Improving the coverage range of ultrasound-based localization systems

Location awareness is of benefit to a rich set of applications in indoor environments such as asset tracking, resource discovery, interactive virtual games, location-aware sensor networking, navigation support for humans and robots, etc. There exists a vast array of location sensing systems, but they mostly operate under dense indoor deployment due to the limited range and coverage of the sensing device. In this paper, we focus on improving coverage range - a critical prerequisite for localization. Our experiments using the existing Cricket system reveals many of its limitations. We overcome these hurdles, and present the design, implementation and evaluation of a custom designed omni-directional ultrasonic receiver unit integrated with the existing Cricket motes. The modified Cricket system improves the coverage range by ≈20% in comparison to the original Cricket. The lessons and experiences also provide an analytical and system-level understanding of how various factors affect the ranging characteristics.