A secure and scalable time synchronization protocol in IEEE 802.11 ad hoc networks

IEEE 802.11 standards support ad hoc mode which are ad hoc networks with all nodes within each other´s transmission range. Time synchronization is crucial in such ad hoc networks. A distributed timing synchronization function (TSF) is specified by IEEE 802.11 to provide synchronization service, but it suffers from the scalability problem due to its inefficient synchronization mechanism. Furthermore, TSF is designed without taking into account security. Such an insecure time synchronization protocol may cause serious problems on the applications and protocols based on synchronized time. To the best of our knowledge, currently no secure time synchronization mechanisms are proposed for such environments. In this paper we propose our scalable and secure time synchronization protocol SSTSP. We prove that SSTSP can synchronize the networks with the maximum clock difference under 20mus without any uncontinuous leaps in clocks. We also conduct simulations to evaluate the performance of SSTSP. The results show that without attacks, the performance of our approach is significantly superior to TSF and is among the best of currently proposed solutions in terms of accuracy and scalability. Besides, our approach can maintain the network synchronized even under malicious attacks