Introduction and Overview of Wireless Sensor Networks

Introduction

A sensor network is an infrastructure comprised of sensing (measuring), computing, and communication elements that gives an administrator the ability to instrument, observe, and react to events and phenomena in a particular environment. The supervisor typically is a civil, governmental, commercial, or industrial body. The environment can be the corporal world, a biological system, or an information technology (IT) structure.

Network(ed) sensor systems are seen by viewers as a vital technology that will practice major exploitation in the next few years for a surplus of applications, space study, vehicular movement and critical movement detection are few examples of its applications.

Today’s wireless sensor networks are made up of a big number of inexpensive devices that are networked via low power wireless communications. It is the networking potential that basically distinguishes a sensor network from a mere collection of sensors, by enabling cooperation, coordination, and collaboration among sensor assets (Swami, Zhao, & Hong, 2007).

Whilst several sensors can be connected to controllers and processing stations directly (e.g., using local area networks), a large number of sensors send the gathered data wirelessly to a centralized processing station. This is needed since many network applications require hundreds or thousands of sensor nodes, often set up in remote and unreachable areas. Thus, a wireless sensor is equipped with not only a sensing element, but also on-board processing, communication, and storage capabilities. With these developments, a sensor node is usually responsible for data collection, for in-network analysis, correlation, and fusion of its own sensor data and data from other sensor nodes. Many sensors collectively monitoring large physical environments, form a wireless sensor network (WSN). Using their wireless radios, Sensor nodes communicate with each other and also with a base station (BS) allowing them to broadcast their sensor data to remote processing, visualization, analysis, and storage systems. For example, Figure 1 shows two sensor fields monitoring two different geographic regions and connecting to the Internet using their base stations (Dargie & Poellabauer, 2010).

Figure 1.

Wireless sensor networks (Dargie & Poellabauer, 2010)

The sensing and control technology comprises electric and magnetic field sensors; radio-wave frequency sensors; optical, electro-optic-, and infrared sensors; radars; lasers; location/navigation sensors; seismic and pressure-wave sensors; environmental parameter sensors (e.g., wind, humidity, heat); and biochemical national security–oriented sensors. Today’s sensors can be described as ‘‘smart’’ inexpensive devices equipped with multiple onboard sensing elements; they are low-cost low-power multifunctional nodes that are logically homed to a central sink node (Sohraby, Minoli, & Znati, 2007).

Background And History Of Wireless Sensor Network

A Sensor is a device that uses a sensing technique to collect information about a physical entity or process, including the occurrence of actions such as, changes in state e.g. a drop in temperature or pressure). Other examples include natural sensors, for example the human body is equipped with sensors that are able to receive and capture optical information from the surroundings (eyes), audio information such as sounds (ears), and smells (nose). These are considered as remote sensors, that gather information of the monitored object without touching them.. However, from a technical viewpoint, a sensor is a device that translates occurrence of events and their parameters in the physical world into signals that can be precisely measured and examined.

Another frequently used word is a transducer, that converts energy from one form into another. A sensor, may thus be considered as a type of transducer that converts energy in the physical world into electrical energy that can be sent to a computing system or controller. An example of the steps performed in a sensing (or data acquisition) task is shown in Figure 2.

Figure 2.

Data acquisition and actuation (Dargie & Poellabauer, 2010)