Research On Performance Of Full Duplex-Based Cognitive MIMO Systems

The rapid development of wireless communication service and application leads to the prominent contradiction between the limited spectrum resources and the increasingly spectrum requirement. Cognitive radio provides an effective way to solve the shortage of spectrum resources and low spectrum utilization. It is necessary to solve the problems of spectrum sensing, the communication mechanism of cognitive users in cognitive radio system. Multiple input multiple output(MIMO), cooperative relay and full duplex are taken into consideration to improve the system spectrum detection performance and throughput.Three different system schemes are proposed, and the system throughput performance is studied. The main work and innovations of this thesis are summarized as follows:(1) The full duplex single secondary user cognitive radio MIMO system is investigated, and the joint optimization scheme of opportunistic spectrum access and optimal power allocation is proposed. Under the limit of the total transmit power, the trisection algorithm is used to obtain the optimal sensing time, and the optimal power allocation scheme is obtained by the convex optimization algorithm. The simulation results show that the proposed scheme achieves the higher system average throughput than sequential convex approximations for matrix-variable programming optimal power allocation and half duplex equal power allocation scheme.(2) The full duplex relay-assisted cognitive MIMO system is investigated, where the full duplex relay assists cognitive user in multi-antenna cooperative spectrum sensing and transmitting data. Then the frame structure design, joint antenna selection and optimal power allocation scheme are proposed. The simulation results indicate that the proposed scheme can improve the system average throughput with the increase of the interference threshold and the total power.(3) The performance of relays-assisted cooperative cognitive MIMO system in interference aware opportunistic spectrum access is studied, and the effect on spectrum detection performance over the imperfect report channel is considered. Then a new frame design, the best full duplex relay selection and power allocation scheme joint optimization scheme is proposed. The simulation results show that the proposed scheme can improve the performance of cooperative spectrum sensing detection and the higher average throughput.