Push-to-talk (PTT) radio is a mission critical communications technology and has some unique advantages over public networks, yet it is increasingly being required to integrate into the wider world of IP-based communications for both commercial and public safety applications.
As more PTT radio systems are becoming IP-based there is an opportunity to evolve into an application rich environment using a unified communications approach. This will not only allow users to deploy applications more quickly, it will also take account of some of the uncertainties over standards and the vendor specific nature of many new applications.
A good example of this inexorable drive for technologies that will enable rich applications like real time video, is in the emergency services sector. It is also a prime example of market driven requirements racing ahead of evolution of standards.
The government’s drive to replace the emergency services’ Airwave network with an all IP system based on 4G/LTE has been in the headlines lately as police officers are seen routinely relaying live video feeds from scenes of crime and using GPS tracking applications on their smart devices.
PTT voice up in the air
One thing that has been left up in the air with the new service is what the solution will be for push-to-talk voice. It is anticipated that PTT voice will be enabled over 4G/LTE, but there is as yet no standard and there is unlikely to be one until after 2018. So what are the options?
Do the police continue to use off grid radio networks for PTT such as TETRA, which will mean carrying both a smart phone and a PTT terminal? There seems little desire to include PTT in the central capabilities technology known as the enhanced packet core (EPC) given the relatively low number of users involved and the inherent security risks. So, it is likely that PTT will be an add-on function in some way to the emergency service 4G/LTE network for many years to come.
4G is just another IP network
One approach, which would enable push-to-talk to function as part of an upgraded 4G/LTE network, but would not need to be incorporated into the EPC, is to look at 4G purely as an IP network that can carry a huge variety of technology applications. We are perfectly relaxed about running applications like Skype over 4G, so why not consider it a suitable carrier for push-to-talk radio?
Naturally, it assumes a need for radio systems that are IP connected, such as the Simoco Xd DMR, which is built around an end-to-end IP infrastructure. Once connected into an all IP unified communications (UC) platform PTT radios can be integrated into the 4G network. Because all devices on the UC cloud speak the common language of IP we can envisage communication between tablet devices, PTT radios, PBX phones and smart phones.
This unified communications approach to integrating PTT radio into IP networks is not just theory. We at Affini have already deployed just such a solution at Heathrow Airport where there was a similar need for PTT radios to come in from the cold and be able to work with other devices around the airport estate.
The specific highly regulated environment of an international airport meant that for many applications such as ramp communications, PTT radio was the only possible choice, so it had to be part of the ultimate solution. By divorcing the technology from the communications environment we were able to include PTT without having to compromise on safety or interoperability.
DMR migration with UC
The unified communications approach is also the optimal solution as organisations upgrade their PTT radios from analogue to the newer digital standards like DMR. Traditional approaches to migration were either system based or terminal based. With the latter you have a phased migration where new terminals can talk to both the old analogue or the new digital network.
In most cases this adds cost and complexity to the end-user device. So, the migration from old to new is possible, but it’s a question of implementing the new infrastructure side-by-side, then gradually moving users over to the new system. Then, once all users are switched over, we decommission the old network.
The downside of the terminal based approach is that it is almost a given that you will have to connect to a specific vendor’s infrastructure. A Motorola handset will only talk to a Motorola analogue network and a Motorola digital new network, so you are effectively locked into one vendor.
The system-based approach is a wholesale switchover to a new system, which is the big bang solution with all the cost and disruption that this may entail. At the end of the process you have a bright new DMR system with all the benefits that it brings in terms of spectral efficiency, better signal integrity and lower costs of ownership but it still doesn’t solve the problem of integrating a push-to-talk radio environment (users, processes, applications) with the organisation’s other IP-based platforms, systems, processes, applications, data and people.
With a unified communications approach you can buy yourself a degree of flexibility. Instead of having a Motorola device directly talking to a Simoco one, you have them both connected into a common IP backbone, which then allows you to integrate not only PTT radio, but ultimately all your other communications technologies like Wi-Fi, 4G and LTE.
Using an IP-based unified communications infrastructure you can create integration between 2G, 4G, push-to-talk, telephony, desktop and wider business applications and information sources. Also, you can achieve this without compromise, enabling you to use best of breed devices and applications for a particular role rather than being locked into one specific vendor.
Whether it’s about bringing PTT into a 4G/LTE network environment or it’s a question of upgrading current PTT solutions to DMR, the ability to divorce the communications environment from specific technologies is at the heart of the unified communications approach.
Not only does this deliver robust PTT voice on existing radio infrastructures and technologies, it also paves the way for whatever developments may be in the pipeline for PTT on smart devices. I can envisage a time when PMR manufacturers embrace the possibilities of IP wholeheartedly and develop PTT software applications alongside their equipment specific PTT offering.
For many years to come the PMR manufacturers will continue to have a strong place in mission critical communications, but with a unified approach their voice will continue to be heard at the heart of real time communications strategy.