Performance Metrics in Wireless Sensor Networks

The design of SN is a challenge because many influencing factors such as fault tolerance, scalability, production cost, operating environment, network topology, hardware constraints, transmission media, power consumption and others have to be considered. The performance of the network is then measured based on quantifiable parameters called performance metrics. This however varies according to need and the nature of SN.

System Lifetime: System lifetime is exhibits by number of rounds in simulation which determines the longevity of the nodes. Lifetime is the most crucial thing in SN so from all aspects of the node and the network, energy has to be utilized in the most effective way possible.

Latency: Data resulted from triggered events are generally time sensitive, however in most of the cases periodic sensing is okay to implement for resulting latency comes in a fraction of a second.

Quality: End user never requires all the data, the only data about the events are processed in BS for analysis. So quality of the network is determined by the quality of data aggregation scheme and protocols implements besides the specific need of the application used.

Delay and Delay Variation: Delay measures time to send and receive a unicast packet from one node to another while the variation of a delay metric with respect to some reference value is determined with delay variation. In sensor networks, delay in data collection from nodes to the BS and interpretation in the BS are concerned with delay.

Bandwidth, Capacity and Throughput: These indicate the capacity of data which can be sent over a link within a given time, however since the data size is very small bandwidth rarely matters.

Hop Count: No of hop in communication determine the cost of path, and eventually the energy consumed in the process.

Signal Strength: SNR as an indication for the link quality and the distance between two nodes is helpful to compute and determine the nodes and their reachability during the communication process.

Ease of Deployment: Sensor network consist of few to several hundred sensor nodes, and these nodes have to be able to communicate with each other even in absence of established network infrastructure.