Behavior of clock-sampling mutual network synchronization in wireless sensor networks: convergence and security

摘要

Clock synchronization is an important component of wireless sensor networks (WSNs) both for co-ordination of node communications and for time stamping sensor data. The previously presented clock sampling mutual network synchronization (CS-MNS) algorithm is simple, has low communication and processing overhead, and allows fully decentralized operation. We present some simulation results that indicate the potential of CS-MNS to achieve high clock synchronization accuracy in mobile multi-hop wireless networks. Past work has shown clock convergence under specific conditions in single-hop networks. We show analytically that in the absence of offset errors, the network clocks converge. In the presence of offset errors, we present conditions on the degree of clock asynchrony under which the network clock rates show convergent behavior. The analysis is applicable as long as the network topology is connected and, thus, is of interest in both single-hop and multi-hop environments. As a side result, we also show how a network designer can use these conditions to add a bias term to the CS-MNS algorithm and, thus, improve the start-up dynamics of the algorithm. Furthermore, we discuss the algorithm from a security standpoint. Finally, we propose a method for adding external reference synchronization that is compatible with our security Discussion.