TOA Ranging Using Real Time Application Interface (RTAI) in IEEE 802.11 Networks

Ranging and positioning of wireless mobile devices using time-of-arrivals (TOA) method is becoming an increasingly interesting and challenging research topic. There are various TOA-based ranging algorithms and positioning systems, but most of them require either specially designed hardware or modifications to existing firmware. Using only off-the-self hardware, we present a novel software-based TOA ranging approach which accurately measures TOAs using the Real Time Application Interface (RTAI) operating system. A prototype system is implemented which provides precise measurements of round trip time (RTT) using IEEE 802.11b MAC layer ACK frames and the real-time communication mechanism provided by RTAI. Experiments show that using RTAI can achieve a ranging result with precision close to the accuracy obtained by hardware based methods.