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標題: | 多輸入多輸出中繼站於廣播通道之設計與應用 Design and Application of MIMO Relay Station in Broadcast Channel |
作者: | Chun-Che Chien 簡均哲 |
指導教授: | 李學智(Hsueh-Jyh Li) |
共同指導教授: | 蘇炫榮(Hsuan-Jung Su) |
關鍵字: | 多輸入多輸出系統,中繼器,廣播通道,功率控制,波束合成,最佳化設計,裝置對裝置通訊,中斷機率, multiple-input-multiple-output (MIMO),relay station (RS),broadcast channel (BC),power allocation,beamformer design,convex optimization,device-to-device (D2D) communication,outage probability, |
出版年 : | 2013 |
學位: | 博士 |
摘要: | 近年來,因無線移動通信系統的高服務品質的需求,現有通訊系統架構已經廣泛的使用多輸入多輸出(MIMO)技術。藉由配置多根天線於通訊裝置上,可增強無線終端的傳輸率並可降低對通道衰減效應或避免鄰近用戶的干擾。在此同時,為了提高基地台涵蓋範圍邊緣用戶的傳輸量,採用中繼站的佈建技術已被視為一種可行的方案,如此可降低網路佈建的成本。這兩種技術已經被採納在幾個蜂巢式無線標準中,例如3GPP LTE或IEEE 802.16 WMAN 。為了得到上述兩種技術的好處,一種結合MIMO技術與中繼站技術的複合式技術已被提出,亦是本篇論文的主要重點。 MIMO中繼站可以分為兩種類型,一種是固定的中繼站,設置於某些無法被基地台有效覆蓋的特定區域。另一種為移動式的中繼站,藉由用戶裝置當作中繼站來協助其他用戶端的接收。本文將在蜂巢式系統架構下,分別探討這兩種類型的中繼站。
對於固定式MIMO中繼站的部分,在符合每個使用者端(MS)個別的信號 - 干擾加雜訊比(SINR)之前提下進行MIMO廣播中繼通道的設計。藉由探索位於基地台(BS)或中繼站(RS)之下行通道-上行通道的對偶性(Duality),我們提出了兩個解決方案,分別在BS和RS上進行功率分配和波束合成設計。我們先評估在BS和RS實際可用的功率下是否能符合個別SINR的限制條件。然後再探討在SINR的限制條件總功率的最小化問題。以上兩個問題皆可以在Convex Optimization的框架下,藉由聯合功率分配和波束合成的最佳化的問題來獲得解決。我們進一步提出在中繼站進行子通道配對的優點,並將現有問題擴展到多次跳躍中繼(Multihop Relay)的應用,以進一步提高功率使用效率。 移動式MIMO中繼系統則是使用不同的設計策略。由於使用者間的多次跳躍形成了連續的裝置到裝置(D2D)鏈結,這種多次跳躍的中繼結構可以視為在蜂巢式通訊系統下的多個D2D通訊。由於在此D2D架構下,具有靈活的路由路徑選擇特色,因此我們提出了兩個具有高頻譜使用效率以及可避免傳輸錯誤的多次跳躍協定。在第一個協定中,用戶將自己的數據流解碼後進行轉送,之後的用戶則利用此接收訊號進行干擾消除計算來消除從基地站接收的干擾。在在第二個協定中,用戶進行自身訊號的解碼並從所接收的數據流中將自身訊號消除後再轉送,之後的接收用戶則結合前次接收到的向量進行自身訊號的解碼。本研究分別分析各個協定每次跳躍所獲得的接收多樣性以及路徑選擇多樣性。 本論文先針對每個研究課題提供相關技術背景或知識。比較所提出的技術與傳統方法在效能和計算複雜方面的差異。最後,一些可用來擴展現有成果的研究方向則在結論中被提出。 Nowadays, the demand for high throughput of wireless mobile communication systems has arouse widespread of multi-input-multi-output (MIMO) technologies. It is well known that with the deployment of multiple antennas at wireless terminals, capacity enhancement as well as robustness against channel fading or interference avoidance can be achieved. In the meanwhile, in order to enhance the cell-edge users' throughput, the deployment of relay stations has been a promising scheme which can prevent the wired backhaul costs. Both techniques have been adopted in several wireless cellular standards such as 3GPP LTE or IEEE802.16 WMAN. In order to exploit the benefits of above two techniques, a compound scheme that incorporates MIMO technology into the relay architecture has been proposed and is the main focus of this thesis. The MIMO relay station could be two types, which are the fixed relay station placing at some specific location for filling in the coverage hole, and the mobile relay station which is also a function of users’ mobile device , it can support the receiving of other mobile stations. Both types of relay stations will be analyzed in the cellular systems in this dissertation. For fixed MIMO relay station, a system design of MIMO broadcast relay channel based on individual signal-to-interference-plus-noise ratio (SINR) constraints at the mobile stations (MS) is considered. By exploring the structure of downlink-uplink duality at either the base station (BS) or the relay station (RS), we propose two schemes of joint power allocation and beamforming design at the BS and the RS. The problem of existence of feasible solutions under practical power constraints at the BS and the RS with given SINR targets is considered first. Then the problem of sum power minimization is considered. Each design problem can be solved efficiently using optimal joint power allocation and beamforming under the framework of convex optimization. We also show the benefit of subchannel pairing at the RS and generalize the problem to multi-hop scenario in order to further improve the power efficiency. Different design strategy is adopted for the mobile MIMO relay system. The multi-hop relay links between each user pair form consecutive Device-to-Device (D2D) links, and this structure can be regarded as multiple D2D communications under the cellular system. Due to the flexibility of routing path selection in this D2D enabled system, two spectrally efficient as well as outage tolerant multi-hop protocols are proposed. In the first protocol, a user forwards its own data stream after decoding, then interference cancellation is performed at each receiving node to eliminate the interference from this user. In the second protocol, a user decodes and cancels its own signal from the received vector and forwards the remaining signal. The receiving nodes decode their own streams by jointly considering the previous received vectors. The receive diversity as well as selection diversity of each protocol is analyzed in each additional hop. The background or preliminaries of associated technologies are provided before entering each research topic. Comparisons of proposed schemes in terms of performance evaluation and complexity calculation show the benefits over traditional schemes. Finally, some future research directions to complete or extend the research results are provided in the conclusion part. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/58777 |
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顯示於系所單位: | 電信工程學研究所 |
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