## 2 Scope of Applicability and Use-Case Scenario  
The platform addresses a mobile ad hoc setting, where each mobile node can communicate directly with all other nodes within its communication range. The associated coverage area around each node is called the node's neighborhood, and the platform provides all the necessary mechanisms for an effective neighborhood perception. Specifically, as discussed in the introduction, the position and motion of all nodes in the neighborhood are particularly important attributes of the neighborhood's status. Accordingly, the platform provides means so that each mobile node may obtain quasi-real-time updates of the position and motion of itself and all its neighbors. More precisely, each node obtains updates about its own position and motion through a GPS-based localization process and advertises this updated information to its neighborhood by means of periodically broadcast beacons.  
By leveraging the updated status of its neighborhood, a mobile node holding messages that must be routed to their destination can evaluate the appropriateness of its neighbor nodes as next hops for each such message, according to an employed routing protocol (whose metric differentiates between neighbor nodes on the basis of their suitability). When the application of the routing protocol indicates that there exist neighbor nodes more suitable than the current node, the latter forwards the message to the most suitable such neighbor. The modular design of the platform facilitates the implementation of appropriate routing protocols, ensuring the proper interaction between the routing module and the modules responsible for the neighborhood perception.  
Another worthwhile feature of the platform is the absence of requirements for a tight coupling between the core processes of the platform (which undertake the neighborhood perception and ad hoc networking functions) and the robotic devices employed for implementing the physical motion of the MANET nodes. This characteristic proved valuable during the initial deployment of the platform for realizing MANET-related experiments in the context of the ATLAS research project, implemented as part of the second Open Call from the RAWFIE European project (in the Horizon 2020 Framework Programme, under the FIRE+ initiative) [35]. RAWFIE developed and made available a wide variety of different UxV devices, together with a comprehensive (and complex) infrastructure for the coordination and control of these devices. Avoiding the need for tight integration with this infrastructure enabled a flexible and rapid deployment of the MANET platform for the realization of the ATLAS experiments. Moreover, due to the lack of integration requirements, it became straight-forward to apply the MANET platform in further experiments beyond the scope of ATLAS/RAWFIE.  
The ATLAS experiments aimed at assessing the performance of various routing protocols (detailed further in Section 3.2.4) suitable for use in UxV-based opportunistic networks under a variety of real-world conditions referring to the concrete use-case of providing connectivity to remote maritime areas, as depicted in Figure 1. According to this scenario, a remote island without networking infrastructure obtains opportunistic network connectivity via another area already equipped with network access. The network gateways at the two areas are connected by means of an opportunistic network of USVs acting as mobile nodes.  
The evaluation results presented in Section 5 also refer to message exchanges between two fixed endpoints, but this time across stretches of land rather than water. In connection with this point, it is noted that the platform can readily accommodate additional scenarios beyond the case of Figure 1, involving further types of terrain or different traffic endpoints.