Wavelet-Aided OTFS for RIS-Assisted High-Mobility Wireless Channels.

Orthogonal time frequency space (OTFS) modulation and reconfigurable intelligent surface (RIS) are promising methods for next-generation wireless systems. We first incorporate the wavelet transform (WT) into the OTFS system. A simple matrix multiplication-based mathematical model is developed for the proposed wavelet-based OTFS (W-OTFS) system. Then, RIS-assisted communication is considered using the W-OTFS modulation. We use Haar and Daubechies wavelets for our investigations and observe that substantial improvements in terms of bit error rate (BER), peak-to-average power ratio (PAPR), and system complexity are attainable using the W-OTFS system. Our investigation reveals W-OTFS and RIS-assisted W-OTFS to exhibit superior performance compared to conventional OTFS in a high-mobility channel.