Public Safety Advocate: 3GPP Standards Update, MCPTT, FirstNet Deployables

This week we will look at a comprehensive report from The FirstNet Authority about the 3GPP standards body and its work in progress, discuss Mission-Critical Push-To-Talk/video/data and why this is taking so long, and see what it takes to manage the FirstNet fleet of deployables. 

3GPP Standards Update

In an Advocate entitled, “Why are We Waiting for a PTT Interoperability Solution?”  a few weeks ago, I was critical of having to wait for the 3GPP standards that seem to be taking forever and thought we would be better served if the public-safety and vendor communities could come together and push forward to provide full interoperability on the road to a standard. However, some suggested a better solution would be for the 3GPP to continue its efforts and it is. 

The FirstNet Authority recently published a recap of the September 14-21, 2020 3GPP Plenary Meetings in its tech talk blog and it is encouraging to see that both The FirstNet Authority and FirstNet (Built with AT&T) are active participants in the 3GPP. The report presents a detailed discussion of the 3GPP’s efforts to add public-safety features and functions to its work and FirstNet is well represented. While reading the report, I was wondering why this is taking so long and when we will see results that will help public safety with Push-To-Talk (PTT) interoperability issues that are so prevalent on broadband networks, including FirstNet, and LTE-to-Land Mobile Radio (LMR) interoperability. 

This week I find myself playing Monday-morning quarterback to what this recap classifies as accomplished, revisited, and proposed. It starts out this way:

“The third quarterly 3GPP Plenary meetings of 2020 recently concluded. As a reminder, the 3GPP Plenary meetings ending in early July officially froze Release 16 (R16) that contains 5G phase 2, as well as additional mission critical services (MCS) features and security enhancements, including basic interworking protocols for connecting an LTE-based MC system to a legacy LMR (land mobile radio) system.”

The rest of the introduction cites progress and momentum as development of Release 17 commences, but this was followed by an announced three to six-month slippage of this release. Release 17 does include items of interest to public safety including enhanced location services, enhanced mission-critical capabilities, and unmanned aerial vehicles (UAVs, drones). Also mentioned were direct mode including sidelink relay, something I don’t think has value for the public-safety community, and 5G Multicast, which caught my attention. 

I believe multicast is of vital long-term importance to the public-safety community. While multicast of LTE has been approved in the past, I don’t know of a single network that has implemented it. To reach a number of devices on LTE, today I have to address each device or, if I am in PTT mode for LTE, I can address them via a group. However, there is no way to broadcast citywide, countywide, regionwide, or even districtwide quickly and easily. Yet land mobile radio has been providing this capability for many years by virtue of how LMR systems are deployed. Multicast on 5G makes sense, but why, if multicast has not been implemented for LTE networks, is it such a priority?   

The balance of The Authority’s recap is divided by the type of plenary with the first being the Radio Access Network (RAN) plenary, which is working to provide 5G access to unlicensed spectrum. More importantly for public safety, the 3GPP folks in this group (600 in attendance per The Authority) are also working on solutions for better positioning accuracy and Enhanced 911 using network and non-network dependent technologies. 

It is also addressing 5G satellites and issues that need to be understood before providing hand-offs from one satellite to another, how much latency will be introduced, and more. Its last activity, completion of work on technical specifications for R14 Mission-Critical Push-To-Talk (MCPTT), push-to-video, and push-to-data conformance tests has a direct bearing on public safety. The recap cautioned that these tests would be finalized after the release of the specification itself. Issues with current MCPTT standards were discussed in a later section. 

Next came the Core Network and Terminals (CT) Plenary Sessions, which were attended by at least 200. These gave all of us who do not eat, breath, and sleep standards a look into how the need for changes or modifications arises after a standard has been established and implemented in the field. The report states that over the last three months, more than thirty corrections and clarifications were made to Release 16 and earlier Mission-Critical protocols, and four improvements were made to Release 17. It is good to see follow-on work after a standard finds its way into the field.

As the public-safety community gains more experience with Mission-Critical Push-To-Talk and push-to-everything else, it is quite possible that more changes will be necessary. This is to be expected since this is the first time the 3GPP has worked at the applications level. Judging by attendance at these sessions, there are more experts familiar with commercial and business-user requirements than there are with expertise in public-safety requirements, and even fewer with field experience. In the case of public safety, field personnel working routine and emergency incidents should be consulted and their input should determine the development of standards. I again caution that uses and needs differ from one department to another, from one location to another, and from one coast to the mid-west to the other coast, so it is vital to gather information from all segments of the public-safety community.

