Low complexity hybrid algorithm for improving PAPR BER and PSD in OTFS under diverse channel conditions.

In this study, the Peak-to-Average Power Ratio (PAPR) and Bit Error Rate (BER) performance in Orthogonal Time Frequency Space (OTFS) modulation with Non-Orthogonal Multiple Access (NOMA) over Rayleigh fading channels were investigated. Simulations with 256-QAM and 512-QAM modulation schemes on 256 subcarriers evaluated several PAPR reduction techniques, including the Vandermonde matrix-based Partial Transmit Sequence with Companding (Vm-PTS+Companding), Vm-SLM+Companding, conventional PTS, Selective Mapping (SLM), Companding, and Clipping & Filtering (C&F). The proposed Vm-PTS+Companding achieves up to 9 dB PAPR reduction for 256-QAM and 8.9 dB for 512-QAM at a Complementary Cumulative Distribution Function (CCDF) of [Formula: see text], outperforming existing methods. Under a [Formula: see text] channel estimation error, the PAPR performance degrades, yet the proposed scheme maintains a 2.9-9.9 dB gain over conventional approaches. BER analysis showed Signal-to-Noise Ratio (SNR) improvements of 3.5-13.7 dB in ideal channels and up to 16 dB under error conditions. Power Spectral Density (PSD) evaluation further confirmed the reduced spectral leakage, with the method achieving a level of [Formula: see text] dB. These results demonstrate that Vm-PTS+Companding effectively optimizes both the PAPR and BER in OTFS-NOMA systems, supporting high data rates in error-prone wireless environments.