland.

The first public safety networks based on the TETRA standard started their rollout at the very end of the last millennium. This led to several major nationwide public safety networks such as VIRVE (Finland), ASTRID (Belgium) and Airwave (United Kingdom) being fully operational by the mid-2000s. 

Meanwhile, a major, pan-European public access mobile radio (PAMR) network, operated by Dolphin Telecom, failed in its mission to extend TETRA’s reach to public networks. However, multiple non-public safety sectors did start embracing TETRA, which became the dominant digital LMR solution across the Middle East region and parts of Latin America and Asia-Pacific, where the appropriate spectrum was made available. 

For diverse reasons, public safety entities in North America, Australia, New Zealand and some parts of Asia preferred APCO and TIA’s Project 25 (P25) alternative standard for digital LMR systems.

Meteoric rise of the smartphone

Moving briskly forward to the early 2010s, we observe the meteoric rise of the smartphone within the much larger, global commercial market. This inevitably generated a widespread concern among a growing number of public safety agencies about the lack of a serious data capability within their existing TETRA/P25 networks. 

The inability to transmit high-resolution images and video from major, or even routine, incidents meant that hundreds of millions of consumers – and perhaps more importantly, almost every criminal gang – now had access to more advanced communications features than first-responders.

2012 was an important year in our journey to broadband. The US government set up the First Responder Network Authority (FirstNet) with dedicated spectrum in 700MHz and several billion dollars earmarked from future spectrum auctions. Also, TCCA set up its broadband group (CCBG) to start engaging with global standards bodies and the wider community. 

Early public safety LTE programmes such as the UK’s Emergency Services Network, and then Korea’s SafeNet (in the wake of the 2014 ferry disaster), were also created. The importance and urgency of public safety’s needs were recognised by 3GPP, which set up an entirely new group, SA6, to accelerate the first release of mission-critical push-to-talk standards during Release 13, published in 2016.

Mission-critical data and video standards followed in Release 14, completing the basic set of features considered necessary to launch mission-critical services during the 2010s. However, with the exception of the UK’s ambitious ESN programme – which later had to backtrack on its original plans – no other agency was considering switching off their existing TETRA/P25 network until the next-generation network was fully up, running and offering all possible services to users’ satisfaction.

Critical communications enters the 2020s

The first three years of the current decade have been eventful, to say the least. With the first year barely weeks old, COVID-19 started sweeping the world, killing millions of people and confining a significant proportion of the global population to their homes while government health programmes scurried to find reliable vaccines to allow the return to some kind of normality. 

Fake news and endless conspiracy theories started spreading across social media; global supply chains were disrupted and relationships between different nations, cultures, religions and social groups became strained. 

In the wider communications space, meanwhile, new platforms have emerged, allowing us to communicate with each other remotely, opening up new opportunities for the global workforce. 5G has reached its first one billion users, without yet fulfilling its promise of revolutionising industry and commerce. 

5G’s more advanced features such as network slicing, ultra-reliable, low-latency and massive machine-type communications are still in their infancy. Mobile operators and new system integrators are struggling to apply new business models – such as private and hybrid networks – that guarantee availability, reliability and privacy to vanguard enterprises pushing ahead with digital transformation programmes.

In the critical communications space, the public safety sector is continuing to struggle to complete the much-heralded transition from legacy narrowband technology to the next generation of broadband LTE/5G-based solutions that were expected to dominate the market by the early 2020s. 

Other sectors such as automotive, railways, utilities, ‘factories of the future’, ports, airports and so on have joined the 3GPP party. They are now being awarded private spectrum to build their own private networks, but are still lacking the economies of scale and full range of devices and applications required to complete the transition.

With that in mind, what is stopping us making the full transition to critical broadband? Back around 2012, when FirstNet and CCBG came into being and the UK government started looking at LTE as a credible replacement for its maturing Airwave network, emergency services and other critical users could have expected a full solution to have been ready by the end of that decade. It is therefore important to understand why this did not happen anywhere at scale, and what the prospects are for a successful migration in the short to medium term, most definitely before the end of this decade.

Successful deployment

Firstly, when we look back at the successful deployment of TETRA across Europe during the 2000s, we must remember that these nationwide networks were replacing a myriad of incompatible local and regional systems. We must also remember that TETRA was specifically designed with mission-critical services in mind. 

Perhaps the most successful public safety LTE deployment so far, in South Korea, came as the result of a national tragedy in 2014 and that this new network was replacing a myriad of incompatible local and regional LMR networks. In the US, FirstNet has completed its nationwide deployment and has over four million users, but has not yet attempted to replace existing critical voice networks, thereby avoiding UK ESN’s ongoing trials and tribulations.

