Peak-to-Average Power Ratio Reduction via Symbol Precoding in OTFS Modulation

Orthogonal time frequency space (OTFS) has recently attracted widespread attention for it leverages frequency dispersion as a source of diversity and mathematically unifies the classical multiple-access schemes. However, as a multi-carrier modulation in nature, OTFS is susceptible to the problem of high peak-to-average power ratio (PAPR), especially when the number of symbols is large in order to obtain a high Doppler resolution at the receiver. In this work, we recast the problem of PAPR reduction as constrained optimization of the precoding matrix. To efficiently solve the underlying nonconvex maximum-norm minimization problem, we propose an iterative algorithm based on block coordinate descent. Simulation results show that the proposed method can significantly mitigate the PAPR without unduly compromising the reliability of data transmission.