Public Safety Advocate: FirstNet Authority Off-Network Communications Solutions RFI, L3Harris, HPUE

APCO 2021

The APCO 2021 conference is taking place in San Antonio this week. Many attendees come from the public-safety community or are involved in some way with public-safety communications. Many others are the people who make up public safety’s front-line, handling incoming calls from citizens and dispatching public-safety resources to a multiplicity of incidents around the United States. Once again, APCO has devoted an entire conference track to FirstNet.

FirstNet Authority RFI

According to an article in Urgent Communications, the FirstNet Authority has issued a Request For Information (RFI) concerning off-network communications, primarily Push-To-Talk (PTT) voice communications. As many readers know, I have been skeptical about the section of the 3GPP Mission-Critical Push-To-Talk (MCPTT) standard that attempts to address off-network broadband communications. Samsung’s MCPTT solution includes Proximity Services (ProSe) embedded in its chip. Motorola recently announced it will also offer 3GPP-compliant MCPTT capabilities later this year but these products will not include ProSe. 

The issue with ProSe as a broadband off-network technology is that today’s handsets are limited to one-quarter of a watt output power (0.25 watts), and most handsets do not support external antennas. The downside to building antennas into smartphones or other devices is that built-in antennas are not very efficient. However, Land Mobile Radio (LMR) portables provide output transmit power of 5, 3, or 2 watts depending on the band, and they all sport external antennas and hefty batteries.

ProSe was intended to increase the range of unit-to-unit communications by enabling use of a relay between two units that want to communicate but are both out of network range and too far apart from each other. As I pointed out at the time, relays are not practical for communications during an incident since the person/unit serving as the relay could potentially be assigned to another task and have to change locations; the relay point would be lost.

There were some early attempts at crafting broadband off-network Push-To-Talk (PTT) and, more recently, I published a set of tests that I believe may help to determine if a proposed off-network broadband solution will be workable (see below).

Shortly after the February 2012 creation of FirstNet, some of us began searching for a way voice could be used to complement FirstNet. In 2012, many of us thought FirstNet would provide data and video services for public safety while land mobile radio systems would provide the voice component. None of our crystal balls predicted the advancements that would be made in push-to-talk over broadband technology. 

One thought was that spectrum for two 1-MHz guard bands would be an ideal place for inclusion of voice services including push-to-talk. This additional spectrum would be in addition to the original spectrum granted to FirstNet for what we thought would be a standalone 20-MHz nationwide public-safety broadband network. We discussed whether FirstNet could purchase spectrum from the existing license holders for guard bands on either side of public safety’s 20 MHz of Band 14 spectrum. As I recall, the license holders were willing to sell out for around $2million. 

Off-Network Tests

Below is the series of tests for use in determining if an off-network broadband solution would be capable of providing the same level of off-network one-to-one and one-to-many communications public safety has had for many years with LMR (originally published in the Advocate April 16, 2020).

  • Test One: Street-Level
    • expected range, 2-4 miles flat terrain, semi-urban areas
  • Test Two: In-Building
    • street-level to sub-basement
    • street-level to top floor rear
    • street-level to middle floor rear
    • street-level to street level around entire building perimeter
  • Test Three: Industrial Fire
    • device to device
    • staff to firefighters
    • law to law
    • law to Incident Command (IC)
  • Test Four: Wildland Fire
    • air boss airborne to IC on the ground

Technology Solutions

According to the Urgent Communications article dated August 14, 2021, “FirstNet officials released a request for information (RFI) seeking input about direct mode and other technological solutions to address the issue of providing broadband support for off-network when first responders are in a location not supported by FirstNet’s terrestrial macro LTE system.”

Also according to Urgent Communications,” Jeff Bratcher, FirstNet Authority’s Chief Technology Officer (CTO), responded saying, “This RFI focuses on any type of technology for device-to-device communications. Leverage 3GPP standards for other mechanisms but we’re not limiting it to 3GPP for this.” Another quote advises “…respondents should not be constrained by perceived or assumed requirements nor should respondents be constrained by preconceived ideas of what off-network functionality is today.” Anyone interested in responding to this RFI needs to submit questions by September 1, 2021 and responses by September 30, 2021.

It will be interesting to see what types of responses this request for information solicits. I am concerned that the September 30 deadline will not allow sufficient time for some organizations to submit adequate responses. Another issue is that, from what I can tell, the RFI is focused on providing off-network communications outside FirstNet LTE coverage. However, off-network communications outside FirstNet LTE coverage represents only one element of all off-network communications needs. 

