# Satellite-Assisted Disrupted Communications: IoT Case Study
## 1 Introduction  
In the dynamic landscape of modern technology, satellite utilization has become fundamental for various critical applications. Communication infrastructure based on satellite technology has emerged as a cost-effective solution, serving not only isolated regions where the establishment of terrestrial networks proves infeasible but also providing a viable alternative in emergency scenarios. In addition, the versatility of satellite services is exceptional [1], encompassing a diverse array of applications including military purposes, remote sensing, Earth observation, space exploration, maritime operations, agriculture, and communication provision over the Internet [2, 3]. The existing literature has extensively explored the influence of space design parameters on satellites [4, 5], including implementations in the Objective Modular Network Testbed in C++ (OMNeT++) [6] and protocol evaluation in space environments [7]. However, limited works have integrated real measurements from Internet of Things (IoT) devices and have demonstrated scenarios for satellite communications such as those described in the present effort. To this end, our research focused on the communication of IoT devices via satellite constellations. We aimed to evaluate the reliability and effectiveness of satellite constellations across diverse IoT scenarios with regard to the Round-Trip Time (RTT) and data loss. We investigated the potential use of space infrastructure, in particular, Low-Earth Orbit (LEO) satellite constellations positioned at a 600 km altitude, as a viable substitute for the communication among ground stations or, more broadly, among any real-time sensitive \"smart\" device capable of generating and transmitting data. Assuming that communication is feasible, wherein these devices can establish connectivity with the satellite infrastructure,satellites can prove beneficial in diverse scenarios, including environmental emergencies or situations requiring enhanced security measures [8]. In particular, LEO satellite constellations can play a significant role in the smart city and IoT scenarios, which are characterized by intermittent or disrupted communications. These constellations can serve as a primary communication channel in remote areas where terrestrial infrastructures are impractical or can act as backup links [9] in situations involving compromised or damaged equipment. We posit a hypothesis suggesting that denser constellations with enabled inter-satellite links would yield improved results in terms of RTT and data loss. Across the majority of our experiments, the aforementioned hypothesis was confirmed, as we observed a reduction of the mean and range RTT with lower ping loss when we increased the number of satellites and enabled inter-satellite links. However, notable exceptions have emerged with sensors exhibiting superior performance in constellations comprising fewer satellites. Therefore, we concluded that in certain cases, the position of the ground nodes relative to the satellites' orbit prevailed as a major factor and significantly influenced the results in comparison to the effect of the number of satellites. Our major contributions are listed below. * We analyzed the influence of the satellites' design parameters, e.g., the number of ground stations, satellites, planes, and inter-satellite links, on the reliability (i.e., the RTT and packet loss) of the ground-to-satellite connections. * We demonstrated two scenarios involving the utilization of LEO satellite constellations for the communication among the IoT devices. * We performed a Case Study, in which we integrated the real data obtained from the Smart Santander sensors into OMNeT++ to examine the transmission to the testbeds located in the EU and the U.S. The remainder of this paper is organized as follows: In Section 2, we outline the related work, focusing on the relevant research areas and the implementations in OMNeT++.