Machine-type Direct-to-Satellite Communications: Modeling and Performance Analysis
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
OP auditorium (L10), Linnanmaa
Topic of the dissertation
Machine-type Direct-to-Satellite Communications: Modeling and Performance Analysis
Doctoral candidate
MSc. Muhammad Asad Ullah
Faculty and unit
University of Oulu Graduate School, Faculty of Information Technology and Electrical Engineering, Centre for Wireless Communications - Networks and Systems (CWC-NS)
Subject of study
Communications Engineering
Opponent
Professor Symeon Chatzinotas, University of Luxembourg, Luxembourg
Custos
Associate Professor Konstantin Mikhaylov, University of Oulu
Machine-type Direct-to-Satellite Communications: Modeling and Performance Analysis
Despite the massive progress in 5G and beyond systems , the deployed terrestrial networks do not provide ubiquitous coverage on land. The situation is worse in the open sea, which covers 70% of the Earth's surface. The lack of coverage illustrates a significant digital divide. To address this vital need , global wireless coverage stands as one of the most crucial requirements for the upcoming 6G wireless networks.
This dissertation advocates for massive machine-type communication (mMTC) and low Earth orbit (LEO) satellite integration to enable direct connectivity from low-cost, low-power end devices to satellites without relying on a terrestrial network. This emerging form of connectivity, machine-type direct-to-satellite (DtS) communications, promises to bridge the digital divide for Internet-of-Things (IoT) machines. However, DtS presents challenges of its own which need to be carefully examined and addressed. Among these challenges is LEO satellite mobility, which introduces a strong Doppler effect and time-varying channel conditions. Similarly, the long link distance ranging from hundreds to thousands of kilometers and the wide satellite footprint contribute to high propagation losses and massive interference, respectively. Additionally, terrestrial end devices possess limited energy resources. Therefore, successful DtS operation requires high energy efficiency, allowing the low-power signals to reach satellites orbiting thousands of kilometers away from Earth.
Motivated by the low-power and long-range capabilities of LoRaWAN , this thesis selected LoRa and LR-FHSS-based solutions for the modeling. This dissertation develops novel Monte Carlo simulation and analytical models for DtS communications performance analysis. The results confirmed the feasibility and potential of both LoRa and LR-FHSS for DtS communications and highlighted the trade-off of different parameter configurations. In summary, LR-FHSS reveals better performance compared to LoRa .
LR-FHSS end devices are expected to be powered by battery, therefore, it is vital to investigate the energy consumption of LR-FHSS. This work conducts experiments using real-life end devices and measures the LR-FHSS air-time and current consumption. We leverage these empirical measurement results to develop analytical models which give us the energy efficiency and battery lifetime of LR-FHSS end devices. LR-FHSS air-time model is highly important for accurate collisions modeling and scalability analysis .
This dissertation advocates for massive machine-type communication (mMTC) and low Earth orbit (LEO) satellite integration to enable direct connectivity from low-cost, low-power end devices to satellites without relying on a terrestrial network. This emerging form of connectivity, machine-type direct-to-satellite (DtS) communications, promises to bridge the digital divide for Internet-of-Things (IoT) machines. However, DtS presents challenges of its own which need to be carefully examined and addressed. Among these challenges is LEO satellite mobility, which introduces a strong Doppler effect and time-varying channel conditions. Similarly, the long link distance ranging from hundreds to thousands of kilometers and the wide satellite footprint contribute to high propagation losses and massive interference, respectively. Additionally, terrestrial end devices possess limited energy resources. Therefore, successful DtS operation requires high energy efficiency, allowing the low-power signals to reach satellites orbiting thousands of kilometers away from Earth.
Motivated by the low-power and long-range capabilities of LoRaWAN , this thesis selected LoRa and LR-FHSS-based solutions for the modeling. This dissertation develops novel Monte Carlo simulation and analytical models for DtS communications performance analysis. The results confirmed the feasibility and potential of both LoRa and LR-FHSS for DtS communications and highlighted the trade-off of different parameter configurations. In summary, LR-FHSS reveals better performance compared to LoRa .
LR-FHSS end devices are expected to be powered by battery, therefore, it is vital to investigate the energy consumption of LR-FHSS. This work conducts experiments using real-life end devices and measures the LR-FHSS air-time and current consumption. We leverage these empirical measurement results to develop analytical models which give us the energy efficiency and battery lifetime of LR-FHSS end devices. LR-FHSS air-time model is highly important for accurate collisions modeling and scalability analysis .
Last updated: 30.8.2024