## 1 Introduction
gested frequency band. IALA has indicated that when AIS data link loads exceed 50%, it can give rise to severe problems such as information congestion, affecting navigation safety. The performance of the AIS system is directly influenced by factors such as link load. As the link load increases, the time slot multiplexing ratio rises, along with the time slot conflict rate. When the conflict rate reaches a certain level, the communication reliability of the system is compromised. The AIS system is of crucial importance for ensuring safe navigation, and its effectiveness is of paramount significance [9]. Moreover, the increasing demand for data exchange is a key driver that necessitates an upgrade of the AIS system. As the demand for maritime data communication keeps rising, designing and managing efficient wireless communication networks becomes indispensable [10; 11]. To address AIS frequency band congestion, multi-band communication technologies can be utilized to optimize spectrum usage. Additionally, enhancing the network's adaptive capabilities to monitor and adjust communication parameters in real time can help alleviate the risk of information blockages [12]. Furthermore, implementing a cloud-based management system that leverages big data analytics to optimize data flow and resource allocation can significantly enhance overall communication efficiency. Through these measures, the ultimate aim is to achieve a more secure and efficient maritime wireless communication network to meet the growing demand [13; 14]. To alleviate the strain on AIS channels caused by this increased occupancy, VDES leverages the existing AIS infrastructure by introducing ASM and VDE to enhance data transmission capabilities comprehensively. The risk of AIS link overload necessitates the adoption of VDES, which offers improved data transmission rates and advanced protocols, as recommended in ITU-R M.2092-1. However, the increased complexity of VDES, particularly its Very-High-Frequency Data Link (VDL), makes it more susceptible to various issues. Consequently, diligent monitoring of the VDL is crucial to mitigate potential impacts and ensure the reliability and resilience of VDES operations [15]. Notably, on 14 December 2023, the \"Guidelines for Integrity Monitoring of Very-High-Frequency Data Exchange System Data Links (G1181)\", led by China, were approved by the IALA Council and officially released [16]. These guidelines emphasize that the wireless nature of VDES introduces inherent vulnerabilities in its VDL, including factors such as radio interference and spoofing messages, as illustrated in Figure 2. Radio interference affecting the VDES data link includes co-channel interference from non-VDES services, adjacent channel interference from other maritime operations, and spurious emissions from high-power devices [17; 18]. Additionally, interference in the VDES domain may stem from VDES base station slot collisions and atmospheric disturbances [19]. Such interference can compromise the capacity of VDES equipment to accurately demodulate signals, thus jeopardizing navigational safety by propagating errors in message transmission [20; 21]. Furthermore, VDES base stations transmit various messages to facilitate navigation, including safety-related and hydro-meteorological messages. However, because the messages broadcast by VDES base stations lack encryption and the system does not incorporate an authentication mechanism [22], malicious actors can exploit genuine base station information for identity spoofing, spreading false information to vessels, misguiding navigational decisions, and endangering safety [23]. Consequently, if vulnerabilities compromise the VDES data link--leading to information loss, content errors, or the dissemination of false messages--the confidentiality, integrity, and availability of wireless communication are severely impacted. These vulnerabilities not only threaten the credibility and security of maritime communication but also create significant navigational safety risks.