中文摘要：

针对基于OFDM的协作通信系统,主要研究了解码转发（DF）协议下的时间与载波频率同步技术。设计了一种新的训练序列结构,它能在一个OFDM符号的长度下同时实现多个时间偏移与载波频率偏移的估计。通过相关类型的算法得到时间偏移估计,同时通过基于子空间分解的算法得到载波频率估计。调整训练序列的结构能够使得系统的误差最小,从而获得最优的系统性能。

英文摘要：

For the OFDM - based cooperative communication system, the timing offset and carrier frequency offset （CFO） problems in decode and forward protocol are investigated. New training se- quence structure with adjustable parameters, which consists of one OFDM block, is proposed for both the multiple timing offsets and CFO estimation. Timing offsets estimation can be obtained through using a cross - correlation approach and at the same time, CFO estimation can be also achieved by utilizing subspace decomposition - based algorithm. The parameters of the proposed training sequences are adjusted properly to acquire better system performance.