Off-network communications are also required within the FirstNet coverage area. When dispatching to an incident today, the dispatch center assigns one or more off-network land mobile radio channels for the different agencies for one-to-one and one-to-many communications during the incident. For example, New York City Fire Department (FDNY) first responders rely on off-network communications during an incident even when they have network coverage. 

Going forward, no one really knows if broadband technology is capable of providing the same level of off-network communications public safety has today. This RFI acknowledges that LMR off-network communications are far more robust than ProSe, and it addresses vehicle-to-everything communications. No limits have been set for the types of solutions that might be viable in the future, thus the RFI invites potential respondents to consider a multiplicity of solutions including cloud-based applications.

Available Today

The starting point for public-safety off-network communications includes today’s LMR systems’ capabilities, higher-power devices, larger-capacity batteries, and external antennas. However, ideas about how to deliver off-network broadband communications should not be limited to duplicating what is already available with LMR systems.

Two or more companies are offering combination FirstNet/LMR handheld radios. The upside to these devices is that they include LMR off-network capabilities; the downside is that the LTE element does not support Android or iOS applications. The one exception is L3Harris radios with L3Harris BeOn push-to-talk that includes broadband on-network push-to-talk.

We now have higher-power broadband devices permitted to operate in public-safety Band 14. Their power output is up to 1.25 watts compared to 0.25 watts for standard broadband devices. Currently, high-power devices are limited to vehicular systems due to their power and heat dissipation requirements. Future higher-power could possibly be available in handheld devices with external antennas. While these devices might not meet all the off-network criteria described above, they might be usable in a number of situations.

The RFI discusses devices in pelican cases and backpacks, and the advent of Low Earth Orbiting (LEO) satellites for enhanced communications. While satellites might provide a solution, they probably will not provide coverage inside buildings, sub-basements, or other areas that do not have a view of the sky.

Some solutions might include external devices to extend off-network coverage. My pushback is that I believe public safety needs an off-network solution that is available both within and out of coverage that is part of or built into every communications device first responders will carry.

I am hopeful a number of companies, organizations, and individuals will come forward with ideas to address the off-network problem. The other side of this is that I do not believe land mobile radio systems will simply disappear, even if a valid off-network solution for broadband systems including FirstNet becomes available.

Technology is advancing so rapidly that it is not possible to look very far into the future. I am sure many companies have been thinking about and developing concepts for how to provide an acceptable level of off-network broadband communications. I commend the FirstNet Authority for issuing this RFI and I expect there to be many useful responses.

After all is said and done, we will still have to determine how many devices to build for off-network broadband communications. When FirstNet was envisioned, one concern was that vendors would not be interested in building devices for 10 million or so first responders. However, the successful bidder (AT&T) not only agreed to build out Band 14, it agreed to give FirstNet users priority and preemption on all its existing LTE spectrum. Now major broadband handset vendors are building a variety of devices that include Band 14 and have been FirstNet Certified™

It is not clear whether there will be demand for a broadband off-network solution for non-public safety use. Other critical-communications systems may want to include off-network capabilities, and perhaps citizens would find a use for both on- and off-network communications capabilities in the same device. If so, the volume of devices needed to meet the demand may entice major vendors to step up and build the products. However, commercial network operators might not want off-network capabilities built into devices used on their networks. With the availability of off-network communications, users would spend less time on the networks and commercial operators would lose money. 

Being old-school, I have deep-seated ideas about what first responders need and what they have come to rely on in the field. As LMR systems are updated and become more Internet Protocol (IP)-centric, at least in the back end of the network, there will be an all-IP solution that should be an incentive for many interesting types of devices and services. Next-Generation 9-1-1 (NG911) is all about broadband, FirstNet is all about broadband, and LMR can use broadband (IP) back-ends going forward. 

Responding to the RFI

The first technology issue to be resolved, if possible, is how to design a FirstNet smartphone or tablet that will deliver a solid off-network experience that approximates what the public-safety community is accustomed to with LMR off-network communications. 

Once available, the solution needs to be integrated into a FirstNet broadband device or a combination FirstNet/LMR device. It seems to me the first step is to decide how the device will operate. If it is to be a FirstNet-only device, the primary considerations are how to activate off-network communications and how many “channels” or talk groups should be supported. Today, all smartphones and tablets are controlled by the network when they are in range. The network verifies the device is within the coverage area and then adjusts the device’s output power to the minimum required to communicate with the nearest cell site. 

Finally, will the solution for talk-around be patented by the inventor or should it be an “open standard” so other vendors can design products arounnd the same solution?


I realize the RFI is designed to learn about ideas the brightest of the bright have been considering to provide off-network broadband. However, all the questions below, as well as others, will need to need to be addressed before a product is actually built. 

For off-network communications, will the device have to switch between network-controlled and user-controlled? Will the power level still have to be regulated? If the device is in range of the network, does it “hear” both network traffic and off-network traffic? If it is out of range, how easy is it for users to switch to talk-around/simplex mode and how are channels or groups selected? Many incidents require multiple off-network channels. When I was helping set up units in a base camp during a California wildland fire, there were times when we assigned many different simplex channels to different strike teams, logistics, and others who needed to communicate without interfering with each other or other traffic at the incident.

Should a device be developed to enable operating at higher power levels on Band 14? If so, what does operating at higher power do to battery life? 

Is it possible to build a high-power element that could be married to an existing device with off-network capabilities and maybe an external antenna? If a dual FirstNet/LMR device is built, would the off-network portion be LMR? Should the device be able to run Android or iOS applications? What size battery would it need, and should it be field replaceable? Could there be a shell to hold a smartphone with add-on LMR, for example? Sonim was developing a slide-on to hold a device for off-network using 900-MHz unlicensed spectrum. However, only low power is permitted on this spectrum, so that device would not meet public-safety requirements.

As the FirstNet Authority stated in the RFI, the issue of off-network communications continues to be a stumbling block for public-safety broadband. Is there a potential solution for broadband off-network communications that will be viable and inexpensive enough that every first responder will be enabled with broadband off-network capabilities? Let’s see how creative the response to this RFI will be.

Florida L3Harris

L3Harris recently announced that its contract with Florida to upgrade its statewide system and provide interoperability with FirstNet is worth $450million, the largest single LMR contract ever awarded. This upgrade will enable agencies all over Florida to communicate with any other agency within the state using either the new P25 network or FirstNet, and outside agencies will also be able to communicate seamlessly when they are assisting with an incident.

High-Power User Equipment (HPUE), MegaRAnge ™

FirstNet (Built with AT&T) and Airgain, one of two vendors with FirstNet Certified high-power Band 14 devices, are currently offering a discount package that reduces pricing for the AirgainConnect (HPUE) solution. If you have been impressed by your agency’s test results or test results published by a number of us who have performed drive tests, this might be the time to invest in high-power devices for your agency. 

Winding Down

Some may remember that in the early 1970s I worked for Biocom in Culver City, just outside Las Angeles. The next few years were some of the best in my life. Biocom built the first voice and EKG paramedic radios and they were featured on the TV show Emergency. During my time at Biocom, I traveled across the United States, helping cities establish their paramedic programs and training paramedics how to use our radio. 

I also spent time on the set of Emergency and worked with some of the writers on several episodes. Working with the writers was interesting, but they did not like it when I told them what they wanted to script was not possible. However, they did the impossible anyway since they never let facts get in the way of their effort to keep audiences involved in the action. 

There was an announcement last week that Emergency stars Randy Mantooth and Kevin Tighe will be making a documentary about paramedics. When medical care was first being provided in the field, emergency room doctors and many of the nurses did not believe paramedics could make treatment decisions. Not only did we have to train the paramedics how to set up and operate the Biophone, we ended up having to prove to the doctors in almost every city we visited that the three-lead EKG they were seeing on the Biocom console screen could be trusted. Time and time again we had to set up a BioPhone, start sending an EKG, and physically transport doctors to patients in the field so they could see for themselves that the technology was viable. 

At first, paramedics were not allowed to even start an IV without contacting a hospital and a doctor ordering the IV. Biocom radios were instrumental in developing confidence in paramedics’ capabilities and today there are hundreds of standing orders paramedics can follow when they determine what is needed to treat a patient. Many times, the only contact they need with the hospital is when they are ready to transport the patient. 

The addition of the FirstNet network has already provided for deeper levels of field treatment. For example, it is now possible to send a real-time ultrasound to an ER so the doctor can actually see if a patient is bleeding internally and should be transported by air or if the patient is stable enough to be transported by ground ambulance. 

I cannot wait to see the documentary they put together and, like the show they starred in, I am hopeful the documentary will encourage more teens to become EMTs and paramedics.

Until next week…

Andrew M. Seybold
©2021, Andrew Seybold, Inc.


1 Comment on "Public Safety Advocate: FirstNet Authority Off-Network Communications Solutions RFI, L3Harris, HPUE"

  1. Great article Andy – as usual. I think the topic of “Off-Network Communications” is a very important and interesting one. I applaud FirstNet for issuing the RFI seeking alternatives to the legacy approach of high power devices talking peer-to-peer. With the proliferation of Low-Earth-Orbit Satellites, wireless broadband (5G) everywhere and other out-of-the-box imagination, the solution will likely be very different – and probably superior – to what we are discussing today. I am very excited to see what ingenuity will surface from the RFI responses. Capitalism at its best 🙂

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