Cognitive Radio Techniques

Transcription

1 Cognitive Radio Techniques Spectrum Sensing, Interference Mitigation, and Localization Kandeepan Sithamparanathan Andrea Giorgetti ARTECH HOUSE BOSTON LONDON artechhouse.com

2 Contents Preface xxi 1 Introduction to Cognitive Radios Introduction Definition of Cognitive Radios Software-Defined Radios The Cognitive Cycle The Radio Scene Analysis Spectrum Occupancy Classification Hidden Terminals Locating Primary Users Dynamic Spectrum Access and Management Spectrum Underlay and Overlay Regulatory Aspects 13 vii

3 viii Cognitive Radio Techniques The IEEE DySPAN Standards Committee The IEEE WAN Standards The ETSI-RRS Technical Committee Application Clusters Cellular Mobile Networks Energy Efficiency is Wireless Networks Public Safety Communications Coexistence of UWB Radio Technology Wireless Networks for Smart Grids Vehicular Networks Defense Application Systems 19 References 20 Parti Spectrum Sensing in Cognitive Radios 23 2 Fundamentals of Spectrum Sensing and Detection Introduction Statistical Detection Techniques Maximum A Posteriori Detection Maximum Likelihood Detection The Neyman-Pearson Detector The Bayesian Risk-Based Detector Continuous and Discrete Signal Detection Detection Performance Detection Performance Versus the SNR Detection Performance Versus the Signal Observation Length The ROC Curves Area Under the ROC Curves 34

4 Contents ix 2.5 Wireless Channel Models Mean Pathloss Shadowing Small Scale Fading Basic Models for Spectrum Occupancy The Poisson-Exponential Model The Markov Modulated Poisson Process The Poisson-Pareto Burst Process Stochastic Analysis of Radio Signals Blind, Partial, and Complete Context Aware Signal Detection Blind Signal Detection Partial-Context Aware Signal Detection Fully Context Aware Detection Summary 43 References 43 3 Introduction to Spectrum Sensing Techniques Introduction Spectrum Sensing with Energy Detection Energy Detector Energy Detector in Gaussian Channel Energy Detector in Fading Channels Energy Detector in Fading Channels with Shadowing 51

5 X Cognitive Radio Techniques 3.3 Energy detection and noise power uncertainty ED Threshold Mismatch SNRWall Existence of the SNR Wall Spectrum Sensing with Cyclostationaiy Feature Detection Cyclostationarity Analysis Cyclostationary Feature-Based Detector Spectrum Sensing with Matched Filter Detection Other Spectrum Sensing Techniques Covariance-Based Method Eigenvalue-Based Method Wavelet-Based Edge Detection Spectral Estimation Methods Summary 65 References 65 4 Temporal Spectrum Sensing and Performance Analysis Introduction Temporal Periodic-Spectrum Sensing Primary User Spectral Occupancy Model with Poisson Arrival Exponential Random Spectral Occupancy Time Pareto Random Spectral Occupancy Time 73

6 Contents XI Classifying Primary User Spectrum Occupancy Levels Detection Performance of Periodic-Sensing with Poisson Arrival and Deterministic Occupancy Time Spectral Occupancy Probability Probability of Detection False Alarm Probability Primary User Misdetection Risk Regions Temporal Periodic-Sensing with Poisson-exponential Occupancy Model Temporal Periodic-Sensing with Poisson-Pareto Occupancy Model Temporal Periodic-Sensing Performance Comparison with Deterministic and Random Occupancies Temporal Periodic-Sensing in Noise Temporal Periodic-Sensing in Noise with Signal Fading/Shadowing Optimum Sensing Period Reality of Spectrum Occupancy Models Summary 93 References 94

7 xii Cognitive Radio Techniques 5 Cooperative Spectrum Sensing Introduction Spatio-Temporal Fusion Strategy Synchronized Reporting Nonsynchronized Reporting Hard Decision Fusion Chair-Varshney Fusion Strategy The Af-out-of-A^Fusion Strategy Soft Decision Fusion Optimal Soft Decision Fusion Equal Gain Soft Decision Fusion Maximal Ratio Soft Decision Fusion Cluster-Based Cooperative Spectrum Sensing Space-Divisional Cluster Frequency-Divisional Cluster Time-Divisional Cluster Noisy Reporting Channels Other Issues in Cooperative Sensing Cooperation Overhead and the Reporting Channel Unreliable Reporter and Accreditation Security Issues Knowledge Distribution Spatial Limitation Summary 117 References 118

