# Marine Internet for Internetworking in Oceans: A Tutorial
## 5 Internetworking Strategies of Marine Internet
### Integrated Coastline Network (ICN)  
An ICN aims to not only extend cost-effective terrestrial Internet services to near water areas in oceans, but also enhance maritime radio systems for large service capacity. Although the ocean is huge, actually most human activities therein take place in water areas near coastlines. For example, many domestic maritime shipping routes are set about 2-20 nautical miles away from the coastline (1 nautical mile = 1.852 km). This phenomenon is further shown by Figure 2a, where ship traffic density near the coastline is much higher than that in other water areas, showing the majority of marine Internet users are distributed therein.  
An ICN tries to integrate mobile communication and maritime radio systems to achieve the following objectives:  
* Making use of the abundant radio spectrum of mobile cellular systems in oceans to overcome the bandwidth bottleneck of the maritime radio system and improve the utilization of precious and expensive radio spectra, while extending terrestrial Internet services to near water areas. Some well-developed functions of maritime radio systems can be used to set up network connection in oceans. For example, long-range low-rate communication can be used as signaling for networking. Furthermore, the infrastructure for both systems including those for AISs can also be integrated to reduce deployment cost.
* Exploiting newly developed technologies to improve service capability in oceans [19; 20]. For example, a combination of radio over fiber (RoF) and distributed antenna systems has been considered as a promising technology to increase the capacity of mobile cellular systems, with  
\begin{table}
\begin{tabular}{l c c c c c c} \hline  & **System** & **Coverage** & **System** & **Safety of** & **Service Cost-** & **Underwater** \\  & **Capacity** & **Size** & **Reliability** & **Infrastructure** & **Effectiveness** & **Coverage** \\ \hline \multicolumn{1}{l}{Maritime radio system} & Small & Medium & High & Unsafe in & Medium & No \\ \hline \multicolumn{1}{l}{Mobile cellular network} & Large & Small & High & extreme & High & No \\ \hline \multicolumn{1}{l}{Wireless ad hoc network} & Medium & Small & Low & weathers & Very high & Yes \\ \hline \multicolumn{1}{l}{High altitude platform} & Large & Medium & High & Safe & High & No \\ \hline \multicolumn{1}{l}{Satellite system} & Large & Largest & High & Safe & Low & No \\ \hline \multicolumn{1}{l}{Cabled underwater system} & Largest & Medium & Highest & Safe & Low & Yes \\ \hline \end{tabular}
\end{table}
Table 8: The main characteristics of communication networks available or feasible for marine Internet.  
which a BS can be simplified into an antenna system equipped with a tx/rx module relaying radio signal. Multiple such systems are linked through optical fibers to a central unit for further processing of signaling, communication and networking [20]. Duct communication can be used to support long-range communication at high speed in oceans.  
The ICN illustrated in Figure 6 is mainly composed of terrestrial BSs probably installed near or along coastlines or on islands, acting as a gateway between the terrestrial Internet and marine Internet. Then, terrestrial Internet service can be extended seamlessly to near water areas, where the majority of marine Internet users are present. The current maritime radio services are privileged over other marine Internet services with higher requirement on reliability, timeliness and accuracy. This strategy can create a win-win situation to mobile operators, maritime transport and marine industries (e.g., offshore oil industry), ocean scientists and other marine Internet users.