Peak-to-Average Power Ratio Reduction in OFDM Systems Using All-Pass Filters

A low-complexity peak-to-average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed. The proposed scheme produces OFDM sequences by rotating the symbol phase using multiple all-pass filters, whereas the phase rotation of conventional selected mapping (SLM) scheme is performed with multiple complex multiplication modules in conjunction with inverse fast Fourier transform (IFFT) modules. As such, the proposed scheme does not require multiple IFFT modules that incur a heavy computational burden. Analysis results show that the proposed PAPR reduction scheme can significantly decrease computational complexity over the SLM scheme, though the reduction is achieved at the cost of slightly worse PAPR reduction performance. As an instance, the proposed scheme with eight first order all-pass filters for 2048 subcarriers reduces the number of required multiplications by 69.2% and additions by 63.1% at a sacrifice of only 0.25 dB PAPR increase over the conventional SLM scheme with eight IFFT modules.