【摘要】 针对LEO卫星网络中多媒体业务的应用,分析了一种基于动态多普勒的切换管理算法,利用多普勒频移效应及卫星几何关系求出卫星发生切换的时间和位置。通过改进该算法和移动性模型为该应用提出一种基于切换预测的策略。为适当选取服务卫星,提出了最大服务时间、最大空闲信道数和最短距离这3种切换准则,它们都基于阻塞概率和中断概率的权衡。每个准则既可用于接入也可用于切换,故形成9种不同的切换准则组合。最后,以类Teledesic系统为例对改进算法和切换策略进行了仿真,结果表明所提方法是有效的。更多还原

【Abstract】 Aiming at the application of multimedia in LEO network,a handover management algorithm based on dynamic Doppler is analyzed,which uses the Doppler effect and the geometry of satellites to obtain the time and position of the handover.This algorithm and mobility model are improved in order to provide an efficient handover strategy based on prediction of handover.Based on a tradeoff of the blocking and forced termination probabilities,three different handover criteria are proposed for the appropriate selection of the servicing satellite.Each criterion can be applied either to new or handover calls,therefore nine different combinations of handover criterion are investigated in this paper.Finally,with an example of Teledesic-like system,the improved algorithm and the handover strategy are evaluated and the results indicate that the algorithm is effective.更多还原