# Coverage Strategy for Small-Cell UAV-Based Networks in IoT Environment
## 2 Related Works  
A significant existing body of literature investigates interesting features of UAV technological performance and reducing cost. For instance, [PERSON], [PERSON] et al. [4] discuss the problem of data gathering and energy transfer in a UAV-assisted flying access network for IoT applications. The authors propose a joint optimization scheme that aims to minimize the energy consumption of the network while ensuring that the data gathering and energy transfer requirements are met. The proposed scheme involves the deployment of UAVs that act as flying base stations for IoT devices. These UAVs use energy transfer techniques, such as wireless power transfer, to recharge the IoT devices and prolong their operational lifetime. The authors consider two scenarios: one where the UAVs are stationary and one where they are mobile. To optimize the energy consumption of the network, the authors propose a two-stage optimization algorithm that jointly optimizes the UAVs' trajectories and the energy transfer parameters. The algorithm takes into account the energy consumption of the UAVs, the energy consumption of the IoT devices, and the energy transfer efficiency. The authors evaluate the proposed scheme using simulations and show that it outperforms other existing schemes in terms of energy consumption and data gathering efficiency. They also discuss the limitations of the proposed scheme and identify future research directions. [PERSON] et al. [5] propose a novel solution for wireless connectivity in the Internet of Flying Things (IoFT). The authors propose using unmanned aerial vehicles (UAVs) as flying gateways for Long Range Wide Area Network (LoRaWAN) technology to overcome the challenges of wireless connectivity in the IoT. The proposed solution involves equipping a UAV with an LoRaWAN gateway and using it as a mobile base station to provide wireless connectivity to IoT devices. The authors describe the technical details of the proposed solution, including the hardware and software architectures, and discuss the challenges of deploying a flying gateway in the IoFT. The authors conducted a proof-of-concept experiment to demonstrate the feasibility of their solution. The experiment involved deploying a UAV with an LoRaWAN gateway in a rural area and connecting it to a network of IoT devices. The authors measured the signal strength and data transmission rate and compared the results to a traditional stationary gateway. The results showed that the UAV-based gateway achieved better signal strength and higher data transmission rates than the stationary gateway. To investigate connectivity issues in depth, the authors of [24] address the challenge of improving the connectivity and coverage of flying networks, which consist of a set of unmanned aerial vehicles (UAVs) that are deployed to provide wireless communication services over a geographic area. The authors propose a new relay-positioning algorithm that takes into account both the energy consumption and the performance of the network, in order to maximize the network's overall performance while minimizing the energy consumption of the UAVs. The proposed algorithm considers the mobility of the UAVs, as well as the quality of the wireless links among them, in order to determine the optimal placement of relays. The authors also consider the impact of interference and the energy consumption of the UAVs on the performance of the network. The paper presents simulation results that demonstrate the effectiveness of the proposed algorithm in improving the performance of flying networks compared with other existing relay-positioning algorithms. The authors also discuss the potential applications of their work in areas such as disaster response, surveillance, and transportation. The problem of power-splitting relaying protocol for simultaneous wireless information and power transfer (SWIPT) in a downlink non-orthogonal multiple-access (NOMA) Internet of Things (IoT) network with multiple unmanned aerial vehicles (UAVs) is described and detailed in [25].