Roughly a decade and a half ago, the public safety sector universally was convinced that Internet Protocol (IP) technology never would be used for first responder communications systems because it suffered significant issues concerning jitter, latency and reliability. The technology had its benefits, to be sure. One person could speak with another person on the other side of the country, or even the planet, for free. But at the time, it was completely unsuitable for other purposes, particularly those that are mission-critical in nature — and it was unthinkable that the situation ever would change.
However, as always happens, the technology continued to evolve, and in a short amount of time, IP phones were finding their way onto desks of businesses worldwide, in part because they enabled companies to avoid the draconian long-distance charges being imposed by local exchange carriers of the era, but also because the jitter and latency issues had been resolved. Today, one would be hard-pressed to walk into any business and find anything but IP phones on workers’ desks.
The moral of this story is: Never bet against the technology innovators.
Now, the public safety sector is contemplating the implementation of an IP-based network known as the nationwide public safety broadband network (NPSBN). Although this network was intended from the beginning to exponentially ramp up public safety’s data capabilities in the field, a question was raised almost immediately after federal legislation authorized the NPSBN and the First Responder Network Authority (FirstNet), which is tasked with implementing the network: Could the NPSBN someday replace the land mobile radio (LMR) systems that traditionally have provided mission-critical voice service?
Predictably, the initial answer to that question was a resounding “no,” for a variety of good reasons having to do with coverage, capacity and reliability. But then the technology innovators got involved. First, the Third Generation Partnership Project (3GPP), the body responsible for developing the standards for Long-Term Evolution (LTE) — the commercial wireless communications technology upon which the NPSBN will be based — did something that many observers did not believe it would do: it added a voice over LTE (VoLTE) component to LTE, which originally was contemplated as a data-only play.
Then 3GPP followed that up with something truly mind-boggling by announcing in March 2016 that mission-critical push-to-talk (MCPTT) would be an element of LTE Release 13, which is expected to be implemented in 2018. Although it will take several years of system and device development and testing to ensure that MCPTT over LTE truly is public safety-grade, it now seems clear that the NPSBN eventually could satisfy all of public safety’s voice and data needs. The big question, however, is when.
This raises yet another critical question for public safety agencies whose legacy LMR systems are approaching end of life: Should plans for replacing those systems be abandoned in the hope of transitioning to the NPSBN in a few years? In the following information, we explain why that is a bad idea.
Certainly, the suggestion to abandon legacy older LMR systems makes sense on the surface — why burn up precious financial resources on an LMR system that could be obsolete in just a few years? But a deeper dive reveals that the only prudent option for public safety agencies is to invest in replacement of legacy radio systems that are reaching end of life. The following are just a few of the reasons:
Talkaround still will be an issue. Talkaround is an essential capability for first responders, particularly firefighters. It enables one portable radio to communicate directly with another without going through an LMR system repeater. For example, firefighters often find themselves deep inside large structures that prevent talk-out transmissions to be received from the repeater and that prevent talk-in transmissions to be received by the repeater. In such situations, the firefighters’ safety — indeed, their survival — depends on the ability to communicate with each other radio-to-radio.
Although LTE Release 13 reportedly will enable talkaround, it likely will not be as effective as the capability provided by LMR systems. LTE systems use more radio antenna sites than LMR systems by an order of magnitude, enabling LTE devices to be significantly smaller. So, although portables that operate on the NPSBN most likely will resemble traditional LMR portables, they almost certainly will operate with considerably less output power and have much smaller batteries. This means that the distance that NPSBN-capable portables can be from each other while still operating in talkaround mode will be much shorter compared with LMR portables — and that’s a problem for first responders, especially firefighters. Until talkaround on the NPSBN replicates talkaround provided by LMR systems, it would be imprudent for any public safety agency to abandon its LMR system or, at a minimum, to abandon devices that are both LTE and LMR equipped.
System hardening still will be an issue. In the aftermath of major natural disasters, particularly tornadoes and hurricanes, commercial wireless systems often become inoperable. For example, after Hurricane Sandy — a Category 3 storm that caused $75 billion in damage — struck the northeast United States in October 2012, the FCC reported that 25 percent of commercial cellular sites were inoperable in the immediate aftermath. In contrast, public safety LMR systems for the most part stayed operational, in part because they were designed to stand up to such forces, but also because they had backup power.
