Public Safety Advocate: FCC 4.9 GHz Reply Comments; FirstNet Authority and FirstNet (Built with AT&T)–Still Being Confused; Broadband/LMR PTT Nationwide Interoperability–Still Waiting

Unfortunately Andy is still unable to write his Public Safety Advocate. Therefore, once again, ATFN staff is posting “The Best of Andy” past articles.

As you saw, last week we published the Public Safety Spectrum Alliance’s (PSSA) comments on the Federal Communications Commission’s (FCC) Eighth Notice of Proposed Rulemaking (NPRM). The PSSA was not alone, a number of other comments were filed as well. Next come reply comments, which are due at the FCC before Christmas (the closing date is right after Christmas). 

A number of these submitted comments are worth reviewing and perhaps filing reply comments. For example, radio astronomers are concerned about what will happen if the 4.9-GHz public-safety band is taken away and given to the states. Radio astronomers have reason to be concerned since they use the spectrum just above the public-safety 4.9-GHz band. I think they would feel better if the FCC would agree that the public-safety spectrum should be licensed on a nationwide basis with a band manager. The band manager would work closely with the radio astronomers to ensure there would be no interference in either direction on a nationwide basis. Without this manager, radio astronomers would potentially have to deal with a large number of individual license holders across the United States. 

Of course, some of the comments disagree with the idea of a single nationwide public-safety license and a band manager. Most of the comments against a nationwide license approach were filed by organizations with regional frequency coordinators in their membership who would not be needed to coordinate the 4.9-GHz, though they might work with incumbent public-safety license holders to ensure they are protected as called for in the PSSA’s filing. These organizations have a vested monetary interest in promoting frequency coordination in the band.

Even so, in one way or another, most of the comments support the FCC’s original eighth filing that will return the 4.9-GHz band to public safety and they approve of its wording. Again, I ask that anyone interested in helping preserve this spectrum for public safety take the time to file reply comments acknowledging your support. And don’t forget to mention your support for protecting existing public-safety users and perhaps permitting secondary users on the band in areas where public safety may not need all of the spectrum. However, it is imperative for the public-safety community to have full priority and pre-emption on the entire 50 MHz of the spectrum.

I believe secondary use should follow the model Congress and the Executive Branch established when the law creating FirstNet was signed. This law provided 20 MHz of 700-MHz broadband spectrum that falls under FCC Rule Part 90 for public safety; it allows the private contractor to build out Band 14 for public safety use; and it permits the contractors’ commercial customers to use Band 14 when public safety is not using all of the spectrum on a local, regional, state, or nationwide basis. This means secondary users will have access to the spectrum most of the time, but public safety can pre-empt secondary users when needed. 

This arrangement could easily be used for the 4.9-GHz band to ensure when it is needed public safety has access to the spectrum and when it is not being used by public safety the spectrum is available for secondary use. This model is being used for Band 14 spectrum and device manufacturers have been able to build Band 14 into their smartphones, tablets, and other devices, thus keeping Band 14 device costs about where they have been for commercial-only broadband devices.

Unlicensed 4.9-GHz Use Should Not Be Permitted

Some of the comments indicated that using one of the new and yet-unproven methods of spectrum frequency or use control could be used to assign frequencies for unlicensed devices. I strongly disagree with this concept. If there is an interference issue and both licensed and unlicensed users are occupying the band, there is no way for licensed users to identify the source of the interference. Moreover, they couldn’t force the interfering device(s) off the air until the cause of the interference is identified and corrected. Public safety simply cannot tolerate interference that could potentially impact their ability to use the spectrum for priority and mission-critical communications.

Automatic Frequency Control (AFC), Spectrum Access Sharing (SAS)

In a previous Notice of Proposed Rulemaking, the FCC indicated interest in two ways intended to ensure that different types of uses for specific portions of the radio spectrum can co-exist with minimum potential for interference. The first method is known as “Automatic Frequency Control” (AFC) and it is being touted for use within the 6-GHz band where the FCC has decided to permit unlicensed Wi-Fi 6 devices to operate underneath critical-communications microwave point-to-point and point-to-multi-point systems. 

