Capacity Enhancment and Iterference Reduction in Cooperative Cognitive Radio Networks

Cognitive radio users are secondary users armed with sensing capability to observe any available spectrum holes which are temporarily and/or spatially unused by the primary users to use them for their own transmission. In this context, the demand for maximizing the secondary users´ network capacity while maintaining high protection level to primary users is very crucial. This research work presents two operational modes for the cognitive users´ network, namely, constant primary user protection (CPUP) and constant secondary user spectrum usability (CSUSU). The simulation results show that cooperating all secondary users in the network does not necessarily lead to attain the optimum performance, but instead, it is achieved by cooperating a certain number of users who possess the highest primary user´s signal-to-noise ratio values at their receivers.