ators coordinate spec- trum, not only among all their managed transmitting devices but also among each other. There are several parameters fed to the SAS, including CBSD-ID, location, height, antenna characteristics, and transmit power levels. There are several types or categories of equipment allowed to operate in the CBRS band: A User Equipment (UE) device operates <23 dBm Effective Isotropic Radiated Power (EIRP) (typically a handset) Sense Assign/ register PAL user Incumbent Coordinate Other GAA user Incumbent FIGURE 1-6 SAS components. SAS, spectrum allocation system. 12 Open Radio Access Network (O-RAN) Systems Architecture and Design not required to be registered to a SAS Category A CBSD (CBRS Device) operates <30 dBm EIRP (per 10 MHz) required to be registered to a SAS Category B CBSD (CBRS Device) operates <47 dBm EIRP (per 10 MHz) required to be registered to a SAS. There is the CPI (Certified Professional Installer) requirement for all Category B CBSDs as well as Category A CBSDs that are (1) installed above 6-m Height Above Average Terrain and (2) unable to geolocate. The ESC is a network of sensors that detects incumbent activity in the CBRS band along the coast and transmits this information to a SAS, which determines which part of the CBRS spectrum can be used by the two other tiers-PAL and GAA. PAL and GAA users are not allowed to use CBRS channels while they are in use by incumbent users. Coexistence The SAS is responsible for spectrum allocation among users. PAL users are prioritized with GAA users getting access to remaining spectrum. SAS authorization is required for both PAL and GAA users. GAA users only need to register but do not need a license. SAS operates in real-time, but in practice, allocation is assumed stable over time. SAS assigns the spectrum for GAA, but it does not coordinate access among GAA users. Coexistence methods such as IEEE 802.19.1 need to be deployed to guarantee access among GAA users. Given technology neutrality in CBRS, these methods need to be working across standa