The Citizens Broadband Radio System (CBRS) spectrum band (3.5 GHz) is currently in the headlines because the Federal Communications Commission (FCC) on July 23 launched a spectrum auction that will divvy up 70 MHz of the 150 MHz spectrum in this band. This is the first major auction of mid-band spectrum in the U.S. and it is important because CBRS spectrum can be used for many different things, including providing 5G coverage, building a private wireless network for an enterprise, or operating a fixed wireless network to provide coverage to rural areas with limited connectivity options.
What makes CBRS different
The CBRS band ranges from 3550 MHz to 3700 MHz and is unique because there are existing users of this slice of spectrum that have been “grandfathered in” and have priority use of it. This group of existing users includes the U.S. Navy as well as commercial fixed satellite stations.
The FCC instituted a three-tiered hierarchical framework for this spectrum band as a way to make it possible for those existing users to still have access to the spectrum but also make it available to new users. In this hierarchical framework, the incumbent users have the highest priority followed by the Priority Access Licensees (PALs) and the General Authorized Access (GAA) users, which are unlicensed.
The licenses that are being bid upon in this current FCC spectrum auction are PALs. The winners of those licenses will share the spectrum with incumbent users and the GAA users. Last January the FCC started allowing the GAA users to use the CBRS spectrum and they have 80MHz of the band available for their use.
The urban-rural divide
Unfortunately, many rural Americans still lack access to a robust internet service. According to the Task Force on Agriculture and Rural Prosperity Report that was compiled by the U.S. Department of Agriculture, as of 2014 39% of the rural population still lacked reliable access to broadband. This connectivity gap prevents rural Americans from participating in the global marketplace and means businesses in rural America miss opportunities to serve global customers.
One potential use case for CBRS spectrum is providing fixed wireless access to areas that are currently under-served by broadband providers. Preston Marshall, chief wireless architect at Google, is considered a top expert on the CBRS band. Marshall recently told FierceWireless that he believes WISPs will use CBRS spectrum to provide broadband service around the country and they will be able to do so using the same 3GPP-standardized equipment that wireless operators use today. This makes it possible to offer a hybrid fixed/mobile solution to customers.
Viaero's Kansas CBRS use case
Viaero Wireless is a wireless operator based in Fort Morgan, Colorado, that provides both fixed and mobile wireless services to residential and business customers in eastern Colorado, Nebraska, Wyoming and Kansas.
Aurora Insight looked at Viaero Wireless’ coverage area and discovered that the wireless operator is currently using unlicensed CBRS spectrum in the 3660-3679.8 MHz range to provide LTE service. It appears the company, which caters to consumers living in rural areas, wants to extend its existing wireless coverage to more customers.
Aurora’s proprietary technology, which uses a network of sensors to measure radio frequency spectrum, was able to determine that Viaero has deployed 125 transmitters in the CBRS spectrum to provide additional coverage and capacity in areas of Colorado, Nebraska and Kansas. Aurora was also able to pinpoint that Viaero is using 49 eNodeBs, which is a technology used to manage the uplink and downlink resources in the network.
While Viaero Wireless is using CBRS GAA unlicensed spectrum today to extend its LTE service, it is also one of the bidders listed by the FCC to participate in CBRS PAL auction.
Viaero has experimented with CBRS spectrum in the past. Last September the wireless operator filed paperwork with the FCC to use an experimental license to test the propagation characteristics and throughput of wireless services using the 3550-3600 MHz band of CBRS.
The current CBRS PAL auction is notable because the FCC is auctioning 22,631 licenses, which is the most licenses ever offered in a spectrum auction. Plus, there are 271 qualified bidders that are competing for those licenses (in June, the FCC revealed its list of qualified bidders that had registered to participate in the auction).
The qualified bidders include some familiar names such as Verizon, AT&T and T-Mobile, Cox Communications, Charter Communications, Comcast and CenturyLink. But there are smaller telecom operators on the list including U.S. Cellular, Cincinnati Bell and Carolina West Wireless. And there are also some non-traditional bidders on the list including oil and gas companies Chevron and Occidental Petroleum, and power company San Diego Gas and Electric.
This CBRS auction has been very competitive thus far and could raise as much as $4.4 billion.
But the auction rules forbid any single entity from purchasing more than 40MHz of spectrum in any license area. This 40 MHz rule is intended to prevent deep-pocketed Tier 1 wireless operators from winning all the licenses in the auction and is likely the reason that we see some non-traditional bidders and smaller wireless operators in the mix.
Aurora Insight is tracking the use of CBRS spectrum around the globe and will be monitoring the progress and the results of the CBRS auction in the coming weeks.