Research On Beam Management Technology Based On Millimeter Wave Distributed Antenna Array

Millimeter wave communication and large-scale antennas are the two key technologies of 5G systems.The millimeter-wave band provides a rich communication spectrum resource,and a large-scale antenna system based on millimeter wave usually utilizes a hybrid beamforming structure to achieve both high spectral efficiency and high beamforming gain.However,when using millimeter-wave narrow beam communication,the beam is easily blocked.On the other hand,in order to ensure the quality of the communication link between the transmitter and receiver,the two beams should point to the direction of departure and arrival of the best propagation path,so the problem of beam alignment needs to be considered.Based on those,this paper mainly studies the anti-blockage problem and beam alignment problem in millimeter wave narrow beam communication system.In order to solve the blockage problem of millimeter wave narrow beam and the beam alignment problem in moving millimeter wave system,this paper proposes a fast beam switching algorithm based on distributed antenna array structure.The distributed antenna array structure can effectively resist blockage and enhance coverage.Based on this structure,a fast beam switching algorithm based on user location information is further designed.This algorithm utilizes the feature that the optimal beam pair remains unchanged when the line of sight is present.The optimal sub-array and beam pair and the alternate sub-array and beam pair are measured during the system deployment phase to establish a position-beam mapping table.In the actual communication phase,the user predicts the next switching point and switching information based on the location information and the motion speed.The simulation results verify the anti-blockage and enhanced coverage characteristics of the distributed antenna array structure and the rationality of the fast beam switching algorithm.Secondly,in order to reduce the time complexity of the beam search algorithm,this paper proposes a multiple radio frequency link assisted parallel beam search algorithm and a beam coding assisted parallel beam search algorithm.The multiple radio frequency link assisted parallel beam search algorithm uses multiple radio frequency links on the base station side to simultaneously transmit multiple beams carrying orthogonal sequences.In the user side,multiple beams are distinguished by cross-correlation operation,thereby implementing parallel beam search.The algorithm can effectively reduce the time complexity of the beam search,and the performance loss caused by the reduced complexity is also within an acceptable range.The beam coding assisted parallel beam search algorithm improves the existing beam coding algorithm by encoding the transmitting beams and the receiving beams.All the beams in the transmitting codebook are simultaneously transmitted and the receiver receives signals using all the beams in the receiving codebook.In the receiver,the orthogonal transmit beams and receive beams are resolved by cross-correlation operations,thereby implementing parallel beam search.The algorithm reduces the time complexity of the beam search algorithm to one at the expense of a small performance penalty.