WSNs being energy constrained systems, one major problem is to employ the sensor nodes in such a manner so as to ensure maximum coverage and connectivity with minimal or optimal number of nodes and furthermore elongate network lifetime with maximum e

Power consumption is an important design criterion in the design of wireless sensor networks. Hybrid radio frequency/free space optical wireless sensor networks (RF/FSO WSN) have been proposed to reduce the energy consumption of traditional R

In wireless sensor network，cluster algorithm of nodes is all effective approach and key technology to implement energy saving and flexible management．To improve security and lifetime of clustering network，a secure clustering was pro— posed based on t