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.

翻译：仿射频分复用（AFDM）是一种基于离散仿射傅里叶变换（DAFT）的、适用于高移动性通信的新型多载波技术。通过适当调整DAFT模块中的两个参数，DAFT域中的有效信道可完全避免路径重叠，从而构成时延-多普勒剖面的完整表示。然而，AFDM存在一个关键问题——高峰均功率比（PAPR），其根源在于调制符号的随机性。为降低AFDM的PAPR，本文提出一种名为分组预啁啾选择（GPS）的新算法。该算法以非枚举方式在不同子载波组间改变预啁啾参数，并从所有候选信号中选择PAPR最小的信号。我们详细阐述了GPS算法的操作流程，并从PAPR性能、计算复杂度、频谱效率和误码率（BER）性能四个方面对其进行分析。仿真结果表明所提GPS算法能有效降低PAPR。在轻微牺牲通信性能的代价下，采用GPS的AFDM在保持较低调制复杂度的同时，可获得优于正交时频空（OTFS）的PAPR性能。