Affine Frequency Division Multiplexing: From Communication to Sensing

TL;DR

This paper explores the use of Affine Frequency Division Multiplexing (AFDM) for integrated sensing and communication, demonstrating its advantages in low-complexity interference mitigation, sub-Nyquist sampling, and high-resolution delay estimation in various radar configurations.

Contribution

It introduces AFDM's application in ISAC systems, highlighting its compatibility with low-complexity SIC, sub-Nyquist sampling, and resource flexibility for interference mitigation.

Findings

AFDM enables low-complexity self-interference cancellation in monostatic sensing.

Supports sub-Nyquist sampling without hardware changes in bistatic sensing.

Resource flexibility of DAFT enhances interference mitigation in multiradar environments.

Abstract

Affine Frequency Division Multiplexing (AFDM) has been proposed as an effective waveform for achieving the full diversity of doubly-dispersive (delay-Doppler) channels. While this property is closely related to range and velocity estimation in sensing, this article focuses on other AFDM features that are particularly relevant for addressing two challenges in integrated sensing and communication (ISAC) systems: (1) maintaining receiver complexity and energy consumption at acceptable levels while supporting the large bandwidths required for high delay/range resolution, and (2) mitigating interference in multiradar environments. In monostatic sensing, where direct transmitter-receiver leakage is a major impairment, we show that AFDM-based ISAC receivers can address the first challenge through their compatibility with low-complexity self-interference cancellation (SIC) schemes and reduced sampling rates via analog dechirping. In bistatic sensing, where such analog solutions may not be feasible, we demonstrate that AFDM supports sub-Nyquist sampling without requiring hardware modifications while preserving delay resolution. Finally, we show that the second challenge can be addressed by leveraging the resource-assignment flexibility of the discrete affine Fourier transform (DAFT) underlying the AFDM waveform.