From M-WFrFT Towards OTFS

Orthogonal- Time-Frequency-Space (OTFS) has been suggested as a way to achieve higher performance over Delay-Doppler (DD) channels compared to the Orthogonal Frequency Division Multiplexing (OFDM) system. OTFS transforms the Time-Frequency (TF) channel's domain defined in OFDM towards a Delay-Doppler (DD) channel's domain. This gives a useful tool to overcome challenges encountered in frequency-selective channels. Furthermore, an advantage is brought by the Fractional Fourier Transform (FrFT) compared to the classical Fourier Transform (FT) retained in OFDM. To do that, a simplification of the generalized Weighted Fractional Fourier Transform (WFrFT) approaches led to the named FrFT. In this process, the Multi-Weighted Fractional Fourier Transform (M-WFrFT) has attracted our attention. In this paper, it will be seen how OTFS design comes as a result of M-WFrFT. It describes the design of an OTFS system based on an OFDM system. For that, the Multi-Weighted Fractional Fourier Transform is used. Simulation results demonstrate the M-WFrFT based OTFS system gives better performance compared to WFrFT-OTFS system.