Given the frantic pace of LTE development and the falling cost of ownership, the hot question of the moment is ‘Will LTE replace LMR?’. It may surprise you to know that the consensus among those with the biggest stakeholders in mission-critical LTE is that, while they anticipate LTE (and eventually 5G) to take over many of the functions of LMR, we should expect to see the continued use of LMR for many years to come. Andy Seybold explains the situation well in his article on LMR and LTE.

Even the operators of these major LTE systems warn that that public safety agencies cannot rely on LTE alone. They see LMR as a necessary element of public safety critical communications for the foreseeable future. To quote a statement from FirstNet:

“First responders currently use land mobile radio (LMR) networks for mission critical voice communications. When the nationwide public safety broadband network (NPSBN) is launched, it will not replace their LMR systems. The network is expected to initially transmit data, video, and other high-speed features, such as location information and streaming video, as well as non-mission critical voice. Public safety entities will continue to use LMR networks for their mission critical voice needs.”

One reason is that for all critical communications users (not just public safety), LMR remains the technology which is still available when others have failed. LMR was designed with a variety of failsafe options to preserve communications, even when major components of the network are damaged or become inoperable.

Thus, if the core network fails in a multi-site LMR system, each working individual site can switch to local standalone operation and can still connect any units within range. And if all sites are down, units can still talk to each other in direct (simplex/talkaround) mode without a network.

Public safety relies on these fallbacks, which at this stage LTE networks struggle to offer. LTE standards (e.g. ProSe for Direct Mode, IOPS (Isolated E-UTRAN Operation for Public Safety) for standalone site comms) have been developed to address these critical concerns, but it is early days for the commercial products. A great deal of real-life testing lies ahead before public safety feels totally safe with the delivered goods.

So far, LMR is the technology that comes closest to delivering public safety grade systems. It has taken a few decades of field and interoperability testing, customer experience, standards and product refinement to reach this point. LTE, in the view of its developers and organization users, is still in learning mode. Their strong recommendation is to retain LMR for mission-critical voice alongside LTE for broadband data.

This recommendation has an underlying message: ‘No technology is good at everything, so why stick with just one?’

LMR has been battle-tested in emergency situations and its combination of wide-area voice coverage where no telco wants to tread, tried-and-true voice call services, ultra-reliable networks with built-in failsafe, and a better handle on interoperability than its competitors. LTE brings dazzling broadband data performance, low latency, a ready platform for the development of custom applications, and a path to the future.

The challenge will be how to merge and manage these technologies, to unify them, without compromising the benefits of either.