## 2 Background and Related Work  
### E-Navigation Test Beds  
Since 2010, under the guidance of IMO, e-Navigation Test Beds have been successively established in Europe, America and other countries [6]. They are used to verify the research results of the system framework structure, data model, information communication and system function of e-Navigation. The EfficientSea project in the European Union include different maritime related groups brought together into unified electronic navigation and commercial activities at sea to improve the efficiency of ship-shore information exchange and provide security for the ship voyage [7]. The services available include meteorological and oceanographic data on the voyage service, maritime safety information service, route exchange and route recommendation service, collision avoidance service, etc. The MONALISA project is the Baltic Sea intelligent highway and electronic navigation project [8]. Its main functions include four parts: Dynamic forward-looking route planning, electronic crew visas, quality assurance of hydrographic survey data and global sharing of maritime data. The e-Navigation Test Beds constructed by the ACCSEAS project implement regional maritime unimpeded navigation [9]. The services provided include route switching, safety information services, water depth services, ship operation coordination, ship location prediction, vessel traffic service (VTS) scheduling data exchange and automatic failure analysis reports. As one of the main advocates of e-Navigation, the basic technical research provided by the United States greatly promotes the development of the e-Navigation system. Japan actively engaged in research work using the AIS binary message to broadcast maritime safety information and established a Testbed on the VHF Data Exchange System (VDES) operations system to collect the location information of small fishing boats [10]. This system supports local port operation, provides environmental information and gradually promotes it in the Japanese coastal areas. A series of comprehensive field trials have been conducted in the lab, land and open sea in Singapore Straits to measure the performance of the developed ship-borne VDES mobile station [11]. South Korea has designed and implemented SMART-Navigation [12], which is a comprehensive maritime digital communications security system. This system can provide an accident prevention service for vulnerable ships, real-time context-aware monitoring services, customized service for a fishing vessel, and Electronic Navigational Charts (ENC) Streaming Services for Small ships. Canada has launched the e-Navigation project on the St. Lawrence River. [PERSON] presents a method by which multiple domains of the Universal Hydrological Data Model S-100-based data can be integrated according to the characteristics of such data [13]. These projects promise to greatly facilitate S-100-based e-Navigation systems' handling of multiple and various domains' data. In order to implement e-Navigation, scholars from all over the world have researched ships and shore-based communications and S-100. [PERSON] et al. believe that the collection, exchange and integration of maritime information need to be standardized [14]. [PERSON] et al. developed the display module including S-57 and S-101 standards, and developed a data management system by referring to the method of S-101 management of ENC [15; 16]. [PERSON] et al. proposed a maritime information service platform based on Shore, which can provide sensor information such as an electronic navigation chart, weather, current and AIS information, as well as integrate map information and web services [17]. [PERSON] summarized the EU's five e-Navigation projects in terms of solutions, testing, navigation monitoring and unmanned ships, and concluded that there is still room for improvement in the safety and efficiency of ship traffic management [18]. [PERSON] outlines the conceptual framework and priorities for Canadian e-Navigation [19].