Affine Filter Bank Modulation: A New Waveform for High Mobility Communications

TL;DR

This paper introduces Affine Filter Bank Modulation (AFBM), a new waveform for high mobility ISAC systems that offers low PAPR, minimal out-of-band emissions, and robustness to doubly-dispersive channels.

Contribution

The paper presents AFBM, combining filter-bank structures with DAFT precoding, providing improved PAPR and OOBE performance over existing waveforms for high mobility scenarios.

Findings

AFBM maintains quasi-orthogonality in DD channels.

Achieves 3 dB lower PAPR compared to AFDM.

OOBE as low as -100 dB with PHYDYAS filters.

Abstract

We propose a new waveform suitable for integrated sensing and communications (ISAC) systems facing doubly-dispersive (DD) channel conditions, as typically encountered in high mobility scenarios. Dubbed Affine Filter Bank Modulation (AFBM), this novel waveform is designed based on a filter-bank structure, known for its ability to suppress out-of-band emissions (OOBE), while integrating a discrete affine Fourier transform (DAFT) precoding stage which yields low peak-to-average power ratio (PAPR) and robustness to DD distortion, as well as other features desirable for ISAC. Analytical and simulation results demonstrate that AFBM maintains quasi-orthogonality similar to that of affine frequency division multiplexing (AFDM) in DD channels, while achieving PAPR levels 3 dB lower, in addition to OOBE as low as -100 dB when implemented with PHYDYAS prototype filters.