WHAT IS LTE, WHO IS BEHIND IT, AND HOW DOES IT WORK?
LTE (Long Term Evolution) is a global cellular standard created to deliver high bandwidth mobile data using a completely redesigned core and RAN (Radio Access Network). Many smartphones have LTE already – it allows your phone to stream video, for example.
The LTE standard is controlled by 3GPP (Third Generation Partnership Project) and almost every part of the creation of these standards is open. So you can see clearly what the new standards will deliver, and even contribute to them if you wish.
3GPP doesn’t operate like the old-style standards bodies that you might be familiar with. Part of its evolutionary philosophy is a forward pipeline of new functionality which builds on already-deployed systems. They’re a bit like the Borg on Star Trek. It’s not quite “resistance is futile”, but they certainly assimilate anything of value from other standards, rather than reinvent the wheel. The content of each release is signalled well in advance, so vendors can take advantage of new features as they evolve. New LTE releases have provided significant benefits for mission critical communications.
WHAT’S THE ROLE OF CELLULAR IN MISSION CRITICAL COMMS?
Although current cellular networks and devices are designed for commercial use, for a decade or more, mission critical organizations around the world have been using cellular technology pretty much ubiquitously.
Have you ever been at a big game when you can’t access your cell network because everyone else is? Imagine what happens in an emergency! At times of peak load, even first responders can’t get onto the cellular system.
Despite the public safety community lobbying 3GPP to include features that directly support mission critical functionality, previous generations of cellular technology have not been able to adequately prioritize mission critical communications, nor deliver other essential features like Direct mode, PTT or Group mode to a level that first responders could rely on. Attempts to “bolt” these on failed.
LTE Release 12 and Release 13 offered substantial support for precisely this mission critical functionality, and Release 14 will offer more enhancements for mission critical users.. And perhaps more significantly, the core LTE network itself is being improved to the point where it can offer the resilience and robustness that mission critical needs.
WHAT ARE LTE CELLULAR STANDARDS PROMISING FOR MISSION CRITICAL NETWORKS?
Currently, LTE networks deliver really fast data, and newer ones also deliver voice, albeit without mission critical features. Releases 12 and 13 support true mission critical functionality. Release 12 is probably the biggest single standard that 3GPP has ever released, and around 70% of the new features directly benefit mission critical users one way or another.
Of course, not all of these features are there to support mission critical users. For example, the new proximity services have a wider application. Retailers can see that you are in the vicinity and send targeted ads directly to your phone: “Last time you visited us you bought this. Now we’ve got a special on these items.” Crucially though, it does a very good job of direct mode functionality – an important feature for mission critical users.
These new features are service enablers, so-called because they deliver the capability to deliver a service, rather than delivering the service itself. So in the proximity services example, the retailer – not the carrier – is creating content to attract you. The carrier provides the capability to deliver it in the right context.
Likewise other service enablers in the mission critical space: the carrier uses external sub-systems to deliver things like group mode, or MC-PTT service. These may be located within the carrier infrastructure or may be delivered through third parties. This is complex, as it must take into account access control (via tokens), billing and service control. But the result is a very flexible platform with a lot of future capability through carriers and other specialist parties.
COULD LTE CARRIERS TAKE OVER MISSION CRITICAL COMMS COMPLETELY?
Generally, mission critical users don’t like being guinea pigs. They want to see mature capability before they commit themselves. So LTE (or any other technology) systems need all the features we think of as unique to LMR, proven on commercial carrier networks before they will count as mission critical.
A prime example is LMR’s mission critical push-to-talk (PTT), which is fundamental to first responders. Cellular-based PTT has had a checkered history. Previous attempts tried to replicate the fast set up and volley times of a true mission critical system, but failed. They were “over the top” solutions, which means they just flowed data through a carrier network. The carrier didn’t distinguish it from other data types – it just saw data coming from the phone, going to another device. Making PTT work properly requires core system changes.
The latest LTE MC-PTT standards closely replicate LMR, and new LTE systems are designed for mission critical grade performance, with the network itself contributing to that performance. They will perform for mission critical.
