PAPR Reduction for OTFS Signals Based on Precoding Optimization

Orthogonal time frequency space (OTFS) modulation is increasingly being applied in high-mobility scenarios due to its robustness against Doppler shifts and time delays. As a multi-carrier modulation scheme, OTFS suffers from high peak-to-average power ratio (PAPR) caused by in-phase signal superposition, which can drive the power amplifier (PA) into its nonlinear region, leading to signal distortion. In this paper, we derive the average power of OTFS signals, simplify the power-constrained precoding matrix optimization problem. To address the non-convex constraints, a first-order convex approximation is employed. Furthermore, a block coordinate descent iterative optimization algorithm is proposed to solve the large-scale decision variable optimization problem, and the impact of block size on the results is analyzed. Simulation results demonstrate that, compared to traditional algorithms and the power-constrained precoding matrix optimization methods, the proposed precoding optimization approach not only achieves better data transmission reliability but also exhibits superior PAPR suppression performance, approaching 0 dB.