18-01-2013, 03:20 PM
Introduction To Wireless Sensor Networks
Introduction To Wireless.ppt (Size: 2.43 MB / Downloads: 27)
Wireless Sensor Networks
A wireless sensor network is a collection of nodes organized into a cooperative network. Each node consists of processing capability may contain multiple types of memory have an RF transceiver, have a power source (e.g., batteries and solar cells), and accommodate various sensors.
Communication Network
A communication network is composed of nodes, each of which has computing power and can transmit and receive messages over communication links, wireless or cabled.
Basic Network Topologies
Star Topology
Ring Topology
Bus Topology
Tree Topology
Fully Connected Networks
Mesh Networks
Star Topology
All nodes of the star topology are connected to a single hub node. The hub requires greater message handling, routing, and decision-making capabilities than the other nodes. If a communication link is cut, it only affects one node. However, if the hub is incapacitated the network is destroyed.
Ring Topology
In the ring topology all nodes perform the same function and there is no leader node. Messages generally travel around the ring in a single direction.
However, if the ring is cut, all communication is lost.
Wireless Sensor Networks
A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations.
Usage of Sensor Networks
Environmental Observation:
Sensor networks can be used to monitor environmental changes. An example could be water pollution detection in a lake that is located near a factory that uses chemical substances. Sensor nodes could be randomly deployed in unknown and hostile areas and relay the exact origin of a pollutant. Other examples include forest fire detection, air pollution and rainfall observation in agriculture.
Military Monitoring:
Military uses sensor networks for battlefield surveillance; sensors could monitor vehicular traffic, track the position of the enemy.
Building Monitoring:
Sensors can also be used in large buildings or factories monitoring climate changes. Thermostats and temperature sensor nodes are deployed all over the building’s area. In addition, sensors could be used to monitor vibration that could damage the structure of a building.