Abstract: The method for communicating between a first device and a second device includes the steps of: the first and second device communicating by exchanging messages that are based on signals that are transmitted through a plurality of communication channels; the first device sending a challenge message to the second device over one communication channel; the second device sending, upon reception of the challenge message, a response message to the first device through at least two communication channels that have essentially identical signal propagation velocities; the first device measuring the time elapsed between the sending of the challenge message to the reception of the response message; and the first device computing its distance to the second device based on this time, knowledge about travelling speed of the challenge and the response message and the processing delay that the second device adds to generate and send the response message.

Abstract: A method for communicating between a first device and a second device, includes the steps of the first and second device communicating by exchanging messages that are based on signals that are transmitted through a first communication channel and/or through a second communication channel, wherein the first and second communication channel have different signal propagation velocities; at least one of the first and second device computing the distance to the other device based on communication signal delays caused by the signal propagation velocities; wherein the method includes the further steps of controlling access of the second device to the first device depending on the computed distance.