Protocol Design and Stability Analysis of Cooperative Cognitive Radio\n Users

A single cognitive radio transmitter--receiver pair shares the spectrum with\ntwo primary users communicating with their respective receivers. Each primary\nuser has a local traffic queue, whereas the cognitive user has three queues;\none storing its own traffic while the other two are relaying queues used to\nstore primary relayed packets admitted from the two primary users. A new\ncooperative cognitive medium access control protocol for the described network\nis proposed, where the cognitive user exploits the idle periods of the primary\nspectrum bands. Traffic arrival to each relaying queue is controlled using a\ntuneable admittance factor, while relaying queues service scheduling is\ncontrolled via channel access probabilities assigned to each queue based on the\nband of operation. The stability region of the proposed protocol is\ncharacterized shedding light on its maximum expected throughput. Numerical\nresults demonstrate the performance gains of the proposed cooperative cognitive\nprotocol.\n