A low complexity scheme for joint channel estimation and PAPR reduction technique

In a series of previous related works, a joint Channel Estimation and Peak-to-Average Power Ratio (PAPR) (CEPR) for Orthogonal Frequency Division Multiplexing (OFDM) has been addressed by some authors of this paper. While the performance evaluation in terms of PAPR reduction and channel estimation have been widely investigated in these works, the complexity of the CEPR technique was shortly evaluated. Then, a deep analysis of the complexity is clearly required. In this paper, we propose to review the basics of the CEPR technique, its complexity related issues and then will propose an efficient and very simple implementation technique. The target of this paper is manifold. Firstly, using a uniform distribution (over the whole set of subcarriers at the input of Inverse Fast Fourier Transform IFFT) of the sequences used for joint channel estimation and PAPR reduction and, a multiplicative law between the chips of these sequences, the time-domain signal will be simply represented as a geometric sum. The latter could be simply used to reduce one peak of the time domain signal. Secondly, to reduce multiple peaks, we propose to superimpose shifted sequences at the input of the IFFT. Finally, we show that the novel modified CEPR technique, called fast shifted CEPR (FS-CEPR), is efficient in terms of PAPR reduction value and channel estimation. Moreover, it is very simple to be implemented at the transmitter.