8 Contents xiii 6 Distributed Spectrum Sensing Introduction Parallel Topology-Based Distributed Sensing Sequential Topology-Based Distributed Sensing Detection Performance Tree Topology-Based Distributed Sensing Ring-Around Distributed Sensing Message Passing in Ring-Around Sensing Hard Decision Fusion with the OR Rule Equal Ratio Combining Soft Decision-Based Fusion Summary 132 References Advanced Spectrum Sensing Topics Introduction Spectrum Sensing in UWB Radios with Frequency Sweeping Spectrum Sensing in OFDM Systems The Likelihood Ratio Test Frequency Domain Detection Combined Localization and Detection of Primary Users Detection Using the Likelihood Function fr\hi{v\h^

9 xiv Cognitive Radio Techniques Detection Using the Output of Sequential Spectrum Sensing The Sequential Probability Ratio Test Spectrum Sensing with Ordered Statistics Spectrum Sensing with Reconfigurable Antennas Frequency Reconfigurability Radiation Pattern Reconfigurability Spectrum Sensing in 3D-Space Summary 153 References 154 Part II Coexistence and Interference Mitigation Techniques Fundamentals of Coexistence and Interference Mitigation Techniques Interference in Cognitive Radio and its Characterization Intentional Interference: From Jamming to Emulation Unintentional Interference Metrics to Quantify Interference and its Effects Coexistence Scenarios Spatial Configuration of the Systems From Narrowband to Ultrawideband The Coexistence Region 172

10 Contents xv 8.3 Interference Mitigation Techniques Interference Mitigation in Spread Spectrum CRs Power Control Band Relocation Spectrum Shaping Adaptive Antenna Techniques Summary and Further Readings 176 References Coexistence Analysis Coexistence Between Heterogeneous Wireless Systems Channel Model Block Fading Channel Interference Modeling Gaussian Approximation Tone Approximation Multitone Approximation Band-Limited Gaussian Process Approximation Pulse Train Model Modeling the Interfering Power The Effect of Narrowband Interference on a Wideband Communication Single-Carrier WB Communication in the Presence of NB Interference Multicarrier WB Communication in the Presence of NB Interference 203

11 xvi Cognitive Radio Techniques 9.5 The Effect of Wideband Interference on a Narrowband Communication Single-Carrier Presence of WB Interference 209 NB Communication in the Multicarrier NB Communication in the Presence of WB Interference Summary and Further Readings 217 References Coexistence in Network Scenarios Coexistence Between Heterogeneous Networks Network Scenario Definition Statistical Characterization of Network Interference Interference Generated Outside the Guard Zone Interference From the Whole Plane The Effect of Interference on Performance of Coexisting Networks Transmission Characteristics of the Nodes Narrowband Communication in the Presence of Wideband Network Interference Wideband Communication in the Presence of Narrowband Network Interference Performance Examples of Heterogeneous Coexisting Networks Summary and Further Readings 245 References 246

12 Contents xvii 11 Interference Mitigation Techniques Enabling Coexistence Cognitive Radio Transmission Techniques Enabling Coexistence Spectrum Interweave: Interference Avoiding Behavior Spectrum Underlay: Interference Controlling Spectrum Overlay: Interference Mitigating Behavior 251 Behavior The Secondary User Perspective: Performance of CR Transmission Strategies System Model Comparison of the SU Achievable Rates The Primary User Perspective: Impact of CR Transmission Strategies The Scenario Cognitive Network Interference as a Misdetection Problem PU Outage due to Misdetection by a Single SU PU Outage due to Misdetections in a Cognitive Network A Case Study Summary and Further Readings 265 References Advanced Interference Mitigation Techniques Interference Mitigation Techniques in UWB Radios 270

13 xviii Cognitive Radio Techniques Interference Mitigation in UWB Impulse Radio Interference Mitigation in MB-OFDM UWB Radio Interference Mitigation in Spatial Domain Example: MIMO Beamforming Summary and Further Readings 287 References 287 Part III Localization and Radio Environment Mapping Fundamentals of Ranging and Localization for Cognitive Radio Ranging Techniques and Enabling Technologies Time-Based Ranging RSS-Based Ranging Other Ranging Techniques Error Sources in Time-Based Ranging Performance Limits of Time-based Ranging: From Theory to Practice Theoretical Performance Limits Practical Schemes Cognitive Ranging Localization Techniques Single-Hop Localization Multihop Localization 311

14 Contents xix Anchor-Free Localization Location Tracking Case Study Summary and Further Readings 316 References Localization of Primary Users Localization of Noncollaborative Emitters Range-Free Localization of PUs Semirange-Based Localization of PUs RSSI-Based Localization of PUs Other Range-Based Algorithms Tracking of PUs Case Study Radio Environment Mapping Radio Cartography Database for SU Access Control Summary and Further Readings 339 References Conclusions and Future Work 343 Glossary 349 About the Authors 355 Index 357