II. WIRELESS SENSOR NETWORKS
A. OVERVIEW OF WIRELESS SENSOR NETWORKS
Originally motivated by military applications like battlefield surveillance,
wireless sensor networks have rapidly become a growing industry with applications for
both civilian and military interests. These networks are made up of spatially distributed
autonomous devices that incorporate sensors to monitor physical and environmental
conditions. The individual devices, or motes, are made up of a radio transceiver, a
microcontroller, and batteries for a power source.
Sensor networks form ad-hoc networks upon deployment, allowing the transfer of
sensor data to a parent node where the data is collected. A few examples of possible
applications are battlefield condition reporting, home automation, and traffic control.
Eventually, this new technology may affect all aspects of typical daily lives.
1. Devices
The functions that are typical of wireless sensor devices are communication,
computation, and sensing. In order to perform these tasks, these devices incorporate a
microcontroller for computation, a small amount of RAM for dynamic data, one or more
flash memories that store the program code and long-lived data, a wireless transceiver, an
antenna, an analog-to-digital converter (ADC), single or multiple sensors, and a power
source [10]. Many variations of these devices are available. For example, a variety of
power sources is possible. Batteries, solar power, and external power are all being
utilized depending on the type of deployment. Also, some devices feature multiple
processors in order to incorporate a digital signal processor (DSP), although these chips
tend to consume greater amounts of energy. As the hardware capability improves and
additional applications are targeted, the number of variations can also be expected to