基于LMS估计的卫星移动通信定时同步优化

针对采用长期演进（LTE）通信标准的地球静止轨道（GEO）卫星移动通信系统上行定时误差会影响单载波频分多址技术正交性的问题，在LMS线性估计算法的基础上提出了一种适用于大时延环境下单载波频分多址定时同步优化方法。该方法对用户与卫星之间传输时延的变化进行估计，通过闭环控制补偿减小上行定时误差。仿真表明：该方法在使用LTE标准帧结构时，能保护用户上行信号正交性，避免符号间干扰，且传输速率损失约为9%，远低于传统拓展帧结构方法带来的损失，验证了方法的优越性。

Timing synchronization optimization for satellite mobile communication based on LMS estimation

The uplink timing error using Long Term Evolution(LTE) communication standards will affect the orthogonality of single-carrier frequency division multiple access technology(SC-FDMA) in Geostationary Earth Orbit(GEO) satellite mobile communication system.To solve this problem,an SC-FDMA timing synchronization optimization method based on LMS linear estimation algorithm is proposed.The method estimates the changes in transmission delay between the user and the satellite,and reduces uplink timing error through closed-loop control compensation.The simulation results show that the method can protect user uplink signal orthogonality and avoid intersymbol interference with about 9% transmission rate loss when the LTE standard frame structure is used,which is much lower than that of traditional method in which the frame structure is expanded.The advantages of the method are demonstrated.