Optimized Multiplicative Pre-Distortion PAPR Reduction Scheme for OTFS Signals

We present an iterative peak-to-average power ratio (PAPR) reduction scheme with multiplicative pre-distortion vectors for orthogonal time frequency space (OTFS) systems by making a compromise between the PAPR reduction and the bit error rate (BER) performance. In the scheme, the multiplicative pre-distortion vectors are introduced to weight the symbols in the delay-Doppler (DD) domain with the same delay (i.e. a vector in the Doppler domain) which cause the peak of the OTFS signal rather than all the delay-Doppler domain symbols. In each iteration, the multiplicative pre-distortion vector is optimized to minimize the introduced in-band distortions before and after the pre-distortion with the preset PAPR constraint using the error vector magnitude (EVM). Simulation results demonstrate that the gain of PAPR reduction in our scheme is about 3.0dB for QPSK and 16-QAM over conventional OTFS signals at the complementary cumulative distribution function level of 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> with negligible BER performance degradation and low complexity.