Monitoring Wireless Sensor Network Performance by Tracking Node Operational Deviation
Yaqoob J. Al-raisi, Nazar E. M. Adam · InTech eBooks · 2010
IntroductionWireless Sensor Network (WSN) is a very powerful tool that enables its users to closely monitor, understand and control application processes.It is different from traditional wired sensor networks in that its characteristics make it cheap to manufacture, implement and deploy.However, this tool is still at an early stage and many aspects need to be addressed in order to increase its reliability.One of these aspects is the degradation of network performance as a result of network nodes deviation.This may directly reduces the quality and the quantity of data collected by the network and may cause, in turn, the monitoring application to fail or the network lifetime to be reduced.Deviations in sensor node operations arise as a result of systematic or/and transient errors (Elnahrawy, 2004).Systematic error is mainly caused by hardware faults, such as calibration error after prolonged use, a reduction in operating power levels, or a change in operating conditions; this type of error affects node operations continuously until the problem is rectified.Transient errors, on the other hand, occur as a result of temporary external or internal circumstances, such as various random environmental effects, unstable hardware, software bugs, channel interface, and multi-path effects.This type of error deviates node operations until the effect disappears.These two types of error may directly and indirectly affect the quality and the quantity of data collected by the WSN.They directly affect sensor measurements and cause drift by a constant value (i.e.bias); they change the difference between a sensor measurement and the actual value, (i.e.drift); and can cause sensor measurements to remain constant, regardless of changes in the actual value, (i.e.complete failure).In addition, they affect the communication and exchange of packets by dropping them.On the other hand, the abovementioned errors can have an indirect effect on the network's collaboration function, the construction of routing tables, the selection of the node reporting rate, and the selection of data gathering points.Analysis of the data collected by the network (in some practical deployments, such as (Ramanathan, 2004), (Tolle, 2005)), shows that these error reduces the 1 www.intechopen.com