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Title
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Energy-efficient positioning for the Internet of Things
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Author
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Abstract
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| Location data is required for a plethora of Internet of Things (IoT) applications running on billions of mobile devices worldwide. A few example applications include asset tracking, search-and-rescue operations and the scientific monitoring of air or water quality. Global Navigation Satellite Systems (GNSSs), such as Global Positioning System (GPS) or Galileo, have been established as the standard for worldwide localization. However, the rapidly increasing need to locate IoT devices in recent years has exposed several shortcomings of traditional GNSS approaches. These limitations include the weak signal propagation in indoor and dense environments, a high energy consumption and the inability to communicate a location to a remote end user. Therefore, several industries have shown an increasing demand for alternative, innovative, and energy-efficient positioning solutions that are more suited in an IoT context. In contrast to GNSS, Low Power Wide Area Networks (LPWANs) were designed for energy-efficient communication of small sensor readings in a metropolitan area. In this type of terrestrial networks, thousands of IoT devices can send a message to nearby gateways, which in turn deliver the message to a central server. Interestingly, the uplink communication signals can be exploited to locate the mobile transmitter. Such a localization approach benefits from the low-power and low-cost LPWAN communication, as well as from the coverage in indoor environments. Another very promising alternative to GNSS is the use of satellites in Low Earth Orbit (LEO) for Positioning, Navigation and Timing (PNT). Driven by the recent ‘New Space’ movement, the commercialization of the space market has opened the door to a myriad of opportunities. The thousands of LEO satellite launches of Iridium, SpaceX, Amazon, OneWeb and many others enable applications such as high-quality satellite telephony, worldwide Internet access and smart agriculture through Earth Observation. Providing PNT services through LEO satellites in an energy-efficient way will only improve the value of these applications in the the emerging market of satellite IoT. The objective of this thesis is to investigate innovative, large-scale, and energy-efficient positioning technologies and techniques in the context of IoT. I examine how wireless networks, either terrestrial or space-based, can be leveraged for locating IoT devices, and how I can improve their positioning performance. The performance analysis and optimization of localization using LPWAN technologies constitute a significant part of the work in this thesis. To this end, three major LPWAN technologies are investigated: Sigfox, LoRaWAN and Narrowband IoT (NB-IoT). Localization experiments are carried out using real-world measurement data collected in Antwerp, Belgium. Within these experiments, I analyze the performance of Received Signal Strength (RSS)-based positioning algorithms. More specifically, I evaluate different path loss models in range-based algorithms and apply Machine Learning to optimize the performance of RSS-based fingerprinting methods. Furthermore, I discuss how the positioning performance can be further improved through changes in network infrastructure and User Equipment (UE). In the final part of this work, I conduct a survey for the European Space Agency (ESA) with the goal to explore innovative space-based PNT solutions, again with a focus on low energy consumption. I analyze the state-of-the-art performance of novel GNSS approaches, such as Assisted GNSS (A-GNSS) and snapshot processing techniques (S-GNSS). When compared to conventional pseudoranging, these techniques significantly reduce the overall energy consumption of the UE. Moreover, my survey covers the potential of Doppler positioning techniques leveraging LEO satellite Signals of Opportunity (SOOP), as well as the promising dedicated LEO-PNT systems under development. IoT-enabled devices have different constraints and application requirements. Therefore, the important trade-off between positioning accuracy and energy consumption is discussed throughout this work. There exists no one-size-fits-all technology that performs excellent in any use case in terms of these two parameters. Thus, interoperability between technologies is key to enable global energy-efficient communication and positioning applications. |
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Language
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English
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Publication
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Antwerp
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University of Antwerp, Faculty of Applied Engineering
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2023
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ISBN
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978-90-5728-772-5
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Volume/pages
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xxvi, 172 p.
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Note
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Weyn, Maarten [Supervisor]
:
Berkvens, Rafael [Supervisor]
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Full text (open access)
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