An alternative double-sided two-way ranging method

Abstract

Symmetric double-sided two-way ranging is a well-known technique to deal with clock drift in time-of-flight measurements between unsynchronised devices. However, the requirement for symmetric reply delays is often not feasible. This paper presents an alternative way to process double-sided two-way ranging measurements that eliminates the need for this impractical constraint. The error of the proposed method is of the same order of magnitude as the best case error of symmetric double-sided two-way ranging. Crucially, the error depends only on the clock drift of one of the devices, which can be exploited if one of the device has a better timing reference than the other.