Browsing by Author "Garzaniti, Nicola"

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    Architecting CubeSat constellations for messaging service, Part I
    (Elsevier, 2024-10-01) Osipova, Ksenia; Camps, Adriano; Golkar, Alessandro; Ruiz-de-Azua, Joan A.; Fernandez, Lara; Garzaniti, Nicola
    In today's modern and globalized world, connectivity is a key factor for businesses, production facilities, sensor networks, and ordinary people. However, there are still populated areas which are not covered by ground-based telecommunications infrastructure. This is where telecommunication satellite constellations come in, as they can provide coverage to remote and uninhabited regions and fill existing connectivity gaps to ensure data transfer. LoRa is one of the technologies designed for data transmissions over long distances with low power consumption. Alongside with other technologies of the Low-Power Wide Area Network family, it is widely used for Internet of Things applications. LoRa chirp spread spectrum modulation is robust against the Doppler frequency shifts encountered in low earth orbits, and it has already been used in IoT satellite communications. Due to the low transmitted signal power, the achieved data rate is not high, making it a suitable technology for telecommunications payloads on CubeSat platforms for messaging services. As compared to existing traditional communication satellite systems, CubeSat constellations are low-cost and may offer an affordable connectivity service to developing regions. This study is divided in two parts. In Part I the demand model is built based on the population distribution not covered by cell towers. The LoRa link performance is analyzed, considering the impact of LoRa channel parameters variation, such as spreading factor and channel bandwidth, while satellite orbital height, transmission antenna beamwidth, and transmitter peak power have a direct impact on the payload mass. Among thousands of possible configurations, 73 feasible payload designs have been downselected. In Part II of the study, the satellite mass and the total system cost are estimated based on the payload parameters obtained. Messages transmission simulation via a constellation is conducted in order to identify optimal constellation architectures for messaging service, as well as the main drivers of the system economic profitability. The presented analysis results provide a deeper understanding of LoRa connectivity advantages and limitations together with the performance drivers, which will support the optimization of future LoRa-based satellite communication systems and other IoT satellite constellations.
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    Enhancing 5G global connectivity via satellite constellations: preliminary sizing of phased array antennas using a heuristic solver with genetic algorithms
    (International Astronautical Federation (IAF), 2023-10-06) Koenig, Anton; Morea, Albert; Capell, Elliot; Vargas Avila, Gerardo; Garzaniti, Nicola
    Satellite 5G connectivity to handheld devices is a critical technology that has significant benefits in various areas, such as remote healthcare, emergency response, and global connectivity. Achieving this requires state-of-the-art satellite constellations that can provide high-speed, reliable, and low-latency connections. Phased array antennas are a key component of these constellations, providing directional, high-gain signals, and beamforming capabilities to enable the delivery of high-speed and reliable data transfer. In this paper, we propose an approach to preliminary sizing of phased array antennas for 5G satellite connectivity accounting for stakeholders’ requirements and use cases constraints. To optimize the configuration of phased array antennas, we explore the tradespace of feasible design configurations using a heuristic solver approach leveraging genetic algorithms. The tradespace exploration has been constrained with link budget limit, launcher mass and volume, launch capacity, and minimum system performance. Building on this information, the solver identifies the near-optimal configurations that meet design specifications while maximizing satellite throughput. The results stemming from the application of the method and related tool, demonstrate the potential of our approach to build systems that deliver high-speed and reliable connectivity to handheld devices from space, enabling remote healthcare, emergency response, and global connectivity. Overall, this paper presents a novel and efficient approach to optimizing the configuration of phased array antennas for satellite 5G connectivity, and our findings offer opportunities to enhance the design and performance of satellite constellations by quickly converging to a preliminary sizing of a viable option eventually refined in later stages of design and development of the spacecraft system.
