Public Safety Advocate: September Ends with IWCE, October Begins with a Roar

Last week was the first live IWCE conference since 2019. Meanwhile, on the last day of September, the Federal Communications Commission (FCC) voted 4-0 in favor of moving forward with the Eighth Notice of Proposed Rulemaking for 4.9-GHz spectrum. 

One large Land Mobile Radio (LMR) vendor wants to solve the Push-To-Talk (PTT) interoperability issue for FirstNet/LTE/LMR using its Critical Connect cloud service. However, a much smaller company provides push-to-talk interoperability that is available today. This solution is an example of how we can reach the goal of nationwide push-to-talk interoperability on FirstNet/LTE systems and integrate broadband PTT with LMR PTT services.

Last month, I joined a US Department of the Interior webinar series to listen to the portion provided by FirstNet (Built with AT&T) and a number of FirstNet users from multiple Tribal Nations. I will cover this webinar in more detail next week.


The annual IWCE conference and exhibition is usually held in the spring. In 2020, it was scheduled, canceled, and then rescheduled for September 2020. As Covid-19 continued to rage, it went from a live, in-person conference to a virtual conference as have many others over the last eighteen months.

Finally, IWCE 2021 was scheduled for the end of September this year as a live/virtual event and was held as planned. As you might imagine, there were fewer attendees and exhibitors than at previous IWCE springtime events. There were a number of reasons for this with Covid-19 being the most significant and still an issue in many parts of the United States and around the world. Another reason was that covid-related federal restrictions on travel prevented many people from federal agencies from attending.

Even with the smaller crowds and fewer exhibitors on the show floor, the conference was upbeat and the list of attendees read like a Who’s Who of the wireless industry.

As mentioned a couple of weeks ago in the Advocate, I participated in four panels. As is usual, the exhibit hall was not open Monday and Tuesday and panel sessions were of longer duration.


My first panel on Monday was called, “The Flavors of Interoperability.” It was well run and all participants shared their views on how we can move forward not only with push-to-talk interoperability but also with data, video, and other forms of interoperability that are needed by public safety on a nationwide basis.

I began by explaining interoperability goals I believe should be addressed and in what order. Priority should be given to nationwide push-to-talk over broadband and the ability to marry LMR PTT and broadband PTT so any FirstNet/broadband user, regardless of where he/she is, will be able to communicate with any other FirstNet/broadband user with push-to-talk voice. I write about this often because I believe nationwide fully-interoperable push-to-talk is the most important next step.

During the discussion, I referred to a time in my father’s life when he was a labor arbitrator working with management and unions to solve complex issues. I am sure some of his techniques would help solve our PTT interoperability issue quickly. Taking a page out his book, I described how I would rent a meeting room and require every push-to-talk vendor to send a representative to a special meeting. I would put the designated representatives into a room where there were no chairs and no water would be provided. And they would not be permitted to smoke or leave the room for a restroom break. Once the issue of push-to-talk interoperability was solved and agreed upon by all parties, everyone would be allowed to leave the room.

Next, I talked about an upcoming report on data, video, and Computer-Aided Dispatch (CAD) interoperability. Some may remember that I wrote about this type of compatibility some weeks ago. 

I spent several hours in conversation with John Constable who used to be the Statewide Interoperability Coordinator (SWIC) in Maryland among the many hats he has worn during his career. John went over a slide deck with me discussing how video interoperability issues have already been solved in the Maryland DC area and how the same type of solution can be applied to data, computer-aided dispatch, and any other form of data that needs to be shared. John gave me permission to use his slides or to provide them to interested parties. If you would like a copy, please email me and I will send his detailed presentation.

My next session, held on Tuesday, was about network resiliency. Once again, the moderator and presenters were top-notch and knew the subject matter well. I started out my part of the discussion by talking about land mobile radio and its ability to gracefully degrade if systems begin to fail. For example, a P25 trunking system can fall back to repeater mode with a final fallback to off-network or simplex. I pointed out that most trunking systems have a single brain (core) that could be a major point of failure. However, some vendors, including EF Johnson, Kenwood, L3 Harris, and even Motorola if pushed, can build a P25 trunking system in which the system brains are redundantly available at every site, and connectivity between sites is 100% IP-based. I wrote a white paper about this type of trunked/simulcast network for EF Johnson a few years ago and it is posted on the EF Johnson website. I learned recently that Santa Barbara County, California, which was long overdue for a radio system upgrade, has chosen the EF Johnson system primarily based on its redundancy feature.

