Date Added: Mar 2013
In this paper, the author discussing what wireless sensor networks is. Sensor nodes are battery powered devices and the main issue is how to reduce the energy consumption of nodes so that the networks lifetime can be increased to a sufficient level. Energy can be conserved using three schemes: duty cycling, data driven and mobility based. Various duty cycle based MAC protocols are introduced to save the energy consumption and increase the performance of the wireless sensor network. In this paper, they will discuss about S-MAC, U-MAC and TA-MAC. They also discuss about the Minimum-Energy Multicast Tree Construction and Scheduling (MEMTCS) problem in Duty-Cycle Wireless Sensor Networks (DC-WSNs).