Research On SWIPT For Full-Duplex MIMO Cognitive Radio Network

Recently,the cognitive radio(CR)network based on full-duplex(FD)and MIMO technology is researched to improve the spectrum efficiency.At the same time,the simultaneous wireless information and power transmission(SWIPT)is introduced in CR network to solve the power charging of the power-constrained device.However,the self-interference(SI)is cancelled to improve spectrum efficiency in traditional SWIPT network,which neglects the positive effect of SI on improving the energy efficiency.Therefore,it is important to harvest the energy of SI through SWIPT technology.In addition,due to the higher power sensitivity of energy harvester,the possibility of information leakage will increase.Hence,it also important to investigate the effect of SI harvesting to security transmission.In this paper,a newly CR network with FD MIMO is established to harvest the SI;and consider that the energy harvester at FD node can eavesdrop the confidential information.First,to tackle the neglection of the SI,a FD relay assisted CR MIMO network is established to harvest the SI through the energy harvesting(EH)technology.The transmission covariance and power splitting(PS)ratio are jointly designed under the constrain of secondary transmit power,which aims to obtain the maximized system energy efficiency.We obtain the optimum value through semidefinite relaxation(SDR)and water-filling algorithm.Simulation results show that,compared with traditional SI cancellation scheme,the proposed scheme not only guarantees the spectrum efficiency,but also improves the energy efficiency by 13.9%.Then,the physical layer security(PLS)is investigated.We establish a FD MIMO CR network,consider the effect of SI harvesting to the PLS problem.The transmission covariance and PS ratio are jointly designed under the constrains of harvested energy,security rate and secondary transmit power,which aims to obtain the maximized security energy efficiency(SEE).The closed-form expression of transmission covariance is derived through alterative algorithm,and the optimal PS ratio is obtained through greedy algorithm.Simulation results show that,compared the SI harvesting scheme based on security rate maximization,the proposed scheme not only guarantees the security rate,but also improves the SEE by 21% when the transmit power of secondary user is lower than 12 dBm.In addition,the gap increases with the increase of secondary user transmit power.