The standardization of the sixth-generation (6G) has recently commenced to address the rapidly growing demands for enhanced wireless network services. Nevertheless, existing wireless systems, particularly at the physical layer waveform level, remain inadequate for achieving the ambitious key performance indicators (KPIs) envisioned for 6G. Specifically, orthogonal frequency division multiplexing (OFDM), the widely adopted waveform in fifth-generation new radio (5G-NR) networks, suffers from inherent limitations in satisfying these stringent requirements. In practice, OFDM can experience severe inter-carrier interference (ICI), resulting in a pronounced data rate error floor caused by high Doppler shifts. Additionally, the repetitive usage of cyclic prefixes (CPs), intended to combat multipath delays, results in significant spectral inefficiency. These fundamental drawbacks pose critical obstacles to fulfilling 6G performance objectives. Orthogonal time frequency space (OTFS) modulation has recently emerged as a promising waveform candidate, addressing the aforementioned challenges by exploiting the unique characteristics of the delay-Doppler (DD) domain channel. Unlike OFDM, OTFS is inherently resilient to channel distortions induced by delay and Doppler effects, while remaining sensitive to time and frequency shifts. Such intrinsic properties are instrumental in enabling OTFS, with joint communication and sensing capabilities, to embrace, rather than combat, dynamic channel conditions. Motivated by these compelling advantages, this article investigates the feasibility and practical implementation of OTFS modulation leveraging the current OFDM-based wireless systems.

翻译：为应对日益增长的增强型无线网络服务需求，第六代（6G）移动通信的标准化工作已正式启动。然而，现有无线系统——特别是物理层波形层面——仍难以实现6G愿景中设定的关键性能指标。具体而言，正交频分复用作为第五代新空口网络中广泛采用的波形，在满足这些严苛要求方面存在固有局限。实际应用中，OFDM可能遭受严重的载波间干扰，导致高多普勒频移引发显著的数据速率误码平台。此外，为对抗多径时延而重复使用的循环前缀会造成显著的频谱效率损失。这些根本性缺陷对实现6G性能目标构成了关键障碍。正交时频空调制作为新兴的候选波形，通过利用时延-多普勒域信道的独特特性，有效应对了上述挑战。与OFDM不同，OTFS对时延和多普勒效应引起的信道失真具有天然鲁棒性，同时保持对时频偏移的敏感性。这种内在特性使得具备通感一体化能力的OTFS能够主动适应而非对抗动态信道条件。基于这些显著优势，本文研究了在当前OFDM无线系统基础上实现OTFS调制的可行性及其实践部署方案。