A ranging scheme for asynchronous location positioning systems

In a real-time locating system which does not require time synchronization among nodes, it takes a very long time to complete a ranging process for a single location estimation. Long ranging time makes mobile nodes consume a significant amount of battery power and limits the number of mobile nodes that a single fixed node can handle during a specific time interval. Therefore, it is crucial to shorten the ranging time in asynchronous locating systems without degradation in ranging or locating accuracy. In this paper, we propose an asynchronous two-way ranging scheme which reduces ranging time by replying with multiple packets to a single ranging request. The algorithm reduces ranging time by 17% or more, compared to that of existing methods.