Towards 6G maritime secure communication: channel modeling methods and future challenges

Under the vision of 6G space-air-ground-sea integration, maritime secure communication faces severe challenges due to dynamically non-stationary channels and the coupling of multiple physical effects. This paper reviews the research progress and trends in channel modeling for 6G maritime secure communication. First, the typical characteristics of maritime channels, such as sparsity and atmospheric duct effects, along with their derived security risks are analyzed. Then, it surveys spatial scattering modeling methods for three scenarios: satellite, unmanned aerial vehicle (UAV), and coastal base station-to-ship communications, while elaborating on the integrated application paths of key technologies including reconfigurable intelligent surfaces (RIS), multiple-input multiple-output (MIMO), and fluid antenna systems (FAS). Furthermore, the practical schemes of intelligent optimization frameworks driven by convex optimization, deep reinforcement learning, and large models are summarized. Finally, the paper points out core challenges in current research regarding dynamic modeling accuracy, AI model robustness, and secure transmission adaptability, and prospects future research directions.