OTFS Waveform Based on 3-D Signal Constellation for Time-Variant Channels

Orthogonal time frequency space (OTFS) is a new waveform modulated in the delay-Doppler domain that can achieve better communication performance than the conventional waveform, such as orthogonal frequency division multiplexing (OFDM), in high-mobility scenarios. In this letter, we introduce the three-dimensional (3-D) mapper into the conventional OTFS modulation scheme to further reduce the bit error rate (BER) at higher modulation orders. Moreover, the minimum Euclidean distance of the 3-D signal constellations and detector complexity analysis of the proposed 3D-OTFS are presented. The simulation results demonstrate that the proposed 3D-OTFS system outperforms the conventional OTFS system in terms of BER performance for higher modulation orders in time-variant channels, such as the Extended Vehicular A (EVA) channel and the Extended Pedestrian A (EPA) channel. Furthermore, performance comparisons between the proposed 3D-OTFS and 3D-OFDM in different time-variant channels show that the proposed 3D-OTFS is better suited for high-mobility communication scenarios.