Designing, building and operating large-scale mission-critical mobile broadband networks in the early 2020s is not for the faint-hearted. Just for starters, either entirely new networks need to be built across a wide geographical area, or existing commercial networks need to be extended and enhanced to provide sufficient coverage and capacity for critical users with the necessary levels of availability and reliability. 

Then, this new network needs to be rigorously tested in real time over extended periods to verify full compliance. The right mix of devices with the right form factors and functionality – including the full range of mission-critical services – also need to be available and running smoothly and seamlessly over the critical communications network in order to launch services for end-users.

Even when network, devices and services are in place, meanwhile, a significant number of challenges remain before existing networks can be switched off and first-responders can rely on the new solutions for all their communications needs. These include interworking, device-to-device, multicast, full redundancy and fully open interfaces, among others. 

Most public safety agencies have expressed a wish to keep the transition period from TETRA to LTE as short as possible. However, due to the complexity of the migration process, it has become clear that there will be a significant period when both solutions will be operating together, requiring interworking.

Following completion of Stage 3 work within 3GPP on the so-called IWF (interworking function) during Release 16, the LMR standards bodies, ETSI and ATIS, have been completing work on their side. Technology company Etherstack has already announced agreements with major suppliers, so solutions should become available soon that will then need to be proven at scale.

Another question is device-to-device (D2D) communications – Direct Mode/DMO in the TETRA standard. This provides the ultimate level of resilience and redundancy for first-responders when networks go down, are saturated or users find themselves out of network coverage or prefer not to rely on the network for specific operations. 

This functionality is a given in the TETRA and P25 worlds but previously unheard of in commercial networks, which make their money from charging customers to use their networks! 3GPP developed ProSe (Proximity Services), which was never really implemented because of the lower power – and therefore shorter range – of mobile devices. 

Higher power is available for vehicle-mounted devices, but higher-class devices come with their own challenges. More recently within 3GPP, public safety agencies and other verticals have been collaborating with the automotive industry on V2X (vehicle-to-everything) services which include a sidelink that provides D2D capabilities. It is likely in the short term that additional frequencies and accessories will be required to provide D2D services until an acceptable alternative is developed.

LMR’s traditional operating model has also been based on half-duplex (PTT), one-to-many group calls, where potentially hundreds of first-responders in a local area can communicate with each other during a major incident. 

Mobile telephony has always been based on one-to-one communications, with a separate channel required as the number of users increases (unicast mode). In order to allow the efficient, synchronised delivery of mission-critical voice, data and video, so-called multicast/broadcast standards have been developed within 3GPP as eMBMS (evolved multimedia broadcast multicast services). 

eMBMS becomes increasingly essential for the successful operation of mission-critical LTE networks as the number of users increases. The 5G equivalent – 5MBS – is currently being standardised within 3GPP Releases 17/18.

3GPP standards continue to evolve with 5G Advanced and beyond, offering more flexible architectures. It also offers open platforms and interfaces; greater integration between terrestrial and non-terrestrial networks, public and private networks; 3GPP and non-3GPP networks; and much more. All this will benefit public safety and other critical users in the future, once the transition has been made. 

With all this in mind, it is therefore clear that existing legacy solutions are likely to be required for longer than anticipated; however, there is also a clear consensus about the path to be taken. A growing number of public safety agencies and other critical users are now making the move to standards-based mobile broadband, and these agencies are talking to each other much more and sharing experiences. 

The European Commission-funded BroadWay programme has now been completed and is moving towards an implementation phase as BroadNet. We are most definitely on the right track, and now it is time to press the accelerator.

The road ahead – pressing the accelerator

So, here we are in early 2023, at a crossroads. There can be no going back to the ways of the past. And yet there is almost certainly no final goal in this new reality of continuous improvement where more open, flexible, software-defined networks allow upgrades to take place in an instant without the need to replace expensive hardware. 

Over the next three to five years, we will see many more public safety agencies and other critical users make the successful move to mobile broadband solutions. This will involve using a combination of their own and mobile operator spectrum; a combination of fixed and mobile; connecting people, places, things, vehicles, sensors, robots, with increasingly orchestrated and automated processes. 

Solutions such as TETRA will probably remain as a fallback for some time to come, although some agencies will bravely switch them off and fully embrace the future. 

More mistakes will inevitably be made, but there will also be important breakthroughs, new initiatives, exciting new products and services. Then, sometime around 2030, we will look back again and realise we have entered a very different critical communications world, with its own unique set of opportunities and challenges.

We will be led by a new generation of thought leaders and decision-makers – human or otherwise – building upon the modest successes of the previous generation to accelerate our path towards the smarter, safer, greener, fairer world that lies just over the horizon.