Orthogonal time frequency space (OTFS) modulation has been verified to provide significant performance advantages against Doppler in high-mobility scenarios. The core feature of OTFS is that the time-variant channel is converted into a non-fading 2D channel in the delay-Doppler (DD) domain so that all symbols experience the same channel gain. In now available literatures, the channel is assumed to be quasi-static over an OTFS frame. As for more practical channels, the input-output relation will be time-variant as the environment or medium changes. In this paper, we analyze the characterizations of OTFS Modulation over a more general multipath Channel, where the signal of each path has experienced a unique rapid fading. First, we derive the explicit input-output relationship of OTFS in the DD domain for the case of ideal pulse and rectangular pulse. It is shown that the rapid fading will produce extra Doppler dispersion without impacting on delay domain. We next domenstrate that OTFS can be interpreted as an efficient time diversity technology that combines space-time encoding and interleaving. The simulation results reveal that OTFS is insensitive to rapid fading and still outperforms orthogonal frequency-division multiplexing (OFDM) in such channel.
翻译:在高移动情景中, OTFS 的核心特征是将时间变换通道转换成一个非淡化的多普勒(DD) 频道, 以便所有符号都能够体验同一频道的增益。 在目前可用的文献中, 频道被假定为在 OTFS 框架上是准静态的。 至于更实用的频道, 输入输出关系将随着环境或中位变化而具有时间变量性。 在本文中, 我们分析了 OTFS 移动在更普通的多路径频道上的特性, 每一个路径的信号都经历了独特的快速淡化。 首先, 我们从 DTFS 的清晰的输入输出输出关系中, 以理想的脉冲和矩脉冲为例。 显示快速淡化将产生额外的多普勒扩散, 而不会影响延迟域 。 我们下个菜单后, OTFS 可以被解释为一个高效的时间多样性技术, 从而将空间感应变速度变的轨道和多频度技术结合到多位图像。