A Modified Hadamard Based SLM without Side Information for PAPR Reduction in OFDM Systems

High peak-to-average power ratio(PAPR) is a concern in orthogonal frequency division multiplexing(OFDM) systems. Hadamard based selected mapping(HSLM) which uses Hadamard code as the phase sequence in selected mapping(SLM) is an attractive technique to reduce PAPR. But it requires sending side information(SI) to the receiver for each data block, and this results in a reduction in bandwidth efficiency. In this paper, we proposed a modified PAPR reduction method called semi-Hadamard based selected mapping(semi-HSLM) to decouple the phase information matrix into a phase rotation matrix for PAPR reduction and a SI matrix for side information hiding. We proposed a semi-hadamard matrix generation method to generate the phase rotation matrix, and designed a cyclic shift matrix as the SI matrix. Compared with the traditional HSLM, the semi-HSLM saves half of the phase storage and achieves good PAPR reduction performance.