Research On Attitude Information Aided Millimeter Wave Beamforming Technology

Millimeter wave(mmWave)with enormous underused spectrum resources has been proposed as an important communication frequency band of the fifth generation mobile communication technology.However,compared with traditional low frequency signal,the severe propagation characteristics make mm Wave communication challenging.In order to establish reliable communication link s,it is necessary to implement beamforming technology in mm Wave systems.In practice,the prerequisite for beamforming at transceivers is the knowledge of channel state information(CSI).With the deployment of large scale antenna arrays,the mm Wave channel matrix becomes huger.Moreover,since mm Wave signals are sensitive to the scattering environment,more frequent beam tracking is required to maintain the quality of communication links.This will lead to huge training overhead for traditional beamforming methods.In order to balance the performance and overhead,out-of-band information is used to assist mm Wave communications in recent years.Out-of-band information refers to the information that can be obtained outside the mm Wave system and does not occupy the communication resources.It mainly includes channel information of low frequency bands,position and attitude information of the base station(BS)and the user equipment(UE).This thesis studies attitude information assisted mm Wave beamforming algorithms.Attitude information obtained from the gyroscope sensor can reflect the spatial orientation of the antennas at the receiving and sending end,so it can be used to predict the angle information in mm Wave channel.Existing studies only consider the how to utilize attitude information in simple application scenarios,ignoring the influence of terminal number and mobility.In this paper,the following researches are carried out:1.This thesis studies attitude information aided(AIA)digital beamforming for multi-user scenarios.In multi-user systems,the attitude change of one UE will introduce interference into the received signal of other users,which makes the user performance coupled together and makes the transceiver design very complicated.In this paper,we use the subspace projection block diagonalization(BD)algorithm based on angle of departure(AoD)to eliminate the interference between users.We further consider the method of single-end rotation compensation to reduce the feedback overhead.By solving maximization and spectral efficiency while keeping the transmitter design unchanged,AIA-BD receiver design with zero feedback is derived.Compared with the joint transceiver design,this paper proves that the performance loss caused by zero feedback design is generally zero,and the approximate optimal performance can be achieved.2.This thesis studies attitude information assisted mm Wave channel reconstruction and analog beamforming in the terminal moving scene at low speed.In the mobile scene,the user’s position is calculated by pedestrian dead reckoning technology.At this time,the terminal’s attitude change not only reflects the change of arrival Angle,but also has a close relationship with the user’s direction of travel.In this paper,the terminal motion is decomposed into translation motion and rotation motion.The relationship between attitude information and line-of-sight(LOS)parameters is analyzed,and the reconstruction expression of channel direct vision path parameters at the end of each gait is derived.Based on the reconstructed mm Wave channel,we further consider only adjusting the receiver to reduce the feedback overhead in mobile terminal scenarios.3.This thesis studies robust beamforming algorithm assisted by attitude information.Attitude information measurement error will affect the accuracy of mm Wave channel reconstruction,lead to beam direction deflection,and reduce the communication performance.In this paper,the influence of attitude information measurement error on mmWave channel error is analyzed for stationary terminal scenes and mobile terminal scenes,respectively.On this basis,by maximizing average beamforming gain,a robust transceiver design modified by error statistics is derived.Compared with the transceiver designed by angle information directly,the simulation results show that the proposed robust transceiver can effectively reduce the performance loss caused by attitude information measurement errors.