# Adaptable and Automated Small UAV Deployments via Virtualization
## 2 Related Work  
The softwarization of network functions, or NFV, is currently considered a key component in the context of the fifth generation of mobile networks (5G networks). In this paper, we consider this technology as an enabler with the potential to support the flexible and adaptable deployment of functions and services over a set of SUAVs. In this context, the European Telecommunications Standards Institute (ETSI) is leading the standardization activities on NFV, which encompasses the definition of a reference architectural framework [13] for NFV deployments. Among the main reference blocks of this architecture, the Virtual Network Function (VNF) is the element in charge of providing the functionality of a network component (e.g., a residential gateway, an access point, a firewall, etc.) through a software implementation. The description of a VNF in terms of its deployment and operational behaviour is covered by the Virtual Network Descriptor (VNFD). A set of interconnected VNFs creates a Network Service (NS), e.g., a number of virtual network routers may provide a data communication service to end users. In this case, the Network Service Descriptor (NSD) defines the characteristics of an NS, including its constituent VNFs and the interconnections between them. Secondly, the NFV Infrastructure (NFVI) provides the hardware and software resources that are needed to deploy, execute and manage the VNFs. These include hardware resources such as computing, storage and networking, which are allocated to the VNFs through a virtualization layer abstraction that enables the decoupling of the VNF software from the underlying hardware. Finally, the Management and Orchestration (MANO) framework supports the proper coordination of all the operations carried out in the NFV environment. These operations enable the automated deployment of network services composed by the VNFs over the NFVI. For this purpose, the definition of the MANO framework contains three functional elements: (1) the Virtual Infrastructure Manager(VIM), controlling the hardware and software resources of the NFVI; (2) the VNF Manager (VNFM), which handles the life cycle of VNFs; and (3) the NFV Orchestrator (NFVO), in charge of building up end-to-end services, and coordinating with the VNFM and VIM functions the available resources and the deployment and configuration of the VNFs. On the other hand, the utilization of softwarization and cloud technologies has already been considered in resource-constrained environments, such as those contemplated in the context of the Internet of Things (IoT). In this respect, different works in the literature focus on the definition of an IoT cloud model to enhance the scalability of traditional wireless sensors networks. The work in [14] presents a mathematical model to virtualize the physical resources offered by a sensor node. This work propose a paradigm shift in applications based on wireless sensor networks, to consider cloud platform technologies. In [15], the authors described an interactive location-based model for IoT, which uses the cloud to enable the collection of sensor data on demand according to the locations of interest established by the user. The work in [16] introduces an interactive model to support an IoT cloud capable of offering sensing services on demand at the same time, but with different latency requirements. Focusing on the provision of network functionalities and softwarization in UAV environments, even though these aspects have received consideration by the research community, our review of the recent literature reveals that no solution has been proposed to date to support the agile integration of services and functions into UAVs, or to deploy adaptive communications infrastructures based on these devices. In [17], the authors presented a recent and detailed review of the state of the art on UAV-based communication networks. In [18], the authors proposed the use of a cloud application for monitoring UAVs and adjust flight trajectories to avoid collisions.