International Journal of Electronics and Computer Science Engineering 465 Available Online at www.ijecse.org ISSN- 2277-1956 ISSN 2277-1956/V2N2-465-471 Coverage in Wireless Sensor Networks: A Survey Jyoti Yadav 1 , Sandeep Mann 2 1 Department of Information Technology, Banasthali University, Jaipur Campus, Jaipur, Rajasthan, India 2 Department of Computer Science, Assistant Professor, Government College, Gurgaon, Haryana, India jyotiyadavit@gmail.com, sandeep.mann23@gmail.com Abstract – Wireless Sensor Network is an emerging field which is accomplishing much importance because of its vast contribution in varieties of applications. Wireless Sensor Networks are used to monitor a given field of interest for changes in the environment. Coverage is one of the main active research interests in WSN.In this paper we aim to review the coverage problem In WSN and the strategies that are used in solving coverage problem in WSN.These strategies studied are used during deployment phase of the network. Besides this we also outlined some basic design considerations in coverage of WSN.We also provide a brief summary of various coverage issues and the various approaches for coverage in Sensor network. Keywords— Coverage; Wireless sensor networks: energy efficiency; sensor; area coverage; target Coverage. I. INTRODUCTION In recent years Wireless Sensor Networks(WSN) have seen tremendous advancements in design and applications.WSN is extensively used in various domains such as military applications, environmental monitoring [7],object tracking, target surveillance, traffic control and disaster prevention and etc.Due to this wide range of potential applications,WSN have attracted a plethora of research efforts. In general a WSN consists of one or more base Stations(or sinks) and a large number of sensor nodes that organize themselves into a wireless network and work together to sense the environment, perform simple data processing and communicate wirelessly over a short distance. Depending upon the application and the environment, deployment and placement of a sensor node can be done either randomly or in a predefined statistical distribution over a geographical area. The purpose of deploying a WSN is to collect relevant data for processing/reporting. There are two types of reporting [8]: event-drive and on- demand a sensor collects data periodically or continuously depending on the nature of the application and forwards the data to a node called the base station (BS) which provides the necessary connections to infrastructure networking. A sensor node is equipped with a device that supports connectivity between two nodes or between anode and the Base station. Sensor nodes have three modes of operation. In the active mode, a sensor observes the environment and communicates with other sensors. In the sleep mode, a sensor cannot monitor or transmit data. In off mode, the nodes are completely turned off. A sensor can change to active mode from sleep mode to active mode whenever it receives appropriate signal from the other sensors or from the base station. A Sensor node has several resource constraints such as limited memory, battery power, signal processing, communication and computation capabilities.so, it can sense only a small portion of environment. Some sensors are able to move on their own that is done by mounting the sensors on the mobile platform as in robomote [9].mobility of sensors help them to self deploy and self repair thus adding more to its value. Our major in this paper focuses on coverage problem of WSN.Coverage is the key research issue in WSN as it can be considered as the measure of the Quality of Service(QoS) of sensing function for a sensor network. The goal of coverage is to have each location in the physical space of interest within the sensing range of at least one sensor. Additionally the coverage formulations try to find the weak points i.e. the points which are least covered by the sensors in a sensor field and suggest future deployment and reconfiguration schemes for improving the coverage performance. Generally the coverage involves the two basic ideas [10]: