Affine Frequency Division Multiplexing: Extending OFDM for Scenario-Flexibility and Resilience

TL;DR

This paper introduces affine frequency division multiplexing (AFDM), a chirp-based waveform designed to improve reliability and flexibility in highly dynamic, Doppler-affected wireless channels, outperforming traditional OFDM.

Contribution

The paper presents AFDM with tunable parameters that achieve optimal diversity in doubly dispersive channels, addressing OFDM's limitations in high-mobility scenarios.

Findings

AFDM achieves optimal diversity order in doubly dispersive channels.

AFDM demonstrates robustness against severe Doppler spreads.

Potential applications include vehicle-to-vehicle, UAV, and satellite communications.

Abstract

Next-generation wireless networks are conceived to provide reliable and high-data-rate communication services for diverse scenarios, such as vehicle-to-vehicle, unmanned aerial vehicles, and satellite networks. The severe Doppler spreads in the underlying time-varying channels induce destructive inter-carrier interference (ICI) in the extensively adopted orthogonal frequency division multiplexing (OFDM) waveform, leading to severe performance degradation. This calls for a new air interface design that can accommodate the severe delay-Doppler spreads in highly dynamic channels while possessing sufficient flexibility to cater to various applications. This article provides a comprehensive overview of a promising chirp-based waveform named affine frequency division multiplexing (AFDM). It is featured with two tunable parameters and achieves optimal diversity order in doubly dispersive channels (DDC). We study the fundamental principle of AFDM, illustrating its intrinsic suitability for DDC. Based on that, several potential applications of AFDM are explored. Furthermore, the major challenges and the corresponding solutions of AFDM are presented, followed by several future research directions. Finally, we draw some instructive conclusions about AFDM, hoping to provide useful inspiration for its development.