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The ability of unmanned aerial vehicles (UAVs) to communicate and cooperate among themselves in an aerial swarm network is of paramount importance for collaborative missions. It enables the swarm to function as a collective unit to plan trajectories, share tasks, coordinate flight route for collision avoidance or to optimize a given mission objective. In this work, a cellular radio interface known as "sidelink"is investigated for establishing efficient UAV-to-UAV (U2U) multi-hop communication within the aerial swarm network. First, we look into the salient features of cellular sidelink (PC5 radio interface) as a key enabler of U2U communication, and then present a multi-hop network model design to extend cellular connectivity services to out-of-coverage UAVs during missions. Using extensive simulations, we evaluate and study the performance of sidelink-assisted multi-hop U2U communication model in terms of the packet delivery ratio (PDR) for different key scheduling parameters of mode-4 sensing-based autonomous resource selection.

The chaotic growth of the Internet of Things (IoT) determined a fragmented landscape with a huge number of devices, technologies and platforms available on the market, and consequential issues of interoperability on many system deployments. The recent W3C Web of Things (WoT) standards aimed to ease the deployment of heterogeneous systems by introducing uniform and well-defined software interfaces among the systems’ components. Although the WoT reference architecture is generic and agnostic to the target devices, its widespread adoption depends on the availability of specific tools named Servients, which enable the run-time operations of WoT applications. In this paper we aim at contributing to the adoption of the W3C WoT standards by presenting WoT Micro-Servient (WMS), a framework for bringing the WoT paradigm to the extreme edge of an IoT environment. Through WMS, developers can design, compile and install WoT applications on micro-controllers and embedded systems with constrained hardware capabilities. We describe the architecture and functionalities of the tool, and demonstrate its effectiveness in terms of reduced latency and energy consumption compared to the state-of-art proxy-based solution enabled by Node-wot, i.e. the official implementation of W3C WoT. Finally, we discuss a real-world application related to smart home, where WMS is used to enable a WoT-based remote monitoring and control of indoor plants, by enabling seamless integration between micro-controllers and mobile devices.

UAV-aided Wireless Sensor Networks (WSNs) constitute an energy- and cost-effective solution for the deployment of large-scale IoT monitoring systems. At the same time, the integration of UAVs into IoT scenarios poses some practical challenges which are far to be addressed, like the synchronization issue (how can the Wireless Ground Sensors (WGSs) be aware of the presence of the UAV?) and the channel contention in high-dense scenarios (how can the WGSs cope with the limited transmission opportunity?). In this paper, we address both the issues above by proposing a novel Energy Load Aware Sensor To aIr Communication (ELASTIC) platform, supporting the deployment of scalable and energy-efficient UAV-aided WSNs. The proposal includes two main components, working in synergy at the PHY and MAC layers. First, the paper describes the design and implementation of Active Wake-up Radio mechanisms through which the WGSs can be notified of the UAV’s presence and hence of the transmission opportunity; the proposed architecture supports two operative modes (Switch and Low-Power) that can be properly orchestrated so that the energy consumption of the WGSs in standby phase is minimized. Second, since multiple WGSs can be activated from a wake-up signal and access the channel at the same time, a novel priority-based MAC scheme has been designed: the proposed solution performs distributed contention control among the WGSs, by taking into account the length of the transmission opportunity for each WGS and the actual channel load. The simulation results demonstrate that the proposed ELASTIC MAC protocol guarantees a +50% throughput improvement when compared to the legacy CSMA/CA MAC in high-dense WSNs, and show its ability to adapt to different traffic loads and UAV speeds.