LTE puts data on the street, but voice remains PMR

However, at this early stage of its deployment, LTE can’t be all things to all users even though, as an IP-based technology, it more readily fits into a wider development community. It doesn’t support voice today and only a very limited range of LTE-enabled terminals and devices are available.

That means it isn’t suitable for all types of mission-critical communications and public safety organisations will need to continue to use other technologies such as TETRA, P25 and DMR to support the needs of users in the field.

US network

In the US, the Government has committed $7bn to rolling out a nationwide public safety LTE network, which will provide coverage to more than 95% of the country using band 14 spectrum already set aside for public safety use. That sum will cover the construction of base stations and the associated equipment, but it won’t cover the terminals and the applications.

It is also a similar cost to the commercial LTE networks being rolled out in the US by Sprint, Verizon and AT&T, which will have similar levels of coverage and offer potentially greater capacity. So why can’t public safety users strike deals with commercial providers for LTE rather than going to the expense of building their own network?It’s about resilience, say Fred Scalera, director of public safety and emergency management for strategic industries at Alcatel-Lucent.

‘Having a private network for public safety makes a huge difference,’ he says. ‘I was in New York City for 9/11 and present in the aftermath of Hurricane Katrina. What happens during those periods is that cellphones get used by responders and the public, and when networks go down it leaves a big void. By building our own public safety system in band 14 it will never fail. It’s the same standard, but instead of having millions of users, it has thousands.’

Although vendors are reluctant to claim LTE, IP-based technology has reached mission-critical status. Darren McQueen, corporate VP of private broadband at Motorola Solutions, emphasises the benefits of improved public safety data connectivity.

Public saftey debate

‘The debate in the US is not only surrounding public safety data applications but also mission-critical voice,’ he says. ‘Motorola is very cautious about mission-critical voice performance in terms of what happens at the cell edge, but we are very bullish in terms of what public safety LTE can do as a data connection.’

Even so, without voice over LTE (VoLTE) and a mature ecosystem of devices and applications, the mission-critical LTE era remains years away. ‘Within three years we will be demonstrating mission-critical [LTE],’ adds Scalera.

‘In five years, mission-critical will be fully available but remember we’re agnostic, we just build the network, anybody can work over us. The problem is that manufacturers for mission-critical devices aren’t manufacturing yet because the market isn’t there. It won’t be at the mission-critical stage until people design devices and software [specifically for public safety].’

Data carrier

Motorola Solutions’ McQueen agrees: ‘We don’t see LTE today as able to support mission-critical voice communications,’ he says. ‘Even the commercial operators have rolled it out as a data carrier. We will, however, start the VoLTE journey. For us there are things we still need such as the capacity, the coverage, direct mode operation, efficient group call and fast call set up.’

Scalera points out that public safety LTE networks won’t operate in isolation from commercial networks and other public safety network technologies. ‘We’re showing a Wi-Fi router with our partner Cassidian for band 14 and, even if the public safety network went down, it can backup to a commercial network without the officer having to do anything,’ he says.

‘There is a backup so the router in the vehicle will automatically default. In terms of connecting to P25 or TETRA, we already connect P25 over LTE or even Wi-Fi. You can be on P25 and talk to an iPad and push to talk back and forth.’

McQueen identifies many of the advantages of commercial LTE as being transferable to public safety applications. ‘LTE brings latency improvements on the consumer side to enable applications such as real-time gaming but for us it allows public safety users to look at real-time video applications and situational awareness applications,’ he says.

‘It also gives workforce mobility improvements such as enabling report writing and e-citation. And it gives a second pair of eyes to a police officer, for instance by supporting connection between vehicle mounted cameras and the command centre. It’s worth remembering that most police vehicles in the US are single crewed.’

Best of both worlds

‘LTE standards are appropriate for public safety as they focus on the end user applications,’ concludes McQueen. ‘When we talk to officers going through Police Academies today, a lot have iPhones and Android devices and we hand them a police radio and they say: “what is this?” In time it becomes clear that the police radio provides them with a mission-critical lifeline, and with LTE we can complement that with applications like video and situational awareness and with LEX. We give them the best of both worlds - an applications device designed for mission-critical users.’