Patent ID: 9226252
Filing Date: 2015-12-29
Classification: H04W

Abstract:
1. A computer-implemented recursive time synchronization protocol method for a clustered wireless sensor network (WSN), comprising the steps of: electing a single reference node i for offset and drift compensation, the electing being limited to nodes that are clusterheads; calculating a time read by a logical clock of the i where α i is the clock offset deviation from ideal time at the reference time t=0 and β i is the frequency of the clock; re-synchronizing the clock within a time T≦δ/2ρ, where δ is an offset and ρ is a skew rate; estimating the offset and a drift of the clock, thereby re-synchronizing the clock; initiating a time synchronization request, the time synchronization request being initiated by any initiating node in the clustered WSN, wherein the step of initiating the time synchronization request comprises the steps of: recursively forwarding the time synchronization request from the second intermediate node to the reference node, thereby establishing a request-path, the reference node receiving the forwarded time synchronization request at the reference node's local time T2; using a REP (reply to time synchronization) message to forward the time T back to the initiating node via the request-path; and compensating the time T with a propagation delay time at each hop in the request-path, thereby time synchronizing all clustered WSN nodes in the request-path, wherein the step of compensating the time T comprises the steps of: