Thu Jan 26 17:56:27 2017
In June 2009, APCO International (APCO), The National Emergency Number Association (NENA), and The National Public-Safety Telecommunications Council (NPSTC) publicly endorsed the wireless industry standard known as “Long Term Evolution” (LTE) for their envisioned Nationwide Public Safety Broadband Network. Was that a good idea? What was wrong with WiMAX or UWB that Sprint and Verizon were respectively supporting or the TDD-WCDMA network New York had deployed? This week’s Advocate will examine the history of Public Safety’s selection of LTE and why it became the foundation of FirstNet.
Before FirstNet was created in February of 2012, fourth-generation wireless broadband had only begun being developed or deployed. Multiple technologies were competing in the standards bodies and in the marketplace, and back then, like all of the preceding wireless technologies, these technologies were limited to making use of one portion or band of the spectrum at a time. WiMax and the TDD-WCDMA technologies were designed for Time Division, whereas UWB and LTE used Orthogonal Frequency Division. Since then a lot has transpired and the 3GPP, the global standards body, and the vendor community has made major changes to the underlying specifications of 4G technologies that could, perhaps, be of benefit to FirstNet. However, after a period of time, it became apparent that only the LTE technology would offer the benefits that APCO, NENA, and NPSTC were looking for in their broadband network. The market agreed; by 2010, WiMAX and UWB were gone and TDD-WCDMA had only achieved a couple of deployments since the New York City network build.
A little history is in order at this point. During the days when the Public Safety Spectrum Trust (PSST) and the Public Safety Alliance (PSA) were working with Congress, the Executive Branch, and the FCC to gain access to the spectrum that is now licensed to FirstNet, one of the issues that helped convince some of those who opposed the idea of a nationwide broadband network was that during localized incidents there could be a large number of Public Safety responders from various disciplines all vying for a finite amount of spectrum in a confined area. The PSA quickly learned that LTE was designed early on to follow the Internet model of more speed in the down direction (to the device) and less from the device up to the network (up direction).
This design was used to make actual measurements of video and data transmissions in the then approved 5X5 MHz of Public Safety spectrum. The results showed that during incidents in contained areas that were covered by one or only a few cell sectors, Public Safety responders would run out of bandwidth very quickly. Based on these tests, and other information provided, Congress ended up allocating Public Safety the full 20 MHz of spectrum (10X10) requested. The thought was that Public Safety might roam occasionally onto commercial networks but would basically be confined to using the FirstNet (band 14) 20 MHz of spectrum.
However, even with the full 10X10 MHz of spectrum there could and probably will be instances where the capacity of the network for close-in incidents will not be able to keep up with the demand. But if the RFP winner also has built and is running its own LTE networks on different portions of the spectrum it would be an easy matter for that network operator to permit spectrum aggregation on a prioritized and as-needed basis. This would ensure that during incidents with high concentrations of first responders in small geographic areas, the needed bandwidth could to be made available.
One of the attractive features of LTE that the PSA noted early on was that it provided a long-term roadmap chock full of successive releases to improve network performance or provide additional features. Each release of LTE offered new capabilities that have been agreed to by the global 3GPP standards body and its members. One of these that has become available since FirstNet was formed is the ability to aggregate spectrum to provide for either more capacity in a given area or faster data speeds in a given area. The technology released for LTE permits network operators that have LTE deployed in multiple portions of the spectrum (700 MHz, 1900 MHz, AWS-1, AWS-2 etc.) to be able to combine two or more of these spectrum bands and make the combined bandwidth available by devices that are capable of the technology. While this part of the LTE standard was not included in the FirstNet Partner RFP, the RFP did request that bidders bring different and unique methods of serving the Public Safety community to the table for consideration.
Carrier aggregation is only one of the enhancements to LTE. If you add this to today’s commercial capability to move between different segments of the spectrum depending on existing network demand, it is possible to see that adopting a few of the LTE enhancements would be of great benefit to the Public Safety community. There have been more enhancements to LTE since FirstNet was created, and even since FirstNet issued its RFP last year. Each release brings more capabilities and now with those involved with the Public Safety community being part of the 3GPP standards process many of these features and functions will serve not only commercial operators but Public Safety systems around the world. For example, LTE now supports a broadcast or one-to-many mode. This was originally developed to provide one-to-many streaming and broadcast in the confines of a stadium or other event but will certainly be of value if it is implemented in the FirstNet network. Push-to-talk and other features have also been included in the new standards but at the moment it is too early to implement them. Further, several network operators in the United States have added one or more levels of priority service for their own networks. While this is certainly not the grade of priority needed by Public Safety, it is a good start.
Normally when a network operator views a new release of LTE it goes through all of the enhancements and then picks and chooses which ones it thinks it should implement for its installed base. So it is possible that one network operator’s network using LTE will differ in certain aspects from another network operator’s network. If, as I have said, the RFP winner is an existing commercial network operator, and if the Public Safety community is to have access not only to FirstNet’s spectrum but the network operator’s spectrum as well, I imagine any decisions of what to add to the commercial network will also (or should be) included in the FirstNet system. This will provide complete compatibility when Public Safety moves from band 14 to one or more of the other LTE segments operated by the commercial and FirstNet operator.
