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  • The Islamic University of Gaza

    Postgraduate Studies

    Faculty of Engineering

    Electrical Engineering Department

    Spectrum Handoff Strategies in

    Cognitive Radio Networks

    Submitted by: AbdElghani Ibrahim Abu Tair

    Supervised by:

    Dr. Fady El-Nahal Dr. Musbah Shaat

    A Thesis Submitted in Partial Fulfillment of the Requirements for the

    Degree of Master in Electrical Engineering

    May, 2014

  • ii

    ABSTRACT

    Today, Cognitive Radio (CR) have a promising solution to both spectrum inefficiency

    and spectrum scarcity issues by enabling secondary users (SUs) to exploit the idle

    frequency bands temporarily in opportunistic manner as long as the primary users (PUs)

    do not occupy their spectrum.

    The SUs must vacate these frequency bands when the PUs come back and reuse

    them. This is one of challenge in CR technology. In this case, the communication links

    of the SUs must be finding another idle frequency bands to resume their communication

    links. This is called spectrum handoff which is affecting to the performance of system

    by main factors such as: link maintenance probability, the number of spectrum handoff,

    switching delay.

    Spectrum handoff may be happen more than once for a wide range of the

    spectrum available in CR. This switching change the characteristics of propagation

    transmission loss which is affects the overall system performance. Thus, in this thesis,

    the path loss and coverage area are essential factors studied to enhance the system

    performance and make it more immune to propagation losses.

    In this dissertation, we aim to overcome these issues by proposing a systematic

    selection method to select and assign new appropriate frequency channels efficiently to

    achieve a better transmission performance. Additionally, the adaptation power

    technique is applied in order to control base station transmitted power and estimate the

    appropriate coverage area to reduce and avoid interference and also to conserve power

    dissipation in the system.

    The combining of these approaches, selection method and power adaptation, is

    found to be helpful to achieve an efficient spectrum utilization, reduce power

    consumption, maintain the connectivity link, decrease the number of spectrum handoffs

    from failure which are very important to improve overall system performance. The

    simulation results show a comparison of the proposed strategy with other techniques by

    increasing the wide of frequency switching up to 70% and also studies the effect of the

    adaptation technique on the system performance.

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  • iv

    To my parents, wife, sons and daughters

  • v

    ACKNOWLEDGMENTS

    I would like to express deepest gratitude for my parents who have always been

    there to support me. Also many thanks to my wife who continually encourage me to the

    end of this thesis.

    I am also express my greatly thankfulness to my thesis advisor, Dr. Fady El-

    Nahal and Dr. Musbah Shaat for their guidance, patience, and support during writing

    this thesis. I would also like to thank the committee members, Dr. Talal Skaik and Dr.

    Abd elhakeem Husein, for their time in reviewing my thesis.

    Most importantly, I would like to thank all my friends who helped me through

    my studying. Special thanks to, Mohammed El-Astal, Alaa El Habbash, and Ahmed Al

    Shantti.