Then I explained that redundancy and resiliency for LMR systems and broadband systems are not always the same. For example, FirstNet (Built with AT&T) has both high-level and low-level cell sites and this provides flexibility. If one or more low-level sites fail, high-level sites can fill in until the low-level sites are back on the air. In many cases, cell sites are made versatile by using tiltable antennas that can expand or shrink the coverage area of a cell sector. Also, FirstNet has more than 100 deployable cell sites that are available and positioned at strategic locations around the United States, and some agencies can buy smaller cell sites manufactured by Rescue 42. These can be towed behind a vehicle and set up in a matter of minutes with either direct or satellite backhaul.

In the next session, I joined in on the conversation about spectrum issues. (It is interesting that this panel was held the day before the FCC was to vote on 4.9-GHz spectrum.) Moderated by Alan Tilles, this session also featured a number of experienced and talented people. Panelist Chief Johnson (Ret), Executive of the Western Fire Chiefs Association, predicted that the vote on 4.9 GHz to take place the following day would be 4-0 in favor of moving forward with the Eighth Notice of Proposed Rulemaking. That is exactly how it turned out.

We discussed spectrum issues that affect public safety and all others who use this finite radio spectrum resource. The takeaway from this session was that there will continue to be more and more pressure exerted by commercial entities, especially those wanting to serve the unlicensed wireless market, and this will result in all public-safety and other services having to be vigilant and respond swiftly to future FCC actions that could create interference issues.

This brings me to the final panel, which was also moderated by Alan Tilles. This session began with a focus on the 6-GHz band used by public safety, utilities, broadcast, and other entities for point-to-point microwave systems. Last year, the FCC voted to permit WiFi 6 unlicensed devices to operate across the entire 6-GHz band. Some of the spectrum will be available for outdoor unlicensed WiFi and some for unlicensed inbuilding WiFi.

I strongly suggest that anyone interested in these issues listen to this session. All the sessions were recorded and they should be available soon on the IWCE website. The reason I suggest you listen to this session is that Richard Bernhardt, who is deeply involved in unlicensed WiFi in this band, gave a very good description of what is going to happen, and he believes there will be more than 2 million WiFi devices operating underneath critical-communications microwave systems.

He talked about the FCC’s intention to require Automatic Frequency Control (AFC) for at least outdoor WiFi systems. AFC is an automated method for informing WiFi devices where within the 6-GHz band they can operate with the least potential for interference to existing microwave users. It should be noted that AFC systems will rely on the FCC’s Universal Licensing System (ULS). This does not bode well for microwave users since the ULS is well-known for its inaccuracies. It includes systems that have been off the air for years, systems that may not be listed correctly, and other errors, all of which cast doubt on the accuracy of this data and the resultant spectrum selections. At this point, automatic frequency control is not required for inbuilding WiFi. Apparently, the thought from the FCC is that since it is to be used inside buildings, inbuilding WiFi will not create interference issues.

This presenter, who has spent many hours working with a consortium of companies determining how this band sharing can work, did not say all would be well with this type of band sharing. In fact, he stated several times that there are many unknowns and uncertainties when it comes to interference issues. I give him credit for his honesty in delivering the facts as he sees them and his conclusion that we really don’t know what effect the introduction of WiFi in this band will have.

I talked about the tests run by Southern Company and the Energy Innovation Reform Project (EIRP) that I wrote about several weeks ago showing even inbuilding devices interfered with point-to-point microwave. I also voiced my concern about millions of WiFi devices on 6-GHz spectrum substantially raising the noise floor. The higher the noise across a band, the more difficult it is for receivers to hear signals they are intended to hear.

I then expressed concern for being unable to identify unlicensed WiFi devices that are causing interference to the microwave systems. There are rules about who is responsible for interference and who is responsible for correcting the problem when all parties sharing the spectrum are licensed. For example, the most recent user to be licensed is responsible for curing any interference problem caused to existing license holders. 

When all users are licensed, it is fairly easy to determine the source of the interference. However, it takes time and money to identify interfering unlicensed devices and correcting the problem. Currently, costs will have to be absorbed by the license holder since the rules do not call for unlicensed operators to reimburse the license holder for any related expenses. 

