Cooperation in Cognitive Radio Networks

The operation of cognitive radio (CR) networks involves opportunistic access to the spectrum licensed to primary users (PUs) by secondary users (SUs). Traditionally, this access is performed in such a way that the PUs suffer minimal interference to their access to the spectrum, trying to make the SUs as transparent as possible to PUs. However, this study demonstrates that the SUs, when positively influencing PU communication, can improve the performance of both primary and secondary networks. In order to achieve this, we propose a cooperation scheme based on retransmissions performed transparently by SUs, which simultaneously improves the performance of the primary network and increases their own opportunities to use the licensed spectrum. The performance of the proposed scheme is evaluated using the ns-3 simulator, showing improvements in primary and secondary throughputs when compared to a scenario without cooperation.