关键词: 通信技术 , 正交频分复用 , 信道估计 , 最大似然 , 有效信道长度

Abstract: To acquire a better performance, the receiver in orthogonal frequency division multiplexing (OFDM) systems must estimate the channel state information. Maximum likelihood (ML) channel estimation for OFDM systems needs to know the effective length of channel impulse response for achieving optimum performance. Existing ML channel estimation schemes do not offer an available scheme to track the variation in effective length of channel impulse response. Based on the analysis that the ML channel estimator performance depends on the assumed effective length of channel impulse re?sponse, a modified ML channel estimator which combines the ML estimation with a policy of line search was proposed to improve the precision of the ML channel estimator. The simulated results un-der the multi-path Rayleigh channel show that the improved algorithm in this paper can track effective length of channel impulse response effectively and improve performance of the ML channel estimator.

Key words: communication technology , orthogonal frequency division multiplexing , channel estima?tion , maximum likelihood , effective length of channel impulse response