Joint Resource Optimization in Decode and Forward Multi-Relay Cognitive Network With Direct Link
This paper presents an optimal scheme to optimize an OFDM based cooperative cognitive network resources so that the total system capacity is maximized while guaranteeing that the interference introduced to the primary system is not harmful. The optimal scheme adopts the dual decomposition technique and in order to reduce the computational complexity of the optimal scheme, a greedy suboptimal algorithm is proposed. The performance of the different schemes is discussed through the numerical simulations. Most of current frequency bands have been already allocated and it will be very hard to find vacant bands for the emerging wireless systems or services.