AT&T Needs Supplemental LTE Band 14 Solutions To Build FirstNet

April 25, 2017 —

By Louis Lambert

FirstNet’s award to AT&T to build the Nationwide Public Safety Broadband Network (NPSBN) was well-received by the public safety communications community.

NPSBN holds the promise of much-needed advanced wireless broadband communications and interoperability among first responders. NPSBN is a national, seamless, IP-based high-speed mobile communications network that gives first responders around the country their own dedicated multimedia capabilities over a common and dedicated LTE 700 MHz Band 14 (B14) network.

As an early commitment to provide first responders with priority communications, AT&T announced that for any States opting-in to the FirstNet program it will give preemptive priority to first responders already using AT&T’s commercial cellular network. This priority will assure first responders access to LTE services ahead of FirstNet network availability, and certainly will be a motivator for the States to opt-in.

Building a separate LTE network on B14 spectrum will not come without challenges that loom big for AT&T: a) achieving coverage objectives, b) building the network on time, and c) leveraging capital expenditures (capex).

As a first pass, AT&T likely will install macro LTE Band 14 eNodeBs (eNBs) in major urban centers to overlay its existing national commercial cellular network that involves some 40,000 cell sites. This near-term approach helps AT&T leverage its lease agreements with tower companies in major metro markets around the country and activates truly segmented LTE B14 network in dense population areas where a separate first responder network is imperative.

Questions are already being raised, however, as to how much NPSBN coverage AT&T can achieve over the next five years. There are five criteria or datasets that determine where the FirstNet network will be built. These are: 1) Number of police, fire and EMS users in a given jurisdiction, 2) Public safety high risk/areas of interest, 3) U.S. Census block population data, 4) Developed areas/buildings (what firefighters call the “built environment”), and 5) State and Interstate roadways. These datasets help develop suitable coverage maps on a state-wide basis.

Even so, coverage maps show lots of open spaces where the FirstNet network will not reach. This limitation suggests that many small towns and rural areas may not adequately be covered by the NPSBN for quite some time, if at all.

Urban, suburban and rural first responders will continue relying on legacy technology such as P25 Land Mobile Radios (LMR) systems whether there is NPSBN coverage or not. These widely-deployed P25 LMR systems, although not interoperable for the most part, do provide individual police, fire and EMS organizations a way to communicate. These older P25 systems are not going away even where AT&T will install the FirstNet B14 network. Coverage for first responders is not just outdoors; coverage is needed indoors in underground parking garages and other challenging areas for any radio system. As such, It will take time for the FirstNet LTE network to reach these areas and match the coverage the numerous P25 systems deliver today.

Timing of the NPSBN build-out is another big issue. AT&T committed to a build-out schedule that achieves 60 percent coverage in two years, 80 percent in three years and near full build-out in five years. Even with a sense of urgency and AT&T’s offer of preemptive first responder priority on its public LTE network, building a separate and autonomous FirstNet NPSBN in that timeframe is questionable without a significantly different approach to network design and deployment. Faced with the prospect that some critical sites may not be built for some time, the state governors or AT&T itself may elect to accelerate and augment the FirstNet main deployment plan with supplemental coverage.

Finally, there’s the money. Expect the lion’s share of AT&T’s planned $40 billion capital investment to construct NPSBN in major cities and populated areas. How much will go to small town and rural areas is still an open question. Capex for extending NPSBN to small town and rural areas probably needs be scaled proportionally. In other words, from an equipment perspective, the same large macrocells used in high-traffic areas probably are not the ones needed in applications involving fewer first responders who operate over wide areas. Are the small cells offered by AT&T’s LTE established equipment suppliers suitable for rural FirstNet deployments? They certainly were not designed to serve few users over wide areas like the FirstNet challenge poses.

In these situations, when planned coverage will not be delivered for some time a better solution is a much smaller, self-contained and all-outdoor eNB. These fit-for-purpose eNBs are very well suited as supplemental eNBs – they are highly-functional, easy-to-deploy, and come at a much lower price. Supplemental eNBs offer additional coverage, reach and capacity like large eNBs but for areas with low first responder density.

It is important to note the supplemental eNBs will not operate in isolation from the NPSBN. Rather, supplemental eNBs enable the state governors, FirstNet and AT&T to deliver communications in a complementary manner supporting all the same handheld devices (smartphones, radios), laptops and tablets and all FirstNet applications but at much less expense. In fact, supplemental eNBs will connect directly to the NPSBN evolved packet core (EPC) via wireless or fiber cable backhaul.  Supplemental eNBs will only be used with FirstNet and AT&T’s approval, and will enable a faster, less expensive means to build a truly separate B14 coverage overlay, where macrocell density is not needed.

Typical use cases include: rural towns, cities and villages, rural road coverage, national parks, aboriginal lands, rail lines, long stretches of highways, and industrial sites such as oil and gas, mining, forestry.

The point is: supplemental eNBs are a part of the FirstNET architecture and design. They can help FirstNet, AT&T, the state governors and public safety communications officials, and the U.S. taxpayers achieve much greater coverage, while meeting FirstNet’s performance requirements faster and for less money than merely extending the same large-scale infrastructure components used in the backbone network.

Supplemental eNodeB OEMs

Several radio manufacturers have proven the viability of supplemental eNBs in recent field trials.

Redline Communications (www.rdlcom.com) successfully demonstrated its end-to-end LTE B14 supplemental network solution at The Ohio State University (OSU) football stadium in November of 2016. Although in an urban area, there is a clear need for a separate LTE B14 network for first responders to have autonomous, dedicated broadband communications capabilities. Operating over a supplemental LTE B14 network, OSU first responders ensured security and safety of the more than 100,000 fans in attendance who all carry smartphones and can easily bog down the commercial cellular network during a game.

The OSU field trial confirmed consistent and reliable operation of programmed handheld devices with push-to-talk (PTT) capability, laptops and tablets over the Redline LTE B14 network. Moreover, purpose-built servers and gateways delivered PTT interoperability between the LTE B14 and several older P25 LMR networks.

In the end, supplemental eNBs will augment coverage in areas where the NPSBN network cannot or will not reach, and can be deployed in timely and economic ways that first responders expect.


Louis Lambert is VP-Business Development for Markham, Ontario-based Redline Communications, a leading provider of wide-area wireless networks for the most challenging applications and locations. He can be reached at llambert@rdlcom.com

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