The principle of orthogonal time-frequency-space (OTFS) signaling is firstly analyzed, followed by explaining that OTFS embeds another signaling scheme referred to as orthogonal short-time Fourier (OSTF). Then, the relationship among OTFS, OSTF, orthogonal frequency-division multiplexing (OFDM) and single-carrier frequency-division multiple-access (SC-FDMA) is explored, demonstrating that OSTF/OTFS are fundamentally the extensions of OFDM/SC-FDMA from one-dimensional (1D) signaling to two-dimensional (2D) signaling. Hence, the characteristics and performance of OSTF/OTFS schemes can be perceived from the well-understood OFDM/SC-FDMA schemes. Accordingly, the advantages and disadvantages of OSTF/OTFS are discussed. Furthermore, from the principles of OFDM/SC-FDMA, the multiuser multiplexing in OSTF/OTFS systems is analyzed with respect to uplink and downlink, respectively. Added on this, a range of generalized multiplexing schemes are presented, whose characteristics are briefly analyzed.

翻译：本文首先分析了正交时频空间（OTFS）信号传输的基本原理，进而阐释了OTFS内嵌了另一种称为正交短时傅里叶（OSTF）的信号传输方案。随后，探讨了OTFS、OSTF、正交频分复用（OFDM）和单载波频分多址（SC-FDMA）之间的内在联系，论证了OSTF/OTFS本质上是从一维信号传输向二维信号传输的扩展。因此，OSTF/OTFS方案的特性和性能可基于已深入理解的OFDM/SC-FDMA方案进行认知。据此，本文讨论了OSTF/OTFS的优劣势。此外，基于OFDM/SC-FDMA的原理，分别从上行链路和下行链路角度分析了OSTF/OTFS系统中的多用户复用问题。在此基础上，本文提出了一系列通用化复用方案，并简要分析了其特性。