A query-driven indoor location system based on smartphone

Smartphone is the best device to provide the location based service in a query-driven indoor location system, since the query of location based service from the user may appear any time or any where. This paper presents a query-driven indoor location system based on commercial available time of arrival (TOA) devices and Android smartphone. An energy-efficiency dynamic TDMA protocol is designed to localize the target according to the query command. The computing engine, an application for Android phones, is developed to send query command, run the localization algorithm and display the position of the targets. The system can responses the query in 495.72 ms and return the position of the mobile objects with the mean accuracy at 0.99 m. Life time of our protocol is compared with a typical TDMA protocol used in periodic location system. The result shows that our protocol has an improved life time in such a query-driven system.