However, 3GPP is adopting standards that will allow cellular sites to maintain communications “off network.” This mode would be used when the site is isolated from the core because of a backhaul failure and would allow users connected to that specific cell to maintain communications. This is essential for devices that may not have connectivity to the core. This is coming, and is therefore not a long-term obstacle.
The National Public Safety Telecommunications Council (NPSTC) published a report in 2014 that detailed public safety’s expectations for network hardening. In the case of the NPSBN, scale is the issue. An LTE network requires roughly 10 times as many sites as an LMR system to provide the same coverage. Extrapolate this over the entire United States, and another critical question emerges: Will AT&T, the commercial partner selected by FirstNet for the NPSBN implementation, have the financial resources required to harden all of its sites to public safety standards. Unless the answer to that question is “yes,” public safety should think long and hard about abandoning LMR.
What about coverage and capacity? Both are critical considerations for public safety agencies. The first refers to the area in which a radio signal can be received, while the second refers to system availability. The coverage maps provided by FirstNet reveal numerous areas where coverage will be lacking. This wasn’t unexpected — the NPSBN will make use of commercial infrastructure, which generally is concentrated in urban areas, because that is mostly where the commercial customers are. Although there has been talk about making the NPSBN available through non-terrestrial means such as satellite, it is likely that public safety agencies in some rural areas never will be able to access the NPSBN, and will need LMR for the foreseeable future, and possibly forever.
However, increasing the coverage provided by an LTE system is much easier and far less costly compared with many LMR systems. An LTE system is designed so that all data traffic flows over a single channel — voice is simply another data application. In contrast, LMR systems are designed so that a channel is needed for every talk path — the number of channels depends on the number of system users. It is not unusual for an LMR site to have 10, 20 or even more channels, with every channel requiring a dedicated repeater. Other equipment, such as combiners, also might be required. In the case of a simulcast system, every site must have the same number of channels and repeaters.
The bottom line, literally, is that LTE sites have far less electronics and a much smaller footprint compared with LMR sites. This means that they are far less expensive to implement than an LMR site, which can cost several million dollars to construct. An LTE site also can be deployed just about anywhere, not only because of its comparatively small footprint, but also because its coverage footprint is much smaller than that of an LMR system. Where an LTE antenna usually extends no higher than 150 feet above ground level (AGL), an LMR antenna generally needs to be at least 200 feet AGL to cover a much wider area.
The flexibility afforded by LTE systems is particularly advantageous to the public safety sector. Because of numerous factors, with cost chief among them, LMR systems are designed for a 15-year lifecycle, at a minimum. Much can change in a community over a decade and a half. Housing developments, shopping malls, warehouses and schools are built as populations grow — and they all have the potential to create coverage gaps. Population growth alone is often an issue, as it tends to spread into previously uninhabited areas that might not have been considered when the LMR system originally was designed.
Given the cost and cumbersome nature of LMR sites, it is no small matter to add a site to address a coverage gap; in contrast it is quite easy and cost-effective to add an LTE site for this purpose. Because coverage gaps are the bane of first responders’ existence, it could be argued that at least in this context, an LTE system is the better option for public safety agencies compared with LMR systems.
The more worrisome aspect, however, concerns capacity. When lives are on the line and seconds count, a public safety communications network must be available whenever and wherever it is needed. So far, neither FirstNet nor AT&T has provided any insight regarding the capacity levels for public safety that will be designed into the NPSBN, much less how they will be accomplished. That should be unsettling to every public safety agency considering a migration to the NPSBN, particularly as it concerns voice communications.
Public safety agencies have complete visibility into their LMR systems regarding capacity requirements and how they are achieved. Certainly, AT&T has formulas and metrics that it uses to design and build out its commercial network to meet the capacity needs of its customers. At this point, however, it appears that AT&T has no intention of providing public safety with any visibility into its commercial network design — which is understandable given that AT&T is a publicly traded company whose sole responsibility is to its shareholders, and revealing such details could place it at a competitive disadvantage. But that leaves public safety in the dark regarding the capacity the NPSBN will provide. Would you buy a car without knowing what is under the hood?
