  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 the pre-chirp parameter and the post-chirp
parameter in the DAFT, 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. In this letter, a novel algorithm named grouped pre-chirp selection
(GPS) is proposed to reduce PAPR by strategically varying the pre-chirp
parameter across subcarrier groups. Initially, it is established that key AFDM
properties are maintained when implementing GPS. Next, we proceed to detail the
operational procedures of the GPS algorithm, elucidating its principle for PAPR
reduction and emphasizing its computational efficiency advantages. Finally,
simulation results employing the complementary cumulative distribution function
(CCDF) validate the effectiveness of the proposed GPS in reducing PAPR.
