论文部分内容阅读
在协作分集系统中,不同中继与目的端之间信号的时间延迟和频率偏移均不相同,因而同时估计各中继与目的端之间的定时和频率偏移是协作分集系统同步中最关键、最具挑战性的部分之一.本文针对协作分集OFDM(orthogonal frequency division multiplexing)系统中中继到目的端的同步,设计了一种新的训练序列结构并提出了相应的时频同步方案.在定时同步方面,它首先利用训练序列的时域共轭对称性完成粗定时同步,在此基础上进一步通过接收信号与本地时域训练序列分段移动相关完成细定时同步;在频率同步方面,它利用频域训练序列良好的自相关性通过分段移动相关估计整数倍频偏,利用前后两个相同训练符号对应子载波上的相位差估计小数倍频偏.理论分析与仿真结果表明,相比传统方案,该方案不仅具有更好的定时和频率偏移估计性能,而且复杂度大大降低.
In the cooperative diversity system, the time delays and frequency offsets of the signals between different relays and the destination are different. Therefore, it is also estimated that the timing and frequency offset between the relays and the destination are the highest One of the key and the most challenging one.In this paper, we design a new training sequence structure and propose a corresponding time-frequency synchronization scheme for the synchronization of relay to the destination in the orthogonal frequency division multiplexing (OFDM) system. In the aspect of timing synchronization, it first uses the time-domain conjugate symmetry of the training sequence to perform the coarse timing synchronization. On the basis of this, it further complements the fine timing synchronization through the correlation between the received signal and the segmentation movement of the local time-domain training sequence. In terms of frequency synchronization, It uses the good autocorrelation of the training sequence in the frequency domain to estimate the integer multiple of the frequency offset by the segment move correlation and estimates the fractional frequency offset by using the phase difference between the two same training symbols corresponding to the subcarriers.The theoretical analysis and simulation results show that, Compared with the traditional scheme, this scheme not only has better timing and frequency offset estimation performance, but also greatly reduces the complexity.