A hybrid DE-optimized PTS scheme for PAPR and BER enhancement in optical OTFS waveform for 256-QAM modulation schemes

Abstract Optical orthogonal time frequency space (O-OTFS) modulation provides resilient performance in doubly dispersive and high-mobility wireless channels by symbol mapping in the delay-Doppler plane. Like conventional multicarrier systems, OTFS has the drawback of high peak-to-average power ratio (PAPR), thus degrading power amplifier efficiency as well as causing nonlinear distortions. In this paper, a hybrid reduction scheme of PAPR is introduced by integrating the partial transmit sequence (PTS) method with a differential evolutionary (DE) optimization algorithm. The PTS approach partitions the OTFS time-frequency signal into subblocks and performs phase rotations, while DE minimizes the PAPR by optimizing the phase vector. Simulation results show that for 64, 256, and 512 subcarriers, the DE-PTS approach achieves PAPR reductions of about 4.9 dB, 5.8 dB, and 6.4 dB, respectively, at a CCDF of 10 −3 . Further, BER analysis indicates that DE-PTS achieves a reduced SNR to attain a BER of 10 −3 from 19.2 dB (original OTFS) to 15.1 dB with a gain of 4.1 dB. These findings identify DE-PTS not only reduces PAPR dramatically but also improves BER performance without compromising system fidelity. The proposed methodology is computationally efficient and scalable and hence can be applied to real-time OTFS communication in future high-mobility wireless networks like 6G and vehicular communication.