# Best-Suited Communication Technology for Maritime Signaling Facilities: A Literature Review
## 1 Introduction  
Maritime navigation safety includes a set of rules such as radio communication, construction of ships, fire protection, life-saving appliances, the carriage of cargo, and special measures for high-speed ships. Navigation under severe environments requires information gathering that can compensate for adverse conditions and a cautious mindset that can ensure safe navigation. The increased maritime traffic over the past decade has also led to a significant increase in traffic in seaports [1, 2, 3]. As maritime activities continue to grow worldwide, there is a corresponding need for an increased number of marine aids to navigation (AtoNs) as soon as possible. The purpose of AtoNs is to mark navigational routes and identify obstacles that pose hazards to navigation. These obstacles are assumedto be static and do not change shape [4]. Obstacles can be marked by fixed or floating objects of maritime signaling. Floating objects used for marine signaling are known as buoys. A phenomenon known as buoy drift refers to the movement or displacement of a buoy from its original position. The buoys drift often and can be caused by tides, marine currents, wind patterns, and water temperatures [5; 6]. Furthermore, by changing their positions, the AtoNs lose their functionality, resulting in inaccurate information about the navigational routes for ships. This could lead to maritime accidents, ship collisions, groundings, and other negative consequences for human lives, property, and marine ecology. To mitigate these risks, accurate and reliable AtoN positions must be maintained. The traditional, manual monitoring of AtoN positions requires on-site inspections. By establishing a remote monitoring system, real-time data about the status and position of AtoN are possibly received. The combination of remote monitoring and GPS (global positioning system) technology enables proactive monitoring, reduces navigation risk, and ensures safety, reliability, cost-efficiency, and effective maintenance [7; 8]. Guided by the aforementioned issues, a literature review in relevant scientific databases was conducted using keywords related to the discussed topic to select the most optimal communication technology for this purpose. The identified scientific papers were filtered according to the criteria outlined in the subsequent section of the paper. A detailed analysis of the papers and the technologies employed for data transmission, crucial for a remote monitoring system, was conducted. Moreover, this paper adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) guidelines to ensure that the review process meets adequate standards. The PRISMA guidelines allowed us to clearly define search criteria, data sources, and study selection procedures, ensuring the objectivity and reproducibility of our review. Furthermore, the motivation for writing this paper was the state of the remote monitoring system for maritime signaling facilities in the Croatian part of the Adriatic Sea as a typical example of a rugged coastline. It is worth noticing that a Croatian part of the Adriatic Sea has become the top yachting destination in the world in the last two decades [9; 10]. Furthermore, the coastline of the Adriatic region is highly rugged [10]. The Adriatic coast makes up almost a quarter of the European part of the Mediterranean Sea coast, with 1.246 islands, islets, and rocks [9; 11; 12; 13]. Based on the information presented, it can be emphasized that the Adriatic Sea analysis carried out in this work also applies to other sea locations worldwide. There are 1275 marine AtoNs installed in the Croatian Adriatic. Of this total number, approximately 13% of AtoNs consist of floating objects of maritime signaling--buoys. Of the mentioned total AtoNs, 103 are under remote monitoring, representing 8,07% of the total marine signaling facilities [14]. It has to be pointed out that the construction of new AtoNs does not necessarily imply an increase in remote monitoring capabilities.