Cooperative Reception of Small Satellites' Signals Based on Diversity Combining

Haidar Najim Abbod AL-ANBAGI

Doctoral thesis

Optimization of new generations communication, broadcasting and IoT networks

Abstract:

Internet of Things (IoT) networks connect countless devices in endless daily life applications. However, current IoT coverage is not yet ubiquitous to the less inhabited and harsh environments such as oceans, forests, mountains, poles, and deserts. Accordingly, for an omnipresent coverage of the future Sixth Generation (6G), satellites must be integrated into terrestrial IoT networks. Small satellites in the Low Earth Orbit (LEO) are very popular nowadays and have already attracted attention towards such integration. However, the size constraints of small satellites impose limited transmitting power and tiny antennas onboard. Consequently, weak signals and higher outages are more probable at the receiving Ground Station (GS). Therefore, the GS must utilize high gain directive antennas with complex and expensive steering resources to collect such weak signals via a single radio link. This traditional communication scheme can track only one satellite at a time with more vulnerability to outages resulting from possible severe signal degradations or from sudden steering engine failures. To contribute to a successful integration of the popular but restricted small satellites into the future 6G ubiquitous IoT networks, this work presents a GS-based solution through a cooperative reception scheme in which diversity combining is utilized. The theoretical part of this work structured, modeled, and simulated the suggested cooperative scheme and developed a simple yet efficient combining method. The results of the simulated model revealed a significant reduction in the Bit Error Rate (BER) for a group of GSs when working in a diversity mode compared to the conventional single site mode. To validate the proposed concept, this dissertation carried out a real deployment of the cooperative reception scheme in combining real small satellites' signals. According to the experimental findings, if multiple GSs worked cooperatively in a diversity mode and shared their received streams, they could generate a combined version that was always better than any other individually received stream. Indeed, the endorsed cooperative reception assured a significant reduction in BER, decreased probability of outages, and meanwhile enabled the simultaneous tracking of multiple satellites. The achieved diversity gain is promising enough to even trigger the idea of replacing the current expensive directive receiving antennas and their complex steering resources with much more affordable omnidirectional ones.

Abstract:

Internet of Things (IoT) networks connect countless devices in endless daily life applications. However, current IoT coverage is not yet ubiquitous to the less inhabited and harsh environments such as oceans, forests, mountains, poles, and deserts. Accordingly, for an omnipresent coverage of the future Sixth Generation (6G), satellites must be integrated into terrestrial IoT networks. Small satellites in the Low Earth Orbit (LEO) are very popular nowadays and have already attracted attention towards such integration. However, the size constraints of small satellites impose limited transmitting power and tiny antennas onboard. Consequently, weak signals and higher outages are more probable at the receiving Ground Station (GS). Therefore, the GS must utilize high gain directive antennas with complex and expensive steering resources to collect such weak signals via a single radio link. This traditional communication scheme can track only one satellite at a time with more vulnerability to outages resulting from possible severe signal degradations or from sudden steering engine failures. To contribute to a successful integration of the popular but restricted small satellites into the future 6G ubiquitous IoT networks, this work presents a GS-based solution through a cooperative reception scheme in which diversity combining is utilized. The theoretical part of this work structured, modeled, and simulated the suggested cooperative scheme and developed a simple yet efficient combining method. The results of the simulated model revealed a significant reduction in the Bit Error Rate (BER) for a group of GSs when working in a diversity mode compared to the conventional single site mode. To validate the proposed concept, this dissertation carried out a real deployment of the cooperative reception scheme in combining real small satellites' signals. According to the experimental findings, if multiple GSs worked cooperatively in a diversity mode and shared their received streams, they could generate a combined version that was always better than any other individually received stream. Indeed, the endorsed cooperative reception assured a significant reduction in BER, decreased probability of outages, and meanwhile enabled the simultaneous tracking of multiple satellites. The achieved diversity gain is promising enough to even trigger the idea of replacing the current expensive directive receiving antennas and their complex steering resources with much more affordable omnidirectional ones.

Keywords

Cooperative reception, Diversity combining, Receive diversity, Software defined radio (SDR), SIMO, Satellite Internet of Things (SIoT), Small satellites, Virtual ground station.

Language used: English

Date on which the thesis was submitted / produced: 31. 10. 2023

Accessible from:: 31. 12. 2999

Thesis defence

• Supervisor: Doc. Ing. Jiří Masopust, CSc., Ing. Ivo Veřtát, Ph.D.

University of West Bohemia

Faculty of Electrical Engineering

Doctoral programme / field:
Electrical Engineering and Information Technology / Electrical Engineering and Information Technology