臺灣博碩士論文加值系統

近年來展頻通訊的技術發展極為快速，不論在軍事通訊上或商業通訊上都廣泛的使用展頻技術，展頻通訊主要包含兩大類，一是直接序列(direct sequence)系統，一是跳頻(frequency hopped)系統。在跳頻系統中，衰減通道效應會導致訊號的損害，另一個會對訊號造成損害的是刻意或非刻意的人為干擾。因此我們使用分集結合(diversity-combining)的技術來降低訊號衰減程度與抑制人為干擾。
多頻調干擾(multitone jamming)和部份頻帶干擾(partial-band noise jamming)是兩個主要的干擾模型。衰減通道也可分為兩大類，一類是頻率非選擇性衰減通道(frequency-nonselective fading channel)，另一類是頻率選擇性衰減通道(frequency-selective fading channel)，其中頻率選擇性衰減通道模型會比較接近實際狀況。在現有的文獻當中，抗干擾接收機大致可分成六種：線性結合接收機(linear-combining receiver)、乘積結合接收機(product-combining receiver)、最大可能接收機(maximum-likelihood receiver)、自我正規化結合接收機(self-normalizing receiver)、截取分集結合接收機(clipped-combining receiver)和比例統計結合接收機(ratio-statistic-combining receiver)。本論文主要的研究系統為快跳頻二元頻率鍵移系統(FFH/BFSK)，所使用的接收機為最大可能接收機，主要目的為對抗多頻調干擾和頻率選擇性衰減通道所導致的損害，在本研究中我們使用數學近似的方法來簡化效能分析的複雜度。
在此論文中，我們主要的目的為提出於頻率選擇性衰減通道下抗干擾接收機的架構並分析其系統效能，同時發展出更合適的接收機架構。研究方向主要為接收機之理論推導與架構設計。研究所得之結果預期不論對理論研究或是實際應用都將有很大的助益，且能促進抗干擾接收機於未來無線通訊系統之應用。

Spread-spectrum communication system, including direct sequence (DS) and frequency hopped (FH) systems, was developed rapidly in recent year. There are many applications in both military and commercial fields. In FH system, the signal could be damaged by fading effect. Intention or non-intention jammer also could harm the signal. Therefore, we use diversity-combining scheme to reduce fading and jamming effect.

The multitone jamming (MTJ) and partial-band noise jamming (PBNJ) are two principal categories of the interference models. The fading channel could be separated into two categories. One is frequency-nonselective fading channel and the other is frequency-selective fading channel. Among them, frequency-selective fading channel model is approached the practical situation.
In literature review, we find there are six kinds of anti-jamming receivers as follow : linear-combining receiver, product-combining receiver, maximum-likelihood (ML) Receiver, self-normalizing receiver, clipped-combining receiver, and ratio-statistic-combining receiver. In this thesis, we will discuss fast frequency-hopped binary frequency-shifted-keying system (FFH/BFSK) with MTJ and frequency-selective fading channel by using ML receiver.
Furthermore, we use the approximation to simplify the analyses of the performances.

The research is focus on theory derive and frame design of receiver. The result will be helpful for theory research and practical application and make anti-jamming receiver widely application in wireless communication system in future.

Contents
Abstract iii
Acknowledgements iv
List of Tables viii
List of Figures ix
1 Introduction 1
1.1 Motivation.....................................................1
1.2 Background.....................................................2
1.3 Overview of the Thesis.........................................3
2 FFH/FSK Communication System with Jamming and Fading Channel 4
2.1 Introduction...................................................4
2.2 Jamming........................................................6
2.2.1 Partial-Band Noise Jamming...............................6
2.2.2 Multitone Jamming........................................8
2.3 Fading Channel................................................10
2.4 Diversity-Combining Receiver..................................13
2.4.1 Linear-Combining Receiver...............................13
2.4.2 Product-Combining Receiver..............................15
2.4.3 Self-Normalizing Receiver...............................17
2.4.4 Clipper-Combining Receiver..............................19
2.4.5 Ratio-Statistic-Combining Receiver......................21
2.4.6 Maximum-Likelihood-Combining Receiver...................23
2.5 Summary.......................................................25
3 Maximum-Likelihood Receivers for FFH/BFSK Systems with Multitone
Jamming over Frequency-Selective Rayleigh Fading Channels 27
3.1 Introduction..................................................27
3.2 System Model..................................................28
3.3 Maximum-Likelihood Receiver...................................31
3.3.1 ML Scheme...............................................31
3.3.2 PDF of rml..............................................32
3.4 PDFs of The lth Hop...........................................34
3.4.1 Type ML-A Receiver......................................35
3.4.2 Type ML-B Receiver......................................37
3.5 Numerical Results and Discussions.............................39
3.6 Conclusions...................................................50
4 Conclusions and Future Researches 51
4.1 Conclusions...................................................51
4.2 Future Researches.............................................52
Appendices 53
A Derivation of Equation (3.10) 53
B Derivation of Equation (3.12) 55
C Derivation of Equation (3.14) and (3.15) 57
D Derivation of Equation (3.16) and (3.17) 59
E Derivation of Equation (3.23) and (3.24) 62
F Derivation of Equation (3.25) and (3.26) 64
G Derivation of Equation (3.27) and (3.28) 65
Bibliography 68
Vita 71

List of Tables
2.1 Decision statistic of diversity-combining receivers.............26

List of Figures
2.1 Block diagramof an FH spread-spectrum system.....................4
2.2 PBNJ of FH system : jammer concentrates power in fraction of
spread-spectrum bandwidth, and hops noise band to prevent FH
band avoidance countermeasure....................................7
2.3 MTJ strategies : independent MTJ distributes the tone
pseudorandomly over all Nt FH frequencies; band MTJ places n
tones in each jammed M-ary band..................................9
2.4 Path geometry formultipath-fading channels......................12
2.5 FFH/BFSK linear-combining receiver..............................14
2.6 FFH/BFSK product-combining receiver.............................16
2.7 FFH/BFSK self-normalizing receiver..............................18
2.8 FFH/BFSK clipper-combining receiver.............................20
2.9 FFH/BFSK ratio-statistic-combining receiver.....................22
2.10 FFH/BFSK ML-combining receiver.................................24
3.1 General FFH/BFSK ML receiver....................................29
3.2 ML-A receiver...................................................36
3.3 ML-B receiver...................................................38
3.4 Comparisons between simulated and numerical results.............41
3.5 Performance comparisons between two ML receivers under different
power ratios....................................................42
3.6 Performance comparisons between the ML-A and ML-B receivers with
various cross-correlation coefficients..........................44
3.7 Performance comparisons under different diversity levels among
the ML-A, ML-B, and optimum ML receivers........................45
3.8 Performance BER versus the SNR for different diversity levels
among the ML-A, ML-B, and optimum ML receivers..................46
3.9 Performance comparisons of various receivers....................48
3.10 Performance BER versus the SNR for various receivers...........49

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