MIMO-OFDM迭代时变频偏估计算法

摘要

The MIMO-OFDM,a high-speed communication technology,satisfies the demands of the short time slot and huge data in cooperative communications for the shipborne radars in future.However,the relative speed between the ships arouses the frequency offset of the communications,and the MIMO-OFDM technology has a great sensitivity to frequency offset.Consequently,the time-varying frequency offset must be estimated.Providing that the frequency offset of every MIMO-OFDM signal is the random variable,the time-varying frequency offset estimation and signal detection algorithm that combines the expectation maximization（EM） algorithm and the maximum a posteriori probability（MAP） decoding algorithm is proposed.The computer simulation shows that the algorithm can accurately estimate the time-varying frequency offset,and the more iterative numbers the better BER performances and the higher precision of estimation of frequency offset.%MIMO-OFDM是一种高速的通信技术,满足了未来舰载雷达协同通信时隙小、数据量大的要求。但是舰船间的相对速度会导致通信频率的不断变化,而且MIMO-OFDM技术对频偏又十分敏感,因此必须对时变频偏进行估计。本文假设每一帧信号的频偏都是随机变量,提出了利用期望最大化（EM）和最大后验概率（MAP）译码算法相结合的时变频偏估计和信号检测算法。计算机仿真结果表明,该算法可以准确地估计时变频偏,而且系统的误码率性能和频偏估计精度可以随着迭代次数的增多而提高。