限幅OFDM系统中的判决辅助信道估计

Decision-aided channel estimation in clipped OFDM

在正交频分复用(OFDM)系统中,对基带时域信号限幅是通常采用的一种降低信号峰均比的方法,但是由限幅产生的非线性干扰使系统的信道估计和信号检测性能降低。本文针对OFDM系统的频域插值信道估计方案,分析了限幅对信道估计性能的影响,提出一种利用判决的信号辅助信道估计的方法,并分析了该方法为信道估计所能提供的最大信干比增益。理论分析和仿真结果表明这种方法能够提高信道估计的精度,从而提高信号检测的性能,降低接收机的误符号率。

Clipping is a popular and simple method to overcome large peak-to-mean envelope power ratios (PMEPR) in OFDM systems, but it results in a nonlinear distortion, which degrades the performance of channel estimation and signal detection. In this paper, based on a channel estimation scheme that only part of the OFDM tones are used for pilot, the effect of clipping on channel estimation is analyzed. Accordingly, a signal decision-aided channel estimation algorithm is proposed to mitigate the clipping distortion and derive the potential gain of the algorithm. Theoretical and simulation results show that the proposed method can improve the performance of channel estimation and signal detection in clipped OFDM.