Distributed Power Control and User Selection Algorithms for Cognitive Radios

The interference problem to Incumbent Users (IUs) of spectrum is herein addressed so as to prevent obtrusive cognitive transmissions at IU contours. In this paper, we present autonomous distributed power control algorithms for cognitive radios (CRs) in a Rayleigh fading environment with guarantees on IU protection whilst concurrently supporting an increased number of cognitive users. We further consider the user selection problem to maximise system capacity. Based on analysis and simulations we propose an efficient outage based distributed user removal algorithm that alleviates the interference environment for IUs and CRs alike with a substantial increase in number of supported CRs.