Research On Precoding Techniques Of Multi-beam Satellite Communication System

Satellite communication is an indispensable part of the future integrated information network.Its features include a large coverage area,free from geographical conditions and land-based disasters,large communication capacity,and high transmission quality.With the development of the global mobile Internet,high-throughput satellites providing high-capacity broadband Internet access are the development trend of today and in the future.The technology core of highthroughput satellite is multi-beam technology,and the means to efficiently reuse spectrum is a full-frequency reuse scheme.but its existing interference-limited problem needs to be solved.This paper mainly addresses the issue of highthroughput satellites using multi-point beams combined with full-frequency reuse to cause severe co-channel interference.This paper first analyzes the research status at home and abroad and summarizes the related issues of satellite multi-beam combining full frequency reuse technology.This paper studies the problems of the on-board beamforming technology and the ground beamforming technology that the on-board beamforming network transfers to the ground,and analyzes the problems existing in the beamforming technology on the satellite and the ground beamforming technology transferred from the on-board beamforming network to the ground.And specifically for the ground beam forming technology with more potential for development,the problems of limited feeder link bandwidth and feeder link system error are studied.The application scenarios of on-board beam forming technology and ground beam forming technology are discussed and a hybrid beamforming architecture is proposed.The purpose of high-throughput satellites using multi-beam combining fullfrequency multiplexing is to eliminate inter-beam interference and significantly increase system capacity.This paper compares the terrestrial cellular mobile communication system to analyze the channel capacity mechanism of multi-beam satellite systems.The satellite system communicates with line-of-sight(LOS)transmission,and the beam coverage area is larger.In addition,the roll-off characteristics of multi-beam antennas cause the interference problem between beams to become more prominent.In the study of the multi-beam satellite channel capacity mechanism,a 61 beam arrangement model was used,and the influence of the above influence factors on the system capacity was strictly considered,and the system capacity obtained by applying the optimal linear precoding and the minimum mean square error precoding algorithm was analyzed.This paper considers the problem of severe co-channel interference caused by the efficient use of spectrum by satellite multi-beam combining full frequency reuse technology.After establishing a forward link model considering the severe rainfall attenuation of higher frequency bands such as Ka,a classical low complexity precoding algorithm of ZF is improved,and an R-ZF precoding algorithm considering the influence of system noise is proposed.Based on the dirty paper coding idea,a low-complexity regularized zero-forcing precoding algorithm for dirty paper is proposed.It encodes users sequentially according to the channel conditions to maximize the SINR,thereby increasing the throughput.Accurate channel state information is required in precoding techniques,the phase noise and long round trip delay introduced by the on-board oscillator of the high-rail high-throughput satellite cause the change of the channel state,resulting in the outdated channel state information of the ground gateway.This paper introduces a phase uncertainty model to build a complete and reliable user link model.After the system model is constructed,a convex optimization precoding algorithm with robustness is proposed based on convex optimization theory.The objective function and constraint conditions in the algorithm are more flexible and can adapt to changes in business requirements.