Mission-Critical Voice and LTE: Be Careful!

Do not ignore continued investment in existing mission-critical analog and P25 voice systems because you believe voice over LTE broadband that is mission-critical is just around the corner. Many elected officials in federal, state, and local agencies seem to believe this so continued investment in existing channelized voice systems is not needed.

Do not ignore continued investment in existing mission-critical analog and P25 voice systems because you believe voice over LTE broadband that is mission-critical is just around the corner. Many elected officials in federal, state, and local agencies seem to believe this so continued investment in existing channelized voice systems is not needed. While a lot of progress is being made in the world of broadband voice, it will be sometime in the future (undefined) before all of the pieces and parts of mission-critical voice as defined by NPSTC (soon be to published) are included in LTE. Even then there may be limitations that will hinder the Public Safety community or require some changes to how voice systems are used today.

My view is that our channelized voice systems will be around and needed for at least the next 5-10 years, therefore, continued investment in these systems not only makes sense, it should be a requirement. Progress is being made as you will see below, but even with the definition of mission-critical voice in place I know of no work being done to determine the specific requirements regarding the number of dispatch, coordination, or simplex, talk-around, or peer-to-peer voice channels or circuits that will be required. It is possible that there will be mission-critical voice capabilities on LTE and other broadband networks but that these broadband technologies may not be able to provide the number of voice channels that are used today for major incidents such as wildland fires, etc. It is also possible that broadband voice will not be able to support the number of dispatch areas or zones in use today in major metropolitan areas. It is also possible that the combination of voice and data services will give Public Safety the ability to make changes in the operations to streamline the dispatch and tactical aspects of incidents as well as to operate as it does now.

Where We Are Today; Where We Are Going

As the 700-MHz waiver recipients begin building out their portion of the nationwide 700-MHz broadband network, and as the various committees of the various Public Safety organizations meet and discuss issues, one that keeps coming up is the use of the broadband network for mission-critical voice. I have been saying for a long time now that mission-critical voice (as defined by a recent NPSTC document) is still a long way from becoming real over the LTE broadband network.

However, some progress has been made in recent months. One of the most important elements of Public Safety-grade mission-critical voice has to do with off-network or tactical communications, sometimes referred to by the IT world as peer-to-peer communications. Simply stated, this means the ability for two or more field devices (mobile or handheld) to communicate with each other without having to use a cell site or radio tower system. Many who have discussed this include it as a must-have for times when field units are out of coverage of a network. However, in most cases this type of off-network communications is also a requirement of field units even when they are within network coverage.

Call it what you will—tactical, simplex, talk-around, peer-to-peer—it is the ability for units in the field to be able to communicate directly with each other without any infrastructure required. Today’s Public Safety voice devices all include this feature as standard, but cell phones do not support this mode of operation. I have been skeptical that commercial network operators or others within the LTE broadband community would get behind this mode of communications, but recently, simplex mode communications was introduced at the 3GPP standards body and has been endorsed by some commercial network operators including AT&T, as well as by the U.S. National Institute of Standards and Technology (NIST). In other words, now at least the beginnings of this function are being incorporated into the 3GPP standard for LTE and other broadband wireless technologies. BUT, and this is a big but, it may take years for this to work its way through the 3GPP and be voted on by the membership.

Several federal agencies have funded development work on mission-critical voice over LTE and broadband in general, and several of the bills to reallocate the 700-MHz D Block to Public Safety include additional funding for this type of research and development. However, to date there is no real specification that outlines the number of voice circuits that are or will be needed going forward. If we look back at past major incidents and add up the number of voice circuits that were used at a given incident, is this really the number of voice circuits that will be needed when combined with broadband data services?

For example, if we look at one of the major wildland fires in Southern California over the past few years it is possible to determine how many incident and non-incident voice channels were in use during the incident, but does that translate to how many voice circuits will be needed when we add broadband capabilities into the mix?

The Incident Command System (ICS) clearly defines the roll-out of both the ICS management system as well as the Communications Structure. During a major incident today, the communications leader or someone appointed by him usually completes an ICS form 205, which is the Incident Radio Communications plan that lists the incident name and then radio channel utilization. In most cases, this form is filled out by hand, usually at the staging area where vehicles arriving at the incident report to receive their assignments.

