Worcester Polytechnic Institute Digital WPI Major Qualifying Projects (All Years) Major Qualifying Projects April 2011 Software Defined Radio Localization using 802.11-style Communications Brian Shaw Worcester Polytechnic Institute Ryan Joseph Dobbins Worcester Polytechnic Institute Saul Emmanuel Garcia Worcester Polytechnic Institute Follow this and additional works at: https://digitalcommons.wpi.edu/mqp-all Repository Citation Shaw, B., Dobbins, R. J., & Garcia, S. E. (2011). Software Defined Radio Localization using 802.11-style Communications. Retrieved from https://digitalcommons.wpi.edu/mqp-all/3136 This Unrestricted is brought to you for free and open access by the Major Qualifying Projects at Digital WPI. It has been accepted for inclusion in Major Qualifying Projects (All Years) by an authorized administrator of Digital WPI. For more information, please contact [email protected]. Software Defined Radio Localization Using 802.11-style Communications A Major Qualifying Project Report Submitted to the Faculty of WORCESTER POLYTECHNIC INSTITUTE in partial fulfillment of the requirements for the Degree of Bachelor of Science in Electrical and Computer Engineering by __________________________________ Ryan Dobbins __________________________________ Saul Garcia __________________________________ Brian Shaw Sponsoring Organization: United States Naval Research Laboratory Project Advisor: __________________________________ Professor Alexander Wyglinski Abstract This major qualifying project implements a simple indoor localization system using software defined radio. Both time of arrival and received signal strength methods are used by an array of wireless receivers to trilaterate a cooperative transmitter. The implemented system builds upon an IEEE 802.11b-like communications platform implemented in GNU Radio. Our results indicate substantial room for improvement, particularly in the acquisition of time data. This project contributes a starting point for ongoing research in indoor localization, both through our literature review and system implementation. i Acknowledgements We wish to thank Mr. Douglas Geiger and the United States Naval Research Laboratory at Washington DC for offering us the opportunity to complete this sponsored research and providing technical and financial support, as well as Professor Alexander Wyglinski for overseeing and advising the project and giving us guidance and confidence throughout our work. Additionally, we wish to thank Devin Kelly, Yuan Shi, Ramsey Abouzahra and the rest of the students in the Wireless Innovation Laboratory at Worcester Polytechnic Institute for assisting with laboratory equipment and offering suggestions for improvement. ii Authorship This project is the work of Ryan Dobbins, Saul Garcia, and Brian Shaw. All team members contributed equally. iii Table of Contents Abstract ............................................................................................................................................ i Acknowledgements ......................................................................................................................... ii Authorship...................................................................................................................................... iii List of Figures ................................................................................................................................ ix List of Tables ................................................................................................................................. xi List of Equations ........................................................................................................................... xii Glossary ....................................................................................................................................... xiii Executive Summary .................................................................................................................... xvii 1 Introduction .................................................................................................................................. 1 2 Wireless Networks and Localization Overview .......................................................................... 5 2.1 Localization Techniques ....................................................................................................... 7 2.1.1 Time of Arrival ............................................................................................................... 8 2.1.2 Time Difference of Arrival ............................................................................................. 9 2.1.3 Received Signal Strength ................................................................................................ 9 2.2 Calculating Distance using Timestamps ............................................................................. 10 2.2.1 Synchronized BS and MS, one-packet ToA ................................................................. 10 2.2.2 Synchronous BS, asynchronous MS, one-packet TDoA .............................................. 11 2.2.3 Differential Time Difference of Arrival (DTDoA) ...................................................... 11 2.2.4 Synchronization ............................................................................................................ 13 iv 2.3 Software Defined Radio Platforms ..................................................................................... 13 2.3.1 The Universal Software Radio Peripheral .................................................................... 15 2.3.2 The USRP2 ................................................................................................................... 16 2.3.3 GNU Radio ................................................................................................................... 16 2.3.4 Simulink Communications Blockset ............................................................................ 18 2.4 IEEE 802.11 ........................................................................................................................ 18 2.4.1 BBN80211b .................................................................................................................. 19 2.4.2 SPAN 80211b Receiver ................................................................................................ 20 2.4.3 FTW 802.11p Encoder and Transmitter ....................................................................... 20 2.5 Challenges in Flight Time Calculation................................................................................ 21 2.5.1 Resolution of the Timestamps ...................................................................................... 21 2.5.2 Hardware Delay ............................................................................................................ 24 2.5.3 Multipath Rays ............................................................................................................. 25 2.5.4 Bandwidth limitations................................................................................................... 26 2.5.5 Undetected Direct Path ................................................................................................. 26 2.6 Methods of Detecting Arriving Packets .............................................................................. 27 2.6.1 Peak Detection Using RSSI .......................................................................................... 27 2.6.2 Matched Filter Correlation ........................................................................................... 28 2.6.3 MUSIC-based Correlation Algorithms ......................................................................... 29 2.7 Undetected Direct Paths ...................................................................................................... 30 v 2.7.1 Exploit frequency, temporal, or spatial diversity ......................................................... 33 2.7.2 Use AoA to exploit a non-direct path for localization .................................................. 33 2.7.3 Maintain a history of the MS‘s measurement noise, and use it to reconstruct LOS .... 34 2.7.4 Comparison of UDP compensation techniques ............................................................ 34 2.8 Data Fusion ......................................................................................................................... 34 2.8.1 Least-Squares Error Minimization ............................................................................... 36 2.9 Summary ............................................................................................................................. 37 3 System Design ........................................................................................................................... 38 3.1 Project Motivation and Goal ............................................................................................... 38 3.2 Objectives ............................................................................................................................ 39 3.3 Design Requirements .......................................................................................................... 40 3.4 Design Overview ................................................................................................................. 43 3.5 Mathematical Localization Techniques 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