It should also be recognized that as next-generation 5G or small cell systems are deployed to provide more capacity and data speed for the commercial network’s customers, the same upgrades to the network and to the way the network will operate can and hopefully should be incorporated into the Public Safety network. The premise of 5G is many small cells in highly populated areas, but it could also prove of value in certain rural settings, inside buildings including office buildings and apartment complexes, and it will also mean an even smarter relationship between the network and the devices. These new networks will provide what is being called “hetnet” (heterogenous networks) capabilities with the inclusion of many different types of cell sites from large to very small and with far better network-to-device controls. These new network technologies and capabilities can be of real value to the Public Safety community. The fact that both the network and the devices will be smarter and work together more efficiently will also be a big win for all.
It is true that Public Safety fought hard to be allocated a specific portion of spectrum that belongs to it but that can also be used by others on a secondary basis as long as first responders have absolute priority, but that should not preclude FirstNet and its customers (Public Safety) from the option of deploying band 14 as the main thrust of the network with the ability to make use of carrier aggregation as well as movement across and between all of the network operator’s LTE spectrum.
I believe this system could work much like a Land Mobile Radio trunked system does today. That is, normally all of the units are sitting idle on a control channel. When there is a request for communications, all of the units that are affected or in that group are instantly moved to an open channel and the conversation takes place. At the end of the conversation, all of the units are returned to their home channel. In the FirstNet system, band 14 would be the home channel as well as the prime spectrum of choice for Public Safety communications but since the network operator also controls access to other LTE spectrum assets, Public Safety would have much more flexibility.
I can think of a number of cases where this type of network design would pay off. For example, when there is an incident in a confined area and the capacity of band 14 cannot keep up with demand. In this situation, the first thing that could happen is to move those not directly concerned with the incident to other spectrum, and then to provide spectrum aggregation in order to deliver more capacity to first responders during the incident.
Instead of the Public Safety community having to remain only on band 14, it would have the same capability as commercial customers on the network operator’s network AND still have absolute priory access to band 14 during major events. Several news articles reported that during the recent demonstrations in DC even with all the added capacity, the commercial networks were overloaded. Public Safety would have band 14 to itself during this type of high commercial demand.
The type of spectrum sharing and aggregation I am talking about here is based on a network operator being the winning Partner for FirstNet; a network operator that already has LTE up and running on one or more portions of the spectrum. I don’t think the same advantages would be possible across multiple different network operators’ networks or if the spectrum, when not in use, or is arbitraged to whomever pays the most for it. Instead, I think the close coordination between the FirstNet network and the carrier’s own network would be the reason for these capabilities to be offered as seamless and with priority across all of the spectrum assets. This type of operation might also help convince states that are sitting on the opt-in or opt-out fence to jump onto the FirstNet side instead of simply leasing the band 14, 20 MHz of spectrum for their own use.
The RFP Partner contract is for 25 years. If we look at the advances that have been made in wireless networks, technologies, and devices during the past 25 years we can see that the advances have been huge. The same will be true, I am sure, over the course of the next 25 years. In fact, it has already begun with the advent of 5G or small cell deployment by commercial operators in a number of major urban areas.
So, again, if the RFP winner is an existing network operator it might be possible for FirstNet to follow the technology trends more cost effectively going forward. Suppose, for example, a given area was peppered with small cells operating in the 25-GHz band. The amount of spectrum available in this band could enable the network operator to deploy its own small cells and then if agreeable to FirstNet and Public Safety, carve out a portion of that bandwidth and reserve it for Public Safety use on an as-needed basis. The magic of making all this work is that it all happens in the back-end and it is all software driven. It should, therefore, be possible to do all of this and more going into the future.
It does not make sense that the commercial wireless industry has and will be implementing new capabilities to serve its customers and to limit FirstNet only to its single 20-MHz swath of spectrum. The days of a broadband network operating in one portion of the radio spectrum are gone. Gone, too, are the days when our cellular devices move from 700 MHz, 800 MHz, to 1900 MHz, to some other portion of the spectrum but only employ one of the bands at a time. Today, these devices are capable of many different types of operation and many different configurations depending on the need of the customer. Commercial networks are in business to serve their customers to the best of their ability. In reality, FirstNet and the Partner are in the same business with the same business model.
LTE advances, spectrum sharing, 5G and beyond technologies are all in process and this is the reason APCO, NENA and NPSTC were visionary in their selection of this technology. In the 25 years that FirstNet has a contract with the RFP winner, situations will change, technologies will change, and if a network operator turns out to be the successful bidder, perhaps a closer technical partnership could be considered for the benefit of the ultimate customer, the Public Safety community.
Andrew M. Seybold
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