OFDM系统中基于CE-BEM信道建模的低复杂度均衡*

在移动正交频分复用（OFDM）系统中，时变信道引起子载波间干扰（ICI），从而导致系统性能严重下降。均衡作为消除ICI的主要手段而被广泛采用，但是大多数情况下，由于需要进行高阶矩阵的求逆运算，导致均衡面临着运算复杂度过高的问题。提出采用复指数基扩展模型（CE-BEM）对时变信道进行建模，并利用估计得到的模型系数直接构造判决反馈均衡器（DFE），从而避免了矩阵求逆运算，大大降低了运算复杂度。同时，该DFE通过理论分析和仿真实践均被证明具有良好的均衡效果，能有效地消除ICI并改善系统性能。

Low complexity equalization for OFDM systems based on CE-BEM channel model

In mobile orthogonal frequency division multiplexing (OFDM) systems, channel time-variations in one OFDM symbol result in intercarrier interference (ICI) which degrades the performance greatly. The most effective method of canceling ICI is equalization. But, in most case, the straightforward implementation of an equalizer requires the inversion of a large matrix and has therefore high computational complexity. This paper proposed a low complexity equalization. First, adopted a complex exponential basis expansion model (CE-BEM) to approximate the time-varying channel, and then used the estimated model coefficients to construct a decision feedback equalizer (DFE) directly. The equalizer has a reduced complexity, since no matrix inversion is required. At the same time, theoretical analysis and simulation results show that the proposed DFE can cancel ICI effectively and improve the system performance.