Beep: 3D Indoor Positioning Using Audible Sound

Atri Mandal, Cristina Videira Lopes, Tony Givargis, Amir Haghighat, Raja Jurdak and Pierre Baldi

Abstract

Rapid growth in the number of wireless enabled devices has led to an increased interest in location-aware applications. The backbone of such applications is provided by a location system. In this paper we present Beep, an indoor location system that senses audible sound. The use of audible sound makes our system cheap and easily deployable to most existing roaming devices. Unlike positioning systems using ultrasound and infrared signals, Beep does not require the user to carry any kind of specialized hardware. Our system is based on standard 3D multilateration algorithms. However, the requirement of being able to locate existing devices, whose sound cards were not designed for high-precision signaling, introduces additional challenges to the location problem. This paper describes how those problems were solved and presents experimental results. Beep works with an accuracy of about 2 feet in more than 97% cases. The paper also describes a sensor deployment strategy that requires low sensor density and consequently low installation costs. specialized hardware which is not easily available. Also, some of these systems are prohibitively expensive for wide deployment. In our attempt to build a location system that is both cheap and universally applicable we chose to sense audible sound, because it is available in virtually all roaming devices. In our positioning system we use a PDA (or equivalently, any other roaming device with wireless capability) as a cheap locating device. The use of audible sound eliminates the need for additional infrastructure at the user end. Beep has a sufficiently high level of accuracy for most practical applications, as demonstrated by our experimental results. We envision applications of Beep in places like large departmental stores, shopping plazas, amusement parks, museums, public libraries, office buildings etc.

Appears in IEEE Consumer Communications and Networking Conference (CCNC'05), January 2005.