Abstract: Orthogonal time frequency space (OTFS) modulation, known for its reliable transmission capability in high Doppler shift environments, has become a key technology for high-mobility communication scenarios such as low earth orbit (LEO) satellite systems. However, as a multicarrier modulation technique, OTFS signals are characterized by a high peak-to-average power ratio (PAPR), which can cause power amplifiers to operate in a nonlinear region, resulting in signal distortion and negatively impacting communication reliability and stability. The Golay complementary sequence, due to its unique properties, ensures that the maximum PAPR of the sequence does not exceed 3 dB. Based on the special relationship between Reed-Muller (RM) coding and Golay complementary sequences, a PAPR reduction method for OTFS systems using RM coding is proposed. At the transmitter, RM coding is used to encode the original bitstream into Golay complementary sequence forms, followed by constellation mapping and OTFS modulation to generate a low-PAPR transmitted signal. At the receiver, to accurately decode this specially encoded signal, a two-step concatenated decoding algorithm is designed. This algorithm combines coset selection decoding and monomial coefficient decoding to achieve error correction for RM codes with Golay complementary sequences, ensuring communication reliability. Simulation results show that, in low earth orbit satellite communication scenarios, the proposed coding method suppresses the peak-to-average power ratio of OTFS system transmitted signals to within 3 dB. Compared with the OFDM system, the OTFS system demonstrates greater robustness. The two-step concatenated decoding algorithm achieves higher transmission reliability at high signal-to-noise ratios (>> 6 dB). This proposed scheme not only provides strong technical support for the application of OTFS modulation in high-mobility satellite-to-ground communication scenarios, but also offers a new reference for PAPR reduction in future multicarrier modulation signals.

Key words: peak-to-average power ratio, satellite to ground communication, Reed-Muller coding, Golay complementary sequences, orthogonal time frequency space, cascaded decoding