1.abstract
In this paper, we introduce a new 2D modulation scheme referred to as OTFS (Orthogonal Time Frequency & Space) that multiplexes information QAM symbols over new class of carrier waveforms that correspond to localized pulses in a signal representation called the
delay-Doppler representation. OTFS constitutes a far reaching generalization of conventional time and frequency modulations such as TDM and FDM and, from a broader perspective, it establishes a conceptual link between Radar and communication. The OTFS waveforms couple with the wireless channel in a way that directly captures the underlying physics, yielding a high-resolution delay-Doppler Radar image of the constituent reflectors. As a result, the time-frequency selective channel is converted into an invariant, separable and orthogonal interaction, where all received QAM symbols experience the same localized impairment and all the delay-Doppler diversity branches are coherently combined. The high resolution delay-Doppler separation of the reflectors enables OTFS to approach channel capacity with optimal performance-complexity tradeoff through linear scaling of spectral efficiency with the MIMO order and robustness to Doppler and multipath channel conditions. OTFS is an enabler for realizing the full promise of MUMIMO gains even in challenging 5G deployment settings where adaptation is unrealistic.
摘要表達了以下幾個意思
- OTFS的定義：在一種稱爲延遲-多普勒表示的信號表示中，將信息QAM符號多路複用到與局部脈衝相對應的新型載波波形上
- 實現方式：將時頻選擇性信道變成了不變，分離，正交的相互作用
- 達到的效果：所有的QAM符號經歷了相同的衰落，時延多普勒分集分支進行了相干組合，能夠在多普勒和多徑信道條件下，以MIMO階和魯棒性對頻譜效率進行線性縮放，以達到最佳性能-複雜性折衷的信道容量
- 應用：結合了雷達和通信，產生高分辨率的圖像，實現MU-MIMO的增益