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为了估计定时误差、残留频偏和相位噪声干扰,以降低高阶调制的正交频分复用(OFDM)系统中的误码平台,提出一种基于联合似然的估计算法。该算法通过最大化信道冲激响应与这些干扰间的联合似然函数值,分步获得了定时误差、残留频偏、相位噪声以及信道冲激响应的估计值。仿真结果表明,与已有联合估计算法相比,该算法可准确估计信道响应,有效抑制解调输出中的非Gauss干扰,将解调输出的误码平台降低近一个数量级。该方法可有效应用于提高高阶调制OFDM系统的性能。
In order to estimate the timing error, residual frequency offset and phase noise interference and to reduce the BER platform in OFDM systems with high order modulation, a joint likelihood estimation algorithm is proposed. The proposed algorithm estimates the timing error, residual frequency offset, phase noise and estimated channel impulse response stepwise by maximizing the joint impulse response between channel impulse response and these interferences. The simulation results show that compared with the existing joint estimation algorithm, this algorithm can accurately estimate the channel response, effectively suppress the non-Gaussian interference in the demodulated output, and reduce the demodulation output error code platform by nearly one order of magnitude. This method can be effectively applied to improve the performance of high-order modulation OFDM system.