Affine Frequency Division Multiplexing: From Communication to Sensing
Ali Bemani, Nassar Ksairi, Marios Kountouris
TL;DR
Integrated sensing and communication (ISAC) faces the dual challenges of achieving high range resolution with manageable receiver complexity and mitigating multiradar interference. The paper proposes AFDM, a DAFT-based multicarrier waveform, as a unified solution that provides full delay–Doppler diversity and radar-compatible processing while enabling low-complexity self-interference cancellation and sub-Nyquist sampling in monostatic setups and digital sub-Nyquist sensing in bistatic deployments. A key contribution is the design of multichirp pilots that keep a fixed chirp rate across cells and use cell-specific DAFT-domain sequences to suppress multicell interference without hardware changes, preserving delay resolution. The results demonstrate practical ISAC capabilities with reduced hardware demands and scalable interference management, making AFDM a compelling candidate for future ISAC networks.
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.