PAPR Reduction in AFDM Using a Zadoff-Chu Sequence Matrix and Companding Transform

Affine frequency division multiplexing (AFDM) is an emerging and promising discrete affine Fourier transform (DAFT) domain waveform designed to achieve optimal diversity order in doubly dispersive channels. However, AFDM suffers from high peak-to-average power ratio (PAPR) due to its inherent multi-carrier structure. In this paper, we propose the Zadoff-Chu sequence Matrix (ZCM) as a precoder for AFDM, referred to as ZCM-AFDM and AFDM with normalized A-law companding, referred to as AFDM A-law, for PAPR reduction. Simulation results demonstrate that these schemes achieve moderate PAPR reduction and ZCM-AFDM offers over 0.5 dB signal-to-noise ratio (SNR) improvement at a bit error rate (BER) level of 10−4. Furthermore, we propose two novel schemes by integrating ZCM and companding transforms (normalized μ-law/normalized A-law) with AFDM referred to as ZCM-AFDM μ-law and ZCM-AFDM A-law to achieve further reduction in PAPR. Simulation results demonstrate that the ZCM-AFDM μ-law and ZCM-AFDM A-law schemes outperform all other schemes.