Cognitive Radio Access Optimization Under Primary Queue Stability Constraint

We propose a network access optimization for cognitive radio nodes aimed at throughput maximization under the constraint of primary node queue stability. To maintain primary queue stability, our approach moves beyond the traditional listen-before-talk opportunistic access by allowing cognitive radios to over-hear and utilize ACK/NAK feedback signals on packet reception from the primary receiver. In addition to primary transmitter’s activity sensing in listen-before-talk, the secondary cognitive radio can track the primary queue status through inference based on the primary feedback information. By defining a Lyapunov function that characterize the primary queue stability, we devise a distributed secondary power allocation strategy to control the access of cognitive radio nodes that approximates the optimal solution of a static global sumutility maximization problem. This distributed cognitive access method can achieve high bandwidth utilization under the primary queue stability constraint.