JSE_V4_N1_RP1 C. Kumar Charlie Paul V. Gopi Journal on Software Engineering 2230 – 7168 4 1 4 17 WSN (Wireless Sensor Network), PBS (Pairwise Broadcast Synchronization), NTP (Network Time Protocol) TPSN (Timing sync Protocol for Sensor Networks, RBS (Reference Broad cast Synchronization) TDP (Time Diffusion Synchronization Protocol) Time synchronization is crucial for Wireless Sensor Network (WSNs) in performing a number of fundamental operations such as data co-ordination, Power management, Security and localization. The Pairwise Broadcast Synchronization (PBS) protocol was recently proposed to minimize the number of timing messages required for global network synchronization, which enables the design of highly energy-efficient WSNs. However, PBS requires all nodes in the network to lie within the communication ranges of two leader nodes, a condition which might not be available in some applications. This paper proposes an extension of PBS to the more general class of sensor networks. Based on the hierarchical structure of the network, an energy-efficient pair selection algorithm is proposed to select the best pairwise synchronization sequence to reduce the overall energy consumption. It is shown that in a multicluster networking environment, PBS requires a far less number of timing messages than other well-known synchronization protocols and incurs no loss in synchronization accuracy. Moreover, the proposed scheme presents significant energy savings for densely deployed WSNs. July - September 2009 Copyright © 2009 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=474