Research Of Robust Beamforming Technique

Beamforming technology is one of the most important technologies in the array antenna communication system.By adjusting the amplitude and phase of the complex weights imposed in the back-end processing module,the array can generate beams in the desired direction and suppress specific interference,thus greatly improving the communication rate and reliability.Inevitable errors in practical engineering will degrade the performance of beamforming sharply.Robust beamforming can hold good performance in the presence of errors.Therefore,it is of great practical significance to study robust beamforming technology.In this paper,the robust beamforming technology based on the angle information of incoming wave and channel information is studied respectively.Three different robust beamforming algorithms are proposed for different problems.In adaptive beamforming,beamformer with flat-top beam can effectively resist the error of prior angle information,but the flat main lobe will deteriorate when the steering vector also has error which will cause the decrease of output SINR.To solve this problem,by constraining the upper and lower bounds of the real beam affected by error,a non-convex mathematical optimization model of robust flat-top beamformer is established and a RB-SCA algorithm is proposed.The algorithm solves the non-convex optimization problem by scaling and a series of iteration steps.The simulation results show that the RB-SCA algorithm can also form stable flat-top beams with errors,so it has stable output SINR.In addition,the algorithm has the advantage of low complexity.When the number of antennas increases,the algorithm can still calculate the weight quickly.The unavoidable channel error at the base station will lead to the performance degradation of beamformer.In this paper,additive errors in multigroup multicast channels are considered and we model the robust QoS and MMF problem as non-convex optimization problems.The RB-QoS-SCA algorithm is proposed to solve the robust QoS problem by scaling and a series of iteration steps.The RB-MMF-SCA algorithm solves the robust QoS problem by scaling and using bisection in each iteration step.The simulation results show that compared with the traditional robust beamforming algorithm,the proposed RB-QoS-SCA algorithm only needs lower transmission power when maintaining the preset SINR threshold and the RB-MMF-SCA algorithm can maintain higher minimum user communication rate at a given transmission power.In addition,the proposed algorithm also has the advantage of low complexity and requires less simulation time while achieving better results than the traditional algorithm.