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標題: | 多用戶多輸入多輸出系統減少通道資訊回饋之技術 Feedback Reduction for MIMO System with Inter-User Channel Correlation |
作者: | Pin-Wen Su 蘇品文 |
指導教授: | 蘇炫榮(Hsuan-Jung Su) |
關鍵字: | 通道資訊回饋,減少回饋,多用戶多輸入多輸出,巨量天線,波束成型,排程, CSI feedback,Feedback reduction,Multi-user MIMO,Massive MIMO,Beamforming,Scheduling, |
出版年 : | 2016 |
學位: | 碩士 |
摘要: | 在多用戶多輸入多輸出的系統中,用戶將量測到的通道資訊回傳給基地台可幫助基地台排程欲服務的用戶、提高系統的傳輸效率。然而,在巨量天線系統中,當傳送天線數很多、或用戶很多時,龐大的回傳資訊量是其所須付出的代價。為了解決回傳通道資訊占用過多資源、影響系統傳輸效率等問題,用戶利用已知的閘值決定是否回傳通道資訊、進而降低整體回傳資訊量被視為一有效的解決方法。然而,當用戶之間的通道狀況具有高度相關性時,此方法便不再適用。在本篇論文中,結合正交波束系統,我們提出一種創新減少回傳資訊量的方法。於此方案下,用戶是否回傳通道資訊由一與通道狀況有關的機率函數決定。意即,當通道狀況佳時,用戶回傳通道資訊的機率較大;反之,則機率較小。
本篇論文主要可分成兩大部分。首先,針對用戶之間的通道不具相關性做探討,我們證明設定此函數為步階函數(即等效於閘值決定法)可使得在平均回饋量是相同的條件下,達到最高的系統傳輸速率。接著分析並模擬當用戶之間的通道具有相關性時,我們提出的方法會優於現有的策略。 For the multiuser multiple-input multiple-output (MIMO) downlink channel, users feedback their channel state information to help base station schedule users and improve system sum rate. This incurs a large aggregate feedback bandwidth which grows linearly with the number of users. Feedback reduction by a given threshold has been viewed as a promising solution. However, the system sum rate performance becomes catastrophic when there is correlation among users' channels. In this thesis, a novel feedback load reduction strategy is proposed for scheduled downlink orthogonal beamforming system. In the proposed strategy, whether a user feedbacks its channel state information is governed not only by the user's channel condition but also by a probability function related to the channel condition. We first present a proof which shows that the threshold-based feedback strategy is still the optimal strategy when users are independent. Further, we compare the proposed strategy to the existing feedback reduction strategies in different scenarios with inter-user channel correlation. Simulation shows that the proposed strategy can achieve higher system sum rate than other feedback reduction methods. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76711 |
DOI: | 10.6342/NTU201601867 |
全文授權: | 未授權 |
顯示於系所單位: | 電信工程學研究所 |
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ntu-105-R03942053-1.pdf 目前未授權公開取用 | 1 MB | Adobe PDF |
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