Design Issues in WSN

Wireless sensor networks are made of large number of tiny sensor nodes, which have limited power and less processing capability. The life time of the individual sensor node is not easily predictable and also the network needs to be formed autonomously as it is not possible to manually set up the sensor network for all applications. The sensor network also consists of several different kind of nodes hence heterogeneity needs to be supported. The number of sensor nodes in the network is not constant through out the life time of the network it may vary because of addition of senor nodes or reduction of nodes due to their death . The major factors that need to considered while designing sensor network are listed below.

Fault Tolerance: Possibility of node failure and change of topology of network is quite high in case of WSN. Hence the designer of network should make the network robust and reliable even in case of node failures and topology changes. The network should function smoothly and normally irrespective of node failures and topology changes.

Life Time: WSN are supposed to work for a quite long time with low power consumption. They are supposed to last at-least for 6 months to 1 year. We need to keep in mind that every node in WSN may be powered using just a 3 V battery and this should be sufficient for the entire life time of the node . The design of protocols of WSN should be such that the node consumes as less energy as possible. This will help in making the WSN last longer.

Scalability: The design of WSN should support addition of new nodes any time and also the design should support large number of nodes because some applications in WSN may require quite a huge number of sensor nodes.

Date Aggregation: The sensor nodes in WSN are located close to each other hence the possibility of similar data being generated by the nodes next to each other is quite high. So the data needs to be aggregated and the duplicate data needs to be avoided because the transmission and reception data is the most costly affair in WSN.The data needs to be aggregated at different levels in WSN so that only the necessary data is transmitted and recevied and the redundant data is not communicated.

Cost: The cost of each sensor node is supposed to be 1$ , as WSN can have large number of sensor nodes the total cost of the network can become a quite expensive affair. So the designer of WSN needs to decide on the optimal number of nodes necessary for the application.

Environment: The environment in which the WSN is deployed can be very demanding , so the design of WSN should be such that WSN should be able to survive regardless of the conditions in which WSN s deployed.

Heterogeneity Support: The protocols designed for WSN should support different kinds of sensor nodes and also be able to support variety of applications.

Autonomous Operations: The WSN should be able to organize , reorganize and operate autonomously because sometimes WSN deployed in places where human habitation is not possible.

Limited Memory and Processing Capability : The sensor nodes have very limited memory, power and processing capabilities , so all designs of WSN should not be demanding in terms of processing requirements or memory requirements .