Demonstration of synchronization method for frequency hopping ad hoc network

Anti-jamming capability and protection against interception are key priorities in wireless mobile ad hoc networks (MANETs) or sensor networks for military applications. These features are supported by spread spectrum (SS) techniques such as frequency hopping (FH). In an FH ad hoc network, the phase of hopping sequence, i.e., FH-code phase is typically derived from the local clock reading of each node. Therefore, network-wide time synchronization is needed in order to get the nodes to simultaneously switch to the same frequency channel, i.e., hop synchronously. In this paper, a rarely issued distributed FH-code phase synchronization method for an FH MANET is implemented and demonstrated on wireless open-access research platforms (WARPs). In the earlier studies the considered method has been investigated to be military compliant in the anti-jamming and low probability of detection -sense. Herein, the measurements are reported for static scenarios of two and three nodes. Sufficient time synchronization is managed to be preserved for the frequency hopping operations in the presence of the measured clock drifts. Furthermore, it is shown that the system is able to maintain the FH-code phase synchronization as long as the clock errors are less than half the dwell time.