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系統識別號 U0002-0707201012261800
中文論文名稱 採單一時隙以最大概似估算法作正交多頻分工之載頻追蹤
英文論文名稱 A Maximum-Likelihood Based Frequency Tracking Technique for OFDM using A Single Time Slot Pilot Sample
校院名稱 淡江大學
系所名稱(中) 電機工程學系碩士班
系所名稱(英) Department of Electrical Engineering
學年度 98
學期 2
出版年 99
研究生中文姓名 鄭搏強
研究生英文姓名 Po-Chiang Cheng
學號 697460219
學位類別 碩士
語文別 英文
口試日期 2010-06-25
論文頁數 32頁
口試委員 指導教授-嚴雨田
委員-易志孝
委員-劉鴻裕
中文關鍵字 正交分頻多工系統  最大概似估計法  最小線性均方誤差  通道估計 
英文關鍵字 Orthogonal frequency division multiplexing (OFDM)  maximum likelihood estimation  linear minimum mean square error (LMMSE)  Cramer-Rao bound (CRB)  channel estimation 
學科別分類 學科別應用科學電機及電子
中文摘要 此篇論文在處理良好的頻率追蹤在正交分頻多工系統裡。無論是在時域或在頻域中去執行頻率偏移量的估測,執行良好的頻率追蹤通常是使用多個或一個完整的正交多頻分工的試驗區塊或數據訓練。這裡我們所使用的方法是採用單一樣品,而不是採用多個樣品,這問題可以大大的簡化在所收到之頻域中正交分頻多工的區塊資料,且仍然達到合理的追蹤性能。這證明我們的單一樣品的最大似頻率偏移估測量可以是不偏不移的而且均方誤差將更接近CRB,當訊號雜訊比增加。
英文摘要 This thesis deals with fine frequency tracking in orthogonal frequency division multiplexing (OFDM) systems. The usual practice for fine frequency tracking is to use multiple or an entire OFDM block of pilot or training data, either in the time domain or in the frequency domain to perform frequency offset estimation. Here we show that, instead of the elaborate approach of using multiple pilot samples, the problem can be greatly simplified by using only a single pilot sample from a selected time slot in the received time-domain OFDM block to still achieve reasonable tracking performance. It is proven that our single sample ML frequency offset estimator tends to be unbiased and its mean square error (MSE) will approach the Cramer-Rao bound (CRB) as SNR is increased.
論文目次 CONTENTS

ACKNOWLEDGEMENT I
CHINESE ABSTRACT II
ENGLISH ABSTRACT III
CONTENTS IV
LIST OF FIGURES VI
CHAPTER 1 INTRODUCTION 1
CHAPTER 2 MAXIMUM LIKEHOOD ESTIMATION 4
CHAPTER 3 MULTIPATH FADING AND FADING CHANNEL MODEL 8
3.1 Multi-path Propagation 8
3.1.1 Frequency Selective and Nonselective (Flat) Fading 9
3.1.2 Slow and Fast Fading Channel 9
3.2 Fading Models 10
3.2.1 Rayleigh Fading Model 10
3.2.2 Ricean Fading 12
CHAPTER 4 THE OFDM SYSTEM 13
4.1 The Multi-carrier System Model 13
CHAPTER 5 ACQUISITION AND TRACKING IN OFDM 18
CHAPTER 6 ML TRACKING TECHNIQUE BASED ON
A SINGLE TIME SLOT SAMPLE 20
6.1 Signal model 20
6.2 ML Frequency Tracking Based on
Signal Time Slot Sample 21
CHAPTER 7 SIMULATION RESULTS 25
CHAPTER 8 CONCLUSION 28
REFERENCE 29

LIST OF FIGURE

Figure 4.1 The OFDM system structure 17
Figure 7.1 (a) Estimator variances vs. SNR of 26
Figure 7.1 (b) Estimator bias vs. SNR of 26
Figure 7.2 (a) Estimator variances vs. SNR of 27
Figure 7.2 (b) Estimator bias vs. SNR of 27
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