METHOD AND SYSTEM FOR MULTI-HOP GLOBAL TIME SYNCHRONIZATION IN IP-USN AND RECORDING METHOD THEREOF

摘要

PURPOSE: A multi-hop global time synchronization method for efficiently synchronizing a time is provided to remove inconvenience that an additional device or all nodes must be connected to the Internet. CONSTITUTION: A time is synchronized between a gateway and a server in the wide area network according to one algorithm among NTP(Network Time Protocol) and SNTP(Simple Network Time Protocol). The visual information is broadcasted from gateway to the sensor node. The broadcast time delay is calculated(S130). The time synchronization require-message is transmitted from the sensor node to gateway. The request time delay is calculated. The time of sensor nodes is synchronized through the broadcast time delay and request time delay(S170).