Symbol interferometry and companding transform for PAPR reduction of OTFS signal

This paper presents methods for reducing the peak-to-average power ratio (PAPR) of the orthogonal time frequency space (OTFS) signal. These methods mainly consist of two operations: symbol interferometry (SI) and either $\mu$-law or $A$-law companding. SI spreads the data of one OTFS symbol onto all symbols and is implemented using a simple inverse fast Fourier transform operation on each OTFS symbol. During the second operation, the PAPR of the OTFS signal is significantly reduced. For our performance analysis, the complementary cumulative distribution function, probability density function, and bit error rate are illustrated through simulations performed in MATLAB. The performance is also analyzed using a solid-state power amplifier at the transmitter and compared with OTFS, $\mu$-law-based OTFS, and SI OTFS systems. The results indicate that the proposed OTFS system achieves a low PAPR.