Fusion of wireless ranging and inertial sensors for precise and scalable indoor localization

In recent years there has been a large increase in the use of wireless localization for a broad range of commercial and consumer applications, including to enhance safety and productivity, provide location based services and entertainment. Accurate outdoor localization is provided using global navigation satellite systems (GNSS) such as the Global Positioning System (GPS), while indoor localization is typically obtained using received signal strength (RSS) of access points in wireless networks and has low accuracy. Accurate localization in indoor and GNSS denied spaces remains a challenge in general. This paper presents a low-cost system for accurate localization in challenging environments that uses the fusion of Time-of-Flight (ToF) wireless ranging and micro-electro-mechanical (MEMS) inertial sensors. The key contributions of this paper are a fusion concept and experimental results using a deployed system in outdoor and indoor environments. Compared to the use of the Wireless Ad-hoc System for Positioning (WASP) alone, the fused system is demonstrated to obtain sub-meter accuracy with a much lower update rate, enhancing system scalability and availability, and enabling the system to operate with lower power consumption.