What is Citizen Broadband and Radio Service (CBRS)?
What is Citizen Broadband and Radio Service (CBRS)?
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Overview
Overview
CBRS, which stands for Citizen Broadband Radio Service, refers to the 3.5GHz spectrum that was originally reserved for US Navy radar systems. In 2015, the Federal Communications Commission (FCC) released the spectrum ranging from 3550 MHz to 3700 MHz for public use in commercial wireless services. In the same year, the FCC also completed a process to authorize rules for the commercial use of this 150 MHz-wide broadcast band, while reserving parts of the band for the US Federal Government (more details can be found here).
United States frequency allocations. Go to the image source to learn more.
Opened in 2020 by FCC
Also known as band 48 or b48
Can be used to deploy private networks:
4G LTE (most common)
5G NR (ongoing development)
Access to the medium is managed by a 3rd party entity called the Spectrum Access System (SAS)
Pyramidal access scheme, image provided by CommScope (Image source)
The FCC adopted a three-tiered access and authorization framework to share this band among federal and non-federal and other users. The authorized federal and grandfathered fixed satellite service users (usually referred to as Incumbent Access users) are kept at the top tier of this pyramid-like access scheme.
The middle tier is reserved for Priority Access Licenses (PAL). These users have purchased licenses in FCC-issued Auction 105, which raised a total of roughly $4.55bn. PAL licenses, which are issued on a county-by-county basis, are particularly appealing to Wireless Internet Service Providers (WISPs) and to mobile operators that use this spectrum to increase the available bandwidth for their customers.
At the bottom of this pyramid, we have General Access Users (GAA), which include a broad group of potential users and enterprises that often utilize this spectrum for private networks. Users of these tires concurrently share the same CBRS spectrum; therefore, there might be a chance of interference. Access to the medium is managed by the SAS.
County-based US map with the results of the auction by the top 10 purchasers of CBRS spectrum (source).
There has been a lot of interest from mobile providers to acquire licenses to transmit on the CBRS.
PAL licenses are assigned through auction at the county level.
Auction 105 for CBRS PAL licenses in 2020 raised $4.55bn, with Verizon, Dish Network, Comcast and Charter Communications as major purchasers.
Pros
Low Tx cost per Hz
Ease of deployment
Low interference (for now)
Relatively long-range
Cons
Not many antennas on the market (high cost, little competition)
Not many devices with b48 capabilities
Propagation negatively impacted by leaves
Additional resources
Additional resources
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