Abstract: Orthogonal time frequency space (OTFS) modulation has an excellent performance in high-speed mobile scenarios. However, OTFS is susceptible to the problem of high peak-to-average power ratio (PAPR). Regarding this issue, a selective mapping method without transmitting side information is proposed to reduce the PAPR of OTFS signal. The random phase sequences are employed to scramble the transmitted symbols in the delay-Doppler (DD) domain, and the unique degree of freedom of OTFS pulse pilot position are used to carry the side information, which can be extracted by detecting the difference in energy distribution of the received symbols in the DD domain. Finally, the input-output relationship in the DD domain was derived, and an improved channel estimation and signal detection algorithm was provided. Simulation results show that the proposed method can effectively reduce the PAPR by about 2.4dB, while the performance loss of bit error rate is only 0.4dB with the estimated channel state information.

Key words: orthogonal time frequency space, peak-to-average power ratio, selective mapping, side information