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博碩士論文 etd-0728106-132710 詳細資訊
Title page for etd-0728106-132710
論文名稱
Title
正交分頻多工調變系統中低複雜度之時間與頻率同步演算法研究
Low-Complexity Timing and Frequency Offset Estimation Schemes for 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
49
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
2006-07-07
繳交日期
Date of Submission
2006-07-28
關鍵字
Keywords
同步、正交分頻多工調變系統
OFDM, synchronization
統計
Statistics
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中文摘要
在本篇論文中,我們將提出兩組新的使用在正交分頻多工調變系統中的訓練符元。在第一個方法中,我們將一個正交分頻多工符元在時域上設計成具有重複的方塊的特性,並在每個小方塊中乘上不同的正負號,然後在接收端利用這組訓練符元,我們可以在低硬體複雜度的情況之下,完成時間與頻率偏移的估測。其中在頻率偏移的估測方面,我們將之分成小數與整數兩個部份分開估測,總頻率估測範圍在對子載波間距做正規化後為四分之符元長度。模擬結果顯示出,我們提出的方式比傳統大部分的方式效能要好,或者是只有微小的效能差距,但是複雜度卻相對的低很多。
在第二個提出的訓練符元當中,我們將之分割成四個方塊,其中一個方塊乘上負號,並在時域上設計成具有重複與共軛對稱的特性,利用這兩個特性,我們所提出的時間偏移估測方式,效能會比傳統單獨只利用到一種特性的估測方式還要好。
Abstract
Two novel structures of training symbols are proposed for both timing offset and frequency offset estimations in orthogonal frequency division multiplexing (OFDM) systems.
The first proposed training symbol has repeated sample blocks and a sign pattern on each block. With the proposed structure, system synchronization can be obtained with relatively low complexity. In particular, the frequency synchronization is accomplished using two successive stages to obtain both the fractional and integral parts of frequency offset with an estimation range of sub-carrier spacing. Simulation experiments demonstrate that the performance of the proposed scheme is substantially superior to the traditional schemes, or has negligible difference.
The second proposed training symbol has the form of repeat and conjugate symmetric blocks and a sign pattern on each block. Then, a weighted timing metric is proposed to estimate the timing offset. Simulation results demonstrate that the proposed timing metric substantially improves the traditional schemes.
目次 Table of Contents
Acknowledgement in Chinese..................................................................Ⅰ
Abstract in Chinese...................................................................................Ⅱ
Abstract in English...................................................................................Ⅲ
Table of Contents......................................................................................Ⅳ
List of Figures...........................................................................................Ⅵ
List of Table..............................................................................................Ⅶ

Chapter 1 Introduction................................................................................1
1.1 OFDM System Description...........................................................2
1.2 Synchronization in OFDM System................................................7
1.3 Content about This Thesis.............................................................8
Chapter 2 System Statements...................................................................10
2.1 System Model..............................................................................10
2.2 OFDM Timing Offset and Frequency Offset Estimation
Schemes.......................................................................................11
Chapter 3 A Training Symbol Apparatus for Efficient Timing and
Frequency Synchronization in OFDM Systems.......................16
3.1 Proposed Timing Metric and the Best Sign Patterns for
Sample Blocks..............................................................................17
3.2 First Stage of Frequency Offset Estimation and Compensation...20
3.3 Second Stage of Frequency Offset Estimation.............................22
3.4 Simulation Results and Discussions.............................................25
3.4.1 Simulation Parameters.....................................................25
3.4.2 Performance of the Timing Offset Estimation.................25
3.4.3 Performance of the Frequency Offset Estimation...........27
Chapter 4 A Weighted Timing Metric for OFDM Synchronization.........30
4.1 Proposed Training Symbol and Weighted Timing Metric............30
4.2 Simulation Results and Discussions.............................................34
Chapter 5 Conclusions..............................................................................37
Reference..................................................................................................39
參考文獻 References
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[3]. Jan-Jaap van de Beek, Magnus Sandell, and Per Ola Börjesson, “ML estimation of time and frequency offset in OFDM systems,” IEEE Trans. Signal Process., vol. 45, pp. 1800 – 1805, July 1997.
[4]. Timothy M. Schmidl, and Donald C. Cox, “Robust frequency and timing synchronization for OFDM,” IEEE Trans. Commun., vol. 45, pp. 1613 – 1621, Dec. 1997.
[5]. Armstrong, J., “Analysis of new and existing methods of reducing intercarrier interference due to carrier frequency offset in OFDM,” IEEE Trans. Commun., vol. 47, pp. 365 – 369, Mar. 1999.
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[9]. T. Jiang and G. Zhu, “Nonlinear companding transform for reducing peak-to-average power ratio of OFDM signals,” IEEE Trans. on Broadcasting. Vol. 50, pp. 342 – 346, Sept. 2004.
[10]. Wulich, D., Dinur, N., Glinowiecki, A, “Level clipped high-order OFDM,” IEEE Trans. Commun., vol. 48, pp. 928 – 930, June 2000.
[11]. Byungjoon Park, Hyunsoo Cheon, Eunseok Ko, Changeon Kang, and Daesik Hong, “A blind OFDM synchronization algorithm based on cyclic correlation,” IEEE Signal Processing Letters, vol. 11, pp. 83 – 85, Feb. 2004.
[12]. Hui Liu, and Ufuk Tureli, “A High-efficiency carrier estimator for OFDM communication,” IEEE Communications Letters, vol. 2, pp. 104 – 106, April 1998.
[13]. A.J. Al-Dweik, “A novel non-data-aided symbol timing recovery technique for OFDM systems,” IEEE Trans. Commun., vol. 54, pp. 37 – 40, Jan. 2006.
[14]. Hlaing Minn, M. Zeng, and V. K. Bhargava, “On timing offset estimation for OFDM systems,” IEEE Communications Letters, vol. 4, pp. 242 – 244, July 2000.
[15]. Zhongshan Zhang, Ming Zhao, Haiyan Zhou, Yuanan Liu, and Jinchun Gao, “Frequency offset estimation with fast acquisition in OFDM system,” IEEE Communications Letters, vol. 8, pp. 171 – 173, March 2004.
[16]. Hlaing Minn, Vijay K. Bhargava, and Khaled Ben Letaief, “A robust timing and frequency synchronization for OFDM systems,” IEEE Trans. Wireless Communications, vol. 2, pp. 844 – 839, July 2003.
[17]. M. Morelli, and U. Mengali, “An improved frequency offset estimator for OFDM applications,” IEEE Communications Letters, vol. 3, pp. 75 – 77, March 1999.
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