Patent ID: 9226253
Filing Date: 2015-12-29
Classification: H04W

Abstract:
1. A method for synchronizing a node to a data sink in a wireless network of nodes organized into Destination Oriented Directed Acyclic Graph (DODAG) topology, comprising: transmitting enhanced DODAG information object (DIO) messages from the data sink to the node; transmitting enhanced destination advertisement object (DAO) messages from the node to the data sink; determining a first time of receiving by the node a packet transmitted by a neighboring node; determining a second time of receiving by the data sink or a synchronized neighboring node the packet transmitted by the neighboring node; synchronizing the node to the data sink based on the difference between the first time and the second time; receiving, by the node, a SYNC-REQ packet transmitted by the neighboring node in response to receiving a SYNC-START packet transmitted by the data sink or the synchronized neighboring node; receiving, by the node, a SYNC-RES packet transmitted by the data sink or the synchronized neighboring node in response to receiving the SYNC-REQ packet; determining the offset between the clock of the node and a clock of the data sink based on a time of receiving the SYNC-REQ packet by the node and by the data sink or the synchronized neighboring node; and synchronizing the node to the data sink based on an offset between a clock of the node and a clock of the data sink.