A few months ago, I wrote about how tests run in Georgia belie the opinion put forth by vendors of unlicensed products that both licensed and unlicensed users can co-exist in the same portion of spectrum. The ACF system uses the FCC’s Universal Licensing System (ULS) database, supposedly to pinpoint which portion of the 6-GHz band outdoor unlicensed systems can use that, hopefully, will not interfere with licensed users. However, the FCC’s database is not up-to-date. Depending on the ULS as the only way to determine where existing licensed microwave users are operating is not a fool-proof way of ensuring there will not be any interference. Further, today’s rules do not provide coordination for unlicensed in-building systems. The Georgia tests also proved that even indoor Wi-Fi 6 systems can and do interfere with existing microwave systems. 

Spectrum Access Sharing (SAS) is yet another unproven technology that could be used in the Citizens Broadband Radio Service (CBRS) mid-band spectrum. Here again, this technology has not been implemented and it is not ready for prime time. A number of organizations seem to believe SAS is the best thing since sliced bread, but even these people say SAS should not be used for spectrum sharing when the primary licensed user is a critical-communications (read “public safety”) license holder. 

AFC or SAS, in either case, these new methods for integrating unlicensed or other licensed users with licensed users hopefully will not cause interference with primary licensed users on the same spectrum. While AFC and SAS may be applicable to non-sensitive communications services, they do not appear to be at all suited for spectrum sharing when the primary license holder uses the spectrum for emergency communications services. Public safety cannot afford to worry about unproven technologies being used for sharing the spectrum with unlicensed or even secondary licensed users. What’s more, when and if interference issues arise, they must be resolved nearly instantly, which means immediate identification of the operator whether licensed (easy) or unlicensed (difficult to impossible). 

Finally, SAS provides only “on or off” access to a portion of spectrum for secondary users while priority and pre-emption as practiced in Band 14 provides a graceful degradation. First, secondary users’ data rate is throttled. The next step is to implement priority and pre-emption access. ONLY if public safety needs access to all the spectrum in a given area do secondary users have to vacate the spectrum. Normal access is restored when public safety no longer needs the spectrum. 

After the comments and reply comments periods, the FCC Commissioners will, with their staffs, review the comments and the reply comments for a proceeding and to reach a consensus on the matter before voting on the final rulemaking. You may recall that during the review of the PSSA stay request for reconsideration, the Commission was two members short of the traditional five members, and they voted 4-0 in favor of granting the stay and issuing the Eighth Notice of Proposed Rulemaking. Today, the Commission is only one short with the confirmation of Jessica Rosenworcel to lead the FCC.

The FirstNet Authority and FirstNet (Built with AT&T)

The first five years of the 25-year contract the FirstNet Authority awarded to AT&T after competitive bidding coming to an end, and we are seeing more and more press releases about new cell sites providing additional broadband coverage for both AT&T commercial users and FirstNet users. However, some of these press releases are adding to the still-prevalent misunderstanding about the relationships between the FirstNet Authority, FirstNet (Built with AT&T), and AT&T Wireless.

The FirstNet Authority, created in the law signed by Congress and the President in 2012, is an independent government authority that reports to the National Telecommunications and Information Administration (NTIA), which is part of the U.S. Department of Commerce. This new agency was called “The First Responder Network Authority,” which was shortened to “the FirstNet Authority.” 

AT&T is the private portion of the Nationwide Public Safety Broadband Network (NPSBN). After competitive bidding, AT&T was awarded the contract to build, maintain, and update the network. The FirstNet Authority and AT&T make up the public/private partnership that is charged with building, operating, and updating the nationwide broadband network under the guidance of the FirstNet Authority. 

“FirstNet (Built with AT&T)” refers to the network itself. 

I believe there is still some confusion about the two “FirstNet” organizations. As we near the end of the first five years of the specified build-out period, the volume of press announcements about so many new cell sites being commissioned is adding to the confusion. Because the FirstNet Authority is part of the federal government, it is generally precluded from issuing press releases about new cell sites or new agencies that are signing on to the FirstNet network. Since we hear relatively little from the FirstNet Authority, it is more difficult to understand its role.