Moreover, under the current law, even if a licensed microwave user is able to identify an interfering unlicensed device, the license holder has no standing to have the device turned off. One final point is that over the past few years, the FCC Enforcement Bureau has been gutted and short-staffed. Thus, a timely response to these types of issues is not guaranteed. Instead, they are considered to be merely potential problems for all existing microwave license holders. There is already litigation to address these matters. 

During the remainder of the session, we discussed sharing the 12-GHz band with commercial operators that want to deploy more 5G systems. However, this spectrum is already being used by incumbent satellite providers and Low Earth Orbiting (LEO) satellites. By several accounts, if all the planned little LEOs are actually launched, there will be more than 44,000 of them whirling around over our heads for seconds at a time needing to communicate with terrestrial systems.

Push-To-Talk Interoperability

As mentioned, Motorola is promoting its cloud-based critical-communications service for push-to-talk interoperability. While Motorola’s system is viable, it is concerning to me, and it should be to others, that a large vendor that does not always play nice with other vendors is attempting to capture the push-to-talk interoperability market.

I had an opportunity to sit down and talk with Beck Mitchell of Tango Tango at IWCE. After starting out reselling Kodiak push-to-talk for AT&T, Tango Tango is now a white-label reseller of ESChat, an over-the-top push-to-talk application. 

Located in the South, Tango Tango found that many of the public-safety agencies were using different broadband networks including Southern Linc, Cellular One, Verizon, and FirstNet. This is an issue for Kodiak/Motorola Enhanced PTT systems and other PTT products with Mission-Critical PTT (MCPTT). Because the PTT server is located within the network, the PTT application cannot be easily shared across multiple broadband networks. However, over-the-top PTT applications provide cross-broadband network interoperability. This interoperability, along with the ease of connecting ESChat to LMR systems, led Tango Tango to become a white-label ESChat reseller. While I have followed Tango Tango for a number of years, during this meeting I discovered it has solved many of the push-to-talk interoperability issues.

With the large number of users in the public-safety market, Kodiak/Motorola’s EPTT and ES Chat’s PTT seem to have captured in the neighborhood of 70% of all broadband push-to-talk systems. While many organizations are struggling with PTT interoperability issues, Tango Tango has solved many of the problems. Today, the company has customers in 44 states and its business model is to work with smaller agencies within a county, for example, and then move around the county adding agencies. Eventually, most of the county’s agencies are able to communicate with each other using push-to-talk. The preferred network interconnection uses Radio over IP (RoIP), and Tango Tango has chosen the JPS bridging system for its internetworking interoperability solutions. 

Several of its systems, which have not received much press, have been set up in geographic areas where some agencies are still using analog FM LMR systems and some are using digital systems. Further, some agencies are using Kodiak/Motorola’s EPTT and some are using ESChat’s PTT. Yet Tango Tango has quietly gone about providing gateways for both analog and digital LMR, and both flavors of push-to-talk. In a region such as this, it does not matter whether the customer is using Kodiak/Motorola EPTT or ESChat PTT, or whether an agency’s system is analog LMR or digital LMR. Everyone is able to communicate with everyone else with the Tango-Tango system.

Tango Tango has been able to accomplish this because it is still a small company, it has great backend technology, and it understands that interoperability is king. This transparent interoperability would be possible among the eight FirstNet-approved push-to-talk vendors, but when one vendor asks another to cooperate to enable push-to-talk interoperability, in most cases, the answer is “No.” I am intrigued with how Tango Tango simply went ahead and made it happen. I think this might be a model to move us closer to full nationwide broadband/LMR push-to-talk interoperability.

4.9 GHz

As mentioned, the stay request filed by the Public Safety Spectrum Alliance (PSSA) at the end of last year was approved by the current FCC and an Eighth Notice of Proposed Rulemaking was brought up for a vote in last week’s FCC open meeting. The positive vote from both sides of the aisle speaks volumes for Acting Chairwoman Jessica Rosenworcel’s ability to work effectively with all the Commissioners. This Notice means the previous Rulemaking that took 4.9 GHz away from public safety and would have given it to the states will not take effect. The states would have chosen a master leaseholder that could then sublease the spectrum to others. 