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    FSSCat: the Federated Satellite Systems 3 Cat Mission: demonstrating the capabilities of CubeSats to monitor essential climate variables of the water cycle
    (IEEE, 2022-11-30) Camps, Adriano; Munoz-Martin, Joan Francesc; Ruiz-de-Azua, Joan Adrià; Garzaniti, Nicola
    The Federated Satellite Systems/ 3 Cat-5 (FSSCat) mission was the winner of the European Space Agency (ESA) Sentinel Small Satellite (S 3 ) Challenge and overall winner of the 2017 Copernicus Masters competition. It consisted of two six-unit CubeSats. The Earth observation payloads were 1) the Flexible Microwave Payload 2 (FMPL-2) onboard 3 Cat-5/A, an L-band microwave radiometer and GNSS reflectometer (GNSS-R) implemented using a softwaredefined radio (SDR), and 2) the HyperScout-2 onboard 3 Cat-5/B, a hyperspectral camera, with the first experiment using artificial intelligence to discard cloudy images. FSSCat was launched on 3 September 2020 and injected into a 535-km synchronous orbit. 3 Cat-5/A was operated for three months until the payload was probably damaged by a solar flare and coronal mass ejection. During this time, all scientific requirements were met, including the generation of coarse-resolution and downscaled soil moisture (SM) maps, sea ice extent (SIE) maps, concentration and thickness maps, and even wind speed (WS) and sea surface salinity (SSS) maps, which were not originally foreseen. 3 Cat-5/B was operated a few more months until the number of images acquired met the requirements. This article briefly describes the FSSCat mission and the FMPL-2 payload and summarizes the main scientific results.
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    Spacecraft conjunction assessment optimisation using deep learning algorithms applied to conjunction data messages (CDMs)
    (International Astronautical Federation (IAF), 2023-10-06) Rosales Ruiz, Jose Javier; Garzaniti, Nicola
    The lack of global regulations on space debris management during the early days of the space era until the last few decades of the 20th century resulted in a consistent increase in space debris. Spacecraft collisions in orbit and the industry's growing interest in launching constellations of satellites are now exacerbating the problem. To address those concerns, multiple space organisations worldwide have implemented Situational Space Awareness programmes with integrated Conjunction Assessment systems that allow the detection of spacecraft conjunctions with an estimated collision risk probability. While this approach has proved effective in the last two decades, the foreseen increment of artificial space objects in orbit in the coming years will put any existing system under severe stress if the technology does not evolve to match the new demands. The objective of this research is two-fold: it evaluates different architectures used in the field of Deep Learning to increase the accuracy of on-orbit Conjunction Events forecasting. It provides a multi-purpose modular, Machine Learning based Python library to support Conjunction Assessment activities. The results of this study show that simpler cell architectures used in the Recurrent Neural Networks outperform the corresponding Vanilla versions in terms of accuracy for the problem at hand. It also demonstrates that the attention mechanism provides the best performance with up to 40% more accuracy.
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    System design study of a constellation of small spacecraft to deliver seamless 5G connectivity to unmodified cell phones through an end-to-end non-terrestrial network
    (International Astronautical Federation (IAF), 2023-10-06) Vargas Avila, Gerardo; Anastasopoulos, Marios; Liao, Zuliang; Morea, Albert; Capell, Elliot; Koenig, Anton; López Buqué, Iñigo; Ravishankar, Sreekrishna; Ruiz, Diego Larrauri; Cordova, Asis; Haynez, Guillaume; Kommareddy, Sai Tejaswi; Garzaniti, Nicola
    The increasing demand for high-speed mobile data services has led to the development of 5G and 6G technology, which promises to revolutionize the way people access and use the internet. However, the full exploitation of 5G network potential is often limited by the challenges related to the deployment of the physical infrastructure required to support these networks. In order to address these limitations, a new approach is needed to bring 5G services to areas that are currently underserved. This paper presents the results of a system design study that explores the use of a constellation of small spacecraft to deliver seam-less 5G connectivity to unmodified cell phones, through an endto-end non-terrestrial network. Within the study, several use cases have been considered including offering enhanced service to cities and connecting areas not served by traditional mobile services such as remote regions, ships and offshore platforms, regions hit by natural disasters and contested battlefields. A trade space exploration approach was undertaken to identify the optimal solution for meeting stakeholders’ requirements associated with the different use cases. The analysis explores the effects of key architectural decisions on overall system performance and lifecycle cost, benchmarking them against foreseen customers’ needs and market demand. A variety of alternatives were evaluated including the number of satellites, types of orbits, number of orbital planes, satellite size, weight and power, antenna technologies, inter-satellite links technologies and routing schemes among others. As a result, it was proposed the use of a constellation of about 3000 satellites in a sun-synchronous Low Earth Orbit (LEO) orbit, with a satellite lifetime of 5 years. Each satellite is equipped with a phased array antenna in 5G non-terrestrial band frequency n256 for direct connectivity to unmodified user cell phones and free space optical telecommunication terminals for on-orbit backhauling. Commercial Off-The-Shelf (COTS) components for spacecraft subsystems and sensors were considered when available. With more than 95% of Earth coverage and high system scalability, the mission represents a promising solution for providing global 5G connectivity paving the way for a more connected world.