# Adaptable and Automated Small UAV Deployments via Virtualization
## 3 System Design
In particular, we consider the NFV reference architecture proposed by ETSI [13], which is reviewed in Section 2. Figure 2 illustrates a conceptual vision of our solution, serving as the basis for the definition of its corresponding architectural design. Taking into account the capacity limitations of the typical hardware platforms that can be on-boarded on SUAVs, the Virtualized Network Functions (VNFs) should be developed to provide their intended functionality, but making a responsible use of the available resources. For this reason, in the vision illustrated in the figure, these VNFs are referred to as lightweight VNFs. In general terms, the design of our solution is structured into three main components. 1. The MANO system, located in the GCS, is the component in charge of the management and orchestration of available hardware and software resources, as well as the deployment and interconnection of the lightweight VNFs. It provides an orchestration service, with the execution of an NFV Orchestrator (NFVO) and a VNF Manager (VNFM), and a Virtual Infrastructure Manager (VIM). The GCS offers a stable environment with appropriate resources for the operation of this component, which is convenient given its criticality. 2. The hardware and software infrastructure that supports the execution of lightweight VNFs, i.e., the NFVI. As we have already mentioned, this infrastructure will be on-boarded in the SUAVs. 3. The mission planner, also located at the GCS, which is the entity responsible for specifying the descriptors of the network services to be deployed, each one as a composition of VNFs, in addition to the configuration parameters of each VNF and the policies that determine the allocation of the VNFs to the SUAVs. The mission planner generates this information in concordance with the mission requirements that are provided by the operator of the SUAVs at deployment time. Focusing on the architectural design of the SUAV device, each SUAV carries a general purpose hardware and software platform. This platform, hereafter referred to as a compute node following cloud computing terminology, has a wireless communication interface that enables the exchange of data with every other component of our design that is within the radio coverage of the compute node (i.e., every other compute node and the MANO system). This wireless interface can be based on different technologies, e.g., it may provide a line-of-sight or Wi-Fi radio link. Additionally, as reflected in the figure, some compute nodes may include a secondary network interface to provide wireless access connectivity to ground units. In our design, the compute nodes on-boarded at the different SUAVs form a wireless ad-hoc network that enables multi-hop data communications (that is, communications among compute nodes at different SUAV units, and between the compute nodes and the MANO system). These data communications across the ad-hoc network are supported with the execution of a Flying Ad-hoc Network (FANET) routing protocol at each compute node (e.g., AODV [11] or OLSR [12]) (we assume that the support of this routing protocol is enabled at each SUAV as a prior step to an operational deployment). Besides, to isolate the different traffic types exchanged over this wireless ad-hoc network, our solution defines a set of virtual networks that operate on top of the wireless ad-hoc network. In particular, to support management operations towards the compute nodes (e.g., to monitor the available resources at each compute node, to instantiate and configure a VNF instance, or to terminate that instance), each compute node included in the NFV infrastructure supports two types of communications: (1) communications between the VIM and the compute nodes (labeled as _Infrastructure management_ in Figure 2), to control the computing, storage and networking resources of the compute nodes; and (2) communications between the Orchestration Service and the VNFs (denoted as _VNF management_ in Figure 2), to manage the configuration and the lifecycle of the lightweight VNFs.