PAPR Reduction with Pre-chirp Selection for Affine Frequency Division Multiplexing

TL;DR

This paper introduces a grouped pre-chirp selection algorithm to significantly reduce PAPR in AFDM, a high-mobility communication technique, improving power efficiency while maintaining low complexity and acceptable BER.

Contribution

The paper proposes a novel GPS algorithm for PAPR reduction in AFDM, enhancing power efficiency without increasing modulation complexity.

Findings

GPS effectively reduces PAPR in AFDM.

AFDM with GPS outperforms OTFS in PAPR performance.

The method maintains low spectral efficiency loss and acceptable BER.

Abstract

Affine frequency division multiplexing (AFDM) is a promising new multicarrier technique for high-mobility communications based on discrete affine Fourier transform (DAFT). By properly tuning two parameters in the DAFT module, the effective channel in the DAFT domain can completely circumvent path overlap, thereby constituting a full representation of delay-Doppler profile. However, AFDM has a crucial problem of high peak-to-average power ratio (PAPR), stemming from randomness of modulated symbols. To reduce the PAPR of AFDM, a novel algorithm named grouped pre-chirp selection (GPS) is proposed in this letter. The GPS varying the pre-chirp parameter across subcarrier groups in a non-enumerated manner and then selects the signal with the smallest PAPR among all candidate signals. We detail the operational procedures of the GPS algorithm, analyzing GPS from four aspects: PAPR performance, computational complexity, spectral efficiency, and bit error rate (BER) performance. Simulations indicate the effectiveness of the proposed GPS in reducing PAPR. At the cost of slight communication performance, AFDM with GPS can achieve better PAPR performance than orthogonal time frequency space (OTFS) while maintaining a lower modulation complexity.