Research On Access And Handover Strategy In Low Earth Orbit Satellite Communication System

The low earth orbit(LEO)satellite mobile communication network has good development prospects in the future construction of space-ground integration due to its advantages of high efficiency,low delay,small transmission loss,and strong multiple access capabilities.Therefore,it is an indispensable part of the modern mobile communication system.Multibeam LEO satellites use multiple spot beams instead of a single large-angle beam to jointly cover a larger area,and each beam forms a cell,but when users pass through multiple beams during movement,frequent handover between beams is required.This process will not only cause signal interference between different beams,but also cause a large delay and reduce communication quality.At the same time,additional processing and calculation will increase the energy consumption of the satellite,thereby shortening the service life of the satellite.Therefore,in order to improve the service quality of the multi-beam LEO satellite mobile communication network,it is necessary to design an efficient and reliable access and handover scheme.The existing access handover algorithms in multi-beam LEO scenarios mostly focus on subchannel allocation,the handover model is too simple,less consideration is given to the selection of beams,and there may be local optimal problems.Therefore,this thesis proposes a beam access handover selection algorithm based on multi-attribute combination judgment in LEO satellite multi-beam scenarios,comprehensively considering the performance indicators of inter-beam handover and intersatellite handover,and dynamically adjust under the premise of considering the user’s subjective preference,so as to ensure the stability of communication and better balance the user’s service quality and system performance.In addition,this thesis builds satellite topology based on a beam position generation scheme suitable for low-orbit satellite scenarios,and builds a multi-beam low-orbit satellite system-level simulation platform,which includes resource scheduling,service generation,interference control,access and handover modules,which can realize the user’s uplink and downlink communication.In different user mobility scenarios,the system performance of the proposed algorithm is verified by indicators such as output throughput,signal-to-noise ratio,and handover times.Finally,the performance comparison with other algorithms proves that the proposed algorithm can take into account better signal strength and lower average channel utilization variance compared with the comparison algorithm under the premise of fewer inter-satellite handover times,thus ensuring uninterrupted communication and balanced system.