Research On Codebook Based Beam Management In Millimeter Wave Massive MIMO Systems

Milimeter Massive MIMO is one of the hot techniques in the fifth generation(5G)wireless systems.The millimeter wave(mmW)with short wavelength is conducive to the integration of large-scale antenna panel.Massive MIMO system provides high-directional beam to compensate the transmission loss of the mmW signal through beamforming.MmW Massive MIMO can effectively improve the system capacity and Energy efficiency.The key technologies applied to the system have significant research value.This work was supported by the project 'Research on Key Technology and Business Analysis Technology of New Generation Networks' cooperated with an enterprise.The topic focuses on the research of beam management based codebook in the mmW Massive MIMO system.However,when the beamforming technique is applied at both the base station(BS)and the user equipment(UE),there are numerous beams at the transceiver.Beam management,including beam sweeping,channel measurement,beam searching,beam reporting,beam failure and recovery,become one of the key technologies for the mmW Massive MIMO system.How to search the best transmit andreceive(Tx-Rx)beampair quickly and accurately,and how to reduce the system overhead of beam switching in a mobile scenario are worth studying.To deal with theabove problems,a joint Tx-Rx beam search algorithm and abeamwidth optimization algorithm compromising the system performance and the switching overhead are respectively proposed.Firstly,the paper introduces the basic concept,characteristics and key technologies of mmW Massive MIMO,and summarizes the standardization and research status of beamforming and beam management.Then for the high overhead of beam searching,a joint Tx-Rx beam search algorithmis proposed.In the initialization phase,the initial Tx-Rx beam pair is calculated by the coarse beam sweeping.Then,Rosenbrock algorithm is used to search the optimal beam pair in a two dimensional discrete space formed by the indexes of Tx and Rx beam.In addition,double beam link is used to solve the link failure caused by channel block.Numerical simulation results are given to verify the effectiveness of the proposed scheme.Compared with the traditional beam search schemes,the proposed scheme can greatly reduce the search complexity and management overhead.Finaly,for the mobility of mmW Massive MIMO system,a beamwidth optimization algorithm compromising the system performance and the switching overhead is proposed.Asimplified beam model and scene are used toderive theuser data rate and beam-switching overhead.Considering these two parameters the optimization function is constructed.After proved to be a convex function,the optimization is solved by the KKT condition.Numerical simulation shows that the effective beam width obtained by the proposed algorithm can reduce the frequency of beam switching and achieve the balance,of system performance and switching overhead.