基于二维DCT的OFDMA系统信道估计方法

摘要

在OFDMA(orthogonal frequency division multiple access)系统中,每个用户通过占用若干时频资源块以实现多址传输,此时传统的基于DFT(discrete Fourier transform)的高效信道估计算法将会产生难以消除的平底效应;另一方面,当终端高速移动时,基于DFT的时域插值亦将面临较为严重的性能损失.为了解决上述问题,提出一种基于二维DCT(discrete cosine transform)的信道估计算法.仿真结果表明,所提出的信道估计算法能以较低的实现复杂度获取逼近最优信道估计器的性能,且在低信噪比条件下亦可获取高精度的信道估计,有助于实现"绿色通信".%In orthogonal frequency division multiple access (OFDMA) systems, multiple access is achieved by assigning some time-frequency resource blocks to individual users. In this case, the conventional discrete Fourier transform (DFT) -based channel estimator suffers from an irreducible error floor. On the other hand, the DFT-based filtering and/or interpolation in time-domain also have performance degradation for systems with high Doppler frequency. In order to solve these two problems, a two dimensional discrete cosine transform (2-D DCT)-based channel estimator for OFDMA systems is proposed. Simulation results show that the performance of the proposed estimator can well approach the 2-D linear minimum mean square error (LMMSE) channel estimation with low implementation complexity. Furthermore, the proposed estimator can provide high accuracy channel estimation even in the low signal-to-noise ratio region, which contributes to the implementation of green communications.