Reliability Modeling of Embedded Nodes in Real Time Wireless Systems

Nowadays there is an increasing trend of applying wireless technologies in industrial automation. However, the industrial control environment is harsher and noisier posing more stringent requirements on real-time communication. The variation in wireless signal strength with time and location, and power limitation due to battery usage make the problem even worse. Accordingly, availability and reliability of such system should be seriously analyzed before deployment. Modeling the reliability of these distributed real-time systems with nodes having embedded software has become an integral part of the design process. The time constraints that real-time systems must meet directly affect the reliability measure itself irrespective of the nature of the measure. A metric for calculating system reliability is proposed in this paper and a Monte Carlo simulation based algorithm for calculating the same is presented here. The results show that system reliability stabilizes with time even with increasing network size.