Toward optimal cross-layer solutions for cognitive radio wireless networks

Cognitive radio (CR) networks have been proposed as a viable solution to spectrum scarcity problems. In CR networks, CR nodes exploit spectrum holes in space, time and/or frequency to transmit on licensed frequency bands without affecting primary users. In such a dynamic and unpredictable environment, CR networks require the ability to gather information on the surrounding available spectrum and to exploit this information to maximize CR nodes performance. In a companion paper we deal with sensing architecture and protocols. In this paper, instead, we derive a cross-layer scheme for cognitive radio networks which jointly optimize the sources flow rates, routing and medium access control while accounting for and exploiting the available spectrum resources. The proposed scheme builds on important recent results on close to optimal fully distributed CSMA-based scheduling algorithms, which allows us to derive a fully distributed solution.