# Design of Multi-Modal Ship Mobile Ad Hoc Network under the Guidance of an Autonomous Ship
## 1 Introduction  
With the dramatic increase in the number of ships, ports, waterways, and traffic management are facing pressure and challenges. In view of the development of this situation, a flexible, safe, and reliable maritime chain is necessary to ensure the long-term development of the maritime industry and the continuous growth of the economy [1]. Of course, we have witnessed that the continuous development of scientific and technological means such as computer science, telecommunications, automation, etc. has provided great technical support for solving maritime-related problems. For example, today's indispensable AIS, ECDIS, maritime satellites, etc., have brought revolutionary changes to the development of navigation technology and the maritime industry. A few decades ago, unmanned vehicles, drones, and unmanned ships that seemed out of reach have gradually become reality. Whether it is Scandinavian countries and the United Kingdom, or China, Japan, and South Korea, the research and development of full-scale autonomous ships are in full swing [2]. However, there is still a long way to go before the full technological maturity of autonomous ships, the enlargement of the hull, and the scale of the fleet. Therefore, traditional ships will not be completely replaced for a long period in the foreseeable future, the coexistence of autonomous ships and traditional ships is inevitable and long-term. In this context, how to realize the interaction and coordination between autonomous ships, autonomous ships, and traditional ships is a very complex scientific problem. We name the above situation as the multimodal ship phenomenon. Complex motion scenes will also be formed between multi-modal ships, resulting in the necessity of information interaction. Especially for autonomous ships, based on perceiving their navigation environment, they still need to maintain \"close communication\" with other ships to understand and master the navigation dynamics of other ships around them and to make further navigation decisions. However, the current research on key technologies of autonomous navigation mainly focuses on navigation, perception, collision avoidance, etc., while less consideration is given to the interaction and coordinationbetween ships. Especially in the aspect of collision avoidance manipulation, more often, the ship, as an autonomous ship, undertakes almost all collision avoidance actions, that is, adopts an \"evasion strategy\". This collision avoidance method is contrary to the actual sea navigation situation and the division of collision avoidance responsibility, which will make the autonomous ship in a passive situation for a long time or frequently, increase the navigation risk and navigation cost, and hinder the navigation plan. There is no specific study on whether the introduction of autonomous ships will reduce the risk of ship collision incidents, as communication between ships is critical [3]. The continuous development of modern wireless communication technology has brought a huge impact on all walks of life, the demand for wireless applications is also increasing, and a variety of new wireless communication methods have appeared in the past few decades. Autonomous ships use a variety of wireless communication technologies, such as maritime satellites, ship internet, dedicated narrowband systems, etc. [4]. Mobile Ad Hoc Network (MANET) is a self-organizing, infrastructure-free, wireless network composed of a group of mobile communication devices connected through wireless communication links. Unlike traditional networks, mobile ad hoc networks do not have dedicated routers, and each participating node acts as an end system and router. A node can communicate directly with its neighbors within the transmission range. When two nodes that are not within transmission range of each other need to communicate with each other, intermediate nodes act as routers to forward packets [5].