Spectrum sharing with a primary incumbent imposes constraints on entrant transmitters to limit the associated interference. Existing designs use conservative models of the propagation environment and worst-case entrant power levels for ensuring protection, leading to spectral inefficiency. In this paper, we present an approach where measurements from spatially distributed beacons are used for estimating interference levels at particular incumbent locations accounting for entrant transmit power levels. We propose a computationally efficient estimation algorithm using a maximum likelihood objective for log-normal shadowing, by exploiting channel reciprocity between beacons and the incumbent. Based on the algorithm, we develop protocols for shutting down a subset of entrants by controlling the beacons’ power level, and present numerical results illustrating performance.
