Map Compression for a RFID-Based Two-Dimensional Indoor Navigation System Tsung-Chun Tsai A dissertation submitted to Auckland University of Technology in partial fulfilment of the requirements for the degree of Master of Computer and Information Science (MCIS) 2008 School of Computing and Mathematical Sciences Primary Supervisor: Dave Parry ATTESTATION OF AUTHORSHIP “I hereby declare that this submission is my own work and that, to the best of my knowledge and belief, it contains no material previously published or written by another person nor material which to a substantial extent has been accepted for the award of any other degree or diploma of a university or other institution of higher learning, except where due acknowledgement is made”. Tsung-Chun Tsai 2008 _______________________________________________________ TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ................................................................................. iii ABSTRACT.......................................................................................................iv LIST OF TABLES...............................................................................................v LIST OF FIGURES........................................................................................... vii Chapter 1: Introduction....................................................................................1 1.1 Background ...........................................................................................1 1.2 Motivation ..............................................................................................2 1.3 Organization of dissertation...................................................................3 Chapter 2: Literature Review...........................................................................5 2.1 Introduction............................................................................................5 2.2 Challenge and approach of location and navigation ..............................5 2.3 Location representation method ............................................................7 2.4 RFID technology..................................................................................11 2.5 Compression technique.......................................................................12 2.5.1 LZW ...........................................................................................12 2.5.2 Huffman .....................................................................................16 2.5.3 Fractal compression...................................................................19 2.5.4 MPEG ........................................................................................22 2.5.5 Wavelet compression.................................................................24 2.5.6 Comparison ...............................................................................28 2.6 Review of location representation........................................................31 Chapter 3: Methodology.................................................................................35 3.1 Selection of methodology ....................................................................35 3.2 Design science ....................................................................................35 3.2.1 Concept and discussion.............................................................35 3.2.2 Design .......................................................................................37 3.3 Experimental testing ............................................................................38 3.3.1 Concept and discussion.............................................................38 i 3.3.2 Design .......................................................................................39 Chapter 4: Theoretical Fundamental of the Research.................................41 4.1 Distance...............................................................................................42 4.2 Angle ...................................................................................................46 4.3 Navigation............................................................................................49 Chapter 5: Experimental Methodology and Results ....................................59 5.1 Experiment 1: Distance and angle.......................................................60 5.2 Experiment 2: Navigation.....................................................................75 Chapter 6: Discussion and Conclusion........................................................86 6.1 Conclusion...........................................................................................86 6.2 Discussion ...........................................................................................87 6.3 Strengths and Limitations ....................................................................90 6.4 Future research directions...................................................................91 REFERENCES .................................................................................................92 APPENDICES ..................................................................................................98 ii ACKNOWLEDGEMENTS I wish to express my gratitude to my supervisors, Dr. Dave Parry and Dr. Russel Pears, for their patience, support, guidance and advice throughout this research. I would like to thank my wife Linda, my daughter Jasmine, my parents in and family in Taiwan, and my parents-in-law in China for their support, patience and love in the process of completing this work. Sincere thanks are also extended to helpful friends, participants and all staff of the School of Computing and Mathematical Science for their kindness and encouragement during my studying period at the Auckland University of Technology. iii ABSTRACT Radio frequency identification (RFID) tags can be used to identify a location and some can store a limited amount of data. They have been proposed as a method of storing a distributed map of an area, where a central map is not practical because of infrastructure or security concerns. In order to navigate between a set of RFID tags in a space, location information can be stored on the tags themselves. However, because of memory constraints, it is not practical to store copies of a complete map on every tag. Use of compression techniques is a way to solve the issue of the RFID memory space limitation. The purpose of this study is to implement a compression scheme including the wavelet compression technique on map compression for a RFID based 2-dimensional navigation system and evaluate its performance. Previous work related to wavelet compression technology and location representations were reviewed to explore the background of this study from prior research findings. The methodology of this study is design science study and its testing method is experimental testing. The compression techniques adopted were combined with a navigation scheme to study whether the technique could support movement between various tag layouts. A number of experiments were carried out and the efficiency of this technique in a test environment is calculated. iv LIST OF TABLES Table 1 The five stages of implementation of Huffman tree ..........................17 Table 2 Eight encoding stages of Fractal compression in quad-tree partitioning (Poobal and Ravindranm, 2005) ....................................................21 Table 3 Three decoding stages of Fractal compression in quad-tree partitioning (Poobal and Ravindranm, 2005) ....................................................21 Table 4 The summary of the MPEG video bit-stream (Marshall, 2001)........23 Table 5 The three steps of wavelet compression (Weisstein, n.d.)..............24 Table 6 The comparison of the compression technologies in section 2.5.1 to 2.5.5.......................................................................................................................30 Table 7 The content of the map in each tag ......................................................32 Table 8 Design science research guidelines ....................................................36 Table 9 The percentage of the error in resolution for each distance for Tag1 ....................................................................................................................................65 Table 10 The percentage of the error in resolution of distance, and the AVG of and the STDEV of % error in resolution for fifteen different groups of random number ......................................................................................................67 Table 11 The original size of the distance data, the size of the distance data by using Wavelet compression technique and the size of the distance data by using Zip compression technique for each of seventeen testing tags..68 Table 12 The percentage of the error in resolution for each angle for Tag1 ....................................................................................................................................71 Table 13 The percentage of the error in resolution of angle, and the AVG of and the STDEV of % error in resolution for fifteen different groups of random number ......................................................................................................73 v Table 14 The original size of the angle data, the size of the angle data by using quadrant compression technique and the size of the angle data by using Zip compression technique for