The optimal and quasi-optimal algorithms of two-stage joint estimation of information symbols and frequency response (FR) of multibeam channels in OFDM-based communication systems have been synthesized. They involve the calculation of a posteriori probability density of estimated processes. At the first stage, the recurrent calculation of joint a posteriori distributions of information symbols and the frequency response is performed from two sides of the measurement vector. At the second stage, a posteriori distributions are combined on each of subcarriers that are obtained as a result of the first stage estimation. Based on the obtained a posteriori distributions, estimates of the information symbol and channel FR are determined by the criteria of a posteriori probability maximum and the average mean squared error minimum, respectively. The performance of synthesized algorithms similar to the well-known MMSE algorithm involves the need of knowledge of statistical properties of communication channel. The device implementing the optimal algorithm is multichannel, each channel of which is matched with the corresponding value of symbol from the modulation constellation. The quasi-optimal algorithm was obtained by using the Gaussian approximation of a posteriori probability density. It should be noted that this algorithm preserves its multichannel structure. The approbation of the presented algorithm was conducted using the computer-aided statistical simulation for different parameters of multibeam communication channels and the comparison of the obtained results with the results obtained by the MMSE and LS algorithms. The simulation results showed that the error probability decreases by about 2 times with a maximum signal propagation delay of 100 μs.

中文翻译：

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OFDM通信系统中信息符号和信道频率响应联合估计的两阶段方法

综合了基于OFDM的通信系统中多波束信道信息符号和频率响应(FR)两阶段联合估计的最优和准最优算法。它们涉及估计过程的后验概率密度的计算。在第一阶段，从测量向量的两侧进行信息符号和频率响应的联合后验分布的循环计算。在第二阶段，在作为第一阶段估计的结果获得的每个子载波上组合后验分布。基于获得的后验分布，信息符号和信道 FR 的估计分别由后验概率最大值和平均均方误差最小值的标准确定。类似于众所周知的 MMSE 算法的合成算法的性能需要了解通信信道的统计特性。实现最优算法的设备是多通道的，每个通道都与来自调制星座的符号的相应值相匹配。准最优算法是通过使用后验概率密度的高斯近似获得的。需要注意的是，该算法保留了其多通道结构。对所提出算法的认可是使用计算机辅助统计模拟对多波束通信信道的不同参数进行的，并将获得的结果与 MMSE 和 LS 算法获得的结果进行比较。