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Mind the gap: Obstacles in developing the new emergency services network


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Push-to-talk functionality on the London Underground has been a hard won police radio capability, but its future on the new LTE network faces serious hurdles. Gary Mason reports.


It is somewhat ironic that in a multi-billion pound public safety communication project investing in cutting edge long-term evolution (LTE) technology, a major sticking point is the reliability of push-to-talk voice messages – a capability that has been around since the days of analogue police radios.

This is just the latest problem facing the Emergency Services Network (ESN) project, which at least two recent reports have predicted would not be ready on time. This means the existing system, Airwave, is expected to be maintained for an unknown period after its expensive contract with the Home Office and the UK’s blue light first-responder services expires.

Police concerns about the voice function on the new LTE handsets, whenever they emerge, have been highlighted in the latest Public Accounts Committee (PAC) report, published in January. Push-to-talk allows users to contact their colleagues with only the press of one button. The function must be reliable and work in remote areas – not just rural environments, but also the underground tunnels of the metro systems in London and Glasgow.

Devices with the appropriate levels of robustness, voice and dual-mode capabilities are currently under development. The Home Office told the PAC it had already received prototype devices and was confident a good selection would be available for users to choose from by next year. But the devil, as usual, is in the detail.

Some of the technical challenges in developing mission critical push-to-talk capability on LTE handsets were spelled out in oral evidence to the committee. Under the terms of the ESN contract with the Home Office, Motorola Solutions is responsible for delivering user services, such as data centres, help desks and SIM card management. While the scope of its contract does not include devices, Vincent Kennedy, vice-president and general manager of Motorola Solutions UK, gave the committee an insight into some of the technical challenges that had emerged with prototype LTE handsets.

Push-to-talk latency

The ESN envisages two types of device that will run on the network: 4G data devices and voice devices. The 4G handsets can attach to the new network relatively easily, but voice handling is more complex.

“When you move the voice service on to a commercial mobile phone network, the device has to act in a specialised way,” Kennedy told the committee. “If I picked up my phone and dialled your number, it would take a few seconds to ring. It might take six seconds to you or five seconds [to someone else]. In this world, when I am the commander of a team at a firearms incident and I press the button on the device and say, “Don’t fire”, you instantly all have to hear the same thing. It is a big problem if you hear, “Don’t fire”, and another person hears, “Fire.” That is just an example, but the voice piece makes the device more specialised, and it has to work in a special way.”

The technical term for this issue is push-to-talk latency. Police using the system need to be confident that the latency can be low enough with 4G that it won’t be a problem, and that the voice message received by everyone during an incident will be as near to instantaneous as possible, which it isn’t right now.

Kennedy said Motorola been investing in the research and development of mobile LTE technology for public safety since 2010. He said: “It [LTE] is where the public safety market is going. They will eventually all be using mobile broadband, mobile data and voice. If it works to design, the latency can be solved, but that is why the design is so strict around the devices and the network.”

He told the committee that the latency issue can currently be proved in a lab environment, but it needed to be tested in the field under extreme conditions. A testing regime will continue all through the spring and summer. Operational trials could commence in the autumn of 2017 and will go on for several months.

“These are big technology projects, but they are not like regular IT projects. The people who use this technology – their lives depend on the technology working,” he added.

The example Kennedy gave during the committee hearings bears a chilling reminder of the shooting of electrician Jean Charles de Menezes by Met firearms officers in July 2005 at Stockwell underground station after he was mistaken for a terrorist suspect. At the inquest into the killing, a firearms officer told the court he could have missed important messages over the radio and told the inquest that the signal was weak, faint and fuzzy and would sometimes cut out altogether. Given such real life examples, why has the Home Office chosen to go with unproven technology? In a previous report published last year outlining problems with the ESN project the National Audit Office said that it is ambitious and the first of its kind in the world.

A world first

Other countries are pursuing solutions either fully or partly based on older terrestrial trunked radio (TETRA) technology and dedicated networks, such as Airwave. The Home Office told the PAC that, in an ideal world, it would not want to be first to adopt unproven technology. But it considered that the other options it had for replacing Airwave, such as a hybrid system that uses radio for voice communications and 4G mobile for data, were “equally risky” and that it had to consider a wide range of financial, operational, technological and legal factors when making its decision.

The programme also faces a number of other technical challenges. The new system will operate across a commercial 4G network requiring new software to allow emergency services users priority over commercial customers. EE, who have been awarded the network contract, told the committee it had completed system testing to prove the prioritisation technology would work and that during an emergency its network would be able to prioritise all 300,000 emergency service users, if necessary.

Meanwhile, Motorola has responsibility for setting the specifications and approving devices for use on the ESN. Since it is also a supplier of devices, the Home Office told the PAC committee it had “been very careful to make sure the specifications do not exclude other providers and are not bespoke. It is a standards-based process”.

One of the biggest risks with the new system is ensuring coverage in remote areas and in hard to reach places, such as the London Underground. The Home Office says that using 4G mobile data technology instead of radio opens up more options for plugging gaps in coverage, such as by using temporary masts.

