AFDM-Based Integrated Sensing and Communication System with Composite Pilot-Aided Channel Weighted Estimation

In the current Affine Frequency Division Multiplexing (AFDM)-based Integrated Sensing and Communication (ISAC) system, the sensing pilot and channel estimation pilot share spectrum resources, leading to excessive spectrum overhead. To effectively address this issue, this paper proposes a new composite pilot scheme by introducing sensing frames and data frames in the Discrete Affine Fourier Transform (DAFT) domain, with pilots overlaid in the data frame, thereby minimizing channel estimation errors. To further optimize this scheme, we propose the sensing-aided weighted channel estimation (SAWCE) scheme, which improves channel estimation and data detection performance by flexibly selecting parameters for different scenarios. Simulation results show that the SAWCE scheme can achieve flexible switching between the 'static-low complexity high accuracy' and 'dynamic-real-time tracking' modes through different parameter configurations, validating the effectiveness and advantages of the scheme.