臺灣博碩士論文加值系統

現代數位通訊對高效率傳輸要求越來越提高,所以尋找提高傳輸效率的方法一直是大家追求
的重點. 而本篇論文主要在透過電腦模擬驗證,在相同的前導碼密度(pilot density)條件
下, 使用不同的前導碼排列方式(pilot pattern)可以提高系統傳輸效率及透過電腦模擬證
明鑽石形排列方式具有最高的傳輸效率.

The modern digital communications are more and more enhances to high
efficiency transmission request, therefore to find a way to enhances data
transmission efficiency is popular subject. A communications signal
transmission over wireless channels, that in practice has suffers much
interference and noise influence. Especially, the practice channel is time
variance, which have different channel characteristic at different time. This
thesis mainly to proof that we can enhance the transmission efficiency by
change pilot pattern alignment at same pilot density condition, and to verify
the pilot pattern arrangement in diamond shape have highest transmission
efficiency then any other, by simulation manner.

ENGLISH ABSTRACT i
CHINESE ABSTRACT ii
ACKNOWLEDGEMENTS iii
TABLE OF CONTENTS iv
LIST OF FIGURES vi
LIST OF TABLES x

I Introduction 1
1.1 Background 1
1.2 Motivation 2
1.3 Organization of This Thesis 2
II Overview of OFDM System 3
2.1 Introduction of OFDM Communication System 3
2.1.1 OFDM Architecture 3
2.1.2 OFDM Signals 4
2.1.3 Bandwidth Efficiency 5
2.2 OFDM Modulation 7
2.3 Guard Interval and Cyclic Prefix 8
2.4 Pilot placement 10
III Mobile Wireless Channel 12
3.1 AWGN Channel Model 12
3.2 Mobile Radio Propagation 14
3.2.1 Multipath fading Channels 16
3.2.2 Rayleigh fading 16
3.2.3 Rician fading 19
3.2.4 Doppler shift 20
3.2.5 Jakes’ model simulation 22
IV Pilot-Assisted OFDM Channel Estimation 26
4.1 Channel modeling 26
4.2 Two-Dimensional Channel Estimation 28
4.2.1 2 D-pilot placement 28
4.2.2 Maximum pilot distance 32
4.2.3 Optimal pilot pattern 34
V Simulation Result 37
5.1 Estimator simulation model 37
5.2 Simulation Result 41
VI Conclusions 45
REFERENCES 46

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