BICM-OFDM中一种新型迭代信道估计算法

A novel iterative channel estimation algorithm for BICM-OFDM systems

传统的信道估计与译码分开进行,信道估计可靠性不高.针对比特交织编码调制的OFDM系统(BICM-OFDM),提出了一种基于最大似然估计(ML)的信道估计算法,该算法联合译码进行迭代信道估计.利用比特交织编码调制(BICM)中迭代译码的软判决反馈信息,进行信道估计与译码之间的信息交换,实现了信道响应的逐符号更新.在短波宽带信道下的仿真结果表明,经过2次迭代,系统的误码率基本收敛.与传统ML等算法相比,该算法与理想信道估计性能相近.

Accuracy is not high in traditional channel estimation, since channel estimation and decoding are conducted separately. Hence, we propose an iterative channel estimation algorithm based on maximum likelihood （ML） estimation for BICM-OFDM systems. Using the soft-decision information coming from the decoder of bit-interleaved coded modulation （BICM）, the proposed algorithm exchanges the information between the channel estimator and the decoder, obtaining updated symbols of channel response one by one. Simulation results showed that the BER typically converges after two iterations under a wideband HF channel. Compared with the conventional ML algorithm, the performance of the proposed algorithm approaches that of ideal channel estimation.