A Time Synchronization Improvement Strategy for Wireless Sensor Networks
Chao Xu · Chinese Journal of Computers · 2007
Taking the similarity between NTP(Network Time Protocol) and time synchronization protocol in WSN(Wireless Sensor Networks) into consideration,the authors propose a strategy of introducing simplified algorithms in NTP such as clock filtering,clock selection and clock combining algorithm into WSN to improve synchronization precision.As a proof,a simplified clock combining algorithm in NTP is introduced into BTS(Broadcast Time Synchronization) protocol.Simulation result reveals that in a 8-hop network consist of 81 Mica2 sensor nodes,the synchronization error of every sensor node varies from 67.70% to 91.58% of that in BTS,except for some resister nodes whose synchronization errors keep unchanged.For all sensor nodes with same hop distance from the time beacon node,the ratio of their average synchronization error to hop distance switches from 19.8 to 15.5μs per hop.Furthermore,these improvements cost no extra wireless transmissions.Theoretical analysis shows that these improvements are due to the decrease of the standard deviation of the node′s time offset with the time beacon,which is the result of the applying time combination algorithm.