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针对正交频分复用(OFDM)系统信道的时变特性,提出若干新型算法,依序对OFDM信道进行盲检测。结合OFDM系统的结构特点,给出了一种基于期望最大化(EM)方法的迭代算法(OEM),该算法可用来计算OFDM系统信道参数的最大似然(ML)估计值。在此基础上,为了降低计算复杂度,避免由于矩阵求逆而带来的风险,提出了一种新颖的递归计算方法(ROEM)。仿真结果显示,所提出的算法,其误码率低于其他类型的盲检测/估计算法。
Aiming at the time-varying characteristics of Orthogonal Frequency Division Multiplexing (OFDM) system channels, several new algorithms are proposed to blindly detect OFDM channels in sequence. Combined with the structural characteristics of OFDM system, an iterative algorithm (OEM) based on Expectation Maximization (EM) method is proposed, which can be used to calculate the maximum likelihood (ML) estimation value of OFDM system channel parameters. On this basis, in order to reduce the computational complexity and avoid the risk brought by matrix inversion, a novel recursive calculation method (ROEM) is proposed. Simulation results show that the proposed algorithm has lower bit error rate than other types of blind detection / estimation algorithms.