Chirp Parameter Selection for AFDM with MMSE Equalization in Static Multipath Channels.

Affine Frequency Division Multiplexing (AFDM) has emerged as a promising technique, offering optimal diversity performance with maximum likelihood (ML) detection and comparable results to Orthogonal Time Frequency Space (OTFS) in doubly selective channels. However, the performance of AFDM with minimum mean square error (MMSE) equalization in static multipath channels has not been extensively investigated. In this paper, we analyze the impact of the chirp parameter on AFDM transmission performance with MMSE equalization and derive the lower bound on the bit error rate (BER) performance of AFDM. Our findings reveal that, through appropriate parameter selection, AFDM, similar to OTFS, can achieve a lower bound on the BER performance in static channels. Moreover, we propose a specific parameter selection strategy to facilitate optimal transmission in AFDM. Simulation results demonstrate that this strategy enables the optimal transmission of AFDM signals with MMSE equalization.