A peak-to-average power ratio reduction algorithm for OTFS systems in satellite-to-ground scenarios

Orthogonal time frequency space (OTFS) modulation is shown to enable reliable communication in high-Doppler environments, making it suitable for high-mobility scenarios such as satellite communication. However, its high peak-to-average power ratio (PAPR) often exceeded the linear range of power amplifiers, causing nonlinear distortion. The partial transmit sequence (PTS) algorithm was utilized to mitigate PAPR by dividing data symbols into subblocks and selecting appropriate phase rotation factors. To enhance the PAPR suppression capability of the PTS algorithm, an improved grey wolf optimizer-based PTS algorithm, termed IGWO-PTS, was proposed to address the discrete combinatorial optimization problem, achieving a more optimal subblock partitioning scheme and better PAPR reduction. It was mathematically provened that when the elements of the phase rotation factor set exhibited rotational symmetry, the phase rotation factor combination space could be reduced to <inline-formula><alternatives><math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mrow><mrow><mn mathvariant="normal">1</mn></mrow><mo>/</mo><mrow><mi>K</mi></mrow></mrow></math><graphic specific-use="big" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="alternativeImage/5A2D99AB-015E-4b28-90E4-CE5ADB8F5406-M003.jpg"><?fx-imagestate width="4.48733330" height="2.70933342"?></graphic><graphic specific-use="small" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="alternativeImage/5A2D99AB-015E-4b28-90E4-CE5ADB8F5406-M003c.jpg"><?fx-imagestate width="4.48733330" height="2.70933342"?></graphic></alternatives></inline-formula> of its original size (where <italic>K</italic> denotes the number of set elements) , resulting in significant reduction in system complexity. Simulation results demonstrate that the IGWO-PTS algorithm outperformes traditional methods in PAPR reduction，maintaines reliable transmission in high-mobility satellite-to-ground scenarios.