English  |  正體中文  |  简体中文  |  Items with full text/Total items : 28611/40649
Visitors : 644849      Online Users : 42
RC Version 4.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Adv. Search
LoginUploadHelpAboutAdminister

Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/19003

Title: 針對MIMO STC-OFDM系統以快速子空間分解法進行半盲蔽通道估測
A Semi-Blind Channel Estimation Based on Fast Subspace Decomposition for MIMO STC-OFDM Syatem
Authors: 張麗娜
Contributors: NTOU:Department of Communications Navigation and Control Engineering
國立臺灣海洋大學:通訊與導航工程學系
Keywords: 多輸入多輸出;正交分頻多工調變;空時碼;子空間分解法;半盲蔽式通道估測;適應性等化器
multiple input multiple output (MIMO);orthogonal frequency division multiplexing (OFDM);space-time coding (STC);subspace decomposition;semi-blind channel estimation;adaptive equalizer
Date: 2010-08
Issue Date: 2011-08-17T07:05:56Z
Abstract: 摘要:近年來,無線行動通訊技術發展快速,隨著日益增加的多媒體需求與寬頻服務,通訊系 統必須提供更高的傳輸容量和更快的傳輸速率,以滿足使用者的需求。如何讓頻譜使用更有 效率和降低位元錯誤率,遂成為通訊科技未來發展一關鍵性的研究方向。 結合空時碼(space-time coding, STC)、多輸入多輸出(multiple input multiple output, MIMO) 和正交分頻多工 (orthogonal frequency division multiplexing, OFDM)技術已成為第四 代寬頻行動通訊的標準技術之ㄧ。本研究擬針對MIMO STC-OFDM 系統其訊號所具有的結 構特性,發展一以快速子空間分解法為基礎之半盲蔽式通道估測法並提供接收端一高效能之 適應性等化器,藉此改善現有以子空間分解為基礎之通道估測法的高計算複雜度和收斂慢的 缺點,並使其能適用於時變的通訊環境。 首先,我們將利用訊號自相關矩陣對稱的結構特性,發展以快速子空間分解法為基礎 之通道估測技術來提升通道估測的準確性,並且降低計算複雜度。此外,為了適用於時變的 通道環境,本研究將發展一可追蹤通道環境參數的適應性通道估測法以及可即時解調傳送訊 號的適應性等化器。我們擬藉由一適應性子空間調整法,即時調整訊號自相關矩陣所對應的 雜訊子空間來追蹤通道環境參數。最後,我們擬以實際的多媒體資料傳輸來驗證本研究所提 之通道估測法和適應性等化器的效能。藉由本研究的完成,將提供MIMO STC-OFDM 系統 一高效能之接收機設計方法。 本計畫為期二年,研究重點包含下列各項: 第一年:以快速子空間分解法為基礎之半盲蔽式通道估測研究 (1) MIMO STC-OFDM 系統訊號結構特性之研究:研究針對MIMO STC-OFDM 系統訊號自相 關矩陣的結構特性,藉此簡化通道估測的計算複雜度。 (2) 研究反向取樣訊號之自相關矩陣特性:研究透過反向取樣資料進行通道參數估測的 可行性。 (3) 發展正反向子空間分解法提升雜訊子空間估測準確性:結合正向和反向資料,期能在 不增加天線數目下,獲得雙倍的資料量,以提升雜訊子空間估測的準確度。 (4) 探討正反向資料自相關矩陣所對應之特徵值及特徵向量的結構特性:藉由自相關矩陣 的對稱結構,研究其對應特徵值與特徵向量之特性。 (5) 發展快速子空間分解法減少雜訊子空間估測的計算複雜度:藉由(4)研究的特徵值 與特徵向量之結構特性,簡化正反向子空間分解法中雜訊子空間估測所需之計算 量, 並能達到與正反向子空間分解法相同的估測準確度。 (6) 發展以快速子空間分解法為基礎之通道估測技術:利用雜訊子空間特徵向量具有的對 稱結構特性,進行快速通道估測,提高解調訊號之準確性與效能。 (7) 計算所提演算法的計算複雜度,並以電腦模擬驗證本研究發展之通道估測法的效能與 解調實際傳輸多媒體訊號的能力。 第二年:以適應性子空間調整法為基礎之半盲蔽式通道估測與適應性等化器之研究 (1) 發展適應性子空間調整法估測雜訊子空間之特徵分量:為了因應時變的環境,達到 即時通道參數估測之目的,以增加解調訊號的準確性,研究可依循序的取樣資料調整 雜訊子空間之適應性子空間調整法。 (2) 將(1)之適應性子空間調整法應用於第一年所提之正反向子空間分解法和快速子空間 分解法,以達雜訊子空間適應性調整之目的。 (3) 利用(2)遞迴調整之雜訊子空間進行通道估測:將(2)調整之雜訊子空間,以第一年 研究(6)的程序來估測通道參數,藉此達到即時通道估測之目的。 (4) 發展適應性濾波器以解調訊號之研究:以(3)估測的通道參數發展最小均方誤差和最小平方誤差條件下的韋恩濾波器和LS 濾波器以解調訊號。 (5) 發展適應性等化器以即時解調訊號之研究:以適應性子空間調整法進行適應性等化 器的研究,改善(4)適應性濾波器計算複雜度並減緩通道估測誤差的影響,達即時解調 傳送訊號的目的。 (6) 以電腦模擬驗證本研究所提之適應性通道估測、適應性濾波器和適應性等化器之效 能和可行性。
abstract:Recently, wireless communication techniques have been rapidly developed. As the demand of multimedia and wideband services increases, it becomes essential to provide a communication system with higher capacity and faster transmission data rate to satisfy the user’s requirements. The combination of STC and OFDM techniques is considered as a major technique in the fourth-generation (4G) communications. By utilizing the symmetric property of STC-OFDM data, we will develop an efficient semi-blind channel estimation method