The FirstNet Authority’s report seems to support what I have said above. “During past European Telecommunications Standards Institute (ETSI) Plugtest events to test MC implementations against each other in a lab environment, 24 issues were found that might impact 3GPP MC standards. The FirstNet Authority and AT&T have created fixes in the 3GPP standards for a number of these issues. The remainder were found to only require an explanation of the standards involved. The FirstNet Authority created responses to almost all of these issues and authored a response liaison to ETSI Plugtest to inform them of the changes to the standards that are being undertaken and provide explanations for most of the other issues.”

The FirstNet Authority and FirstNet (Built with AT&T) representatives are to be commended. It has to be tough to come to a consensus when many of those who vote on changes and standards are not familiar with the public-safety community’s requirements, which are often at odds with what commercial broadband network operators are accustomed to. Yet so far, the 3GPP appears to have been able to work with a large number of vendors that are all looking for something specific to give them a leg up over their competitors. So far, these vendors have been willing to leave that attitude at the door, and I hope this continues.

My takeaway’ s from this report are as follows:

  1. Why work on 5G multicast when LTE multicast has not been deployed?
    1. I believe multicast is vital to broadband networks used by pubic safety. 
  2. If Mission-Critical Push-To-Talk is to drive Push-To-Talk, it needs to be implemented more quickly and it must be fully interoperable with other PTT-over-broadband clients and all types of LMR from analog to multiple forms of digital including Tetra, P25 conventional, Trunked P25, DMR, and all other digital voice and data technologies.

Thanks again for The FirstNet Authority blog. Having tried to follow happenings at 3GPP via its website, I find it much easier to examine its work from an article written by someone who understands public safety and can hone in on 3GPP activities that will have an impact.

MCPTT – Additional Comments

At least two vendors, Samsung and Ericsson, are promoting their push-to-talk applications as meeting all mission-critical standards. FirstNet has announced the Samsung version of MCPTT over FirstNet while Ericsson has announced on Southern Linc and now Verizon. Rumors persist that FirstNet (Built with AT&T) has a second MCPTT-approved PTT application it will announce soon.

So far, I am underwhelmed. Both vendors support only a few devices, all based on the Android operating system. Yet many thousands of first responders use iPhones and iPads every day. At this point, MCPTT cannot be labeled a fully-functional standard. Some say we need to be patient and we will see it all unfold. In the meantime, many using Apple’s iOS are using other PTT clients and, in most cases, these clients already work across a variety of networks and on both iOS and Android-based devices. 

I think there was undo pressure to launch MCPTT devices and services and this has had some unfortunate results. First, vendors already in the market with very good PTT applications are not being taken as seriously as they should be simply because they are not, today, MCPTT-compliant. Even so, these vendors have many more PTT customers using their applications today in local, state, and federal public-safety agencies all over the country. I am not a fan of developing part of a solution and bringing it to market to see how it is accepted. Further, we are told this new MCPTT device meets all standards for MCPTT but oh, by the way, you cannot talk to iOS users nor can you truly integrate it into LMR systems, but we will take care of this in the future. 

It is interesting to note Verizon, which did not bid on FirstNet but then renewed its interest in the public-safety sector, has introduced Ericsson’s MCPTT and claims to have Internetwork Function (IWF) capability via a relationship with Mutualink. However, Ericsson’s MCPTT works only on Android devices. The cost to individual Verizon public-safety customers who want both MCPTT ($12 per month) and IWF interoperability with their land mobile radio systems ($10) is being asked to pay $22 per month for services that are limited to push-to-talk. If a police or fire department with 500 devices wanted to provide PTT and PTT-to-LMR, the cost would be $11,000 per month. 

One of FirstNet’s goals was to reduce the cost of equipment and services. When LTE was chosen as the network technology, it was primarily because unlike land mobile radio with only several million customers, LTE had many millions of customers (several billions today). Thus, it was reasoned, devices and services would be less expensive. Now it appears non-FirstNet networks trying to keep their dwindling public-safety customers feel another $22 per-month per-user will simply be absorbed by agencies that are so tight for funding that one fire department that recently needed a new generator had to start a go-fund-me page to pay for it. 

I have often quoted Scott McNealy, the co-founder and CEO of Sun Microsystems, who said, “A standard is only a standard when it is used.” Perhaps today we should ask, “When a standard or partial standard is published, is ready for prime time if not everyone can use it?

Deployables – The United States becomes a Chess Board

The heading for this section is derived from a great video C-Net produced about deploying emergency cell sites, people, equipment, and everything else needed to where they can do the most good during disasters. 

Each network has its own cell sites and today; the United States is host to thousands and thousands of cell sites. Some share tower space and some do not. FirstNet employs all of AT&T’s cell sites as well as some that were established specifically to increase coverage for first responders. It has a nationwide emergency operations center, emergency centers in various parts of the United States, and use of AT&T’s temporary cell sites along with its own fleet of 71 or more that are available on an as-needed basis.

