Research On Consensus Time Synchronization Protocol For Wireless Sensor Networks

With the advancement in microcomputer system,wireless communication technology and digital electronic multifunctional,wireless sensor networks are rapidly developed.As one of the supporting technology in wireless sensor networks,time synchronization has been a hot research topic and has gained much attention.Consensus time synchronization protocols have attracted much and much attention as they are fully distributed and can compensate both clock skew and offset.Most of the researches were based on ideal circumstance.Firstly,the present situation of wireless sensor networks has been analyzed in this paper.Then the consistency theory,graph theory,clock model and the classic consensus time synchronization protocol were introduced.Aimed at the existence of transmission delay in the process of exchange of information between sensor nodes,we proposed a consensus time synchronization protocol for WSNs with time-delay and a least square estimation based time synchronization protocol.Time synchronization was achieved through the establishment of the logical clock and compensation of the clock skew and offset in the two protocols proposed in this paper.In the process of nodes updating,the performance of the protocol was directly determined by the relative clock skew.So the two time synchronization proposed in this paper improve the accuracy of the relative clock skew through weighted average and least squares estimate respectively so that in the case of the transmission delay satisfies some certain distribute,time synchronization can still implement in WSNs.We introduced decay factor into the least square estimation based time synchronization protocol and we explored the effects of the decay factor.Then we verified the original time synchronization protocol is not feasible and the two protocol proposed are convergence in the case of the existence of transmission delay through simulations.Finally,we established a sensor network testbed consisted of the module of CC2530 and verified the two time synchronization protocol.