CBRS stands for Citizens Broadband Radio Service is a band i.e. band 48 of radio frequency spectra from 3.5GHz to 3.7GHz for 3 types of users. 

  1. Incumbent Users 
  2. Priority Access Licensees 
  3. General Authorised Access 

At the start, the CBRS band was reserved for use by the U.S Department of Defense, like U.S Navy Radar systems. But in 2015, the FCC i.e. The Federal Communications Commission dubbed the 3.5GHz band as the “innovation band” to be opened up to new mobile users.

After that the “innovation band” is now known as CBRS. CBRS opens up a major opportunity to unlicensed users and organisations who want to use 5G, LTE, or even 3GPP spectra to establish their own private mobile networks. 

Every CBRS domain contains a Spectrum Access System (SAS). the SAS system is used to connects to FCC i.e. Federal Communications Commission databases and incumbent reporting systems. 

The SAS also interfaces with Environmental Sensing Capability(ESC) systems. ESC systems automatically detect radar use in a particular area.

Either component supporting a CBRS antenna or antenna array is the Citizens Broadband Radio Service Device (CBSD). 

The CBSD also identifies its unique geolocation, height, indoor or outdoor status, and unique call sign registered with the FCC. 

The CBSD and SAS communicate through Hypertext Transfer Protocol Secure(HTTPS), with each message encoded via JavaScript Object Notation(JSON).

To prevent interference across the three tiers, the SAS acts as a frequency coordinator that prioritises access between the Incumbent, Priority Access, and General Access Tiers.