The Transmit Design for ISAC System Based on Affine Frequency-Division Multiplexing

This paper investigates an Affine Frequency Division Multiplexing (AFDM)-based Integrated Sensing and Communication (ISAC) system to address challenges in doubly-dispersive channels under high-mobility conditions. By integrating Minimum Mean Square Error (MMSE) equalization and a Chirped Periodic Prefix (CPP) structure, the system effectively mitigates interference caused by multipath propagation and Doppler shifts. A dual-objective optimization framework jointly maximizes communication signal-to-interference-plus-noise ratio (SINR) and radar Integrated Frequency Signal Ratio (IFSR), incorporating waveform stability constraints. An Alternating Direction Penalty Method (ADPM) algorithm with feasible point pursuit (FPP) initialization is developed to solve the non-convex optimization design, achieving rapid convergence through adaptive penalty factors and closed-form constraint handling. A thorough performance assessment demonstrates that the proposed FPP-ADPM algorithm enhances the overall performance of the AFDM-ISAC system by over 1.3 dB. Furthermore, the optimized system outperforms Orthogonal Time Frequency Space (OTFS) and Orthogonal Frequency Division Multiplexing (OFDM) baselines under balanced resource allocation in scenarios where communication demands dominate subcarrier allocation, yielding superior overall integrated sensing-communication performance.