Research On Relay Selection Method In The Cognitive Full-duplex Relay Network

Cognitive relay technology and full duplex technology can improve the utilization rate of spectrum resource and become the key technology to resolve the shortage of spectrum resource.With the development of mobile communication technology,in the cognitive relay network,there are a large number of candidate terminals that can be used as relay nodes.Different terminals as relay nodes or a relay adopt different duplex modes will bring different effects for the system,therefore,research on cognitive relay nodes selection and relay models selection problem in cognitive relay network is of great significance.The existing cognitive single relay selection technologies lack full/half duplex mode switching criteria,resulting in the problem of single duplex mode of relay nodes,moreover,the existing cognitive only to maximize secondary user systemic performance in the process of relay selection,and resulting the combined performance of the primary user network and the secondary user network is not optimal.Aim at this problem,take the amplify-and-forward protocol and decode-and-forward protocol as examples,the corresponding mode switching criteria are proposed based on the analysis of self-interference critical point,moreover,a low-interference hybrid duplex mode switch relay selection algorithm is propose in this paper.In the algorithm,the best duplex mode is selected according to the mode switch rule in each candidate relay nodes,and the system comprehensive performance income is regarded as indicators for relay selection,it contains the primary user network performance loss and secondary network user performance benefits.Thereby,maximizing the sacrificial value of the primary user system and optimizing the performance of the entire network,including the secondary user network and the primary user network.Finally,the algorithm is simulated and verified,which showed that the proposed algorithm can reduce(or even improve)the performance of the secondary user network,and significantly improve the performance of the main user network system and the whole system.The existing literature have not model the cognitive full duplex multiple relay selection scenario,resulting in no corresponding multiple relay selection algorithm to solve the multiple relay selection problem in cognitive full duplex relay network.Aim at this problem,the cognitive full duplex multiple relay selection problem is modeled as apotential game model where the rate of cognitive relay network is used as the common utility,and we prove that,our proposed game can guarantee the feasibility and existence of the pure strategy NE.On the basis of this,an iterative algorithm for cognitive full duplex relay selection algorithm is proposed.The complexity of proposed algorithm is lower compared with the traditional exhaustive search algorithm.For the convergence of proposed algorithm,it can achieve the pure strategy NE in limited steps without the advance knowledge of the infeasible strategy profiles.Simulation results show that,the proposed algorithm can achieve optimal or near optimal rate performance with low complexity,and offers significant performance gain compared with the traditional half duplex mode.