OFDM系统中新的同步与信道联合估计算法

提出了一种新的基于判决反馈的OFDM同步与信道联合跟踪算法。该算法提取出信道估计结果中包含的同步信息用于实现同步估计,并利用同步估计结果对信道估计结果进行修正,使其尽量逼近真实信道。仿真结果表明该算法在信噪比较大时可以获得较高的估计性能,具有计算量小和实现简单的优点。适当增加块长具有更强的抑制噪声的能力,但却减弱了信道的时变跟踪能力,因此块长的选择必须权衡考虑。

New Combined Symbol Timing and Frequency Synchronization and Channel Estimation Technique for OFDM Systems

There is a dense relationship between the frequency offset estimation and channel estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems. A new combined symbol timing and frequency synchronization and channel estimation technique by using the detected data is developed for OFDM systems. The synchronization information contained in the channel estimated results which is gained by LS channel estimation method is extracted based on the Maximum Likelihood (ML) criterion for synchronization estimation. Then the estimated results of symbol timing and frequency are used to correct the initial estimated channel and make it more close to the real channel. Simulation results show that this algorithm has better performance at high SNR. It is easy to be realized and has low complexity. Increasing the length of the data block suppresses the noise more effectively but decreases the ability of tracking the time variable channel. The block size should be a trade-off between them.