Iterative channel estimation and signal detection in clipped OFDM

High peak-to-average power ratio (PAPR) is an inherit drawback of orthogonal frequency-division multiplexing (OFDM) systems, and it limits the use of OFDM technology. In all the PAPR reduction methods, digital clipping is probably the simplest one and it is very effective in the solution of the PAPR problem in OFDM systems. However, clipping introduces additional distortion, which degrades the performance of channel estimation and signal detection. In this paper, the performance of channel estimation using the simple least square (LS) method in OFDM systems with a clipping operation is analyzed, a decision-aided channel estimation method to mitigate the clipping distortion is developed, and the potential gain in channel estimation of the decision-aided method is derived theoretically. Simulation results show that, in clipped OFDM, the theoretical potential gain in channel estimation can be obtained by a few iterations of an iterative decision-aided channel estimation and signal detection process, and, simultaneously, the performance of signal detection is effectively improved