研究了無星際鏈路低軌衛(wèi)星移動通信系統(tǒng)中的饋電鏈路的切換問題，提出了兩種饋電切換方案－最短饋電鏈路切換方案和最長可視時間切換方案。結(jié)合兩種已有的用戶鏈路切換準(zhǔn)則，在構(gòu)造的非均勻分布全國話務(wù)密度模型上進(jìn)行了系統(tǒng)仿真。仿真結(jié)果表明饋電鏈路切換方案對系統(tǒng)開銷影響較大，選擇最長可視時間饋電鏈路切換方案，可以減少切換帶來的信令開銷，提高服務(wù)質(zhì)量，具有較高的參考和實用價值。

This paper discusses issues of feeder link handover and user link handover in Low Earth Orbit (LEO) satellite mobile communication systems without Inter-Satellite Links (ISL). Two feeder link handover schemes are presented. These two schemes are simulated based on two user link handover principles and non-uniform distributed national traffic model of china. Simulation results show that the longest visible duration scheme can greatly reduce the handover frequency of gateway and improve system performance. Consequently this scheme has better value in practice.