An Accurate and Scalable Clock Synchronization Protocol for IEEE 802.11-Based Multihop Ad Hoc Networks
Issue No. 12 - December (2007 vol. 18)
This paper studies the fundamental problem of clock synchronization in IEEE 802.11-based multihop ad hoc networks. Clock synchronization is important for power saving, network throughput and efficiency of many protocols in an IEEE 802.11-based mobile ad hoc network. The scalability problem of 802.11 timing synchronization has been studied extensively in single hop ad hoc networks and good solutions are available. These solutions, however, do not perform well in a multihop environment. A few multihop solutions for clock synchronization have been proposed recently, but the performances are still not very good. The maximum clock offset is still over 200 ?s for these protocols. This paper proposes an adaptive protocol through beacon transmission prioritization, frequency adjustment and construction of dominating set. The frequency adjustment is proved to be bounded. Simulation studies show that the proposed protocol is able to limit the maximum clock offset to under 50μs after protocol stabilization. The improvement is more than 400% over the current solutions. The proposed protocol also shows great long-term stability, and it handles mobility very well.
IEEE 802.11, MANET, clock synchronization, scalability
D. Zhou and T. H. Lai, "An Accurate and Scalable Clock Synchronization Protocol for IEEE 802.11-Based Multihop Ad Hoc Networks," in IEEE Transactions on Parallel & Distributed Systems, vol. 18, no. , pp. 1797-1808, 2007.