本文爲美國弗吉尼亞理工學院暨州立大學（作者：Mohammad Mozaffari）的博士論文，共259頁。
使用無人機（UAV）等空中平臺已成爲提供可靠和經濟高效的無線通信的一個有希望的解決方案。特別是，無人機可以快速有效地部署，以支持蜂窩網絡的運行，並通過建立視線通信鏈路來提高其服務質量（QoS）。無人機具有機動性、靈活性和自適應高度等固有特性，在無線系統中有着非常重要的潛在應用。值得注意的是，儘管基於無人機的通信具有這些固有的優勢，但很少有人分析將無人機用作空中無線平臺時的性能權衡與折中。
本文的主要目標是爲無人機無線網絡的部署、性能分析和優化奠定分析基礎。本文對無人機通信的各個領域做出了一些基本貢獻，包括：
1）無人機的高效部署；
2）性能評估和優化；
3）新型飛行、三維（3D）無線系統的設計。
在部署方面，利用優化理論中的工具，開發了無人機基站在上下行場景中的三維優化佈局的整體框架。結果表明，所提出的部署方法顯著提高了地面用戶的下行鏈路覆蓋率，使物聯網（IoT）應用中的上行鏈路通信具有超可靠和節能的特點。
在性能優化方面，提出了一種基於無人機的無線系統在無人機飛行時間約束下的數據服務性能優化框架。爲此，利用最優傳輸理論的數學框架，分析推導了在有限的無人機懸停時間內，使地面用戶獲得最大數據服務的最優小區關聯。研究結果爲無人機無線網絡中懸停時間和服務質量之間的權衡提供了依據。
在性能評估方面，本文對無人機通信系統與地面網絡共存時的性能進行了綜合分析。特別地，提出了一個簡單的分析框架，用於分析具有無人機基站和設備到設備（D2D）用戶的網絡覆蓋率和速率性能。研究結果揭示了這種無人機D2D網絡中的基本折衷，從而允許採用適當的系統設計參數。
然後，本文對三種新型無人機無線系統的設計進行了研究。首先，提出了一種在無線網絡中有效使用高速緩存無人機的新框架。結果表明，利用無人機的機動性和以用戶爲中心的信息，用戶的體驗質量是如何顯著提高的。其次，提出了一種新的部署和操作基於無人機的天線陣列系統框架，該系統在最短時間內向地面用戶提供無線服務。結果表明，該無人機天線陣列系統在服務質量、頻譜和能量效率方面都有顯著提高。最後，爲了有效地結合從空中用戶到基站的各種無人機用例，引入了成熟的3D蜂窩網絡的新概念。對於這種新型的三維無線網絡，開發了一個用於部署、網絡規劃和性能優化的統一框架，從而在網絡中產生最大的覆蓋率和最小的延遲。總之，本文的分析基礎和框架爲無人機無線通信系統的有效設計和運行提供了重要的指導。
The use of aerial platforms such asunmanned aerial vehicles (UAVs), popularly known as drones, has emerged as apromising solution for providing reliable and cost-effective wirelesscommunications. In particular, UAVs can be quickly and efficiently deployed tosupport cellular networks and enhance their quality-of-service (QoS) byestablishing line-of-sight communication links. With their inherent attributessuch as mobility, flexibility, and adaptive altitude, UAVs admit several keypotential applications in wireless systems. Remarkably, despite these inherentadvantages of UAVbased communications, little work has analyzed the performancetradeoffs associated with using UAVs as aerial wireless platforms. The key goalof this dissertation is to develop the analytical foundations for deployment,performance analysis, and optimization of UAV-enabled wireless networks. Thisdissertation makes a number of fundamental contributions to various areas ofUAV communications that include: 1) Efficient deployment of UAVs, 2)Performance evaluation and optimization, and 3) Design of new flying,three-dimensional (3D) wireless systems. For deployment, using tools fromoptimization theory, holistic frameworks are developed for the optimal 3Dplacement of UAV base stations in uplink and downlink scenarios. The results showthat the proposed deployment approaches significantly improve the downlinkcoverage for ground users, and enable ultra-reliable and energy-efficientuplink communications in Internet of Things (IoT) applications. For performanceoptimization, a novel framework is developed for maximizing the performance ofa UAV-based wireless system, in terms of data service, under UAVs’ flight timeconstraints. To this end, using the mathematical framework of optimal transporttheory, the optimal cell associations, that lead to a maximum data service toground users within the limited UAVs’ hover duration, are analytically derived.The results shed light on the tradeoff between hover time andquality-of-service in UAV-based wireless networks. For performance evaluation,this dissertation provides a comprehensive analysis on the performance of aUAV-based communication system in coexistence with a terrestrial network. Inparticular, a tractable analytical framework is proposed for analyzing thecoverage and rate performance of a network with a UAV base station anddeviceto-device (D2D) users. The results reveal the fundamental tradeoffs insuch a UAV-D2D network that allow adopting appropriate system designparameters. Then, this dissertation sheds light on the design of three newdrone-enabled wireless systems. First, a novel framework for effective use ofcache-enabled UAVs in wireless networks is developed. The results demonstratehow the users’ quality of experience substantially improves by exploiting UAVs’mobility and user-centric information. Second, a new framework is proposed fordeploying and operating a drone-based antenna array system that deliverswireless service to ground users within a minimum time. The results showsignificant enhancement in QoS, spectral and energy efficiency while leveringthe proposed drone antenna array system. Finally, to effectively incorporatevarious use cases of drones ranging from aerial users to base stations, the newconcept of a fully-fledged 3D cellular network is introduced. For this new typeof 3D wireless network, a unified framework for deployment, network planning,and performance optimization is developed that yields a maximum coverage andminimum latency in the network. In a nutshell, the analytical foundations andframeworks presented in this dissertation provide key guidelines for effectivedesign and operation of UAV-based wireless communication systems.
- 研究動機、項目背景與本文貢獻
- 有效部署多架無人飛行器實現最佳無線覆蓋
- 應用於節能物聯網通信的移動無人機
- 無人機無線網絡中的懸停時間優化
- 地面設備對設備網絡無人機基本性能分析
- 無線網絡中支持緩存的無人機
- 無線無人機天線陣的通信與控制
- 無人機蜂窩網絡中小區關聯的最優傳輸理論
- 無人機B5G：3D無線蜂窩網絡的基礎
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繫留氣球接力高空平臺無人機的和速率分析 -
結論與開放問題
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