A Low Complexity PAPR Reduction Method Based on FWFT and PEC for OFDM Systems

Orthogonal frequency division multiplexing (OFDM) is a multi-carrier modulation technique for transmitting large volumes of digital data but suffers high peak-to-average power ratio (PAPR) at the transmitter. In this paper, we propose a PAPR reduction technique based on the combination of a low complexity transform-Fast Walsh-Hadamard and Fourier transform (FWFT) and the parameter-adjustable piecewise exponential companding (PEC). To reduce algorithm complexity, FWFT uses a fast orthonormal unitary transform to calculate both the Walsh-Hadamard transform (WHT) and the discrete Fourier transform (DFT). In FWFT, WHT realizes precoding to OFDM signals and as a result the PAPR is reduced first. Moreover, the parameter-adjustable PEC transform is adopted to further reduce PAPR by transforming the statistics of the companded signal into exponential distribution with adjustable parameters. Simulation results show that the hybrid method achieves significant PAPR reduction and improves the BER performance of OFDM systems when used in multipath fading channels.