Faster-than-Nyquist Signaling is Good for Single-Carrier ISAC: An Analytical Study

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Hauptverfasser: Li, Shuangyang, Liu, Fan, Xiong, Yifeng, Yuan, Weijie, Bai, Baoming, Masouros, Christos, Caire, Giuseppe
Format: Preprint
Veröffentlicht: 2025
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author Li, Shuangyang
Liu, Fan
Xiong, Yifeng
Yuan, Weijie
Bai, Baoming
Masouros, Christos
Caire, Giuseppe
author_facet Li, Shuangyang
Liu, Fan
Xiong, Yifeng
Yuan, Weijie
Bai, Baoming
Masouros, Christos
Caire, Giuseppe
contents In this paper, we provide an analytical study of single-carrier faster-than-Nyquist (FTN) signaling for integrated sensing and communications (ISAC). Our derivations show that FTN is advantageous for ISAC, and reveal new insights that these advantages come from the fact that FTN signaling can effectively avoid the spectral aliasing due to the mismatch between the symbol rate and the bandwidth of the shaping pulse. Specifically, the communication spectral efficiency advantages of FTN signaling over time-invariant multipath channels are analytically shown, where both upper- and lower-bounds on the spectral efficiency are derived. We show that the gap between these two bounds corresponds to the potential signal-to-noise ratio (SNR) variation due to the presence of multipath delay and spectral aliasing, which diminishes as the symbol rate grows higher. Particularly, in the limiting case, this SNR variation disappears while the degree of freedom (DoF) of the system attain the maximum. Furthermore, the sensing advantages for FTN signals are verified in terms of the expected normalized squared ambiguity function. We show that FTN signals generally enjoy a more robust ranging performance. More importantly, we prove that FTN signaling can effectively avoid the undesired peaks in the considered ambiguity function along the Doppler dimension, thereby reducing the ambiguities in velocity estimation. All these conclusions are explicitly verified by numerical results.
format Preprint
id arxiv_https___arxiv_org_abs_2506_09931
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Faster-than-Nyquist Signaling is Good for Single-Carrier ISAC: An Analytical Study
Li, Shuangyang
Liu, Fan
Xiong, Yifeng
Yuan, Weijie
Bai, Baoming
Masouros, Christos
Caire, Giuseppe
Information Theory
Signal Processing
In this paper, we provide an analytical study of single-carrier faster-than-Nyquist (FTN) signaling for integrated sensing and communications (ISAC). Our derivations show that FTN is advantageous for ISAC, and reveal new insights that these advantages come from the fact that FTN signaling can effectively avoid the spectral aliasing due to the mismatch between the symbol rate and the bandwidth of the shaping pulse. Specifically, the communication spectral efficiency advantages of FTN signaling over time-invariant multipath channels are analytically shown, where both upper- and lower-bounds on the spectral efficiency are derived. We show that the gap between these two bounds corresponds to the potential signal-to-noise ratio (SNR) variation due to the presence of multipath delay and spectral aliasing, which diminishes as the symbol rate grows higher. Particularly, in the limiting case, this SNR variation disappears while the degree of freedom (DoF) of the system attain the maximum. Furthermore, the sensing advantages for FTN signals are verified in terms of the expected normalized squared ambiguity function. We show that FTN signals generally enjoy a more robust ranging performance. More importantly, we prove that FTN signaling can effectively avoid the undesired peaks in the considered ambiguity function along the Doppler dimension, thereby reducing the ambiguities in velocity estimation. All these conclusions are explicitly verified by numerical results.
title Faster-than-Nyquist Signaling is Good for Single-Carrier ISAC: An Analytical Study
topic Information Theory
Signal Processing
url https://arxiv.org/abs/2506.09931