# Inter-UAV Routing Scheme Testbeds
## 1 Introduction  
The birth of Mobile Ad hoc Networks (MANETs) has enabled the decentralization of a massive amount of applications and services. Ad hoc networks can now function in a great variety of environments and conditions without necessarily interfacing with the rest of the internet. All cooperating nodes in such networks are considered peers, with a master-slave relationship between them being nonexistent due to the networks fundamental architecture: each node is both an end-device and a router. Vehicular Ad hoc Networks (VANETs) were the first type of MANETs to be deployed, followed by Flying Ad hoc Networks (FANETs) which are the main focus of this paper. Another type of ad hoc networks which present great interest are cooperative VANET-FANET networks, in which UAVs function essentially as relays between vehicles. According to [1, 2], FANETs differ from VANETs and other types of (ad hoc) networks in matters of:  
* Node mobility (in terms of Velocity/Acceleration/Jerk)
* Topology (FANETs may function in a 3D grid in addition to the more traditional single-layered swarm topology [3]; additionally, a UAV-comprised network shall alter its topology with a significantly higher frequency, due to its nature)
* Availability of energy (arguably the most significant constrain of autonomy in an ad hoc network)  
FANETs find application in both military and civilian fields, such as the ones described in [4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]:  
* Real time monitoring and surveillance
* Search-and-rescue operations* Agriculture
* Relaying of communication  
As envisioned in [16], while the challenges of swarm formation are numerous (routing, path planning, QoS provision, UAV coordination, etc. ), multi-UAV deployments are the future of aerial communications. In surveillance and monitoring applications, routing of information is a means to an end; such is the case in search and rescue-oriented FANET deployments as well as the ones centered around agriculture. High route selection efficiency is mandatory for an acceptable quality of service (QoS) in all mentioned use-cases. As a general rule, routed data shall incorporate desired payload and control messages which forces the scheme developer to take into account the desired application class and packet overhead alike. When considering the relaying of communication between distant parties, routing (and high efficiency thereof) becomes not just a means to an end but rather a goal in itself. Such a use-case, centered around communication relaying as well as VANET-to-FANET cooperation is mentioned in [17]; the researchers have even proposed an application-specific cross-layer routing protocol aimed at enabling close cooperation between VANETs and FANETs, as mentioned previously. The importance of routing efficiency becomes even more highlighted when considering military or emergency/first response operations [4]. There exist a vast number of routing protocols, with many being developed for a very specific use-case and others functioning as a foundation for other schemes. Evaluation of existing/under development protocols is done traditionally using classical simulation software (more often than not, developed for non-ad hoc networks). To counteract the limitations arising from a such approach and obtain usable results, developers resort to the addition of mobile properties to the individual nodes comprising their networks. Thus, in most cases, developed routing schemes are evaluated using conventional networking simulators, which can in many cases, efficiently approximate a mobile ad-hoc behavior. Different mobility models are included as libraries for discreet event network simulators.