Hybrid Beamforming Algorithm For Millimeter-wave MIMO Interference System Based On MMSE Criterion

In recent years,with the rapid development of telecommunication industry,the traditional band spectrum resources are increasingly strained.Millimeter-wave,which has a large number of unused spectrum resources and high transmission rate,has become a popular field of communication research.Due to the short millimeter-wave length,it can be combined with the current research hotspot of massive MIMO beamforming technology,so as to guarantee the transmission quality and improve the communication capacity.However,in millimeter-wave massive MIMO system,the traditional digital beamforming technology is costly,we can not promote it effectively.Thus hybrid beamforming technology emerges as the times require,and becomes a key technology in millimeter-wave communication system.In this paper,in the light of the classical hybrid beamforming technique,a hybrid beamforming algorithm based on alternating iterative method is proposed to solve the system model optimization problem under MIMO interference channel.The main contents are as follows:1 This paper introduces the background of millimeter-wave communication and its channel characteristics,highlighting the necessity of hybrid beamforming technology in millimeter wave communication.Then a millimeter wave hybrid beamforming system is established under MIMO interference channel and the mathematical model of the system is developed.Besides,the mathematical optimization model of millimeter wave hybrid beamforming based on MMSE criterion is established.2 Two hybrid beamforming algorithms are proposed and analyzed.Firstly,a hybrid iterative algorithm based on L-BFGS algorithm is proposed.The performance of that is superior,but it is difficult to prove the convergence.Then a hybrid iterative algorithm based on distributed beamforming is proposed.Based on the idea of distributed solution,the algorithm can solve the nonconvex constant modulus constraint quickly and effectively.Compared to the classical hybrid beam forming algorithm,the system performance of the hybrid beam is more close to that of digital beamforming with full RF link connection.At the same time,the convergence of the Parallel algorithm is proved strictly.3 In this paper,the two proposed hybrid beamforming algorithms are simulated for verifying the performance and convergence.Moreover,the performance of the algorithm is further analyzed by changing the system parameters.Simulation results show that the proposed two hybrid beamforming algorithms have better performance than the classical hybrid beamforming algorithm.