Research On Time Synchronization Methods For Multi RFID Units Based RFID System And Its Application On Security Of Intelligent Building

In the intelligent building, more and more intelligent applications can identify people and objects in the key position within the building. RFID technology is increasingly applied in intelligent building as a kind of effective technology such as parking lot management and identification. In particular, as far as large public buildings are concerned, the RFID system can timely perceive intelligent objects with the RFID electronic tag around the RFID reader. Because the RFID reader distributes throughout the buildings in the large public buildings, several RFID units are often applied in building the RFID system. As the RFID unit perceive information of intelligent objects which contains the local time tag, the accuracy of time label is related to the credibility of sensory data. The composition of the RFID unit need time synchronization for the RFID system.As the RFID technology require that multiple RFID unit need work together in the application of intelligent buildings, the article discusses that RFID unit time is not synchronized in the RFID system: 1) When the RFID unit can access external network, the RFID unit time synchronization method is studied based on NTP service. The phenomenon and feature of network delay is analyzed in the process of time synchronization based on the NTP service and on the basis of the result analysis, RFID unit time synchronization method is put forward considering network latency based on NTP service. The accuracy and availability of the method is verified by the contrast test.2) When RFID work unit can not access the external network in the RFID system, the article described that RFID unit can access external network in the debugging phase while RFID unit cannot access external network in normal work. The feasibility of RFID unit time synchronization method is discussed and the RFID unit time synchronization method is designed based on BP neural network. The rationality and availability of method is verified by the contrast test.The RFID unit time synchronization method based on BP neural network can effectively achieve RFID unit time synchronization, improve the precision of time label, then guarantee the credibility when RFID unit perceive the information of intelligent objects. The solution of time synchronization problem can effectively improve the application of RFID technology in the security and protection system of intelligent building and also help to improve the intelligent level of the building.