Coverage in Wireless Sensor Networks [chapter]

Jie Wu, Mihaela Cardei
2004 Handbook of Sensor Networks  
Recent improvements in affordable and efficient integrated electronic devices have a consider able impact on advancing the state of wireless sensor networks, which constitute the platform of a broad range of applications related to national security, surveillance, military, health care, and environmental monitoring. An important problem receiving increased consideration recently is the sensor coverage problem, centered around a fundamental question: How well do the sensors observe the physical
more » ... pace? The coverage concept is subject to a wide range of interpretations due to a variety of sensors and applications. Different coverage formulations have been proposed, based on the subject to be covered (area versus discrete points), sensor deployment mechanism (random versus deterministic) as well as other wireless sensor network properties (e.g. network connectivity and minimum energy consumption). In this article, we survey recent contributions addressing coverage problems in the context of static wireless sensor networks. We present various coverage formulations and their assumptions, as well as an overview of the solutions proposed. Wireless sensor networks (WSNs) have attracted a great deal of research attention due to their wide-range of potential applications. A WSN provides a new class of computer systems and expands people's ability to remotely interact with the physical world. In a broad sense, WSNs will transform the way we manage our homes, factories, and environment. Applications of WSNs [11] include battlefield surveillance, biological detection, home appliance, smart spaces, and inventory tracking. The purpose of deploying a WSN is to collect relevant data for processing/reporting. There are two types of reporting [4]: event-drive and on-demand. Consider a WSN with a sink (also called monitoring station) and a set of sensor nodes. In the event-driven reporting, the reporting process is triggered by one or more sensor nodes in the vicinity which detect an event and report it to the monitoring station. In the on-demand report, the reporting process is initiated from the monitoring station and sensor nodes send their data in response to an explicit request. A forest fire monitoring system is event-driven, whereas an inventory control system is on-demand. A more flexible system can be a hybrid of even-driven and on-demand. Sensor Coverage Problem An important problem addressed in literature is the sensor coverage problem. This problem is centered around a fundamental question: "How well do the sensors observe the physical space ?" As pointed out in [17] , the coverage concept is a measure of the quality of service (QoS) of the sensing function and is subject to a wide range of interpretations due to a large variety of sensors and applications. The goal is to have each location in the physical space of interest within the sensing range of at least one sensor. Design Choices Sensor nodes, also called wireless transceivers, are tiny devices equipped with one or more sensors, one or more transceivers, processing, storage resources and, possibly, actuators. Sensor nodes organize in networks and collaborate to accomplish a larger sensing task. One important class of WSNs is wireless ad-hoc sensor networks (WASN), characterized by an "ad-hoc" or random sensor deployment method, where the sensor location is not known a priori. This feature is required when individual sensor placement is infeasible, for example battlefield or disaster areas. The characteristics of a WASN include limited resources, large and dense networks, and dynamic topology. Generally, more sensors are deployed than required (compared with the optimal placement) to per-
doi:10.1201/9780203489635.sec5 fatcat:lzs5voefjjef3bnu3myuf2jiky