臺灣博碩士論文加值系統

在此論文中我們將利用一個有效率而且準確的方法來計算在光無線散射通道上正交訊號系統的性能。此方法是利用馬可夫鏈的矩陣穩定性質以及決策回授的特性為基本理論背景。利用此方法我們各別地分析並且模擬了具有symbol-rate和chip-rate迴授等化器的PPM系統的效能，也分析了具有迴授等化器的OOK系統的效能。結果顯示出在光無線散射通道裡使用這些等化器可以有效的減輕訊符間干擾的影響和明顯的改善系統的效能。在PPM系統裡我們引進一改良版的chip-rate迴授等化進器以減輕錯誤蔓延的影響。此改良版chip-rate迴授等化器在平均錯誤率方面比傳統的chip-rate迴授等化器有輕微的改善，但是在連續錯誤長度分怖方面卻能提供明顯的改善。最後我們呈現出Monte Carlo模擬結果去驗証我們的分析結果。

An efficient and accurate method to evaluate the performance of the orthogonal signaling system over wireless dispersive channels is derived in this thesis. The approach is based on the stationary property of the Markov chains and the characteristics of the decision feedback. By using the method, we analyze and simulate the system performance for pulse position modulation (PPM) with symbol rate decision feedback equalization and chip rate decision feedback equalization respectively, and the performance for OOK with decision feedback equalizers. The results show that equalizers can effectively mitigate the influences of ISI and significantly improve the performance on optical wireless dispersive channel. A simple modification of the chip rate decision feedback equalizer decision device is introduced to reduce the effect of error propagation in PPM system. The modified chip rate DFE performs only marginally better than the conventional chip rate decision feedback equalizer in terms of average error probability, but may offer some advantage in terms of the distribution of error burst lengths. Finally, we verify our analytical results by using Monte Carlo simulation.

Abstract in Chinese......................................................i
Abstract in English......................................................ii
Acknowledgment...........................................................iv
Contents.................................................................v
List of Figures and Tables...............................................viii
Chapter 1 Introduction...................................................1
Chapter 2 Basic Principles...............................................4
2.1 Wireless Optical Systems..........................................4
2.1.1 Wireless Optical On Off Keying Systems........................6
2.1.2 Wireless Optical Pulse Position Modulation Systems............8
2.2 Equalization......................................................15
2.2.1 Decision Feedback Equalizer with Erasures.....................15
2.2.2 Symbol-rate Decision Feedback Equalizer.......................18
2.2.3 Chip-rate Decision Feedback Equalizer.........................20
2.3 Markov Chains.....................................................20
2.3.1 Transition Probability Matrix and State Diagram...............21
2.3.2 The l-step transition probabilities...........................23
2.3.3 The State Probabilities.......................................24
2.3.4 Steady State Probabilities....................................25
Chapter 3 System Model and Performance Analysis..........................28
3.1 Non-directed Wireless Infrared Channel and Noise Model............28
3.2 Receiver Model of OOK.............................................30
3.3 Receiver Model of PPM with Symbol Rate Decision Feedback Equalizers................................................................35
3.4 Receiver Model of PPM with Chip Rate Decision Feedback Equalizers.39
Chapter 4 Numerical and Simulation Result................................44
4.1 The OOK System with E-DFE.........................................44
4.2 The PPM System using chip-rate DFE with erasure...................47
4.2 The PPM System with symbol rate DFE...............................51
Chapter 5 Conclusions and Future Works...................................57
References............................................................59

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