ABSTRACT
Wireless sensor networks (WSNs) are gaining in importance because of improvements in wireless communication. WSNs use unlicensed ISM (Industrial, Scientific, and Medical) band for communication. Many standard wireless protocols are used to send data/messages. Some of the standards are: IEEE 802.11, IEEE 802.15, and IEEE 802.16. They also have standards within them.
The wireless sensor nodes behave as transreceivers—i.e., they both act as data originators and data routers. A sensor node consists of a sensor unit, processing unit, communication (transreceiver) unit, and power supply unit.
A WSN contains remote sensor, clustering node (or intermediate processing node), and a final processing node. They are connected in single hop or multi-hop manner. The whole combination is termed as a sensor field. It would operate reliably if sensor locations and their time stampings are precisely known. The nodes collect data, analyze, and compress the same and forward (route) it to the sink.
Topologies used in WSNs are: star, mesh, and hybrid. A WSN is very much power constrained. Thus, communication protocol must be very efficient. Also, node deployment must be very judiciously chosen. Coexistence issue is another area of concern when several wireless networks are sending data simultaneously in the vicinity of each other.