The number of voice radio channels used depends on the size of an incident. During the Tea Fire in Santa Barbara that started on November 13, 2008, burned 1,940 acres, destroyed 210 residences (130 in Santa Barbara, 80 in the county), and caused 30 firefighter injuries, the total number of radio channels in use at the height of the fire was 18 command-and-control channels and 72 tactical or simplex channels used for the fire and by police and other first responders directly involved with the firefighting efforts. Normal operations used an additional 4 dispatch channels and 6 tactical or simplex channels.

The good news is that in California almost all of the fire units that responded from federal, state, and local agencies had multi-channel VHF radios so there was a good amount of interoperable communications available. However, this did not include police, sheriff, highway patrol, and other agencies that were also involved in the firefighting. Coordination between these agencies and the fire command was handled via the dispatch centers and/or the emergency operations center. As you can see, there were a large number of radio channels in use and of these, some of the channels were federal, some state, and others local channels. One of the questions that need to be answered as we add broadband services (data and video) to these types of incidents is how much of the traffic on these channels would be reduced and could a future incident get by with fewer voice channels. Another question is that since this fire covered a large area, could some of the voice channels, in the future, be reused in different sectors? These are questions that can only be answered by those who plan for these types of major incidents and it is their input that will be critical to the development of the requirements for mission-critical voice over broadband systems.

One of the reasons so many voice channels are required during major incidents has to do with the fact that each group assigned to the incident has its own specific task to complete. Since each of these groups must have instant and complete communications capabilities, each group is generally assigned its own voice channel with the commander of each group monitoring both the local working channel and the channel on which they then talk to the next higher ranking officer at the incident. This system has worked well for many years and has provided a highly reliable way of ensuring that anyone who needed help could get on a radio and ask for it, and that someone else, either local to them or within radio range, could hear the call and respond accordingly. Without this type of reliable communications there might have been more injuries or even deaths as a result of someone calling for help and that call being unanswered.

In an ideal world it would be wonderful if every first responder had all of the capabilities needed to do their job and protect themselves and the public in a single device. Such a device would give them all of the voice, video, and data capabilities they need, when they need it. But we don’t have this type of device today. First responders cannot take the time to dial a phone number, and many times they do not have two hands available to change the status of the wireless device or make a menu selection. They need to know that simply by pushing an emergency button or calling for help their location and their need for assistance has been heard and that help is really on the way.

Technology is advancing rapidly and the first responder community, for the first time ever, is embracing a commercial and readily available technology for broadband (LTE). Hopefully, Congress will give the first responders the spectrum they need to build out a nationwide broadband network that will provide fully interoperable communications from border to border and coast to coast. Broadband will provide video for those responding to an incident, which is like giving sight to the blind. It will enable a swat team commander to see, on a mobile device, exactly what his snipers are seeing through their high-powered rifle scopes, all of which translates to better protection for both the citizens they serve and for themselves.

In the future, there is no doubt in my mind the Public Safety community will be able to have a single device that will permit voice, data, and video, but when will that future be? There are, at the moment, about 100 different answers to that question. The general consensus from those working with the technology is that some level of mission-critical voice can and will be available over LTE broadband networks. The remaining questions are how many of the mission-critical voice requirements can actually be met with LTE broadband or future broadband technologies, and how long will it take to be able to prove to the Public Safety community that LTE broadband can provide both voice and data services?

The bottom line is that today’s mission-critical channelized voice systems, and the new systems being deployed, developed, and planned, need to continue to be funded to ensure that when the time comes, the capabilities of LTE broadband can be weighed against the needs of the Public Safety community. If there is a perfect fit, the transition from channelized to broadband mission-critical voice should begin. Perhaps some of the channelized spectrum could be returned to the FCC for reallocation to others but this process should not, today, be viewed as something that will happen overnight but rather that it could take years to accomplish.

Is voice coming to LTE broadband? Yes, it’s the when that is in question. Is mission-critical voice coming to LTE broadband? I hope so, but in the meantime, not maintaining or building new mission-critical Public Safety voice systems should not be an option considered by any local, state or federal agency!

Andrew M. Seybold

One Comment on “Mission-Critical Voice and LTE: Be Careful!”

  1. […] (the D Block and the existing Public Safety 10 MHz of spectrum) will soon be able to support mission-critical voice in addition to data and video services for Public Safety, therefore the 700-MHz narrowband […]

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