OFDM系统高速衰落信道低复杂度估计

Low Complexity Estimation for OFDM System in Fast Fading Channels

高速环境下OFDM系统的快速时变,破坏了信道间的正交性,引起子载波间干扰(ICI),降低了移动应用的性能。因此提出一种低复杂度的二维导频辅助信道估计。首先利用基于线性模型的多项式曲线拟合来逼近实际的快变信道,然后单独在时域和频域插值,最后分别进行两个一维信道估计。实验结果表明,系统在保持高性能的同时降低了计算复杂度。该算法可替代均方误差意义上性能最佳的二维维纳滤波,多项式拟合能有效逼近快变信道,克服ICI的影响,提高移动应用性能。

In high mobility environment, the fast time-varying OFDM system destroys subchannel orthogonality,which degrades the performance of mobile applications because of inter-carrier interference（ICI）. In view of this,a 2D-pilot symbol-assisted channel estimation of low complexity is proposed. This algorithm employs polynomial curve fitting based on the linear model estimator to closely approximate the actual fast-varying channel first, and then interpolates numerical values in time domain and frequency domain respectively. Finally, the estimations for two one-dimensional channels are made respectively. Experimental results show that the system can provide high performance while reducing the implementation complexity. The algorithm can replace the 2D wiener filtering for the minimum mean square error（MMSE） criterion, and the polynomial fitting also can effectively approximate the fast-varying channel, suppress the impact of ICI, and improve the performance of mobile applications.