I believe commercial operators will take over some aspects of critical communications but they will need to work with specialist vendors who are willing and able to deliver a complex, full suite of features and functions. The level of solution is going to need very close relationships with first responders. I see a future where carriers partner closely with specialist mission critical communications vendors, with each contributing to a real solution. This will include LMR.
WHY HAS IT TAKEN SO LONG TO REACH THIS POINT?
It’s been an interesting journey, because neither the carriers nor the standards body understood the key needs of mission critical – even 3GPP fell into this trap initially. Early attempts to deliver a mission critical, push-to-talk standard over existing cellular networks didn’t progress because they didn’t understand the mission critical community’s fundamental needs well enough. That’s all changed now, and 3GPP has created a whole new working group to address this, and to look at mission critical applications going forward. Companies like Tait are involved in these groups to ensure the real needs are clear.
WITH THESE NEW LTE FEATURES FOR CRITICAL COMMUNICATIONS, IS THERE STILL A ROLE FOR LMR?
Absolutely. Simply being able to deliver features and functionality does not deliver a viable solution. There are a couple of reasons why LMR will continue to serve mission critical needs.
1) LMR systems are already proven to meet SOPs – the way that mission critical users operate – because they’ve been developed in concert. So you’ve got a symbiosis, if you like, between the communication system that first responders use and the way they operate. They are completely interdependent at the moment, with LMR delivering precisely what these users need. That is not going to change any time soon, if only because of the huge impact that would have on those procedures and the associated training overhead.
2) Public safety networks are designed to keep populations safe – regardless of their location. Commercial cellular networks are driven by profit, so they primarily target population centers where there are more customers. Rural areas are simply not profitable. But unfortunately, accidents, incidents and emergencies are not always conveniently located in the middle of cities. If you compare cellular and LMR coverage, you’ll see that promised cellular coverage falls significantly short of what LMR systems are already covering, and first responders frequently work where there is little or no cellular coverage.
But there is no denying the impact and appeal of LTE’s really fast data services. The ideal solution for the foreseeable future will be properly integrated systems that combine the best of all available communications (LMR, LTE and WiFi) while maintaining mission critical capability.
SO WHERE IS THE LMR INDUSTRY AT RIGHT NOW, WITH THEIR LTE INTEGRATION SOLUTIONS?
Tait deployed its first LTE system in 2012 so there’s a lot of real world experience here in how to make LMR systems and LTE systems coexist. Rather than take the lowest common denominator – the minimum subset of functionality of each one – and try to glue it together, we’ve come up with ways to get the best out of both systems. So instead of having to choose between the coverage of one, or the performance of another, you get the functionality and the best features of both rolled together.
It’s important to see integration from the end user point of view, rather than that of a cellular carrier or an LMR vendor, so the technical roadmap delivers real user value in a logical way as user needs evolve. One outcome of this is seamless roaming, which allows voice calls to roam seamlessly between networks. For instance, you might start a conversation on your LMR network, and then mid call, seamlessly roam onto an LTE or WiFi network (or vice versa) as coverage changes dynamically. No aspect of the communications is lost during transition. Users no longer have to think about what sort of network they’re connected to, what device to use and whether they are in coverage. They just pick up their favourite (or job-appropriate) device and call. The device operates over whichever network is available or appropriate. It just works – which is surely the essence of mission critical communications.
To wrap up, future communication systems will require a combination of network types. One type is no longer “better” for a particular purpose or industry than another – they will both be necessary to guarantee capability and functionality. Because LTE will likely be provided by commercial carriers, mission critical users won’t need to invest large amounts in LTE-only infrastructure and resource. And they already have reliable LMR systems, which they continuously improve, augment and integrate. That integration includes the “glue” to join an upgraded LMR system to a future LTE system and even WiFi.
The bottom line is that no one should be thinking of making a choice between LMR and LTE – both are needed to deliver modern, robust and resilient critical communications. LMR systems will continue to provide value as they evolve, through closer integration with LTE.
This article is taken from Connection Magazine, Issue 7. Connection is a collection of educational and thought-leading articles focusing on critical communications, wireless and radio technology.
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