Round-trip time-based wireless positioning without time synchronization

In this paper, we suggest a new positioning system that uses two-way time-of-arrival, called round-trip time (RTT). There already exist positioning systems based on time-of-arrival (TOA) and time difference-of-arrival (TDOA). Although these methods have been shown to be effective, they have a serious problem in installing and maintaining hardware for time synchronization. However, in the case of RTT-based method, the time synchronization is not needed even though the delay arose from the node makes it hard to measure the exact round-trip time. In this paper, we put another node called time-reference node that can estimate the internal delay of the node. Using the time-reference node, we can obtain a more accurate RTT measurement and the distance between nodes without time synchronization. We then locate a mobile node without time synchronization. Our positioning system is evaluated using network simulator.