由於通訊網路的快速發展，我們生活中越來越倚重行動通訊設備，造成網路頻寬及傳輸速率的需求量增加，行動網路目前也已經步入第四代行動通訊的通訊架構，預期可增加千倍網路容量的第五代行動通訊，也正積極發展中，預計在2020年登場。為了因應爆漲的網路傳輸量，未來5G的研究方向也以能夠提升頻譜效能的技術為目標，挑戰高容量、高速、低延遲的傳輸品質。非正交多址接取技術(Non-Orthogonal Multiple Access)為目前熱門的候選技術之一，目前的多工接取技術，大多利用時域、頻域或是碼域之區隔，將彼此正交之通訊資源個別分配給多個使用者進行資料傳輸，而非正交多址接取技術，則是在功率域(power-domain)上，將同一通訊資源(時域、頻域等)分享給多個使用者共同使用，並且能有效地提升頻譜使用效能。在本論文中，我們將考慮一下鏈(downlink)多輸入輸出傳輸系統，使用非正交多址接取技術，將訊號利用重疊編碼(superposition coding)疊加並傳送，系統中我們考慮基地台有多根天線，且可根據完美的通道資訊優化傳輸訊號，使用者裝置有單根天線，並且能使用連續性干擾消除提升訊號與雜訊比(signal-to-interference-plus-noise ratio)。我們將根據通道的狀況，以及通道之間的夾角，設計基地台傳輸訊號時的波束賦形向量，以及最佳化二來源訊號之功率分配，使系統總傳輸率(sum rate)達到最大。論文中，我們考慮兩種波束賦形策略，一種是匹配至較強通道(match to stronger channel,MSC)的波束賦形向量，另一種則使用利用梯度法(gradient)找出最大總傳輸率的波束賦形方向。我們的結果顯示，使用非正交多址接取技術下，使用本論文設計的波束賦形以及功率分配，其系統總傳輸速率，會比使用正交多址接取系統之傳輸速率大，並且使用最佳化之波束賦形向量，其可支援的二使用者通道夾角，也比使用MSC的波束賦形向量寬廣。

Due to the rapid development of communication networks, people gradually increasingly rely on mobile communication devices in their daily life, resulting in increasing demand for network bandwidth and transmission rate.To satisfy serve requirement, mobile communications have developed toward the fourth generation systems. In the near future, the Fifth-generation mobile communications network which is expected to boost thousands times of capacity will be deployed in 2020. To deal with explosion amount of data transmission, 5G systems aim to enhance spectrum efficiency, network capacity, transmission rate, and reduce latency in the future. Non-orthogonal multiple access (NOMA) technique is one of key candidates currently. Multi-accepting technologies mostly allocate orthogonal radio resourced multiple users in time-domain, frequency domain, or code domain. By contrast, NOMA technology allows users access and share the same radio resource through multiple-access in power domain in order to effectively improve spectrum efficiency. In this paper, we consider a multi-input multi-output (MIMO) down-link system where using non-orthogonal multiple access technology is adopted.The base station uses superposition coding to superimpose signals regarding multiple users. We propose to optimize the transmission of a MIMO base station toward multiple users equipped with antenna based on perfect channel state information. The user can use successive interference cancellation to enhance the signal and interference plus noise ratio. We will design the beamforming vector of the base station as well as the optimal power allocation of downlink users, in order to maximize sum rate of the downlink system. In this paper, we consider two beamforming strategies, one is to match the beamforming vector to the stronger channel (MSC), and the other is to find the optimal beamforming vector in terms of maximum sum rate. Our results show that the proposed NOMA scheme achieves higher sum rate than conventional orthogonal multiple access system. With optimal beamforming vector, the propose scheme can support higher rate even when the geometrical angle between two users is large.

論文審定書+i
致謝+ii
摘要+iii
abstract +iv
圖目錄+ vii
第一章簡介+1
第二章相關背景+ 5
2.1 重疊編碼+5
2.2 正交多址接收之波束賦形系統設計+7
第三章系統模型+11
第四章波束賦形向量與功率分配設計+14
4.1 匹配較佳通道之波束賦形的最佳功率分配+14
4.1.1 波束賦形匹配通道h1 之最佳功率分配+14
4.1.2 波束賦形匹配通道h2 之最佳功率分配+18
4.2 最佳波束賦形以及最佳功率分配設計+ 21
4.2.1 給定 值且UE-1 通道較佳時之功率分配+21
4.2.2 給定 值且UE-2 通道較佳時之功率分配+25
4.2.3  值與 值之聯合設計+28
第五章模擬結果+32
第六章結論+39
參考文獻+40

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