A method and system of communicating between moving participants such that each participant is provided with a first time slice and a respective priority listing containing the name of each participant once only, each participant thus having the top priority for one first time slice only. Also allocated to each participant is a second time slice during which he must transmit his identity as well as the identities of all his near neighbors within a radius R thereof. For each participant A there is stored the identity of all near neighbors B(A) and all far neighbors C(A) being within a radius R of his near neighbors B(A) and who are not also near neighbors B(A) of A. During each first time slice, any participant having a higher priority for the respective first time slice than all of his near and far neighbors may transmit data including the identities of at least those of his near neighbors who became near neighbors since his previous transmission. During each second time slice, non-transmitting participants update their respective list of near neighbors in respect of a transmitting participant according to whether his transmission is, or is not, received by them.