基於Q學習之低軌道衛星通訊無人機中繼中斷分析與軌跡優化設計;Outage Analysis and Trajectory Design for UAV Relaying over LEO Satellite Communications via Q-Learning

NCUIR > College of Electrical Engineering & Computer Science > Graduate Institute of Communication Engineering > Electronic Thesis & Dissertation > Item 987654321/96273

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/96273

Title:	基於Q學習之低軌道衛星通訊無人機中繼中斷分析與軌跡優化設計;Outage Analysis and Trajectory Design for UAV Relaying over LEO Satellite Communications via Q-Learning
Authors:	邱睿祺;Chiu, Jui-Chi
Contributors:	通訊工程學系
Keywords:	低軌衛星;第六代行動通訊;無人機;解碼轉遞中繼;中斷機率
Date:	2024-12-31
Issue Date:	2025-04-09 17:31:45 (UTC+8)
Publisher:	國立中央大學
Abstract:	低軌衛星位於距地表約200至2000公里的軌道上，其快速運行和廣泛覆蓋使其在第六代行動通訊和數據傳輸中扮演關鍵角色。然由於低軌衛星覆蓋的時間和範圍有限，也易受到周遭環境遮蔽，地面用戶可能會遇到訊號中斷或品質不穩定的情況，因此需要尋求輔助方法來提升通訊效果。在本文的研究成果中，吾人以多無人機的機動性作為行動中繼站來改善低軌衛星與地面用戶之間的訊號品質，無人機可以快速部署並靈活調整位置，以確保訊號覆蓋的連續性和穩定性。吾人採用解碼轉遞中繼策略應用在包括多台無人機的無人機群上，地面用戶可以直接接收到來自低軌衛星或無人機中繼低軌衛星的訊號，利用選擇多樣性方法以提高地面用戶訊號品質。吾人建立了太空-空中-地面的三維的無人機群中繼通訊模型，並且理論分析多無人機各項系統參數對於低軌衛星服務地面用戶通訊效能的影響及效能提升的幅度，同時以電腦模擬驗證無人機群的解碼轉遞中繼策略之系統效能，研究成果顯示無人機作為低軌衛星之行動中繼站，能有效改善地面用戶通訊品質，為第六代通訊技術的發展提供了一個具有前景的解決方案。;Low Earth Orbit (LEO) satellites, positioned approximately 200 to 2000 kilometers above the Earth′s surface, play a critical role in sixth-generation (6G) mobile communications and data transmission due to their fast orbiting speeds and wide coverage. However, the limited coverage time and range of LEO satellites, along with potential environmental obstructions, can lead to communication outage or unstable quality for ground users. It thus necessitates auxiliary methods to enhance LEO communication performance. We utilized the mobility of multiple unmanned aerial vehicles (UAVs) as mobile relay stations to improve the signal quality between an LEO satellite and a ground user. UAVs can be rapidly deployed and flexibly adjusted to ensure continuous and stable signal coverage. We employed a decode-and-forward (DF) relay strategy for a swarm of UAVs, allowing the ground user to receive signals directly from the LEO satellite or via UAV relays, utilizing selection diversity to improve signal quality. We established a three-dimensional space-air-ground communication model for the UAV swarm and theoretically analyzed the impact of various network parameters of multiple UAVs on the communication performance of the LEO satellite serving ground users and the extent of performance improvement. Computer simulations were conducted to verify the system performance of the DF relay strategy of the UAV swarm. The research results indicated that UAVs as mobile relay stations for LEO satellites can effectively enhance ground user communication quality, providing a promising solution for the development of 6G communication technology.
Appears in Collections:	[Graduate Institute of Communication Engineering] Electronic Thesis & Dissertation

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