A memorandum has resulted in regulations from the Federal Communications Commission (FCC) relating to the so-called Citizen's Broadband Radio Service (CBRS) defined for the 3550-3700 MHz band. The CBRS defines three tiers of sharing, with higher tiers providing higher priority of access to spectrum than the lower ones. In general, multiple tiers of users can be defined, although three tiers are a pragmatic choice. The assignment of channels to different tiers and related configurations are performed by a geolocation database and policy management system known as the Spectrum Access System (SAS). In the CBRS, naval radar in littoral waters, and commercial Fixed Satellite Service (FSS) compose the incumbents. The second tier consists of Priority Access Licenses (PALs), and the third tier comprises opportunistic users known as general authorized access (GAA) users. Incumbent radar activity in the CBRS is dynamic, while FSS (space-to-earth) is static. The SAS is charged with protecting incumbents, and PALs. In addition, the SAS authorizes the authorization of spectrum to GAA users.

FIG. 1 schematically illustrates a part of a communications network. In more detail, FIG. 1 schematically illustrates elements of an example SAS functional architecture. In some aspects the SAS functional architecture is part of a core network 120. A first SAS (denoted SAS 1) is operatively connected to FCC databases, another SAS (denoted SAS 2), an Environmental Sensing Capability (ESC), an Informing Incumbent function, a Domain Proxy and a Citizens Broadband Radio Service Device (CBSD) (denoted CBSD 4). The Domain Proxy is in turn operatively connected (optionally via an Element Management System (EMS)) with CBSDs (denoted CBSD 1, CBSD 2, CBSD 3), and an optional CBSD sensing function.