An Integrated Sensing and Communications System Based on Affine Frequency Division Multiplexing

TL;DR

This paper introduces an AFDM-based integrated sensing and communications system that enhances delay and Doppler estimation, balancing spectral efficiency and error probability for high-mobility scenarios.

Contribution

It presents a novel AFDM waveform design and an efficient Doppler estimation method, improving unambiguous delay/Doppler range and system performance in high-mobility environments.

Findings

Enlarged unambiguous delay/Doppler range.

Maintained high spectral efficiency.

Improved peak-to-sidelobe ratio.

Abstract

This paper proposes an integrated sensing and communications (ISAC) system based on affine frequency division multiplexing (AFDM) waveform. To this end, a metric set is designed according to not only the maximum tolerable delay/Doppler, but also the weighted spectral efficiency as well as the outage/error probability of sensing and communications. This enables the analytical investigation of the performance trade-offs of AFDM-ISAC system using the derived analytical relation among metrics and AFDM waveform parameters. Moreover, by revealing that delay and the integral/fractional parts of normalized Doppler can be decoupled in the affine Fourier transform-Doppler domain, an efficient estimation method is proposed for our AFDM-ISAC system, whose unambiguous Doppler can break through the limitation of subcarrier spacing. Theoretical analyses and numerical results verify that our proposed AFDM-ISAC system may significantly enlarge unambiguous delay/Doppler while possessing good spectral efficiency and peak-to-sidelobe level ratio in high-mobility scenarios.