A distributed algorithm for network-wide clock synchronization in wireless sensor networks

Clock synchronization has become an indispensable requirement in wireless sensor networks due to its central importance in vital network operations such as data fusion and duty cycling, and has attracted considerable research interest recently. Assuming exponentially distributed random delays in a two-way message exchange mechanism, this work proposes a network-wide clock synchronization algorithm using a factor graph representation of the network. Message passing using the max-product algorithm is adopted to derive update rules for the proposed iterative procedure. A closed form solution is obtained for each node´s belief about its clock offset at each iteration. The proposed algorithm is completely distributed as the clock offset of each node is determined at the node itself, as opposed to employing a central processing unit to compute all offsets. Simulation results show that the application of the proposed message passing-based network-wide clock synchronization algorithm provides convergent estimates for both regular cycle-free and random topologies.