Research And Design Of Beamforming Scheme For Intelligent Reconfigurable Surface-Aided Massive MIMO Systems With Hardware Imperfections

In recent years,Intelligent Reflecting surfaces(IRS)have become a revolutionary technology that can reconfigure the wireless propagation environment by dynamically changing the phase and/or amplitude of the wireless signal with a large number of reflecting units.By optimizing passive beamforming at IRS,system performance can be further improved at limited cost.In real communication systems,the hardware of transceivers and IRS have inevitable imperfect characteristics.Although the above hardware imperfections can be mitigated by some calibration and compensation techniques,due to the inherent time-varying characteristics of electronic components,the impact of transceiver residual hardware impairments is difficult to be completely eliminated,which will limit the performance of the communication system.Therefore,with the background of IRS-assisted massive MIMO communication system,this paper analyzed the adverse effects of transceiver hardware impairments(TR-HI)and IRS hardware imperfections(IRS-HI)on system performance.The beamforming scheme of IRS-assisted massive MIMO system with non-ideal hardware is studied and designed.The main work of this paper is as follows:Considering the IRS-assisted communication system with both TR-HI and IRS-HI,the adverse effects of hardware impairments on spectral efficiency(SE)and energy efficiency(EE)of the system are studied.First,the upper bound of system SE is derived when there is a direct link between BS and UE.Then,when the direct link between BS and UE is blocked,the closed form expressions of SE and EE are derived.Numerical and simulation results show that the presence of TR-HI will saturate the SE of the IRS-assisted communication system under the condition of high transmitting power and large size IRS.It is worth noting that both TR-HI and IRS-HI have a negative effect on the performance of the system,but the negative effect of TR-HI is far more severe than that of IRS-HI,because TR-HI limits the SE of the system and makes it independent of the number of IRS reflection units,while IRS-HI only reduces the SE of the system.For IRS-assisted massive MIMO systems,a passive beamforming scheme based on statistical channel state information(CSI)to suppress the effects of hardware imperfections is proposed.First,an IRS-assisted massive MIMO system model is established under the influence of hardware imperfections.Then,based on the statistical characteristics of Rician fading channels and maximum ratio merging technique,approximate analytical expressions of uplink reachability and rate are derived.Finally,the optimization scheme of passive beamforming based on AQBFO algorithm is designed to maximize sun rate.AQBFO algorithm based on quantum theory can expand the search range of solution space in the initial iteration,and converge quickly in the later iteration to speed up the search speed.In the process of designing IRS passive beamforming,the influence of hardware imperfections is fully considered,and the uplink ergodic sum rate are effectively improved.