Recently, several efforts have been made in order to present an indicative SAS architecture that accommodates the tiered access to shared spectrum. In Spectrum Access Systems (SAS), the GAA users are able to (1) have access to a database with information about incumbent users' locations and frequency and (2) have access to the results of PAL auctions and subsequent PAL frequency assignments. GAA users need to check if the SAS band is clear to use or not before starting transmission. The incumbent usage will be informed or easy to detect because incumbent is transmitting at a high power.

FIG. 1 is a block diagram of a Spectrum Access System (SAS) 100 for spectrum management according to the FCC regulation. The SAS system includes an exemplary number of two central SAS coordinators 131, 132 for coordinating spectrum use between incumbents, PA (priority access) users and GAA (general authorized access) users according to FCC (Federal Communications Commission) standardization.

The SAS communication system 100 includes an exemplary number of two SAS entities (also referred to as SAS coordinator or SAS controller) 131, 132, FCC databases 141 and an ESC (Environmental Sensing Capability) entity 142 which are coupled between each other. An exemplary number of four CBSD (Citizen Broadband Radio Service Devices) entities 111, 112, 113, 114 are coupled with the SAS1 entity 131, where CBSD1, CBSD2 and CBSD3 are coupled via a proxy network manager 121. The CBSD devices may be coupled to users 101, 102, 103, 104. In the example of FIG. 1 the CBSD1 device is connected to a first user 101 and a second user 102 while CBSD4 device is connected to a third user 103.