Biblio
Hierarchical based formation is one of the approaches widely used to minimize the energy consumption in which node with higher residual energy routes the data gathered. Several hierarchical works were proposed in the literature with two and three layered architectures. In the work presented in this paper, we propose an enhanced architecture for three layered hierarchical clustering based approach, which is referred to as enhanced three-layer hierarchical clustering approach (EHCA). The EHCA is based on an enhanced feature of the grid node in terms of its mobility. Further, in our proposed EHCA, we introduce distributed clustering technique for lower level head selection and incorporate security mechanism to detect the presence of any malicious node. We show by simulation results that our proposed EHCA reduces the energy consumption significantly and thus improves the lifetime of the network. Also, we highlight the appropriateness of the proposed EHCA for battlefield surveillance applications.
Existing approaches to diagnosing sensor networks are generally sink based, which rely on actively pulling state information from sensor nodes so as to conduct centralized analysis. First, sink-based tools incur huge communication overhead to the traffic-sensitive sensor networks. Second, due to the unreliable wireless communications, sink often obtains incomplete and suspicious information, leading to inaccurate judgments. Even worse, it is always more difficult to obtain state information from problematic or critical regions. To address the given issues, we present a novel self-diagnosis approach, which encourages each single sensor to join the fault decision process. We design a series of fault detectors through which multiple nodes can cooperate with each other in a diagnosis task. Fault detectors encode the diagnosis process to state transitions. Each sensor can participate in the diagnosis by transiting the detector's current state to a new state based on local evidences and then passing the detector to other nodes. Having sufficient evidences, the fault detector achieves the Accept state and outputs a final diagnosis report. We examine the performance of our self-diagnosis tool called TinyD2 on a 100-node indoor testbed and conduct field studies in the GreenOrbs system, which is an operational sensor network with 330 nodes outdoor.
Wireless sensor networks offer benefits in several applications but are vulnerable to various security threats, such as eavesdropping and hardware tampering. In order to reach secure communications among nodes, many approaches employ symmetric encryption. Several key management schemes have been proposed in order to establish symmetric keys. The paper presents an innovative key management scheme called random seed distribution with transitory master key, which adopts the random distribution of secret material and a transitory master key used to generate pairwise keys. The proposed approach addresses the main drawbacks of the previous approaches based on these techniques. Moreover, it overperforms the state-of-the-art protocols by providing always a high security level.