“As-needed” requires these deployables to be moved around the United States as if it were a chess board. When calls come in to request emergency communications for wildland fires, hurricanes, tornadoes, auto races, or large event gatherings (e.g., Sturgis and Burning Man), these deployables are staged in locations in or near where they will be needed. How are multiple requests within multiple locations around the United States handled? Think about the last few months. There have been huge and complex fires in California, Oregon, Washington State, and Arizona, hurricanes hitting the Gulf states, and an early snow blizzard in parts of the Midwest, all at the same time. 

Calls pour into FirstNet from all over, “We need coverage, cell towers are out.” Those responsible for responding to these requests must determine where sites are down and how long it might take to access them and restore service. Would it better serve first responders to send Cells On Wheels or Cells On Light Trucks (COWs or COLTs), a blimp, or tethered drones? How will they deploy the necessary support personnel and supplies? Time after time, people who manage deployables at AT&T (and other networks) must determine where temporary coverage is needed, how soon they can deliver deployables to the area, and how long the deployables will need to be in service before they can be redeployed. 

I would highly recommend that you watch the C-Net video to see what goes into this process over and over again. It is an eye-opener and while it does not delve into determining where the deployables are sent, it shows how, after the order is given, these assets and their crews are deployed, how the equipment is set up and put into operation, and how it is connected back into the network. 

Winding Down

For clarification, I want to explain why I believe the MCPTT devices released into the market are pre-mature. There is no one to blame, it is a matter of circumstances. Even before FirstNet became law, several vendors were touting the idea that within only a few years we would have push-to-talk services on FirstNet. One vendor went so far as to tell some members of Congress that it would happen so soon that land mobile radio would no longer be a must-have for public-safety agencies. 

After the network was in operation, some people still expected push-to-talk to be only a few years away. When the Public Safety Communications Research (PSCR) part of the National Institute of Science and Technology (NIST) was gearing up to assist public safety with the broadband network, PSCR engaged with the 3GPP and because of its involvement, public safety began to be recognized as a potential LTE user. As such, PSCR and public safety were able to work within the 3GPP on behalf of the public-safety community.

This in turn led to what has become Mission-Critical Push-To-Talk, followed by push-to-text, push-to-data, and push-to-video activities within the 3GPP. While The FirstNet Authority was crafting its Request for Proposal (RFP) in search of a partner to stand up and operate the FirstNet network, the press publicized many enthusiastic predictions for when MCPTT would be ready for prime time. I believe this is why The FirstNet Authority made the introduction of MCPTT key and included the requirement for its implementation within a specified timeframe. 

As it turns out, those who thought MCPTT would be ready for prime time underestimated how long it would take to craft standards, update them a few times, and then for vendors to create MCPTT-compliant applications. The arbitrary contract deadline served to put pressure on the contractor (AT&T) and I believe this pressure has resulted in the premature launch of MCPTT devices. 

Today we have the beginnings of what we all hope will be true broadband PTT interoperability and that it will be economical to integrate the broadband solution with land mobile radio systems. As more features, functions and, hopefully, operating systems are supported and more devices are in the field, the public-safety community will have an opportunity to kick the tires, verify what works, and share ideas for improvements. This standard needs to meet the public-safety community’s expectations since FirstNet and everything that goes into it is for public safety.

Until next week…

Andrew M. Seybold
©2020, Andrew Seybold, Inc.


3 Comments on "Public Safety Advocate: 3GPP Standards Update, MCPTT, FirstNet Deployables"

  1. You think MCPTT standards are taking a long time? You are aware the the P25 standards are still being amended with new functionality (example – patch and simulselect, a basic function used by all agencies is still not supported across the ISSI). Its been close to 20 years so don’t expect miracles with MCPTT. AT&T is supporting MCPTT as are other carriers and we all hope they work together to make sure users can roam between them in MCPTT mode

  2. Tim thanks for the comments and yes I am well aware that P25 have been in constant transition for over 25 years. However from the beginning P25 devices were available on all LMR networks, there were lots of cases of non-standard P25 to lock out other vendors but basically all agencies on all LMR networks could make use of it which is not the case YET for MCPTT.

  3. Andy, keep up the heat for true MCPTT! Glad to see that you are recognizing what the jump to FirstNet means to an Agency’s budget. Did an APCO presentation last year (Daytona/April) and calculated the LMR infrastructure break-even is at about 54 users (25 sq miles, 1 channel). Also not seeing in your discussion is VOLTE bandwidth user count limitations when deployables are used or the ENODE-B has less than 20MHz. Might get critical . . .

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