## 1 Introduction  
The importance of having reliable wireless communication links and systems during or after manmade or natural disasters is highlighted in [1]. In 2017, Florida was hit by one of the most damaging hurricanes in American history, with winds reaching up to 220 km/h. This resulted in around 50% of cell sites going of service, as well as around 1.2 million subscribers losing their wireless connections. Therefore, during disaster scenarios, space-based wireless communication systems including satellites, aerial Platforms, and unmanned aerial vehicles (UAVs) could offer a wide range of services. These would include, for instance, evaluating damage zones, coordinating rescue teams activities, delivering first-aid kits, accounting for missing people, and delivering good-quality signals in disaster areas [2, 3]. However, terrestrial communication links are often disrupted when disaster strikes, as they are more vulnerable to physical damage. Thus, outer-space communication systems would serve as better solutions [4, 5]. Unmanned aerial vehicles, including drones, and their wide applications are becoming one of the key elements in the current digital era, or Fourth Industrial Revolution (4 IR),as Figure 1 shows. Coupling between 4 IR pillars is seen as an approach that will become an integral part of society and even of our human bodies through such developments as smart cities, wearable technology, smart healthcare, smart farming, and new forms of artificial intelligence. Further, the integration between UAVs and the Internet of Things (IoT) would not only connect billions of items via the Internet, but also allow these connections to function automatically without human intervention. Cisco's definition is \"Bringing together people, processing, data and things to make network communications smarter and more valuable than ever, and transforming data into procedures that create new capabilities, richer experiences and an unprecedented economic opportunity for companies, individuals and countries\". Drones are increasingly integrated with evolving technologies, such as IoT, smart surveillance, artificial intelligence (AI), decision support systems, and machine learning (ML) techniques [6; 7]. Therefore, drone technology has received researchers' attention tin the context of remote sensing and rescue operations for various reasons. These reasons include drones' reliability, flexibility, efficiency, applicability with line-of-sight (LoS) connectivity, low latency, and low manufacturing, launching, and maintenance costs. This integration is vital, especially in the current digital era, when it is anticipated that over 50 billion devices will be connected to the internet by 2030, which in turn could generate real-time data that would open doors towards hyper-connected societies, and thus more global smart connectivity. Many applications could benefit from integration with UAVs, such as telecommunications, remote sensing, the monitoring of disaster-relief activities, high-resolution imaging, atmospheric studies, smart cities, smart agriculture, smart service delivery, wearable devices, traffic monitoring, border monitoring, news gathering, localization, and navigation. Hence, drones can provide seamless communication systems, as well as a variety of sensing applications and connections to grid networks, to support the idea of hyper-connected world in more efficient and timely manner [8; 9]. To the best of our knowledge, this is the first work that considers a modified Hata-Davidson propagation model from a UAV perspective, despite UAVs' advantages of accuracy, coverage, and correction factors. To obtain novelty and mark a noticeable shift from existing work, the key contributions of this work are as follows:  
Figure 1: Technological pillars of the Fourth Industrial Revolution. * Modifying the Hata-Davidson empirical propagation model based on RF drone measurement using the least squares tuning algorithm, which offers the advantages of accuracy, strong connectivity, and wide coverage.