DAFT-Spread Affine Frequency Division Multiple Access for Downlink Transmission

TL;DR

This paper introduces a DAFT-spread AFDMA scheme that effectively reduces PAPR in high-mobility scenarios, enhancing the practicality of AFDM-based communication systems.

Contribution

It proposes a novel DAFT-s-AFDMA scheme with specific chirp subcarrier strategies, providing guidelines for parameter setting and demonstrating improved PAPR performance.

Findings

DAFT-s-AFDMA achieves lower PAPR than conventional O-AFDMA.

Localized and interleaved strategies both improve PAPR performance.

Simulation results confirm the effectiveness of the proposed schemes.

Abstract

Affine frequency division multiplexing (AFDM) and orthogonal AFDM access (O-AFDMA) are promising techniques based on chirp signals, which are able to suppress the performance deterioration caused by Doppler shifts in high-mobility scenarios. However, the high peak-to-average power ratio (PAPR) in AFDM or O-AFDMA is still a crucial problem, which severely limits their practical applications. In this paper, we propose a discrete affine Fourier transform (DAFT)-spread AFDMA scheme based on the properties of the AFDM systems, named DAFT-s-AFDMA to significantly reduce the PAPR by resorting to the DAFT. We formulate the transmitted time-domain signals of the proposed DAFT-s-AFDMA schemes with localized and interleaved chirp subcarrier allocation strategies. Accordingly, we derive the guidelines for setting the DAFT parameters, revealing the insights of PAPR reduction. Finally, simulation results of PAPR comparison in terms of the complementary cumulative distribution function (CCDF) show that the proposed DAFT-s-AFDMA schemes with localized and interleaved strategies can both attain better PAPR performances than the conventional O-AFDMA scheme.