On the Spectrum of OTFS/VOFDM Signals: PSD Analysis and Bandwidth Allocation
Wei Wang, Xiang-Gen Xia

TL;DR
This paper analyzes the spectral properties of OTFS signals, revealing their periodic PSD structure, and proposes a null-space-based precoding method to enable flexible bandwidth allocation for OTFS/VOFDM systems.
Contribution
It provides a detailed PSD analysis of OTFS signals, establishes a relationship with OFDM PSDs, and introduces a novel precoding technique for bandwidth management.
Findings
OTFS PSD is periodic with a specific frequency interval.
The PSD of OTFS equals the sum of component OFDM PSDs under independence.
The proposed NSLP method effectively tailors OTFS spectral characteristics.
Abstract
Orthogonal time frequency space (OTFS)/vector OFDM (VOFDM) is widely regarded as a promising waveform for next-generation mobile communications. However, its spectral characteristics are not yet fully understood. The bandwidth allocation scheme, which is crucial for OTFS's integration into practical wireless standards, also remains unexplored. In this paper, we investigate the spectral characteristics of OTFS signals by analyzing their power spectral density (PSD). We demonstrate that the PSD of discrete-time OTFS signals is periodic with a period of , where is the size of the time/Doppler domain in OTFS, a.k.a., the vector size in VOFDM, and is the sampling interval length of digital to analog converter (DAC), resulting in identical spectral components within the spectral range of the continuous-time OTFS signal. The…
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Taxonomy
TopicsPAPR reduction in OFDM · Digital Filter Design and Implementation · Machine Fault Diagnosis Techniques
