08-08-2012, 03:03 PM
Wireless Sensors for Home Monitoring
[attachment=30605]
INTRODUCTION
The advancement of science and technology are dependent
upon parallel progress in sensing and measurement
techniques. The reason for this is obvious. As science and
technology move ahead, new phenomena and relationships
are discovered and these advances make new types of
measurements imperative. New discoveries in this technological
world are not of any practical utility unless the results
are backed by sensing techniques. Sensory data come from
different kinds of sensors of different modalities in distributed
locations. Basically a sensor is a device that responds
to a physical stimulus, such as thermal energy, electromagnetic
energy, acoustic energy, pressure, magnetism, or
motion, by producing a signal, usually electrical.
WIRELESS SENSORS
A wireless sensor is a sensing module which houses one
or many transceiver nodes and base stations. It uses a wide
range of RF communications techniques. Through software,
the sensor may be configured to measure and monitor various
physical parameters such as force, temperature, motion
etc. Since the wireless sensors employ RF communication, a
network of these sensors is considered as a “Wireless Sensor
Network”. The tasks performed by these wireless sensor networks
include measuring the relevant quantities, monitoring
and collecting data, assessing and evaluating the information,
formulating meaningful user displays, and performing
decision-making and alarm functions.
WIRELESS SENSOR NETWORK CHARACTERISTICS
For measuring and monitoring physical and non-physical
activities in a remote area, various types of wireless sensors
are generally grouped in a network [3, 4]. Apart from the
sensors, the network may incorporate repeater hubs to extend
the transmission range of the retrieved data. The network
may also incorporate processing units to analyze the data.
The sensor networks employ small, low power devices to
do all the tasks. The sensors in the network capture the
activity and the collected data is communicated to a remote
monitoring centre using wireless data transfer techniques
such as Radio Frequency (RF) communication. The size and
cost constraints on these types of network result in corresponding
constraints being exerted on the resources such as
energy, memory, computational speed and bandwidth.
Communication Protocols and Routing
In a wireless sensor network, one can implement different
types of communication protocols and routing techniques.
The protocol employed depends on the application in
which the sensor is meant to be used. A basic communication
pro-tocol consists of packets of data which has a
header for identification, data bits and also some special
frames to identify and correct errors in transmission. When a
sensor node desires to transmit a message, handshaking
protocols are implemented with the destination node to
improve reliability and ultimately the QoS of the wireless
network. This hand shaking protocol makes the sensor node
to retransmit messages that were not properly received.
[attachment=30605]
INTRODUCTION
The advancement of science and technology are dependent
upon parallel progress in sensing and measurement
techniques. The reason for this is obvious. As science and
technology move ahead, new phenomena and relationships
are discovered and these advances make new types of
measurements imperative. New discoveries in this technological
world are not of any practical utility unless the results
are backed by sensing techniques. Sensory data come from
different kinds of sensors of different modalities in distributed
locations. Basically a sensor is a device that responds
to a physical stimulus, such as thermal energy, electromagnetic
energy, acoustic energy, pressure, magnetism, or
motion, by producing a signal, usually electrical.
WIRELESS SENSORS
A wireless sensor is a sensing module which houses one
or many transceiver nodes and base stations. It uses a wide
range of RF communications techniques. Through software,
the sensor may be configured to measure and monitor various
physical parameters such as force, temperature, motion
etc. Since the wireless sensors employ RF communication, a
network of these sensors is considered as a “Wireless Sensor
Network”. The tasks performed by these wireless sensor networks
include measuring the relevant quantities, monitoring
and collecting data, assessing and evaluating the information,
formulating meaningful user displays, and performing
decision-making and alarm functions.
WIRELESS SENSOR NETWORK CHARACTERISTICS
For measuring and monitoring physical and non-physical
activities in a remote area, various types of wireless sensors
are generally grouped in a network [3, 4]. Apart from the
sensors, the network may incorporate repeater hubs to extend
the transmission range of the retrieved data. The network
may also incorporate processing units to analyze the data.
The sensor networks employ small, low power devices to
do all the tasks. The sensors in the network capture the
activity and the collected data is communicated to a remote
monitoring centre using wireless data transfer techniques
such as Radio Frequency (RF) communication. The size and
cost constraints on these types of network result in corresponding
constraints being exerted on the resources such as
energy, memory, computational speed and bandwidth.
Communication Protocols and Routing
In a wireless sensor network, one can implement different
types of communication protocols and routing techniques.
The protocol employed depends on the application in
which the sensor is meant to be used. A basic communication
pro-tocol consists of packets of data which has a
header for identification, data bits and also some special
frames to identify and correct errors in transmission. When a
sensor node desires to transmit a message, handshaking
protocols are implemented with the destination node to
improve reliability and ultimately the QoS of the wireless
network. This hand shaking protocol makes the sensor node
to retransmit messages that were not properly received.