Preserving synchronization accuracy in slow update Wireless Sensor Network perturbed by plug-in of multi-nodes

The plug-in of nodes in already synchronized Wireless Sensor Network (WSN) can perturb the synchronization accuracy. In the case of the plug-in of one node, the consensus based synchronization algorithm permits to deploy the local interactions among nodes, and, as a consequence, to detect and ignore the Non Synchronized Node (NSN). In the case of multiple nodes, the detection of NSNs can be misstated by different causes: (i) number and spatial distribution of nodes plugged-in, (ii) difference between the time values of the NSNs and the common sense of the time of the Already Synchronized Nodes (ASNs). In the paper, a new fully distributed and consensus based algorithm is proposed able to preserve the synchronization accuracy in the case of the plug-in of multiple NSNs. The NSNs are detected by statistical analysis of all the received messages. The messages increasing the standard deviation of the common sense of the time are rejected. Numerical and experimental tests are performed to validate the proposed algorithm.