This Notice of Proposed Rulemaking is favorable to public safety. Still, the public-safety community has a lot of work ahead to ensure the outcome is advantageous for public safety since the pending Rulemaking proposes sharing the spectrum with non-public-safety users.

The FirstNet Band-14 spectrum was ultimately licensed to the FirstNet Authority, which then assigned it to the contractor that would build out the network; the network buildout contract was awarded to AT&T. The Band-14 license permits AT&T to use Band-14 spectrum for its commercial users when public safety does not have a need for all of the spectrum in a given area. However, commercial users are secondary users. If and when public safety needs the entire Band 14, whether for local, regional, or national disasters, there are two designated methods to open up the spectrum. The first is to throttle commercial use to provide better and faster access for first responders. The second is to move commercial users off Band 14 and onto AT&T spectrum. AT&T also provides full priority and pre-emption for public safety on all its LTE and 5G spectrum. 

It is my belief that if public safety is to share 4.9 GHz with other types of users, it must be handled like Band 14 sharing where a single operator is responsible for managing the band. When and if secondary users are to be denied access to the band during a major incident, there needs to be one “band manager,” for want of a better term, for both public safety and secondary commercial users. If the band was split up among multiple broadband operators, it would take a considerable amount of time to clear secondary users from the various networks. As a result, it would be difficult or even impossible to clear the spectrum for public-safety use in a timely fashion. 

A number of other issues will be addressed in filings before the FCC makes its recommendations. Protecting incumbent public-safety users on the spectrum is one other issue, and the PSSA is working in concert with several public-safety organizations to devise a plan that will be acceptable to both the public-safety community and the FCC. Stay tuned.

Winding Down

IWCE 2021 was my first trip since the loss of most of my eyesight. I found the experience to be mentally stimulating and, at the same time, very taxing. I was able to interact with people I have known for years and to meet others who are dedicated to providing public-safety with the communications tools they want and need.

While in Las Vegas, I had some time to sit in front of a slot machine or two. I mention this for one reason. On the last night of the show while playing on a machine, I needed a bathroom break and my wife, who accompanied me on this trip to make sure I didn’t have any problems, came over to watch the machine for me. She sat at the machine to the left and around a slight corner from mine where she could see my chair. However, she did not see the person who walked up on the other side, pushed the cash-out button, and snatched the voucher for what was in the machine. 

Then he quickly cashed the voucher at a nearby atm-type machine. When I returned and we realized what had happened, we flagged a floor attendant and within minutes, three casino police officers joined us. I was amazed at what happened next. The attendant checked the machine’s memory and verified how much money had been taken at exactly what time. They also noted the serial number of the voucher. Meanwhile, the officers called the video room and asked them to look at the video from two minutes before the machine was emptied to two minutes after. They saw the perpetrator empty the machine, what he looked like, and the clothes he was wearing. 

While all this was going on, I noticed two things. First, the police were communicating over their LMR system but when they needed to talk to the video room or others, they used cell phones. As we were waiting for evidence to be gathered, I chatted with the officers and asked about their use of cell phones. Most casinos have inbuilding network capabilities for both their land mobile radios and cell phones. However, they told me from time to time they could not access the cellular network because of the number of users in the casino.

This, of course, led me to ask if they were familiar with FirstNet. The three said they were not and asked me about it, so I spent some time talking with them and explaining absolute priority and pre-emption along with other features of FirstNet. I explained my involvement and gave one of them my card, which includes information about the Public Safety Advocate, All, and how to reach me. I told them to feel free to call me if they had any questions. After the paperwork was done and they started to leave, they thanked me for the information and said they would immediately talk to their supervisor and find out more about FirstNet.

I don’t know how many other casinos are not using FirstNet for their sworn police personnel, but I am confident that at least this one large casino will be contacting FirstNet very soon.

Until next week…

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


1 Comment on "Public Safety Advocate: September Ends with IWCE, October Begins with a Roar"

  1. John Contestabile | October 7, 2021 at 12:28 pm | Reply

    thanks for the shout out Andy….my company Skyline Technology Solutions, like Tango Tango has focused on video interoperability as our product solution…they have solved much of the voice interop problem as we have for video using an effective middleware architecture….my contact info [and correct spelling of my last name] is below….John C

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