Research On Transmission Method Of Full-duplex MIMO-NOMA System Based On SWIPT

With the development of wireless communication technology,the spectrum resources of wireless systems have become more and more precious,and typical technologies that can effectively improve the spectrum efficiency of the system include non-orthogonal multiple access(NOMA),full-duplex(FD)and multiple-input and multiple-out(MIMO)technologies.Due to the limited battery capacity of wireless devices,the development of communication technology has also a great challenge on the supply of electrical energy.In some specific scenarios,the device cannot replace the battery or access the power supply in time,which may cause system communication to be limited or even interrupted.Simultaneous wireless information and power transfer(SWIPT)technology can effectively improve the energy efficiency of the system.And it can recycle the self-interference(SI)which affects system performance in FD transmission.Due to the openness,broadcastability,and time-varying nature of wireless channels,information is highly vulnerable to eavesdropping,and energy efficiency research under the condition of physical layer security is particularly important.In this paper,the transmission performance of SWIPT-based full-duplex MIMO-NOMA system is studied by jointly combining transmit beamforming vector and power split ratio.First,the SWIPT-based FD-NOMA system transmission scheme is studied.The FD cooperative NOMA downlink with SWIPT,to improve the transmission performance,the existing research usually eliminates of SI,ignoring the influence of the SI in energy-harvesting(EH).Aim at this problem,the transmission scheme with self-energy recycling is proposed.With the maximum energy efficiency of the system as the optimization goal,under the condition of ensuring energy collection and QoS,the Dinkelbach theory is applied to convert the optimization target fraction into the difference between the two physical quantities.The semi-determined relaxation(SDR)is used to reconstruct the problem and then use the AGM-based iterative convex approximation algorithm to jointly optimize the transmit beamforming vector and the power split ratio,so that the energy utilization and information rate in the system reach a compromise.Simulations verify that the scheme has advantages in terms of energy efficiency.Secondly,the SWIPT-based FD-NOMA system security transmission scheme is studied.A downlink two-user cooperative FD SWIPT-NOMA system framework with an eavesdropper is constructed,and a self-interference energy recovery scheme is also adopted.The physical layer security energy efficiency(SEE)is used as a measure of system performance,and the transmit beamforming vector and the receiver power split ratio are jointly optimized.To resolve the formulated nonconvex problem with coupled variables,the improved particle swarm optimization(PSO)is applied to design the suboptimal beamforming and power-splitting control simply compared to concaveconvex procedure(CCCP)algorithm.The simulation results show that compared with other EH schemes and transmission schemes,the proposed algorithm can effectively improve the system's SEE by 9.4371bits/J when the transmit power at BS and transmit power at user relay are both 500 mW.