Non-audible Acoustic Communication and its Application in Indoor Location-based Services Kashif Ali EECS, University of California Berkeley, USA kashif@cs.berkeley.edu Tayyab Javed, Hossam S. Hassanein and Sharief M.A. Oteafy School of Computing, Queen’s University, Canada {tayyab, hossam, oteafy}@cs.queensu.ca Abstract—Location-Based services are gaining momentum as an important advancement in context aware services. That is, empowering users to identify potential services in their current space, and the prospect for services that are able to target local users, are pushing interest in research and industry alike. This paper explores the use of non-audible sound as a communication medium to tag and access location based services and gain access to their pertinent information. We propose and demonstrate the indoor implementation of a prototype of a location-based service- enabling system for hand-held devices. The system allows users to use their hand-held devices to search and interact with available services in their surroundings. A beacon placed in the service location broadcasts a service code mappable to the services particular to that location, and encoded via an ultrasound signal. The hand-held device can then identify that signal and prompt the user with the available services. We detail the novel system design and the ensuing architecture, and demonstrate the viability of the system which is tested over a variety of environments and scenarios. We conclude with an overview of the wide range of applications of this system, and note how it can enhance the way clients access location based services. I. I NTRODUCTION Location is an essential aspect of how people relate, organize and communicate with the physical environment. Wireless technologies, the Internet, navigational systems and geographical information systems assist us in meeting our location needs. Location is, in general, linked and related with other information systems to create and provide value added services, a paradigm known as Location-based Services (LBS) [1]. LBS comprise of user devices, position technologies, wire- less network and application servers. All these components communicate together to enable services and enhance mobile user experience. Examples of LBS include outdoor applica- tions, such as congestion-free routing between destinations, and indoor applications, such as collecting socially-ranked items on a menu at your favourite restaurant. Positional technology is an important and enabling compo- nent of any location-based services. Numerous technologies have been developed and utilized to fulfil the positioning needs for both outdoor and indoor LBS. Examples for outdoor positional technologies are Global Positioning System (GPS) [2], assisted GPS, enhanced observed timed distance [1], cell global identity in cellular system [3], and time of arrival for the radio signal. Examples of indoor positional technologies are WiFi [4], Zigbee, Bluetooth [5], Radio Frequency Identi- fication (RFID) and Ultrasound [6]. Various LBS applications requirements demand use of dif- ferent positional technology. The requirements are defined using a wide range of parameters such as positional accu- racy, power consumption, indoor/outdoor, latency, bandwidth, interference and operational scale. The factors play a major role in the adoption (or lack thereof) of LBS’, especially in indoor environments where the abundance of devices coupled with lack of GPS signals cause poor localization. Although much research has been directed in the realm of LBS, most of the current approaches are hindered by factors pertaining to accuracy, battery consumption, cost of such systems, supported data rates, lack of encryption, frequency overlapping, indoor vs outdoor performance discrepancy, access latency, possible interference, range and scalability, in addition to poor traction and adoption by current LBS applications. In this paper we propose a new paradigm for indoor location services, which capitalizes on non-audible acoustic communication. The reason acoustic waves are chosen as the communication channel is that to detect and identify sound waves we do not need any extra hardware on the client side, as hand-held devices already have built-in microphones. Also, sound waves do not penetrate through solid walls and are contained in a closed area making them a good candidate to be used as a location identifier. Our goal for a nominal LBS enabler is to adopt a paradigm that scales with the abundance of resources already with today’s users. In the remainder of this paper we argue for the viability of the non-audible based LBS system that we developed. In Section II we detail the design goals of our LBS system, and its components, along with the Encoding algorithm. Section III details the implementation of (Non-Audible System) NAS- LBS, and the architectural design challenges that entailed its design. Section IV highlights the thorough performance evaluation carried out, and our conclusions are presented in Section V. II. NAS-LBS: NON-AUDIBLE SOUND-LOCATION BASED SYSTEM The focus of our work is to propose and evaluate an efficient and ubiquitous location-based system for mobile devices. Efficiency is defined in terms of time to discovery with minimal system resources. Our objective is to enable smart spaces and associated services for all existing, and potentially IEEE Wireless Communications and Networking Conference (WCNC 2016) - Track 4 - Services, Applications, and Business 978-1-4673-9814-5/16/$31.00 ©2016 IEEE 2174