Finite buffer queuing delay performance in the low earth orbit land mobile satellite channel

Low Earth Orbit (LEO) satellite constellations have been identified for new massive access networks, as a complement to traditional cellular ones, due to their native ubiquity. Despite being a feasible alternative, such networks still raise questions on their performance, in particular regarding the delay and queuing management under realistic channels. In this work, we study the queuing delay of a single satellite-to-ground link, considering a Land Mobile Satellite (LMS) channel in LEO with finite buffer lengths. We analyze the trade-off between delay and packet loss probability, using a novel model based on Markov chains, which we assess and extend with an extensive analysis carried out by means of system level simulation. The developed tools capture with accuracy the queuing delay statistical behavior in the S and Ka frequency bands, where LEO communications are planned to be deployed. Our results show that we can use short buffers to ensure less than 5-10% packet loss, with tolerable delays in such bands.This project was funded by the EU Horizon 2020 re search and innovation program, Drones4Safety-agreement No 861111, the Innovation Fund Denmark project Drones4Energy with project J. nr. 8057-00038A and by the Spanish Government (Ministerio de Economía y Competitividad, Fondo Europeo de Desarrollo Regional, MINECO-FEDER) by means of the project FIERCE: Future Internet Enabled Resilient Smart CitiEs (RTI2018-093475-AI00)

On the queuing delay of time-varying channels in Low Earth Orbit satellite constellations

Low Earth Orbit (LEO) satellite constellations are envisioned as a complementary or integrated part of 5G and future 6G networks for broadband or massive access, given their capabilities of full Earth coverage in inaccessible or very isolated environments. Although the queuing and end-to-end delays of such networks have been analyzed for channels with fixed statistics, currently there is a lack in understanding the effects of more realistic time-varying channels for traffic aggregation across such networks. Therefore, in this work we propose a queuing model for LEO constellation-based networks that captures the inherent variability of realistic satellite channels, where ground-to-satellite/satellite-to-ground links may present extremely poor connection periods due to the Land Mobile Satellite (LMS) channel. We verify the validity of our model with an extensive event-driven simulator framework analysis capturing the characteristics of the considered scenario. We later study the queuing and end-to-end delay distributions under such channels with various link, traffic, packet and background conditions, while observing good match between theory and simulation. Our results show that ground-to-satellite/satellite-to-ground links and background traffic have a much stronger impact over the end-to-end delay in mean and particularly variance, even with moderate queues, than unobstructed inter-satellite connections in outer space on an established path between two ground stations and through the constellation. This might hinder the usability of these networks for services with stringent time requirements.This work was supported in part by the European Union’s Horizon 2020 Research and Innovation Programme under Grant 861111, in part by the Innovation Fund Denmark Project Drones4Energy under Project J.nr.8057-00038A, and in part by the Spanish Government through the Ministerio de Economía y Competitividad, Fondo Europeo de Desarrollo Regional (MINECO-FEDER) by the Project Future Internet Enabled Resilient smart CitiEs (FIERCE) under Grant RTI2018-093475-AI00

Delay over LEO networks: modeling and analysis

RESUMEN: A lo largo de los años las tecnologías han evolucionado, hasta tal punto en que las redes convencionales y satelitales, que han estado siempre presentes, van a cohesionar, con el fin de proporcionar especialmente cobertura desde cualquier punto, sin importar la localización y, así, cubrir la creciente demanda, siendo relevante el incremento del IoT. Entre las diferentes órbitas, este proyecto se centra en el estudio de las comunicaciones satelitales LEO. Una de sus principales ventajas, es la baja latencia, al tratarse de la órbita más cercana a la Tierra. Otra de sus características, es la conexión continua, garantizada por estar en movimiento con relación a la Tierra. A lo largo de este trabajo, se expondrá el modelado del canal tierra-satélite, incluyéndose también enlaces inter-satelitales. Su estudio se realiza mediante un simulador por eventos desarrollado por el Grupo de Ingeniería Telemática. Posteriormente se realizará un análisis estadístico de los resultados, con el fin de estimar el comportamiento de la red en supuestos realistas.ABSTRACT: Technology has evolved rapidly over a relatively short period of time, to such extent that conventional networks and Non-Terrestrial Networks, which have always been there, are being jointly considered to provide coverage from anywhere, regardless the location, and to meet the increasing demand, being particularly relevant the looming of IoT communications. Between existing satellite orbits, this project focuses on LEO communications. One of their key advantages is the low latency, due to the shorter distance to the Earth. Another key feature is the “always-on” connectivity, which is ensured by the continuous movement with respect to the Earth. In this BSc Thesis, we have thoroughly studied the performance of the satellite-to-ground channel, as well as the subsequent inter satellite links. The analysis will be carried out by an event-driver simulator, developed by the Grupo de Ingeniería Telemática. We will extensively analysis the statistics of the obtained results, in order to shed light on the network performance for different realistic scenariosGrado en Ingeniería de Tecnologías de Telecomunicació