On the Robustness of AFDM and OTFS Against Passive Eavesdroppers

Fuente: arXiv
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Main Authors: Savaux, Vincent, Rou, Hyeon Seok, Sui, Zeping, de Abreu, Giuseppe Thadeu Freitas, Liu, Zilong
Format: Preprint
Published: 2025
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_version_ 1866908606032510976
author Savaux, Vincent
Rou, Hyeon Seok
Sui, Zeping
de Abreu, Giuseppe Thadeu Freitas
Liu, Zilong
author_facet Savaux, Vincent
Rou, Hyeon Seok
Sui, Zeping
de Abreu, Giuseppe Thadeu Freitas
Liu, Zilong
contents We investigate the robustness of affine frequency division multiplexing (AFDM) and orthogonal time frequency space (OTFS) waveforms against passive eavesdroppers performing brute-force demodulation to intercepted signals, under the assumption that eavesdroppers have no knowledge of chirp parameters (in AFDM) or the delay-Doppler grid configuration (in OTFS), such that they must search exhaustively over possible demodulation matrices. Analytical results show that the brute-force complexity scales as $\mathcal{O}(\sqrt{N})$ for OTFS and $\mathcal{O}(N^2)$ for AFDM, where $N$ is the number of subcarriers, indicating that AFDM has superior resilience over OTFS. Bit error rate (BER) simulations confirm the analysis by showing that, with AFDM, the signal remains nearly undecodable at the eavesdropper, while OTFS allows partial signal recovery under equivalent conditions.
format Preprint
id arxiv_https___arxiv_org_abs_2510_19525
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Robustness of AFDM and OTFS Against Passive Eavesdroppers
Savaux, Vincent
Rou, Hyeon Seok
Sui, Zeping
de Abreu, Giuseppe Thadeu Freitas
Liu, Zilong
Signal Processing
We investigate the robustness of affine frequency division multiplexing (AFDM) and orthogonal time frequency space (OTFS) waveforms against passive eavesdroppers performing brute-force demodulation to intercepted signals, under the assumption that eavesdroppers have no knowledge of chirp parameters (in AFDM) or the delay-Doppler grid configuration (in OTFS), such that they must search exhaustively over possible demodulation matrices. Analytical results show that the brute-force complexity scales as $\mathcal{O}(\sqrt{N})$ for OTFS and $\mathcal{O}(N^2)$ for AFDM, where $N$ is the number of subcarriers, indicating that AFDM has superior resilience over OTFS. Bit error rate (BER) simulations confirm the analysis by showing that, with AFDM, the signal remains nearly undecodable at the eavesdropper, while OTFS allows partial signal recovery under equivalent conditions.
title On the Robustness of AFDM and OTFS Against Passive Eavesdroppers
topic Signal Processing
url https://arxiv.org/abs/2510.19525