OFDM系统中一种信道估计频域插值算法

Channel estimates based on frequency domain interpolation for OFDM systems

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。

Coherent orthogonal frequency division multiplexing （OFDM） systems need to accurately estimate the channels. This paper presents a channel estimator which suppresses the noise during frequency interpolation. Discrete Fourier transforms （DFT） are used to estimate the channel impulse response using frequency domain plots. Weighting of the channel impulse response according to its envelope then reduces the channel estimation errors caused by noise. The weighting factor can be simplified to reduce hardware complexity. Simulation results show that the method outperforms the traditional DFT-based method and linear interpolation at low signal to noise ratios （SNR）, but that the advantages of the method decrease as the SNR increases. The method is quite simple, so it can be easily realized in hardware.