Research On Sensing Aided Beamforming Technology In Terahertz Communication Systems

Benefiting from the abundant spectrum resource,Terahertz(THz)has become one of the important spectrum technologies in the sixth generation mobile communication system.Compared with the current bands,the path loss in THz is large,which restricts the communication coverage.To deal with that problem,it is necessary to use ultra-massive multiple-input multiple-output(UM-MIMO)arrays to achieve high-gain beamforming.However,as the array size and bandwidth increase,the computation cost and propagation gain of the pilot signals are severely limited,making it impossible to achieve fast beam alignment and efficient energy aggregation in THz frequency band.Compared to traditional communication bands,THz have both high-speed transmission capabilities and high-precision sensing capabilities.Thus,sensing is expected to provide prior information,supporting fast beam alignment and efficient beamforming.Therefore,this article conducts research on sensing aided terahertz beamforming technology based on the characteristics of terahertz channels.The main research content and contributions are as follows:1.To address the problem that terahertz transmission characteristics vary greatly with frequency,a correction calculation method of terahertz path reflection coefficient considering obstacle thickness is proposed.A hybrid terahertz UM-MIMO channel model is established by combining with modified deterministic channel model parameters.Based on the channel model,the spatial channel approximate orthogonality principle under the perspective of UM-MIMO array is derived,and the sparse characteristics of terahertz channel are verified.The simulation results show that the numerical parameters of the proposed channel model are closer to the actual measurement results.2.To address the difficulty of aligning THz narrow beams,a sensing aided beam alignment method is proposed.Firstly,a THz communication perception-integrated front-end architecture based on leaky intermediate frequency wave is designed to achieve simultaneous THz beamforming and angle-of-arrival information perception.On this basis,a beam selection algorithm based on prior spatial information weighting was proposed according to the sensing results.The proposed algorithm reduces the alignment cost and delay by increasing the probability of beamforming in the target direction without occupying additional frequency resources.The simulation results show that the proposed method reduces the required beam alignment cost by 70%under 128 antenna condition.3.To address the problem of energy dispersion in THz beams under ultra-wideband requirements,a sensing aided solution was proposed.The energy dispersion problem is caused by the contradiction between wideband signals and narrowband devices,which severely affects antenna gain and channel estimation performance.Firstly,a communication framework is developed to assist beamforming with sensing channel state information parameters.Then,a joint angle-frequency sensing algorithm and a beamforming algorithm based on sensing results for channel information inversion were proposed within the framework.Compared with methods lacking sensing technology,this method fully captures the mapping relationship between THz beam angles and frequencies,resulting in more than 100%improvement in spectral and energy efficiency.In summary,this paper studies the sensing aided beamforming method in THz communication systems,which is a useful supplement to the theory and methods of THz beamforming.It provides new ideas for reducing beam alignment costs and enhancing beamforming gains,while also providing technical support for THz communication standardization and commercial deployment.