Flexible FTN-OTFS for High-Mobility LEO Satellite-to-Ground Communication

TL;DR

This paper introduces a lightweight, adaptive FTN-OTFS scheme for high-mobility LEO satellite-to-ground links, optimizing spectral efficiency and robustness under realistic channel conditions with low complexity.

Contribution

It proposes a novel SNR-aware flexible FTN strategy with a LUT for adaptive rate control, addressing high-mobility channel effects efficiently.

Findings

Significant throughput improvement over static FTN schemes

Effective mitigation of channel aging effects

Enhanced spectral efficiency and robustness

Abstract

In this paper, a lightweight LEO satellite-assisted flexible faster-than-Nyquist (FTN)-orthogonal time frequency space (OTFS) (LEO-FFTN-OTFS) scheme is proposed to address the stringent constraints on onboard power consumption and the severe impact of fast time-varying channels in non-terrestrial networks. A rigorous system framework incorporating realistic 3GPP Tapped Delay Line (TDL) channel models is established to accurately capture high-mobility propagation characteristics. To counteract channel aging effects while maintaining low computational complexity, an SNR-aware flexible FTN strategy is introduced, wherein a low-complexity Look-Up Table (LUT) is utilized to adaptively optimize the time-domain compression factor based on instantaneous channel responses. Through this mechanism, the trade-off between rate acceleration and interference penalty is effectively resolved, ensuring that spectral efficiency is maximized while strict reliability constraints are satisfied with minimal processing overhead. Moreover, a comprehensive theoretical analysis is provided, in which analytical expressions for effective throughput, energy efficiency, and bit error rate are derived. Finally, it is demonstrated by extensive simulations that the proposed scheme significantly outperforms static FTN benchmarks, offering a superior balance of high throughput and robustness for next-generation LEO communications.