In this paper, we present an new asynchronous, accurate, and real time distance measurement method using chirp signals, which is capable of accurately locating and tracking, thus forming an ad-hoc network among smartphones in an indoor (e.g., smart meeting room) environment. Also we propose a distance measurement which can overcome limitations of previous representative distance measurements of Received Signal Strength Indicator (RSSI) and Time of Arrival (TOA). It operates in spontaneous, smartphone-based ad-hoc networks (SAN), sensory-based context inference, and device-to-device context extraction systems without requiring well–organized infrastructures. We then implement our proposed method on two Samsung Galaxy S5, one of Commercial Off-The-Shelf (COTS) smartphones. Without modifying their hardware or OS kernel. Our experimental results demonstrate that it takes < 1 second to conduct network-wide distance measurements and the measurement error is <10 cm, which is treated as an allowable error, in at least 87% of the experiments. ⓒ 2016 DGIST
Table Of Contents
I. Introduction 7 -- II. Related Works 10 -- 2.1 RSSI 10 -- 2.2 TOA 11 -- III. Challenges of High Accuracy Localization 13 -- 3.1 Challenge of Time Synchronization 13 -- 3.2 Challenge of Asynchronous Localization 15 -- IV. Asynchronous Distance Measurement Method 19 -- V. Implementation Detail 23 -- 5.1 Chirp Signal Design 23 -- 5.2 Chirp Signal Detection 27 -- 5.3 Device orientation 28 -- VI. Evaluation 31 -- 6.1 Hardware Configuration 31 -- 6.2 Test Case Design 32 -- 6.3 Experimental Result 35 -- 6.3.1.1 Case 1 Result 37 -- 6.3.1.2 Case 2 Result 38 -- 6.3.1.3 Case 3 Result 38 -- VII. Conclusion 41 -- References 42
