RECURSIVE TIME SYNCHRONIZATION PROTOCOL METHOD FOR WIRELESS SENSOR NETWORKS

摘要

The recursive time synchronization protocol method for wireless sensor networks provides a modified and extended RTSP method to make it work with clustered networks. In case of non-clustered or flat network, each node is assumed to be a clusterhead in order to run the RTSP method correctly. The RTSP method involves the election of a reference node, and compensation for offset and drift. Simulation results show that the extended RTSP method further improves the accuracy and energy consumption, i.e., it can provide an average accuracy of 0.23 μs in a large multi-hop clustered network while using only 1/7th of the energy consumed by FTSP in the long run.

主权项

1. A computer-implemented recursive time synchronization protocol method for a 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 ith node of the WSN, the calculation utilizing the relation:
Ci(t)=αi+βit, where αi is the clock offset deviation from ideal time at the reference time t=0 and βi, is the frequency of the clock;
re-synchronizing the clock within a time T≦δ/2ρ, where δ is a relative offset and ρ is a skew rate; estimating the relative offset and a drift of the clock, thereby re-synchronizing the clock infrequently; initiating a time synchronization request, the time synchronization request being initiated by any node in the WSN; recursively forwarding the time synchronization request to the reference node, thereby establishing a request-path; 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 WSN nodes in the request-path.