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对信道的准确估计是提高相干解调的正交频分复用(OFDM)系统性能的关键。在OFDM系统中,提出了频域内用均匀分布的导频符号,用离散Fourier变换(DFT)域插值思想,在时域对冲激响应用包络加权的方法完成频域信道估计。与传统的DFT变换域方法、线形插值方法进行了比较,并根据硬件实现的难易对加权因子做了几种简化。仿真结果表明,在低信噪比下,该方法估计的信道归一化均方误差明显小于其他算法,但随着信噪比的增加,性能改善逐渐较小。该方法复杂度增加很少,适合于工程实现。
Accurate estimation of the channel is the key to improving the performance of the coherent demodulated Orthogonal Frequency Division Multiplexing (OFDM) system. In OFDM system, we propose a pilot symbol that is uniformly distributed in the frequency domain. We use the discrete Fourier transform (DFT) domain interpolation idea and the envelope weighting method in the time domain to complete the frequency domain channel estimation. Compared with the traditional DFT domain method and linear interpolation method, the weighting factors are simplified according to the difficulty of hardware implementation. The simulation results show that at low signal-to-noise ratio, the normalized mean square error of channel estimated by this method is obviously smaller than that of other algorithms. However, with the increase of signal-to-noise ratio, the performance improvement is gradually smaller. The complexity of the method increases little, suitable for engineering realization.