Zak-OTFS Implementation via Time and Frequency Windowing
Published in IEEE Transactions on Communications, 2024
Recommended citation: S. Gopalam, I. B. Collings, S. V. Hanly, H. Inaltekin, S. R. B. Pillai and P. Whiting, "Zak-OTFS Implementation via Time and Frequency Windowing," in IEEE Transactions on Communications, doi: 10.1109/TCOMM.2024.3366403. https://ieeexplore.ieee.org/document/10436682
Abstract: This paper presents an efficient practical Zak-OTFS modulation implementation using time and frequency windowing methods. We present two general classes of delay-Doppler (DD) twisted convolution (TC) filters (Type-1 and Type-2), and show that they can be realized by time and frequency windowing functions. We then propose practical methods to generate time domain Zak-OTFS signals, for actual transmission, using the windowing functions. For Type-1, the signals are generated using an interpolation filter. For Type-2, they are generated using a form of precoded OFDM. We show that this allows a wide variety of pulse shapes to be implemented in practice for Zak-OTFS modulation. This was not previously possible. We also show that the Type-2 signals are more spectrally efficient than their Type-1 counterparts. Finally, we compare the channel predictability of the two implementations.