FCC begins 3.5GHz auction, opening ‘prime’ mid band spectrum to 5G

Although the United States has already seen successful deployments of low and high band wireless spectrum for 5G networks, international carriers have largely focused on mid band spectrum — centered on 3.5GHz-adjacent frequencies — for their early 5G deployments. Following extensive preparations and some delays, the FCC today officially kicked off a nationwide auction of “prime” spectrum in the 3.55 to 3.65GHz range, offering carriers the opportunity to bid on seven mid band slices per county, augmenting their existing low and high holdings.

Auction 105 includes 22,631 “priority access licenses” covering counties across the U.S., effectively turning 70Mhz of spectrum into seven separate 10MHz pieces that can be purchased individually or in bundles. The more spectrum a carrier aggregates, the more bandwidth it will have available to deliver high-speed cellular services, a process aided by 5G’s new ability to combine mid band spectrum with either low or high band spectrum for improved performance.

Mid band spectrum has become desirable in the 5G era, offering longer-distance propagation characteristics than millimeter wave and more open stretches of bandwidth — in some countries — than lower bands, which numerous cellular networks had already put in use. Prior to this auction, Sprint’s 2.5GHz holdings were the closest to “mid band” of any U.S. carrier, and they were recently folded into T-Mobile’s network to enable peak mid band data speeds in the 600-700Mbps range and typical data speeds of 200-300Mbps. The FCC’s latest auction will enable other carriers to compete across all bands with T-Mobile, while giving T-Mobile the option to bolster its existing offerings.

Some countries easily allocated 3.5GHz spectrum to 5G, making it the popular or default standard for offering 5G services throughout China, South Korea, and parts of Europe. But in the U.S., the FCC had to juggle the needs of potential and incumbent users, including the navy. Consequently, the FCC requires 3.5GHz licensees to implement a spectrum sharing system that provides immediate access to top priority government users as needed, then to priority licensees, while allowing unlicensed CBRS users to access the same spectrum absent other demands.

The start of Auction 105 was originally planned for earlier in the year, but delayed until today due to the COVID-19 pandemic. Over 270 applicants have been qualified to bid, and though large carriers such as Verizon, AT&T, and Dish Network are expected to chase 3.5GHz spectrum in the auction, regional carriers including U.S. Cellular are likely to bid as well.