System-Level Simulation Research And Performance Evaluation Of LEO Satellite

Compared with high-orbit satellite communication,low-orbit satellite communication has become an effective choice to complement the extension of terrestrial network coverage with its characteristics of small propagation delay and low path loss.Due to the high speed movement of LEO satellites relative to the ground,user links need frequent handover to ensure the continuity of terminal communication services.In addition,considering the limited resources of LEO satellite communication,beam resource management is also an important research content for the timevarying user service demand.To this end,this paper investigates and evaluates the performance of user link handover and beam resource management techniques based on a system-level simulation platform for LEO satellite communications,and the main work and innovations are as follows.Firstly,a system-level simulation platform for LEO satellite communication is designed and built,completing the scene construction module,the satellite-ground channel simulation module,the satellite-borne multibeam antenna module,the user link handover control module and the beam resource management module,proposing a multibeam projection modeling method for moving relative to the Earth’s sphere,and realizing the dynamic operation of the mobile beam coverage scene for LEO satellite communication.The correctness of the platform is verified by calibrating the terminal signal interference-to-noise ratio and user link coupling loss with 3GPP-related proposals.After that,three simple and feasible user link handover strategies are designed for the mobile beam coverage scenario to address the problems of high complexity of current user link handover algorithms and incomplete consideration of mobile beam projection deformation,namely,the handover mechanism based on Reference Signal Received Power(RSRP),the handover mechanism based on the minimum beam angle and the handover mechanism based on the maximum remaining service time.Based on the system-level simulation platform,we evaluated the beam handover frequency,user RSRP and number of link interruptions under different handover mechanisms,and the results show that the handover mechanism based on the minimum beam angle can guarantee the user RSRP better,and the average number of user link interruptions is reduced by 10 times compared with the other two mechanisms,and the overall performance is the best;the handover mechanism based on the maximum remaining service time reduces the handover frequency by 40%,but the overall user RSRP level is lower;the RSRP-based handover mechanism is affected by measurement errors and other factors,and the number of link interruptions and handover frequency are both higher.Finally,to address the problem that the current beam resource management algorithm only considers static or single-star scenarios and does not consider the joint optimization of multi-dimensional communication resources,a beam resource management mechanism based on spatial isolation angle and a beam resource management mechanism based on improved particle swarm algorithm are proposed for mobile beam coverage scenarios,which jointly optimize beam pointing,frequency and power resources.The results show that for full buffer service,the improved particle swarm algorithm-based beam resource management mechanism improves the system capacity by about 25%compared with the spatial isolation angle-based beam resource management mechanism,and the lower the frequency reuse factor,the higher the system capacity;for FTP3 service,the improved particle swarm algorithm-based beam resource management mechanism basically outperforms the spatial isolation anglebased beam resource management mechanism in terms of user service satisfaction and packet sending waiting time,and the higher the frequency multiplexing factor,the more flexible the beam resource allocation is,and the better the performance indexes such as user service satisfaction when the user service load is light.In summary,this paper investigates the user link handover and beam resource management of LEO satellite communication,and evaluates the performance of key technologies by building a system-level simulation platform,which provides a simulation platform basis for the subsequent research of other technologies and also provides a technical solution reference for the design of LEO satellite communication systems.