Citizens Broadband Radio Service (CBRS) refers to 150 MHz of spectrum in the 3550 MHz to 3700 MHz range (3.5 GHz to 3.7 GHz) that the United States Federal Communications Commission (FCC) has designated for sharing among three tiers of users: incumbent users, priority access license (PAL) users and general authorized access (GAA) users.
The incumbent tier is reserved for grandfathered users that had traditionally used the 3550-3700 MHz range. This group mainly includes the Navy as well as commercial fixed satellite stations. The CBRS band was designed taking into consideration the geographical usage of the band as well as predictable data that the incumbents had provided over time in order to limit interference for the incumbents.
The PALs tier is for users that purchase spectrum licenses at the CBRS PALs auction beginning in July 2020. The FCC will auction seven 10-MHz blocks in each county in the United States. In total, the FCC is making 22,631 PAL licenses available in its Auction 105. The licenses are for 10-year terms. The licenses are purchased on a per-county basis, and bidders are limited to 40 MHz in any county.
The General Authorized Access (GAA) tier is unlicensed spectrum that users can access for free.
CBRS provides much needed mid-band spectrum for a variety of users, including wireless carriers, cable operators, and organizations.
Wireless carriers are expected to use CBRS to enhance their networks with mid-band spectrum, especially in dense urban areas. Cable operators that deliver mobile virtual network operator (MVNO) services can use CBRS to offload some traffic from their wholesale wireless providers, saving on wholesale costs. Both wireless carriers and cable companies could use CBRS to deliver fixed wireless access (FWA) services. And enterprises will be able to use the spectrum to potentially build their own 4G or 5G private wireless networks. In addition, CBRS is also expected to outperform Wi-Fi for in-building use.
CBRS is also unique because it includes a spectrum sharing aspect. A group of Spectrum Access System (SAS) managers have been designated to manage the use and sharing of the spectrum. Those SAS managers include Federated Wireless, Google, CommScope, Sony and Amdocs.
When a user wants to use the CBRS band, he puts in a request via the SAS cloud-based system. If the spectrum is free in the desired geographic location, the SAS will grant the request. In order to access the CBRS spectrum, users will need to use Citizens Broadband Radio Services Devices (CBSDs) that must be registered with the SAS.