Joint AFDM Waveform and Beamforming Design for Resilient Cognitive ICAJ Systems

Abstract

Addressing the urgent need for resilient and trustworthy communication in intelligent wireless environment within the sixth-generation (6G) mobile communication networks, this paper investigates the design problem of Integrated Communication and Jamming (ICAJ) systems in high-mobility scenarios. To address the performance degradation of ICAJ systems due to the use of traditional waveforms in dual-dispersion channels, this paper proposes for the first time a sensing-assisted affine frequency division multiplexing (AFDM) secure waveform design and beamforming joint optimization scheme. At the waveform design level, leveraging the high sensitivity of AFDM parameters to demodulation, a physical layer encryption mechanism with a transform domain key based on the shear slope is constructed, and a dual security barrier is established through symbol prescrambling. Simultaneously, a composite jamming signal containing deceptive suffixes is constructed using perception features to induce protocol-level failures in suspicious networks, achieving efficient proactive defense. At the system design level, a joint optimization problem is constructed, tuning the waveform parameters of AFDM in the delay-Doppler (DD) domain and the spatial domain beamforming matrix jointly. The goal is to maximize the average sum rate of legitimate communication users under multiple constraints, including communication quality constraints from multiple potentially suspicious communication networks, power constraints, and waveform design limitations. The non-convexity of the problem and the high degree of nonlinear coupling between variables make it very challenging. To address this, a robust algorithm based on alternating optimization (AO) is proposed. It utilizes the weighted mean squared error minimization (WMMSE) technique to transform the original non-convex problem into a series of tractable equivalent subproblems, and combines successive convex approximation (SCA) and multi-scale search strategies to efficiently optimize beamforming vectors and waveform domain parameters. Simulation results demonstrate that the proposed scheme exhibits excellent system resilience at extremely high mobile speeds and achieves significant spectral efficiency and interference gains in a multi-user environment, providing a novel technical path for the design of cognitive ICAJ systems with intrinsic security and dynamic adaptability under the 6G framework.