Evaluating Lightweight Dependable Adaptation in 802.15.4 Wireless Sensor Networks

To achieve dependable real-time operation in Wireless Sensor Networks (WSNs) we previously proposed a general technique based on non-parametric stochastic analysis. Such technique allows one to overcome the communication uncertainties that are intrinsic to wireless and dynamic environments, and to offer probabilistic real-time guarantees, by continually monitoring and adapting to environment conditions. An underlying assumption of the proposed technique is that the system can recognize changes in the state of the environment quickly enough, compared to the rate at which those changes occur. In this paper we effectively evaluate the validity of such an assumption, in WSNs based on the 802.15.4 networking standard. We present results from various simulation scenarios, as well as from a real network, and conclude that monitoring and adaptation can dependably provide probabilistic real-time guarantees in 802.15.4-based WSNs, in the presence of realistic network dynamics. Keywords-Wireless Sensor Networks; dependability; adaptation; real-time; 802.15.4; non-parametric; lightweight; QoS;