Mission critical applications for 4G LTE

The TCCA’s CCBG working group is collaborating with the LTE standards bodies to incorporate mission critical functionality into 4G. James Atkinson catches up with CCBG chairman Tony Gray and Jeppe Jepson to check on progress

Mission critical applications for 4G LTE

The major narrowband radio standards used by global emergency services agencies – TETRA, Tetrapol and P25 – have evolved highly sophisticated voice and to a lesser extent data functionalities. This functionality is not supported by the current LTE broadband standard, which looks set to eventually replace them.

The TCCA, which represents the TETRA mission critical communications voice and narrowband data mobile standard, is working with the key mobile standards bodies, 3GPP (3rd Generation Partnership Project) and ETSI (European Telecommunications Standards Institute), to incorporate the key features and applications found in mission critical communication wireless standards into the LTE standard.

The work is being progressed through the TCCA’s Critical Communications Broadband Group (CCBG) and is expected to continue until at least 2018. In 2013 the CCBG outlined four key areas to be addressed within the LTE standards to enable a suitable foundation for critical communications services:
• Group communications system enablers for LTE (3GPP GCSE LTE)
• Proximity-based services (3GPP ProSe)
• Public safety networks resiliency
• Push-to-talk (PTT) voice application standard over LTE and its evolution toward multimedia (voice, data, video, etc.) group communications

Speaking to Wireless, CCBG chairman Tony Gray (pictured) says he is delighted with the progress so far: ‘In the greater scheme of things, to still have their attention and keep adding items into the standard so we don’t lose momentum and keep driving forward is fantastic.

‘But we can never lose sight of the fact that we [the PPDR community] are a tiny ecosystem sitting on the back of the 3GPP elephant, which is dominated by the needs of the commercial mobile operators. Fortunately, the US has been vociferous on the subject, so that has helped enormously.’

However, he warns: ‘We have made some significant progress in our first two years, but writing standards is a slow process and it will take time. We will not get everything we had hoped we’d get into LTE Release 12 (due out in December 2014), so some items may move into Release 13 (out 2016).’

Gray reveals that most of the group communication systems enablers for the transport layer will be in Release 12. He adds that ETSI is working on the application layer above that and then plugging that back into 3GPP LTE as a transport mechanism. ‘That is looking quite hopeful for the end of this year,’ he says.

But he adds: ‘It is now clear that we won’t get all the things we hoped for in LTE Release 12 for proximity services (ProSe), such as DMO mobile gateways and full direct mode operation. We will just have a very simplistic, almost RF level application with the rest having to wait for Release 13.’

The third strand of the CCBG’s key areas, public safety networks resiliency, will definitely not happen until Release 13. This will involve looking at how the operational LTE base stations can be made more resilient by emulating the ability of isolated TETRA base stations to continue operating even if cut off from the core network.

‘We’ve defined the work item, but no work has been done on that yet. We need to focus on how to make an LTE eNodeB autonomous from the core to an extent. There are quite a range of potential options as to how to do that, such as using a distributed architecture solution, for example,’ says Gray.

Further to Release 13 and beyond, there will be more consideration of security. The CCBG is gathering the end user requirements and will work with the systems architect groups within ETSI and 3GPP to find a way to beef up security levels on LTE networks.

Gray notes that the UK’s Emergency Service Network, which aims to replace the Airwave TETRA system with a 4G one using a commercial operator, will have to proceed without an LTE mission critical security standard being written.

‘They [the UK Government] have openly stated they will consider accepting a pre-standard security solution, i.e. a proprietary one. We think that is pretty dangerous. There is also the possibility that that proprietary system almost becomes the de facto accepted global standard with the potential for vendor lock in,’ cautions Gray.


Reserving spectrum for PPDR in Europe

The TCCA has been working hard to persuade the EU, national governments and regulators of the benefits of reserving broadband spectrum, preferably harmonised across Europe, for the PPDR community.

Jeppe Jepson, board member & director of broadband spectrum, TCCA, tells Wireless: ‘It looks as if 700MHz is the preferred band for everybody in the EU, which will then provide a single global standard on the same frequency band across the whole world.’

Jepsen reports that the EU is ‘on side’ and supports the idea of reserving spectrum (probably 2 x 10MHz). Any chance of getting 700MHz depends on the outcome of the ITU World Radiocommunication Conference (WRC) in 2015. This meeting will decide whether to reallocate the 700MHz band for mobile services in Region 1, which includes Europe.

‘We are working towards the international community agreeing on 700MHz for PPDR and the WRC in 2015, but we can’t say how it will go until the end of that meeting – there’s a lot of horse trading, so we’ll have to wait for the outcome,’ says Jepsen.

He warns it is not going to be easy, however. ‘The emergency services fully agree about the need for reserving broadband spectrum for PPDR. But those in the regulatory chairs think they can auction it off and get some money and then the emergency services can source mission critical services from the mobile commercial providers.

‘There is a big question mark over that,’ he continues, ‘as it would leave a negotiating partner (governments) with just two choices: accept the price and conditions of the commercial market, or lower the expectation of the mission critical requirements. Then there are the security concerns: do the emergency services or the operators control access and authorisation?

‘We fear if the spectrum is auctioned off that governments will be in a blind alley with few options left open to them. So, we are fighting to put this on the agenda. Research from the London School of Economics and Germany argues it is a beneficial socio-economic decision to reserve spectrum.’

Summing up, Jepsen says: ‘We are cautiously optimistic we’ll get some spectrum, but we don’t think every country will assign dedicated spectrum. But look at those that already have: they’ve all done so on the back of major disasters: 9/11 and Katrina in North America, wild fires in Australia, and earthquakes in China.’

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