OFDM系统中基于DCT的信道估计迭代算法

Iterative algorithm of DCT-based channel estimation for OFDM systems

提出了一种基于离散余弦变换(DCT)的正交频分复用系统(OFDM)的信道估计算法。该算法是一个迭代过程,首先计算导频子载波处的信道响应,然后通过DCT变换域的低通滤波器有效地抑制了加性高斯白噪声(AWGN)和载波间干扰(ICI)的影响,全部子载波上的信道估计由扩展的离散余弦逆变换(EIDCT)得到。利用DCT的特性,该算法消除了基于离散傅里叶变换(DFT)的信道估计方法中的混叠效应,使得OFDM系统在移动条件下能够很好地工作。仿真结果表明了基于DCT的信道估计迭代算法的有效性。

In this paper, a Discrete Cosine Transform （DCT）-based channel estimator for Orthogonal Frequency Division Multiplexing （OFDM） systems is proposed. The proposed algorithm works in an iterative fashion. It computes an initial estimate of the channel based on the pilot sub-carriers. Then, this algorithm employs low-pass filtering in the DCT domain so as to reduce the additive white Gaussian noise （AWGN） and inter-carrier interference （ICI） significantly. By exploiting the properties of DCT, this method mitigates the aliasing effect in the Discrete Fourier Transform （DFT）-based channel estimator when the multi-path fading channels have non-sample-spaced path delays. The channel transfer function for all sub-carriers is obtained by extendible IDCT （EIDCT）. This algorithm enables OFDM systems to work well in mobile situations. The computer simulation results demonstrate effectiveness of the proposed DCT-based channel estimation method.