Energy-Aware Topology Control and Data Delivery in Wireless Sensor Networks A Thesis Presented to The Academic Faculty by Seung-Jong Park In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy • I N S T A I T I U G T R E O • E O G F • • E T H E T C • H F S S P R O G R ES E R V I C E N O A N D O • L L O A G E Y S • • 1 8 8 5 School of Electrical and Computer Engineering Georgia Institute of Technology July 2004 Energy-Aware Topology Control and Data Delivery in Wireless Sensor Networks Approved by: Raghupathy Sivakumar, Advisor Jennifer E. Michaels John A. Copeland Samit Soni Henry L. Owen Date Approved: 7 July 2004 To my companion for life: Young-Jin Juhn. iii ACKNOWLEDGEMENTS I first would like to express my sincere gratitude to my thesis advisor, Dr. Raghupathy Sivakumar. He has always advised me on not only the direction of research but also the way of campus life. I will miss the days and nights having brainstorming which enables me to finish my thesis. I also would like to thank to the members of dissertation committee, Dr. John Copeland, Dr. Henry Owen, Dr. Jennifer Michaels, and Dr. Samit Soni, who have also given many constructive comments during the proposal and final dissertation process. For the helpful discussion about simulation and the thesis, I would like to give special appreciation to Dr. George Riley and Dr. Chuanyi Ji. Thanks are also due to fellow graduate students at GNAN research group. Above all, I would like to express my gratitude in writing to my family, Young-Jin, Katie, and Jason, for their loving support and sacrifice. iv TABLE OF CONTENTS DEDICATION ......................................... iii ACKNOWLEDGEMENTS .................................. iv LIST OF FIGURES ...................................... ix SUMMARY .......................................... xii CHAPTER I INTRODUCTION ............................. 1 CHAPTER II WIRELESS SENSOR NETWORKS ................... 5 2.1 Applications . 5 2.1.1 Data Collecting Applications . 5 2.1.2 Event Monitoring Applications . 6 2.1.3 Object Tracking Applications . 7 2.1.4 Hybrid Applications . 8 2.2 Challenges in Wireless Sensor Networks . 8 2.3 Research in Protocol Layers . 10 2.3.1 Research in Application Layer . 10 2.3.2 Research in Transport Layer . 12 2.3.3 Research in Network Layer . 13 2.3.4 Research in Data Link Layer . 15 2.3.5 Research in Physical Layer . 16 2.3.6 Research in Inter-Layer Planes . 17 CHAPTER III ATC: ADAPTIVE TOPOLOGY CONTROL ............... 18 3.1 Problem Definition . 18 3.2 Motivation . 19 3.2.1 Terminology and Models . 19 3.2.2 Preliminary Observations . 22 3.3 Related Works . 25 3.4 Theoretical Analysis . 26 3.4.1 Per-flow Throughput . 26 3.4.2 Spatial-Reuse Factor and Hop-Count . 27 v 3.4.3 Mini-channel Utilization . 28 3.4.4 Summary of Motivation for Adaptive Topology Control . 30 3.5 Design Goals and Key Ideas . 31 3.5.1 Goals . 31 3.5.2 Key Ideas . 32 3.6 ATC Protocol . 36 3.6.1 Basic Algorithm . 36 3.6.2 ATC-CP . 38 3.6.3 ATC-IP . 39 3.6.4 ATC-MS . 41 3.7 Convergence Analysis of ATC Schemes . 42 3.7.1 Problem Formulation . 43 3.7.2 Analysis . 43 3.8 Performance Evaluation . 45 3.8.1 Evaluation Environments . 45 3.8.2 Evaluation Results . 46 3.9 Summary . 57 CHAPTER IV GARUDA-DN: RELIABLE DOWNSTREAM DATA DELIVERY ... 58 4.1 Problem Definition . 58 4.2 Motivation . 60 4.2.1 Assumptions . 60 4.2.2 Observations . 61 4.3 Related Works . 63 4.4 Design Preliminaries and Challenges . 65 4.4.1 Preliminary Design Choices . 66 4.4.2 Challenges . 70 4.5 Theoretical Approaches . 72 4.5.1 Ideal Solution: Minimum Set Cover Problem . 73 4.5.2 Reduction to Minimum Dominating Set Problem . 74 4.5.3 Performance Ratio between MDS and MSC . 75 4.6 GARUDA-DN Design . 77 vi 4.6.1 Loss Recovery Servers: Core . 78 4.6.2 Loss Recovery Process . 79 4.6.3 Multiple Reliability Semantics . 81 4.6.4 Reliable Single/First Packet Delivery . 82 4.7 GARUDA-DN Framework . 84 4.7.1 Single/First Packet Delivery . 84 4.7.2 Instantaneous Core Construction . 87 4.7.3 Two-Phase Loss Recovery . 92 4.8 Supporting Other Reliability Semantics . 95 4.8.1 Reliable Delivery within a Sub-Region . 96 4.8.2 Reliable Delivery to Cover Sensing Field . 97 4.8.3 Reliable Delivery to Probabilistic Subset . 97 4.9 Performance Evaluation . 98 4.9.1 Simulation Environment . 98 4.9.2 Metrics . 99 4.9.3 Evaluation of Single Packet Delivery . 100 4.9.4 Evaluation of Multiple Packet Delivery . 102 4.9.5 Microscopic Analysis . 105 4.9.6 Evaluation of GARUDA-DN Variants . 107 4.9.7 Summary of Evaluation . 108 4.10 Summary . 111 CHAPTER V GARUDA-UP: ENERGY-EFFICIENT UPSTREAM DATA AGGREGA- TION ........................................... 112 5.1 Problem Definition . 112 5.2 Motivation and Idealized Models . 115 5.2.1 Correlation of Data . 115 5.2.2 Problem Statement . 116 5.2.3 Optimal Solutions for Different Correlation Factors . 118 5.3 Related Works . 121 5.3.1 Default Aggregation in WSNs . 121 5.3.2 Intelligent Aggregation in WSNs . 122 vii 5.3.3 Graph Theory Techniques . 123 5.4 Design Goals and Key Idea . 123 5.4.1 Problem Scopes and Goals . 123 5.4.2 Key Ideas . 125 5.5 GARUDA-UP Design . 127 5.5.1 Overview . 127 5.5.2 Construction of the Core Set . 128 5.5.3 Aggregation at a Core Node . 128 5.5.4 Aggregation among Core Nodes . 128 5.5.5 Synchronization . 129 5.5.6 Message Complexity . 129 5.6 GARUDA-UP Framework . 130 5.6.1 Core Construction . 130 5.6.2 Stage 1: Original Data Transmission . 131 5.6.3 Stage 2: Aggregated Data Transmission . 133 5.6.4 Other Considerations . 134 5.7 Performance Evaluation . 135 5.7.1 Simulation Environments . 135 5.7.2 Different Node Densities . 139 5.7.3 Different Source Densities . 139 5.7.4 Number of Core Nodes . ..