A Low-Complexity PTS-Based Radix FFT Method for PAPR Reduction in OFDM Systems

A low-complexity partial transmit sequence (PTS) technique for reducing the peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal is presented. Signals at the middle stages of an -point radix FFT using decimation in frequency (DIF) or decimation in time (DIT) are considered for PTS subblocking. We show that DIF has a lower multiplicative complexity than DIT for similar PAPR reduction. A higher radix based FFT achieves better PAPR reduction per stage with less multiplicative complexity compared with a lower radix FFT. We further reduce the computational complexity by proposing a new technique, called decomposition PTS (D-PTS) subblocking, where subblocks are assigned through different stages of the transform. This new technique reduces the multiplicative complexity, while providing PAPR reduction similar to other techniques such as original PTS (O-PTS). Moreover, it has lower additive complexity.