and an adaptive equalizer based on a fast subspace decomposition algorithm for MIMO STC-OFDM system. The proposed study will alleviate the computation complexity and improve the convergence rate of the existing semi-blind channel estimation methods based on subspace-decomposition. In the study, we will first analyze the eigen-structure of the correlation matrix corresponding to the received signals of MIMO STC-OFDM system. By utilizing the eigen-structure property, we will develop an efficient semi-blind channel estimation method based on a fast subspace decomposition algorithm which may improve the channel estimation accuracy with less computation complexity. Then, for nonstationary mobile environment, we will propose an adaptive channel estimation and an adaptive equalizer based on an adaptive subspace estimation algorithm. The proposed methods could track the noise subspace and the channel parameters in nonstationary environment and demodulate the transmitted data in real time. Finally, simulations will be performed to validate the performance of our developed methods by using real multimedia data. The study will last two years and focus on the following aspects: 1. In the first year: the study of semi-blind channel estimation based on a fast subspace decomposition algorithm  Analyze the eigenstructure of the correlation matrix corresponding to the received signals of MIMO STC-OFDM system.  Analyze the eigenstructure of the correlation matrix associated with the backward received signals.  Combine the forward and backward received signals to improve noise subspace estimation.  Analyze the property of eigenvector corresponding to the forward and backward smoothed correlation matrix.  Develop a fast subspace decomposition algorithm to reduce the computation complexity.  Develop an efficient semi-blind channel estimation based on the proposed fast subspace decomposition algorithm  Investigate the performance of the proposed estimation method by using real multimedia data. 2. In the second year: the study of adaptive channel estimation and adaptive equalization based on an adaptive subspace estimation algorithm for nonstationary environment  Develop an adaptive subspace estimation method to adjust eigenvectors in real-time.  Develop an adaptive fast subspace estimation method.  Apply the estimated noise subspace to enhance channel estimation.  Develop an adaptive filter based on the adaptive subspace estimation algorithm.  Develop an adaptive equalizer based on the adaptive subspace estimation algorithm.  Investigate the performance of the proposed adaptive channel estimation and equalizer.
Relation: NSC99-2221-E019-004
URI: http://ntour.ntou.edu.tw/handle/987654321/19003
Appears in Collections:[通訊與導航工程學系] 研究計畫

Files in This Item:

There are no files associated with this item.



All items in NTOUR are protected by copyright, with all rights reserved.

 


著作權政策宣告: 本網站之內容為國立臺灣海洋大學所收錄之機構典藏,無償提供學術研究與公眾教育等公益性使用,請合理使用本網站之內容,以尊重著作權人之權益。
網站維護: 海大圖資處 圖書系統組
DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback