International Journal of Smart Electrical Engineering, Vol.5, No.1,Winter2016 ISSN: 2251-9246 EISSN: 2345-622 49 Improvement of Coverage Algorithm in WSN in Terms of Sensor Numbers and Power Amount Iman Khandani, Reza Sabbaghi-Nadooshan, Fardad Farokhi Electrical Engineering Department, Islamic Azad University, Central Tehran Branch, Tehran, Iran Email: iman.persian@gmail.com, r_sabbaghi@iauctb.ac.ir, f_farokhi@iauctb.ac.ir Abstract 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. Keywords: wireless sensor network, coverage, zoning, cycle of tasks. © 2016 IAUCTB-IJSEE Science. All rights reserved 1. Introduction Wireless sensor networks composed of hundreds and thousands small nods, which are called sensor nodes, and these nodes cooperate with each other to do their tasks or special tasks. The wireless sensor networks are based in technical sensors, wireless relations, small embedded equipment and distributed computations. This networks exchange data to environment by sensors and gather and analyze them. Wireless sensor networks are extensively used in environment control, tracking the target, military usage, management of natural disasters and etc. (Borges et al, Prasad 2015, Manikandan et al, 2015). Wireless sensor networks have unique features that separate them from other wireless networks. Some of this features includes large number of nodes, limited use of hardware because of reducing the costs, being in inaccessible environments continuously by humans, being disposed to disrepair and etc. there are many challenges in wireless sensor networks but Not-chargeable, not-changeable and limited power supplies of sensor nodes is the most important one. So, the technique of power saving is the most important ones. If in wireless sensor networks an area isn’t covered, in the other word, the data of a section of environment isn’t sensing, the efficient of network in at risk. Therefore, in wireless sensor networks, coverage is one of the most important challenges (Wang et al 2015). Proposed method for controlling over the wireless sensor networks in a way that, besides having coverage, the power consumption be at desirable level, is controllable usage of task cycle in a manner that some of nodes which have less energy and their operation doesn’t have any risk for coverage, be inactive during in a defined period. For having a global coverage, the network is divided to different sections and in each sections of area, one node is active and other are inactive. The pp.49:52