Decentralized detection of hybrid faults in mobile sensor nodes

The widespread use of sensor nodes that are operating under the Internet of Things paradigm motivates researcher to step forward and build reliable systems capable of detecting their faulty nodes. These nodes lead to decrease in the accuracy and functionality of the networks, which finally result in quality degradation of network services. From the temporal point of view, the faults can be either permanent or intermittent. The detection of the latter one is more challenging since the nodes show contradictory behaviors at different times. from the topological point of view, the mobility of the sensor nodes is an intrinsic characteristic in many IoT-based applications, where numerous mobile nodes are managed by static overlay nodes. The dynamics of these network introduces the second challenge in identifying faulty nodes. Several works have been conducted to address the problem, but there is a research gap in identifying hybrid soft sensor faults in the aforementioned networks. The focus of attention in this paper is the detection of soft faults in the sensing unit of the nodes. We devised a new method, called Hybrid Fault Detection in Mobile Sensors, to detect nodes with mixed permanent and intermittent faults. A software debugging approach inspired the main idea. We also applied data mining techniques such as DBSCAN and K-means to validate sensed data, and differentiate the classes of faults, respectively. We evaluated the devised method using the NS2 simulator in various situations. One of the outcomes of the method is that the mobility of the nodes does not reduce the accuracy, in contrast to most of the traditional methods. Moreover, the evaluation demonstrates promising results for the networks with more than 50% faulty nodes. The results also show perfect performance in detecting permanent and intermittent faults in the networks with various percentage of faulty nodes.