Due to its advantageous functional characteristic of monitoring phenomena of the physical environment with relatively low cost for a broad area, Wireless Sensor Networks (WSN) have been focused as a key infra technology to realize the context-aware systems. However, the limited resources of a sensor node, including memory, battery, and computing capability, have restricted the possible architectural choices to the centralized decision scheme where sensor nodes play just a simple role of low-level sensing information sources to the central decision point. By our research on the characteristics of the context compositions, we found that in many cases a context consists of combination of several sub-conditions (events) among which they have timing and logical relations, and in that case the centralized decision approach shows several drawbacks which are critical in WSN.
We propose a novel context detection mechanism called PROCON in Wireless Sensor Networks in case that the context consists of combination of several sub-conditions. In PROCON, context decisions are made in a distributed way, by cooperation of sensor nodes connected through a context overlay on the network. By performing incremental context decisions along the context overlay, failure contexts are detected in the early stages and successful contexts are fused and then generate new conceptual high-level information.
As a result, the sensor network can deliver context level information, not low level sensing data, directly to proper actuators. Moreover, PROCON achieves highly efficient energy consumption compared to the existing centralized context detection mechanism. The analysis and simulation results show that the proposed mechanism outperforms the existing centralized mechanism in average energy consumption, capability of mitigating congestion to a base station, context service lifetime, and reliability.