直升機在自然災(zāi)害、緊急救援和軍事偵察等場景都有十分顯著的應(yīng)用,在這些場景下大多數(shù)其他系統(tǒng)通常都已經(jīng)失效,此外,直升機也可以比較容易提供運輸和支援作用。在自然災(zāi)害和敵軍破壞等情況下通信網(wǎng)絡(luò)可能已經(jīng)失效,若由于這些破壞而失去通信能力,直升機也就失去了其利用價值。而直升機衛(wèi)星通信可以穩(wěn)定提供有效可靠的高速通信,因此直升機的重要利用價值和其對通信的需求推動了人們對直升機衛(wèi)星通信的研究。直升機衛(wèi)星通信研究的核心論文內(nèi)容主要包括直升機旋翼遮擋模型、采用時分復(fù)用的沃什-哈達瑪編碼。本文首先研究了直升機衛(wèi)星通信信道的屬性和特點,然后基于一些成熟的信道模型提出了帶旋翼遮擋的衰減信道模型。在MATLAB仿真中都采用了這個信道模型,并且也使用了針對其他問題的技術(shù)。致力于提高直升機衛(wèi)星通信性能,本文首先研究了采用碼分復(fù)用的沃什-哈達瑪變換的系統(tǒng)。然后該系統(tǒng)采用精確的雙重時間分集來減少碼間干擾并改善了系統(tǒng)。本文中也這些系統(tǒng)模型進行了仿真和分析。更進一步地,前面提到的系統(tǒng)模型在其接收端通過分集合并得到改進和提升。分集合并方案已經(jīng)被證明為是解決旋翼遮擋問題的最優(yōu)方案并且提升了其傳輸速率。本文也對包括雙重時間分集合并... 

【文章來源】：電子科技大學(xué)四川省 211工程院校 985工程院校 教育部直屬院校

【文章頁數(shù)】：79 頁

【學(xué)位級別】：碩士

【文章目錄】：
摘要
abstract
Chapter 1 Introduction
    1.1 Research Background and Significance
        1.1.1Advancement of Satellite Communication system
        1.1.2 Significance of Helicopter in Communication
        1.1.3 Problems in Helicopter Satellite Communication System
    1.2 State of the art
        1.2.1 International Research Status
        1.2.2 Chinese Research Status
    1.3 Contents and Innovations of the Thesis
    1.4 Outline of the Thesis
Chapter 2 Theoretical Basics
    2.1 Introduction
    2.2 Helicopter Satellite Communication Channel Characteristics
        2.2.1 Free Space Transmission Loss
        2.2.2 Additional Link Loss
        2.2.3 Multipath Fading
        2.2.4 Shadowing decay
        2.2.5 Helicopter Rotor Shelter model
    2.3 Channel Analysis based on Experimental data and Statistics
        2.3.1 Channel Measurement Method Analysis
        2.3.2 Qualitative analysis of channel measurement results
    2.4 Basic Helicopter Satellite Communication Channel Model
        2.4.1 Simplified Channel
    2.5 Walsh Hadamard Transform
        2.5.1 Construction of Walsh Codes
    2.6 Conclusion
Chapter 3 Diversity Combining Schemes
    3.1 Introduction
    3.2 Concept of Diversity
    3.3 Types of Diversity
        3.3.1 Frequency Diversity
        3.3.2 Time Diversity
        3.3.3 Space Diversity
    3.4 Diversity Combining Schemes
        3.4.1 Selection Combining (SC)
        3.4.2 Maximal Ratio Combining (MRC)
        3.4.3 Equal Gain combining (EGC)
    3.5 Performance Analysis of Diversity Combining Schemes
        3.5.1 BER performance of MRC and EGC with Nakagami m-Channel
    3.6 Conclusion
Chapter 4 Modelling and Simulation of Diversity combining schemes in system ..
    4.1 Introduction
    4.2 Performance of WHCDM with time diversity:
    4.3 Performance of System with WHCDM and Time Diversity
        4.3.1 Simple WHCDM Implementation in System:
        4.3.2 WHCDM implementation with Time Diversity in system
    4.4 Performance of WHCDM with Equal Gain Combining
        4.4.1 Transmitter for EGC and MRC schemes implementation
        4.4.2 Receiver for WHCDM with equal gain combining
    4.5 Performance of WHCDM with Maximal Ratio Combining:
        4.5.1 Receiver for WHCDM with Maximal Ratio Combining:
        4.5.2 Pseudo BER calculator
    4.6 Conclusion
Chapter 5 Conclusions
    5.1 Concluding Remarks
    5.2 Future Work
Acknowledgements
References


【參考文獻】：
期刊論文
[1]直升機衛(wèi)星通信的前向鏈路設(shè)計[J]. 張倨卿,高凱,朱江.  無線電通信技術(shù). 2012(05)
[2]適用于直升機衛(wèi)星通信的LDPC譯碼算法[J]. 王健,胡應(yīng)鵬,司飛飛.  通信技術(shù). 2012(09)



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