A clock synchronization algorithm for multi-hop wireless ad hoc networks

In multihop wireless ad hoc networks, it is important that all mobile hosts are synchronized. Synchronization is necessary for power management and for frequency hopping spread spectrum (FHSS) operations. IEEE 802.11 standards specify a clock synchronization protocol but this protocol suffers from the scalability problem due to its inefficiency contention mechanism. We propose an automatic self-time-correcting procedure (ASP) to achieve clock synchronization in a multihop environment. Our ASP has two features. Firstly, a faster host has higher priority to send its timing information out than a slower one. Secondly, after collecting enough timing information, a slower host can synchronize to the faster one by self-correcting its timer periodically (which makes it becoming a faster host). Simulation results show that our ASP decreases 60% the average maximum clock drift as compared to the IEEE 802.11 and reduces 99% the number of asynchronism in a large-scale multihop wireless ad hoc networks.