In wireless sensor networks, sensor nodes have limitation of energy so the lifetime of the networks is very important design factor. There are proposed many routing protocols for the wireless sensor networks recently. One of these protocols, the PEGASIS (Power-Efficient GAthering in Sensor Information Systems) protocol is a chain-based routing scheme that is proposed for reducing energy consumption of communication in the networks. In general, the PEGASIS protocol give twice or more performance in comparison with the LEACH (Low Energy Adaptive Clustering Hierarchy) protocol. The chain-based routing schemes construct the chains for routing path.