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博碩士論文 etd-0915108-103429 詳細資訊
Title page for etd-0915108-103429
論文名稱
Title
多輸入輸出正交分頻多工系統重複式通道估測之研究
A Study on Iterative Channel Estimation for MIMO-OFDM Systems
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
43
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2008-07-31
繳交日期
Date of Submission
2008-09-15
關鍵字
Keywords
多輸入輸出、正交分頻多工、重複式通道估測、通道空間相關
multiple-input multiple-output, orthogonal frequency division multiplexing, iterative channel estimation, channel spatial correlation
統計
Statistics
本論文已被瀏覽 5653 次,被下載 2770
The thesis/dissertation has been browsed 5653 times, has been downloaded 2770 times.
中文摘要
多輸入輸出(multiple-input multiple-output,MIMO)正交分頻多工(orthogonal frequency division multiplexing,OFDM)技術在現今的無線通訊領域上被廣泛的應用。由於無線通道的通道情況往往隨著時間而不斷的改變,導致信號在傳輸的過程中會受到無線通道的影響而失真,因此我們必須正確的估測出通道的脈衝響應(channel impulse response),並且利用此估測的響應來補償通道對信號所造成的失真效應。為了估測通道的狀態我們會將接收端已知的訓練符號放在所欲傳輸的資料符號之前,並且透過訓練符號將通道的響應估測出來。在典型的MIMO OFDM 系統通道估測中,會把通道視為空間上不相關。然而在許多實際情況下,通道是有空間相關(channel spatial correlation)。而通道空間相關也不是能事先知道的。因此能把通道空間相關考慮進去,便能使通道估的更準確。而如何結合估測通道空間相關和通道估測而減少估測誤差便成為一項重要的工作。
在本篇論文中,我們提出一個重複式通道估測和通道空間相關估測演算法。首先,我們利用同步符號(synchronize symbols)來得到通道空間相關估測值,之後的資料符號可利用此通道空間相關估測值來得到初始的通道估測值,接收端可利用此通道估測值來做信號偵測及信號決策,其次我們將信號決策值視為已知的資訊,並且利用這些資訊來做下一步的通道估測及通道空間相關估測。重複以上的通道估測和通道空間相關估測和信號偵測與信號決策程序,我們可以逐漸的縮減因為通道空間相關誤差而導致的通道估測誤差,而通道估測的精確度也會因為增加此重複程序的次數而逐漸提升。模擬結果證實重複式通道估測和通道空間相關估測演算法能夠提供比一般演算法更好的估測均方差(mean-square-error,MSE)性能。
Abstract
Multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) technology has been used widely in many wireless communication systems. Signals will be distorted when they are transmitted in wireless channels. For the reason that wireless channel is time or location variant, we have to estimate the channel impulse response and use the channel state information to compensate the channel distortion. In order to estimate the state of the channel, let the known training symbols put in front of the data symbols and use training symbols to estimate channel response. A typical channel estimate for MIMO OFDM systems is treated as spatially uncorrelated. However in many realistic scenarios, the channel tends to be spatially correlated. Indeed, we have no prior knowledge of the channel spatial correlation. So consider the spatial correlation, the channel can estimate accurately. And it is important that how to combine spatial correlation and channel estimation to reduce the estimation error.
In the paper we propose a iterative channel spatial correlation and channel estimation algorithm. At first, channel spatial correlation estimation is obtained by synchronize symbols. The receiver uses the estimated channel to help the detection/decision of data symbol. And then the channel estimation treats the detected signals as known data to perform a next stage channel estimation iteratively. By utilizing the iterative channel estimation and signal detection process we can reduce the estimation error caused by channel spatial correlation estimation. The accuracy of the channel estimation can be improved by increasing the number of iteration process. Simulation results demonstrate the iterative spatial correlation and channel estimation algorithm can provide better mean-square-error performance.
目次 Table of Contents
誌謝 i
摘要 ii
Abstract iii
目錄 iv
圖索引 v
表索引 vi
第一章 簡介 1
第二章 多輸入輸出正交分頻多工系統 3
2.1正交分頻多工技術的基本概念 3
2.1.1正交分頻多工技術的基本架構 5
2.1.2守護區間 8
2.1.3導航符號排列與設計方式 11
2.2時空區塊碼 13
2.3多輸入輸出通道模型 16
第三章 重複式通道及通道空間相關估測演算法 19
3.1框架結構 19
3.2系統架構 19
3.3叢集時間延遲及通道空間相關估測 21
3.3.1叢集時間延遲估測 22
3.3.2通道空間相關估測 24
3.4協定資料單位通道估測 24
3.5重複式通道估測及空間相關估測的演算法 27
第四章 系統模擬 29
第五章 結論 34
參考文獻 35
參考文獻 References
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