Synchronizing clocks in distributed networks

While various time synchronization protocols for clocks in wired and/or wireless networks are under development, recently it has been shown by Freris, Graham and Kumar that clocks in distributed networks cannot be synchronized precisely even in idealized situations. In this paper by determining the clock synchronization errors in the similar settings of the impossibility result just mentioned, we are able to show that the clocks can get synchronized within an acceptable level of accuracy. After studying the basic case of synchronizing two clocks with asymmetric time delays in the two-way message passing process, we first analyze the directed ring networks, in which neighboring clocks are likely to experience severe asymmetric time delays. We then discuss connected undirected networks with two-way message passing between each pair of adjacent nodes. In the end, we expand the discussions to networks with directed topologies that are strongly connected.