Seminar: Lightweight synchronization to NB-IoT enabled LEO Satellites through Doppler prediction

Abstract

    In the last decade, it has been quickly recognized that backhauling Low Power Wide Area Networks (LPWAN) through Low Earth Orbit (LEO) satellites paves the way to the development of novel applications for a truly ubiquitous Internet of Things (IoT). Among LPWAN communications technologies, Narrowband IoT (NB-IoT) does not suffer from interference by other concurrent technologies since it works on a licensed frequency spectrum. At the same time, thanks to its medium access scheme based on contention resolution and resource allocation, NB-IoT is a key enabler for the specific market slice of IoT applications requiring a good level of reliability. In the architectural configuration analyzed throughout this contribution, an NB-IoT low power User Equipment (UE) can communicate with a LEO satellite equipped with an Evolved Node B (eNB) for a time limited to the visibility window of that satellite from the UE position on the Earth. However, the Doppler effect inherent to the time-varying relative speed of the eNB needs to be dealt with additional resources. The solutions proposed until now are non-trivial, thus making the use of NB-IoT for ground-to-satellite communications still expensive and energetically inefficient. Timely, this contribution proposes a procedure for a UE to infer both the relative position of an eNB-equipped LEO satellite in its scope and the future values of the Doppler shift so that frequency pre-compensation can be easily applied in the following interactions during the visibility time. The presented simulation results show that a UE needs to listen to about 10 beacon signals in 1 second to accurately and robustly predict the Doppler curve, thus enabling a lightweight (and eventually truly energy-efficient) implementation of NB-IoT over ground-to-satellite links.

Bio

Dr. Nicola Accettura is associate researcher within the "Services and Architectures for Advanced Networks" team at LAAS-CNRS, Toulouse, France. His research targets design and performance evaluation of communication networks, focusing on power-efficient protocols for scalable Internet of Things (IoT) environments. Between 2014 and 2015 he was postdoctoral researcher at University of California Berkeley, USA, modeling and implementing scalable IoT networks within the OpenWSN project. He got his PhD in Information and Communication Technologies (2013) from Scuola Interpolitecnica di Dottorato, and both an MSc in Telecommunications Engineering (2007) and a BSc in Computer Systems Engineering (2004) from Politecnico di Bari, Italy.
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