    AbdElghani Ibrahim Abu Tair

    Palestine, Gaza

    May, 2014

  • vi

    TABLE OF CONTENTS

    ABSTRACT ii

    iii

    DEDICATIONS iv

    ACKNOWLEDGMENTS v

    TABLE OF CONTENTS vi

    LIST OF TABLES ix

    LIST OF FIGURES x

    LIST OF ABBREVIATIONS xii

    Chapter 1: Introduction 1

    1.1 Introduction 1

    1.2 Problem Statement 3

    1.3 Motivation and Objective 4

    1.4 Contribution 5

    1.5 Organization of the Dissertation 6

    Chapter 2: Cognitive Radio Background 7

    2.1 Definitions of Cognitive Radio System 8

    2.2 Cognitive Radio Concepts and Capable Technology 10

    2.2.1 Dynamic Spectrum Access 11

    2.2.2 Software Defined Radio 13

    2.3 The Cognitive Radio Cycle 16

    2.4 Main Functionalities of Cognitive Radio 17

    2.4.1 Spectrum Sensing 18

    2.4.2 Spectrum Management 18

    2.4.3 Spectrum Sharing 19

    2.4.4 Spectrum Mobility 21

    2.5 The Architecture of Cognitive Radio Network 21

    2.5.1 Primary Network 22

    2.5.2 Cognitive Radio Network 22

    2.6 Cognitive Radio Standardization 24

    2.7 Applications of Cognitive Radio 27

  • vii

    Chapter 3: Spectrum Handoff in Cognitive Radio Network 29

    3.1 Spectrum Handoff Overview 29

    3.2 Spectrum Handoff Strategies 32

    3.2.1 Non-Handoff Strategy 32

    3.2.2 Pure Reactive Handoff Strategy 33

    3.2.3 Pure Proactive Handoff Strategy 33

    3.2.4 Hybrid Handoff Strategy 34

    3.2.5 Comparison of Handoff Strategies 35

    3.3 Type of Spectrum Handoff 37

    3.3.1 Intracell/Intrapool Handoff 38

    3.3.2 Intracell/Interpool Handoff 39

    3.3.3 Intercell/Interpool Handoff 39

    3.3.4 Intercell/Intrapool Handoff 40

    3.4 Selection Handoff Type in Cognitive Radio Network 40

    3.5 Spectrum Handoff Challenges 42

    Chapter4:Proposed Spectrum Handoff Scheme 43

    4.1 Introduction 43

    4.2 Related Work 44

    4.3 System Model 45

    4.3.1 Description System Model 46

    4.3.2 Frequency Changing and Path Loss 48

    4.3.3 Adaptation Power Control in Secondary Base Station 50

    4.4 Spectrum Handoff Proposed Scheme 50

    4.4.1 Systematic Selection with Adaptation Power 52

    4.4.2 Algorithm Procedures 54

    4.5 Performance and Simulation Results 56

    4.5.1 Case I: Small Cell Application to CR 57

    4.5.1.1 Simulation Analysis and Discussion 58

    4.5.2 Case II: Medium Cell Application to CR 51

    4.5.3 Case III: Large Cell Application to CR 63

    4.5.4 Comparison the Gain of wide frequency switching results between 65

  • viii

    schemes

    Chapter 5 : Conclusion 67

    5.1 Conclusion 67

    5.2 Future Works 68

    Bibliography 70

  • ix

    LIST OF TABELS

    Table Title Page

    Table3.1 Comparison of spectrum handoff strategies 36

    Table 4.1 System parameters in small cell size 57

    Table 4.2 System parameters in medium cell size 61

    Table 4.3 System parameters in large cell size 63

    Table 4.4 Comparison the Gain of wide frequency switching Results

    between Schemes

    65

  • x

    LIST OF FIGURES

    Figure Title Page

    Figure 2.1 Spectrum occupancy blow 3GHz 10

    Figure 2.2 White Space (Spectrum Hole) 11

    Figure 2.3 A taxonomy of dynamic spectrum access 12

    Figure 2.4 SDR transceiver 14

    Figure 2.5 Cognitive cycle of cognitive radio 16

    Figure 2.6 Components in a cognitive radio 17

    Figure 2.7 Spectrum Sharing Function Categories 20

    Figure 2.8 Cognitive radio Architecture 23

    Figure 2.9 Summary of international standardization on CR system 26

    Figure 2.10 Multi-service Network Application 28

    Figure 3.1 CR network communication functionalities 30

    Figure 3.2 Spectrum handoff process 31

    Figure 3.3 Spectrum handoff strategies: a) non-handoff; b) pure reactive

    handoff; c) pure proactive handoff; and d) hybrid handoff

    34

    Figure 3.4 Handoff latency factors 35

    Figure 3.5 Different handoff types in CR networks 38

    Figure 4.1 The coexistence system model of PU and SU. 47

    Figure 4.2 Cell Coverage due to changing frequency (spectrum handoff) 48

    Figure 4.3 Spectrum Band (pool) random Selection (classic) a) Initial state

    select ; b) Low to High HO ; c) High to Low HO ; d) Drop HO;

    e) Block HO.

    51

    Figure 4.4 Flowchart Algorithm Proposed Scheme 53

    Figure 4.5 Spectrum Band (pool) Systematic Selection a) Initial state; b) Low

    to High; c) High to Low; d) Highest HO

    55

    Figure 4.6 IEEE wireless standards classification 57

    Figure 4.7 Outage probability of Femtocell CR application vs. TVWS

    frequency range

    59

    Figure 4.8 Outage probability of Wi-Fi CR application vs. TVWS frequency

    range

    60

  • xi

    Figure 4.9 Outage probability of WiMAX CR application vs. TVWS

    frequency range

    62

    Figure 4.10 Outage probability of LTE700 CR application vs. TVWS

    frequency range

    62

    Figure 4.11 Outage probability of Public Safety CR application vs. TVWS

    frequency range

    61

    Figure 4.12 Outage probability of IEEE802.22 CR application vs. TVWS

    frequency range

    64

  • xii

    LIST OF ABBREVIATIONS

    A/D Analog /Digital

    BS Base Station

    CDMA Code Division Multiple Access

    CPE Customer Premises Equipment

    CR Cognitive Radio

    CRS Cognitive Radio System

    CSMA/CA Carrier Sense Multiple Access with Collision Avoidance

    DSA Dynamic Spectrum Access

    ETSI European Telecommunications Standards Institute

    FCC Federal Communications Commission

    FDMA Frequency Division M