WSN is a mesh network which consists of many small sensor nodes randomly deployed over a vast area either inside a phenomenon or in its surroundings. These nodes are small devices autonomous in their communication and computation capabilities. A sensor node measures physical value in its environment and passes the information to the mote. Mote consists of a small processor, power unit and A/D converter for connecting to sensor. The sensor and mote together are known as a sensor node. A sensor node’s basic architecture is shown in Figure 1.
 |
| Sensor Node Architecture |
Wireless Sensor Networks
Sensor networks previously consisted of passive devices wired to a central processing station where data was collected. Nowadays they consist of active devices that measure and control tasks within a sensor network. Control tasks include data aggregation and refinement, location awareness, routing, etc. Basic operation of such a network is explained in the following paragraph.
Sensor nodes are fixed or randomly deployed over a region or environment around a phenomenon to be observed. They may remain unattended after deployment. Redeployment or replacement occurs on failure or expiry of the nodes. As soon as the deployment phase is over distribution of tasks amongst the nodes is done either by some external enforcement or preferably by self organization protocols and topology transparent algorithms. These small devices doing different tasks can be clustered together as smaller network. Sensors usually communicate with each other using a multi hop approach.
Sensor broadcasts its data to its neighboring nodes. Data is aggregated and filtered before further broadcast. Thus data travels from hop to hop and route back to sink nodes. Sink nodes provide networks an interface to the outside world. Thus, each sensor node scattered in the network has the capabilities to collect data and route it back to the sink without an infrastructure.
Feel free to write