Cross-layer design of multi-user opportunistic spectrum access with cooperative sensing

This paper addresses the cross-layer design of multi-user opportunistic spectrum access (OSA) in cognitive radio networks under the framework of grouped cooperative sensing. We attempt to reveal the mutually conflict nature in the following two processes: a) multi-user collaboration during cooperative sensing in PHY layer; b) the contention emerged during competitive medium access in MAC layer. Specifically, higher reliability of cooperative sensing requires more engaged cognitive users (CUs), which, in turn, may cause more intense competition in access, thereby reducing the overall channel utilization efficiency. By exploiting the inherent interplay between these two processes, we tradeoff their performance with respect to the number of cooperating users in one group. The optimal number that maximizes the channel revenue is determined by a binary search method we propose. Finally, the analysis and performance are validated by extensive simulations.