Research On Offset Compensation Of Consensus-based Time Synchronization Algorithm In Wsns With Random Communication Delays

Recently,with the developments of Micro-Electro-Mechanical Systems(MEMS)and wireless communications,the research on Wireless Sensor Networks(WSNs)has drawn great interests.Micro,low-cost,low-power nodes in WSNs monitor and collect specific information,communicate with neighboring nodes and complete tasks cooperatively.WSNs have significant applications in the fields of environmental monitoring,target tracking,medical care,and intelligent transportation.One of the basic requirements for implementing these applications is that all nodes in the network process information at common time.Therefore,time synchronization is one of the most fundamental and crucial issues in WSNs.In order to solve the problem that the offset estimate of the LSTS algorithm diverges to the negative direction,this paper proposes an offset compensation approach to guarantee the boundedness of the offset estimate for WSNs with random bounded communication delays.Then the equilibrium point of the offset estimate is analyzed.Finally,the performance of the new algorithm(LSTS-DC)is illustrated by a series of numerical simulations.The main work of this paper is as follows:1.In WSNs with random bounded communication delays,it is proved that the offset estimate applying the LSTS algorithm is bounded in the case of a network topology with a single root node,while is divergent in the negative direction in the case of a network topology with more than two root nodes.Then a new offset compensation algorithm is designed by using the first difference of the offset estimate,which is proved to be able to ensure the boundedness of them.Finally,numerical simulations are presented to show the availability of the LSTS-DC algorithm.2.Applying the LSTS-DC algorithm,the equilibrium point of the offset estimate is analyzed.In WSNs with bounded communication delays,whether the equilibrium point exists is decided by the network topology.Then,in the presence of the equilibrium point,the equation between communication delays and delay compensations under a specific topology is obtained by the state equation at the equilibrium point.Finally,the conclusions are verified by several sets of numerical simulations.3.The performance of the LSTS-DC algorithm and the classical CBTS algorithms and the PISync algorithm are compared.In WSNs with random bounded communication delays,a series of numerical simulations illustrate that the offset estimate of the ATS,WMTS,LSTS and PISync algorithms are divergent,and only the offset estimate error of the LSTS algorithm is bounded.Compared with these four algorithms,the LSTS-DC algorithm can ensure both the offset estimate and the offset estimate error are bounded,and has higher synchronization accuracy.