Clapping and Broadcasting Synchronization in Wireless Sensor Network

Although there are a lot of synchronization protocols in WSN, almost all of them face the same problem, that is, synchronization overhead has not been well controlled. The root of this problem is that they have adopted the same basic communication model- pairwise communication model. Increasing communication overhead in synchronization shortens the lifetime of the system and limits the wide application of the WSN. This paper proposes the Clapping and Broadcasting Synchronization (CBS) for sensor network, which is especially designed for large-scale sensor networks with low communication overhea and high synchronization accuracy. On the one hand, the proposed synchronization reduces communication overhead dramatically by utilizing "broadcaster-receiver" communication model. The basic idea of "broadcaster-receiver" is using broadcasting rather than pairwise communication to accomplish synchronization. On the other hand, the initial offset of lock soft clock can be successfully eliminated by the operation of clapping nodes, which can indeed bring benefits in terms of the synchronization accuracy. The advantage in communication overhead is obviously. We prove that the communication overhead after the completion of initialization is close to (W i=1 1 min(Ti ) ), which means the system just need send (W i=1 1 min(Ti ) ) messages to perform synchronization once. And that is close to the minimum message number that let all nodes in the network receive a message. Its communication overhead is at least 50 percent of FTSP or less. The gap between them will increase dramatically with the increase of the network. Additionally, feasibility and reliability of the CBS have been verified in the experiment. The CBS was implemented on the TelosB platform to reach the real parameters of sensor nodes. And the simulation in large-scale was carried out under MATLAB. In Single-hop case, around 80% synchronization errors are bounded in 20?s, and the average per-hop synchronization error in large-scale was in the microsecond range. That means comparing with the existing famous protocol like TPSN or FTSP, the CBS significantly reduce the communication overhead without sacrificing synchronization accuracy. The advantage in communication overhead is obviously. We prove that the communication overhead after the completion of initialization is close to (Σ_i=1^W 1/min(T_i) which means the system just need send (Σ_i=1^W 1/min(T_i) messages to perform synchronization once. And that is close to the minimum message number that let all nodes in the network receive a message. Its communication overhead is at least 50 percent of FTSP or less. The gap between them will increase dramatically with the increase of the network. Additionally, feasibility and reliability of the CBS have been verified in the experiment. The CBS was implemented on the TelosB platform to reach the real parameters of sensor nodes. And the simulation in large-scale was carried out under MAT LAB. In Single-hop case, around 80% synchronization errors are bounded in 20μs, and the average per-hop synchronization error in large-scale was in the microsecond range. That means comparing with the existing famous protocol like TPSN or FTSP, the CBS significantly reduce the communication overhead without sacrificing synchronization accuracy.