In some cases, we are seeing press releases that say something like, “A new cell site was just put into operation by AT&T/FirstNet,” or “such and such an agency has joined FirstNet.” These releases are worded this way when they are issued by FirstNet (Built with AT&T) or by the county or city in which the cell site or agency is located. 

It should be expected that as the end of the five-year build-out period is fast approaching, more cell sites are being put into operation and new agencies are signing on to the FirstNet network. 

When AT&T commissions a new cell site for FirstNet, it incorporates some of its own LTE licensed spectrum. Keep in mind that when public-safety Band 14 is implemented within a cell site, it is designed to be primarily for public-safety agencies use, but it is available to AT&T’s commercial customers when it is not being used by public safety. 

Why Are We Still Waiting for 
Nationwide Broadband/LMR PTT Interoperability?

Here we are, approaching the end of another year and there is still no resolution to the issue of public-safety PTT on FirstNet. Even if there was a solution, it is questionable whether it could be integrated with an agency’s LMR PTT. 

A growing number of local, state, and federal agencies are no longer waiting around for the promised 3GPP Mission-Critical Push-to-Talk (MCPTT). While MCPTT has been available for almost three years, it still does not support iOS devices. Also, the Internetworking Function (IWF) that is supposedly the key to integrating this on-network PTT standard with LMR and perhaps other broadband networks has not been widely available. 

Of the seven choices of PTT approved for FirstNet, at least four offer nationwide broadband PTT integration with other approved PTT applications and PTT integration with existing LMR systems (including Analog FM, P25 conventional and trunked, and in some cases even Digital Mobile Radio (DMR) systems.

Still, some agencies are moving ahead with nationwide broadband PTT and LMR integration. However, unless every agency uses the same flavor of PTT or until there is a workable solution to provide cross-vendor PTT interoperability, public-safety agencies will not be able to communicate with every other agency using PTT on FirstNet.

It has to be frustrating for an agency to adopt one of the FirstNet-approved PTT applications, interface it with its LMR PTT network, and still not be able to use PTT to communicate with a neighboring agency. 

What will it take to solve this problem? How long will it take? PTT is still the fastest and best way to communicate between and among agencies working on a multi-agency incident. Providing nationwide PTT interoperability needs to be given high priority now.  

Winding Down 

By the beginning of 2017, the FirstNet Authority had entered into the 25-year contract with AT&T and by the end of 2017 all the states and territories had decided to opt-in to FirstNet rather than being required to build their own network that could be seamlessly integrated with the FirstNet network. Then the build-out began in earnest.

The contract included milestones to be met by certain dates, basically every six months or a year for the first five years. To its credit, AT&T has blown past most of the milestone completion dates over and over again. As an added bonus, while not required in the contract, AT&T has provided a path for FirstNet members to use its 5G network. The law does require the FirstNet Authority to put a portion of the money it collects back into the network. These funds are currently being used to upgrade the FirstNet Core (brains) for 5G, and to handle LTE or 4G FirstNet traffic. 

In 2022, we will have reached the end of the first five years of the contract. I, for one, have been impressed by AT&T’s dedication to building and then operating the network. The bill that created the FirstNet Authority laid out rules and guidelines for the very large public/private joint venture. At the time, none of us expected to see the progress that has been made in this first five years. Our expectations were that a contract would be awarded and a vendor would build what we thought would be a greenfield (new) nationwide network using only 20 MHz of public-safety 700-MHz spectrum. 

Instead, we have seen AT&T move rapidly and unexpectedly offered up all of its LTE spectrum with full priority and pre-emption as it was building out Band 14. 

Each state and territory was required to opt-in to FirstNet or build its own network, but the law did not require individual agencies to join the network. Yet in the few years FirstNet has been available, the number of agencies and users on FirstNet has grown faster than any of us would have guessed. 

The approaching end of the first phase of the contract does not mean either FirstNet (Built with AT&T) or the FirstNet Authority will kick back and say, “mission accomplished.” They will continue to build and enhance the network and make sure, for the first time, the public-safety community will have the most up-to-date network, devices, and services they have ever had. 

It is great to see what was a distant vision in the early 2000s turn into what FirstNet has become. It is a true nationwide broadband network dedicated to and for the public-safety community.

Until next week,

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


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