Throughput-Optimal Queue Length Based CSMA/CA Algorithm for Cognitive Radio Networks

Cognitive radio networks allow unlicensed users to access licensed spectrum opportunistically without disrupting primary user (PU) communication. Developing a distributed implementation that can fully utilize the spectrum opportunities for secondary users (SUs) has so far remained elusive. Although throughput optimal algorithms based on the well-known maximal weight scheduling (MWS) algorithm exist for cognitive radio networks, they require central processing of network-wide SU information. In this paper, a new distributed algorithm is introduced that asymptotically achieves the capacity region of the cognitive radio systems. The proposed algorithm achieves the full SU capacity region while adapting to the channel availability dynamics caused by unknown primary user activity. Extensive simulation results are provided to illustrate the efficacy of the algorithm.