中文摘要：

研究了正交频分多址接入（OFDMA）上行链路中采用交织子载波分配方案的多用户信号同步及分离．采用交织子载波分配方案的OFDMA上行链路中，每个用户信号在1个OFDM符号内都具有一定的周期性结构．首先利用信号的结构特性，并借助子空间的方法估计得到多用户的频率偏移；然后，对接收到的信号应用最小均方误差（MMSE）滤波恢复单用户信号波形，实现了多用户信号分离及频率同步；最后，基于恢复的单用户训练信号对每个用户的时间偏移进行估计．广义线性调频序列（GCL）具有理想的周期自相关特性、最优的互相关特性和低峰均功率比特性，因而被用作训练序列来估计每个用户的时间偏移．仿真结果表明，本方案在多径衰落信道下是有效的．

英文摘要：

Multi-user signal synchronization and separation for the interleaved orthogonal frequency division multiplexing （OFDMA） uplink are investigated. In interleaved OFDMA uplink, each user＇ s signal has a special periodic structure within an OFDMA block. Firstly, by utilizing the signal structure characteristic and subspaee-based method, multi-users＇ carrier frequency offsets can be obtained. Next, minimum mean square error （MMSE） filters are applied to the received signal to recover single user signal wave thus implementing user separation and frequency synchronization at the same time. Finally, based on the recovered single user training signal, each user＇ timing offset can be estimated. The generalized chirp-like （GCL） sequence has the ideal periodic auto-correlation function, optimum periodic cross-correlation function and low peak-average power ratio （PAPR）. Therefore, GCL sequences are used as training sequences to estimate each user＇ timing offset. Simulation results show the proposed scheme is effective in multi-path fading channels.