射頻(RF)頻譜是一種有限的自然資源,它需要更有效地利用,以便以更高的數(shù)據(jù)速率向大量用戶提供多樣化的服務(wù)。由于無線寬帶,多媒體用戶和應(yīng)用程序市場的迅速擴大,人們對這種寶貴的無線電資源的需求正在增加。在這種有限的資源中容納更多的無線應(yīng)用程序似乎更具挑戰(zhàn)性。然而,由于給定頻譜分段和標(biāo)準(zhǔn)化無線系統(tǒng)的專用頻率分配,可用頻譜資源正變得日益匱乏。認(rèn)知無線電(CR)技術(shù)是一種試圖利用動態(tài)頻譜管理原理來解決頻譜擁塞和頻譜利用不足之間的矛盾的頻譜接入新策略,它允許CR用戶適時地使用主用戶的許可頻譜(PU)。CR技術(shù)的一個關(guān)鍵要求是在短時間內(nèi)實現(xiàn)頻譜的無占用,同時避免對PU的干擾。這種能力直接取決于頻譜感知,而頻譜感知是決定CR系統(tǒng)可靠性的最重要步驟。CR頻譜感知的一個巨大挑戰(zhàn)是能夠在短時間內(nèi)精確檢測主發(fā)射機的狀態(tài)。頻譜感知技術(shù)主要集中在主發(fā)射機檢測上,其中包括匹配濾波器檢測(MFD),循環(huán)平穩(wěn)特征檢測,能量檢測(ED)等。能量檢測(ED)由于具有廣泛的適用性和簡單性以及計算和實施成本低等優(yōu)點,而成為了一種普及的CR頻譜感知技術(shù)。然而,傳統(tǒng)的ED方案對噪聲不確定性效應(yīng)敏感,由于噪聲比(SNR)壁的存在,使...

【文章頁數(shù)】：56 頁

【學(xué)位級別】：碩士

【文章目錄】：
摘要
Abstract
Chapter 1 Introduction to Cognitive Radio
    1.1 Introduction and Motivations
    1.2 Research Background and Significance
        1.2.1 Dynamic Spectrum Access
        1.2.2 Brief history of Cognitive Radio
        1.2.3 Definitions of Cognitive Radio
        1.2.4 Why Cognitive Radio
        1.2.5 How Cognitive Radio is Different from Other Radios?
        1.2.6 Functions of Cognitive Radio
    1.3 Research Background Analysis
        1.3.1 Related work
    1.4 Objective
    1.5 Main Research Content
Chapter 2 Spectrum sensing techniques
    2.1 Introduction
    2.2 Spectrum sensing standards
        2.2.1 IEEE 802.22
        2.2.2 ECMA 392
        2.2.3 802.11af
    2.3 Spectrum Sensing Problem
    2.4 Classification of different spectrum sensing techniques
    2.5 Narrowband Spectrum Sensing
        2.5.1 Narrowband Sensing Techniques
        2.5.2 Local Spectrum Sensing (LSS) Approach
        2.5.3 Cooperative Spectrum Sensing Approach
    2.6 Factors for selecting the fitting sensing method
        2.6.1 CR Device Capability
        2.6.2 Qo S Required for Applications Running on the CR Device
        2.6.3 Priori Information
        2.6.4 Level of Protection Required for PU
        2.6.5 The CR Network Mode and Capability
    2.7 Summary
Chapter 3 Enhanced double threshold energy detection algorithm
    3.1 Introduction
    3.2 Design Parameters
        3.2.1 Threshold
        3.2.2 Number of Samples
    3.3 Employing the Double Threshold Logic
    3.4 Noise power uncertainty consideration
    3.5 Noise Uncertainty Consideration for ED
    3.6 Proposed algorithm
    3.7 Summary
Chapter 4 Simulation result and analyses
    4.1 Non cooperative detection
    4.2 Cooperative detection
    4.3 Summary
CONCLUSION
References
List of publication
Acknowledgement



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