Indoor positioning networks are faced with several challenges. The methods employed by many indoor positioning systems require highly accurate time synchronization. Where many responders must be synchronized together, the accuracy of the time-synchronization can be improved via a synchronization tree that identifies preferable paths to synchronize responders and eliminates ambiguity. Moreover, where absolute location information is available for less than all of the responders, accurate round trip time measurement can be used to obtain the relative locations of the responders to each other. Where the relative locations are known, any absolute location of a responder can be extrapolated to the remaining responders. Finally, with the use of appropriate algorithms, these round trip time measurements can be collected in reference to a device that is stationary or moving.