ROTA: Round Trip Times of Arrival for Localization with Unsynchronized Receivers

Multilateration systems reconstruct the location of a target that transmits electromagnetic or acoustic messages. The required measurement for localization is the time of arrival (TOA) of the transmitted signal, measured by a number of spatially distributed receivers. We present a novel multilateration algorithm that does not require a precise clock synchronization between the receivers. Furthermore, our method does not need any prior information about the transmitted signal. It just must be provided that accurate and identifiable TOA measurements can be derived. For example, the target could emit aperiodic pulses. Our method works with TOA differences between successive messages locally on each receiver. Therefore, our measurement equations do not depend on the receivers' clock offsets, and clock synchronization only needs to be accurate enough to identify each transmitted signal on all receivers. We derive a number of concrete maximum likelihood estimators for a single non-maneuvering target based on this method. In addition, we consider the clock drifts of the receivers.