Information Technology Reference
In-Depth Information
Chapter 1
Introduction: Bird's-Eye View of Wireless
Sensor Networks
Aleksandar Crnjin
Over the course of the last two decades, sensor networks have emerged from complete
obscurity into being an important research subject and are slowly crawling their
way into industrial applications. In this chapter, we present a short introduction to
sensor networks, from the brief overview of technology, through its applications
from the beginning of its history in submarine warfare to diverse civilian applications
possible today, to an overview of the issues that sensor network researches and
developers are confronted with.
Overview of Technology
Sensor networks can be viewed as an extreme extrapolation of two general
trends in computing: miniaturization (making computers ever smaller) and inter-
connection (networking) [ 1 ]. Individual sensor nodes are small devices, running on
limited memory, equipped with microcontrollers used for embedded devices (typi-
cally 8-bit, 4-5 MHz). In addition to a microcontroller, a sensor node typically
includes a small amount of RAM memory (a few kilobytes), a radio transceiver, a
certain number of analog sensors connected to the microcontroller through a A/D
convertor circuit, and a power source to power all these components (typically 2
AA batteries; Fig. 1.1 ).
Individual sensor nodes are not capable of doing very much: they can record
some quality of the environment (such as temperature, air pressure, humidity, etc.)
but their limited processing ability and limited output capability (in terms of a
display, most sensor nodes have just a few LED diodes) mean that sensor nodes
need help to process and display the data they collect (Fig. 1.2 ).
Indeed, sensor nodes are invariably used in sensor networks which consist
of a large number of sensor nodes, which collect data, and one or more gateway
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