Another issue is the way that capacity is increased in an LTE network compared with an LMR system. Increasing an LMR system’s capacity is a matter of adding additional channels — adding more sites isn’t needed. In contrast, additional capacity is achieved in an LTE system by increasing the number of sites, each equipped with eNodeB devices. This means that even if a given area has sufficient coverage, it may lack the surge capacity needed to support a large-scale event or disaster response. Furthermore, LMR systems provide highly predictable methods of evaluating capacity for voice calls, whereas LTE introduces many additional factors, such as competing with bandwidth with other applications. Again, scale is a factor, because there already will be many more NPSBN sites than LMR sites to satisfy similar coverage footprints.
One solution that would give public safety a comfort level regarding coverage and capacity would be for AT&T to enter into service-level agreements with individual public safety agencies. But because AT&T’s contract is with FirstNet, that almost certainly will not happen.
User fees also are a factor. FirstNet already has begun offering service on AT&T’s existing network, with service plans for voice-only service in the range of $20 per month and voice/text/data in the range of $50 per month, which generally is competitive with the fees currently being charged to provide mobile data terminals with wireless connectivity. However, the economics of paying a FirstNet monthly fee, versus purchasing a new LMR system that will last 15 years, are quite different. To effectively compare long-term costs, the total cost of ownership must be calculated over the equivalent life of an LMR system. Depending on the size of the LMR system and the number of users, the total cost per user per month may be significantly less, or more.
What You Should Do
It is reasonable to think that the NPSBN will evolve to the point that it will provide public safety-grade voice service and enable first-responder agencies to abandon their LMR systems. But such a scenario is many years into the future. In the interim, public safety agencies should continue to invest in their LMR systems, even to the point of replacing them if necessary. Above all, they should avoid falling into the dangerous trap of doing the bare minimum to keep their LMR systems operational in the hope that they can migrate operations to the NPSBN in the next few years.
Once communications systems reach end of life, it becomes more difficult and expensive to maintain them, and this increases dramatically over time. In our experience, keeping an end-of-life system operating effectively for a year is daunting enough. The idea of doing it for three to five years — or even longer — until the NPSBN can provide mission-critical voice service is beyond comprehension.
When manufacturer support ends, the public safety agency will need to find a third-party repair shop to do any repair work. Spare parts become more difficult to find and, thanks to the laws of supply and demand, become more and more expensive as stocks dwindle. Eventually, the supplies of parts are exhausted and repairs no longer can be executed. As this scenario plays out, the system becomes increasingly unreliable and system outages begin to occur. Over time, these outages become more frequent and severe, and last longer. In the case of an LMR system, first responders and the public they serve are placed at greater risk. And while a new LMR system will cost several million dollars to implement, the lawsuits that will emerge should first responders or citizens be killed because the voice radio system failed likely will dwarf the cost of a replacement radio system.
The advice then is to avoid a duct tape and bubble gum approach to maintaining an LMR system in the belief that NPSBN-delivered voice communications are coming — because they are not, at least for the foreseeable future.
Instead, replace the LMR systems that have reached, or are reaching, end of life. An ideal time to assess an LMR system replacement is 12 years after the system was implemented, as it typically takes 24 to 36 months to procure and install a new system. Public safety agency radios that are LTE-capable, such as the Harris XL-200P, already are emerging. Such devices not only will be able to communicate on traditional LMR systems, but also the NPSBN via Band 14-enabled LTE chipsets and the vendors’ push-to-talk applications (Harris BeOn and Motorola Wave). Traditional LMR systems may one day be interfaced to the NPSBN or commercial networks via digital radio interfaces or through the inter-RF subsystem interface (ISSI), which is an element of the Project 25 standards suite.
Today, these interfaces are being performed for the purposes of integrating LMR systems with push-to-talk over cellular (PTTOC) providers, which most likely will adopt the MCPTT standard once it is available. From the end-users’ perspective, communicating on the NPSBN in this manner will be as simple as turning a knob on their radio, just as they do now when they want to join a talkgroup.
Abandoning LMR systems is not something that any public safety agency should be considering today. Instead, the prudent approach is to invest in keeping such systems current, and replacing them as needed, to ensure that first responders can perform their mission-critical jobs effectively and safely.
That said, government agencies should continue to track the progress of FirstNet. The day eventually will come when the NPSBN has developed to the point that it truly is a viable alternative to LMR.
Nick Falgiatore is a senior technology consultant for Mission Critical Partners, LLC, a public safety communications consulting firm headquartered in State College, Pennsylvania. He can be emailed at email@example.com.