Time is a factor

Discussions are still ongoing between the Home Office and Transport for London (TfL) on how best to extend coverage into the Underground, as well as contingencies and options for the transition process. The Home Office hopes to make an announcement in the next couple of months on this issue.

Time is a factor, since the rollout of the ESN is just two years away. If TfL cannot roll-out the technology in that time, the Home Office would need to agree an alternative solution with TfL.

This is a crucial issue for the police and fire service in London in particular, as a fully functioning emergency services communications system was a hard fought and long awaited upgrade. The lack of such a system was first highlighted by the inquiry into the response to the King’s Cross fire in 1987. These concerns were then reiterated after the 7 July 2005 terrorist attacks, which centred on London’s transport system.

Airwave was eventually rolled out fully in January 2009 to all 125 below ground London Underground stations. This meant that British Transport Police (BTP), the Metropolitan Police Service (MPS) and the City of London Police are able to use the same radios underground. The rollout linked the emergency services network to London Underground’s Connect digital radio system, part of the Transport for London’s £10bn investment programme.


Natural disasters

The vulnerability of city subway systems not just to terrorist attack, but also to natural disasters is well documented. The need for a robust emergency services communications system that links into the network operated by the transport authority is also well recognised.

When Hurricane Sandy swept through the New York metropolitan area in October 2012, it left behind extensive damage to New York City Transit facilities throughout the subway system. A record storm surge inundated tunnels, filling critical operations rooms that housed electric equipment for signals, relays and communications with highly corrosive saltwater.

The storm also exposed a need for a better and faster way for supervisors to communicate with crew members and customers in times of emergency. Even after three years and thousands of hours of labour spent repairing and restoring service to pre-Sandy levels, the subway system has yet to fully recover, with many related repairs still to be made.

In 2015, MTA New York City Transit received two Federal Transit Administration grants totaling $57.1m (£45.7m) for two major storm resiliency projects in subway stations: a new emergency communications system and a hardening project to protect station rooms critical to service delivery.

Until March 2016 police officers in the transit system could only communicate with each other underground because police were on two different radio frequencies. Using a $100m grant, mostly spent upgrading existing technology, all officers’ radios were reprogrammed to allow them to communicate over ultra-high frequencies on the street and in the subway. Their use was delayed for years, mainly for reasons that had nothing to do with technology, but bureaucratic inertia.


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I know all about getting Airwave working on the underground. Had an engineer turn up my shop one day requesting components to make leaky feeders which I supplied.

The laws of physics are what they are, and as long as you understand them then you know if the end result is achievable or not.

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I still don't get why this is happening.

Airwave works for what we need it for. It isn't perfect, but it works.

Currently I have a secure radio which includes GPS technology. I can hear vital information with pretty good coverage and communicate instantly with colleagues via a rugged device clipped to my chest/belt. The battery in moderate weather with normal.usage will last me a 10 hour shift. I have an easy red button to press when the poo hits the fan and I know that it's only ever failed.to work for.a.xolleague once in the nearly 9 years I've worked for the cops. I trust the kit and it's a lifeline especially with single crewing.

Of course it's the 21St century and so there is now a need.for me to be able to.access data,.emails and make.phone.calls. I've been issued a 4g handset. They are rubbish. The battery lasts barely a shift with moderate usage and about half a shift with active use. But they just about help me enough currently that I'd rather have one than not.

The ESN proposes to merge the two.

Currently I have seen nothing which addresses the following issues:

Battery life - I do not know of a high spec 4g device that will be able to sustain constant monitoring of radio traffic, GPS, 4g data, push email, high definition screen for any amount of time. 

Dual functionality - how will radio traffic work at the same time as all these other functions bein asked for? I don't want to have to be 'off air' to use the new functions on my radio being pushed. It's an officer safety issue and will make my radio a liability.

Practicality - the reason the radio is such a great piece of kit is it does one job brilliantly. Any new device design would need to keep a rugged weatherproof design with hard buttons for push to talk, emergency button, quick change buttons. - Touchscreen is not a viable option for a radio. With the 'uplift' to make them data devices I'm not sure how they are going to manage this without making them prohibitively large. If you see my point they will need a screen the size of a modern smart phone for the new data functions to be worthwhile, but to keep buttons which are big enough for operational use the front of the radio would be overly cumbersome.

Reliability - my phone is 4g. I spend most of my time with poor 4g signal, if any, especially when moving. If we rely on the 4g network for our signal I simply don't trust the coverage at the moment. My other reliability concern relates to the operating system. The airwaves I have used, the sepura and Motorola mth, both work almost without fail because they are so basic - akin to the Nokias of old. If the operating system becomes like android due to the need for xyz processor etc for data/image/video I genuinely believe there will be catastrophic results in handset failures.

PTT - this is the most interesting part. PTT is not a feature of police comms, it IS the nature of police comms. If the technology isn't there to say 'yes of course PTT works as good as airwaves if not better' we shouldn't even be having the conversation about this new network coming in. 


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I think this issue with Airwave is the sheer extortionate cost, I don't understand why the government doesn't have its own network controlled and owned by itself.  To be fair the MoD have the people to help achieve this. 

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