# Seamless 5G Multi-Hop Connectivity Architecture and Trials for Maritime Applications
## 5 Discussion, Conclusions and Future Vision  
This paper described auspicious concepts--cellular backhauling via coastal stations, satellite connectivity and multi-hopping--for providing continuous 5G connectivity in maritime scenarios in general and, in particular, in the ferry route from Helsinki to Tallinn, which will be investigated and trialed in the 5G-ROUTES project. The results of these analyses and field trials will be available towards the end of the project in the 2024 timeframe and will give the following clear indications on the logical steps towards prototypical and ultimately full operational implementation:  
* The necessary technical developments and adaptations;
* The maturation of the value chain and service exploitation models;
* Inputs to the evolution of future 3 GPP releases (specifically with IAB and NTN).  
There is significant potential to build upon the findings of the 5G-ROUTES project to address more general maritime scenarios--such as longer ferry routes, for instance, from Tallinn to Stockholm--or even open-sea use cases. Multi-hop mesh architectures (see  
Figure 14: The 5G private network core and baseband unit.  
Figure 4) are emerging that use a variety of different elements such as base and relay stations on islands, on ships, on oil platforms and even smaller vessels, on airborne platforms and combined with satellites to connect to a 5G core network.  
The future vision of the 5G connectivity maritime ecosystem involves three main scenarios to provide seamless connectivity:  
* Short range--from land stations;
* Multi-hop as a mid-range solution for maritime corridors and internal waters;
* 5G NTN to cover international waters.  
These three scenarios will enable a multitude of additional use cases, supporting enhanced situational awareness and improved goods tracking, improved ship-to-ship and port-to-ship connectivity and also autonomous/automated vessels, making traffic, travel and transport on the oceans safer and more efficient.  
In addition, road and rail transport will also benefit from multi-hop and satellite connectivity as well as their combination, which could complement terrestrial 5G networks and help in closing coverage gaps in rural and remote areas. Continuous and ubiquitous connectivity is beneficial to and even required by many automotive use cases even though the technological maturity and cost-efficiency of the proposed solution both need to be further improved.  
The concepts developed in the 5G-ROUTES project and the results of the field trials will contribute to the vision of continuous 5G connectivity--not just along ferry lines across the Baltic Sea but ultimately everywhere and all the time.  
Conceptualization, A.L., M.M., K.K.K., H.W.Z., J.S., A.S., K.K. and L.N.; Formal analysis, M.M.; Methodology, A.L., M.M., H.W.Z., J.S., A.S., K.K. and L.N.; Supervision, A.L., M.M., M.P., K.K.K. and K.K.; Validation, A.L., H.W.Z. and A.S.; Writing--original draft, A.L., M.M., M.P., H.W.Z., A.S. and L.N.; Writing--review & editing, A.L., M.M., M.P., K.K.K., H.W.Z., J.S., A.S., K.K. and L.N. All authors have read and agreed to the published version of the manuscript.  
This work was funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No 951867-5G-ROUTES and by Generalitat de Catalunya under grant 2021 SGR 00770. The APC was funded by 5G-ROUTES.  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Distance** & **Received Signal Strength** \\ \hline
**(km)** & **(dBm)** \\ \hline
0.0 & \(-\)105.2 \\
1.0 & \(-\)101.36 \\
2.0 & \(-\)104.63 \\
2.9 & \(-\)105.66 \\
3.9 & \(-\)103.1 \\
4.9 & \(-\)100.02 \\
5.9 & \(-\)102.39 \\
6.8 & \(-\)102.51 \\
7.8 & \(-\)100.17 \\
8.8 & \(-\)102.81 \\
9.8 & \(-\)101.52 \\
10.7 & \(-\)104.42 \\
11.7 & \(-\)96.96 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Numerical values of the coverage plot at 700 MHz in Figure 3.