Optimising Beam Size in Multibeam LEO Satellite Networks: Addressing Interbeam Interference, Doppler Shift, and Frequency Reuse

Weththasinghe, K; Ngo, QT; He, Y; Jayawickrama, B

Optimising Beam Size in Multibeam LEO Satellite Networks: Addressing Interbeam Interference, Doppler Shift, and Frequency Reuse

Weththasinghe, K Ngo, QT He, Y Jayawickrama, B

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Publisher:: Institute of Electrical and Electronics Engineers (IEEE)
Publication Type:: Journal Article
Citation:: IEEE Transactions on Aerospace and Electronic Systems, 2024, PP, (99), pp. 1-15
Issue Date:: 2024-01-01

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Field	Value	Language
dc.contributor.author	Weththasinghe, K
dc.contributor.author	Ngo, QT
dc.contributor.author	He, Y
dc.contributor.author	Jayawickrama, B
dc.date.accessioned	2025-01-16T03:25:22Z
dc.date.available	2025-01-16T03:25:22Z
dc.date.issued	2024-01-01
dc.identifier.citation	IEEE Transactions on Aerospace and Electronic Systems, 2024, PP, (99), pp. 1-15
dc.identifier.issn	0018-9251
dc.identifier.issn	1557-9603
dc.identifier.uri	http://hdl.handle.net/10453/183772
dc.description.abstract	Low Earth orbit (LEO) satellites offer a robust and promising solution for enhancing 6G connectivity by providing increased coverage and improved communication capabilities. In multibeam LEO satellite systems, the size of the spot beam plays a critical role in affecting interference and residual Doppler shift experienced by LEO users, thereby significantly impacting overall network performance. This paper focuses on optimising the spot beam radius in multibeam LEO systems by addressing key challenges in practical LEO deployments, such as Doppler shift, interbeam interference, and various frequency reuse schemes. We investigate three scenarios: no frequency reuse, full frequency reuse, and higher frequency reuse. An analytical framework is developed to design a multibeam LEO system with an optimal spot beam size and frequency reuse scheme that maximises system capacity while minimising interbeam interference. Corresponding optimisation problems are formulated for each scenario. To address the non-convex nature of these optimisation problems, we employ the Successive Convex Approximation method, converting them into simplified simplex forms. Through simulations, we determine the optimal beam radius and frequency reuse scheme for each scenario and analyse per-user capacity. Our results are benchmarked against a grid-based search method, demonstrating that our analytical approach provides optimal solutions with lower computational complexity. This study offers valuable insights into the design of multibeam LEO satellite systems that optimise capacity and reduce interference.
dc.language	en
dc.publisher	Institute of Electrical and Electronics Engineers (IEEE)
dc.relation.ispartof	IEEE Transactions on Aerospace and Electronic Systems
dc.relation.isbasedon	10.1109/TAES.2024.3522870
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	0901 Aerospace Engineering, 0906 Electrical and Electronic Engineering, 0909 Geomatic Engineering
dc.subject.classification	Aerospace & Aeronautics
dc.subject.classification	4001 Aerospace engineering
dc.subject.classification	4006 Communications engineering
dc.subject.classification	4009 Electronics, sensors and digital hardware
dc.title	Optimising Beam Size in Multibeam LEO Satellite Networks: Addressing Interbeam Interference, Doppler Shift, and Frequency Reuse
dc.type	Journal Article
utslib.citation.volume	PP
utslib.for	0901 Aerospace Engineering
utslib.for	0906 Electrical and Electronic Engineering
utslib.for	0909 Geomatic Engineering
pubs.organisational-group	University of Technology Sydney
pubs.organisational-group	University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	University of Technology Sydney/Faculty of Engineering and Information Technology/School of Electrical and Data Engineering
utslib.copyright.status	open_access	*
dc.date.updated	2025-01-16T03:25:21Z
pubs.issue	99
pubs.publication-status	Published
pubs.volume	PP
utslib.citation.issue	99

Abstract:

Low Earth orbit (LEO) satellites offer a robust and promising solution for enhancing 6G connectivity by providing increased coverage and improved communication capabilities. In multibeam LEO satellite systems, the size of the spot beam plays a critical role in affecting interference and residual Doppler shift experienced by LEO users, thereby significantly impacting overall network performance. This paper focuses on optimising the spot beam radius in multibeam LEO systems by addressing key challenges in practical LEO deployments, such as Doppler shift, interbeam interference, and various frequency reuse schemes. We investigate three scenarios: no frequency reuse, full frequency reuse, and higher frequency reuse. An analytical framework is developed to design a multibeam LEO system with an optimal spot beam size and frequency reuse scheme that maximises system capacity while minimising interbeam interference. Corresponding optimisation problems are formulated for each scenario. To address the non-convex nature of these optimisation problems, we employ the Successive Convex Approximation method, converting them into simplified simplex forms. Through simulations, we determine the optimal beam radius and frequency reuse scheme for each scenario and analyse per-user capacity. Our results are benchmarked against a grid-based search method, demonstrating that our analytical approach provides optimal solutions with lower computational complexity. This study offers valuable insights into the design of multibeam LEO satellite systems that optimise capacity and reduce interference.

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http://hdl.handle.net/10453/183772