Self-Localization based on Ambient Signals

We present an approach for the localization of passive nodes in a communication network using ambient radio or sound signals. In our settings, the communication nodes have unknown positions. They do not emit signals for localization and exchange only the time points when environmental signals are received: the time differences of arrival (TDOA). The signals occur at distant but unknown positions and they can be distinguished. Since no anchors are available, the goal is to determine the relative positions of all communication nodes and the environmental signals.Our novel approach, the Ellipsoid TDOA method, introduces a closed form solution assuming that the signals originate from remote distances. The TDOA measurements characterize an ellipse from which the distances and angles between three network nodes can be inferred. In contrast to existing approaches, we do not require the receiver nodes to be synchronized. Furthermore, we can calculate the time offsets of the receiver clocks as a result of our calculations and synchronize the receivers in this way.The approach is tested in numerous simulations and in indoor and outdoor settings, where the relative positions of mobile devices are determined using only the sounds produced by assistants with noisemakers.