improvement of coverage algorithm in wsn in terms of sensor numbers and power amount

wireless sensor networks(wsn) have unique properties that distinguished them from other wireless networks and have special challenges. not-chargeable, not-changeable and limited power supplies of sensor nodes is the most important challenge of this networks, and if the power supply of node expired, a part of data maybe lost. because of the importance of covers in wireless sensors, in this work we have presented approaches that in their designs nodes are in special and different areas so that the hole of environment be covered and for saving power consumption, in each active period only one node is active and others are in inactive. for implementing the task cycle and avoiding from over-load of one node, the active node which have the task of sensing and maintaining the cover of area, in the next period, another node will replace it. it seems that by zoning the environment and cycle of tasks, the overall cover of wireless network improves.