Connectivity Recovery In Wireless Sensor Networks

As an important part of Internet of Things, wireless sensor networks (WSNs) have attracted much attention.In practical applications, WSNs are usually deployed in harsh or even hostile environments, where sensor nodes are error-prone. The local or large-scale failures of sensor nodes may compromise the network connectivity so that the degradation in performance occurs. In this thesis, the problem of connectivity loss is studied and several schemes are proposed to satisfy the needs in different design purposes and application demands. The main achievements of research works in this thesis are summarized as follows:(1) For the single node fault, an energy efficient and self-healing recovery algorithm is proposed under the assumption that all nodes in the network are moveable. The proposed algorithm relocates the neighbors of the faulty node for recovery based on their energy value. Simulation results show that the proposed algorithm can maintain the original connectivity of each node without renewing rout table frequently. Moreover, this algorithm can balance energy consumption of each node and extend network lifetime.(2) For the large-scale fault, with the premise of no requirement for fault tolerance, combining with Steiner tree, this thesis presents an improved minimum spanning tree recovery algorithm. The proposed algorithm tries to recover network connectivity with a minimum of relay nodes. Simulation results show that the proposed algorithm can reduce restoration cost. In addition, average node degree is larger after recovery, which enhances the robustness of the network.(3) For the large-scale fault, with the requirement for fault tolerance, this thesis constructs fan-shaped topology and dual-ring topology to restore network connectivity, respectively. Fan-shaped topology is suitable when priority on the restoration cost is given, while dual-ring topology is suitable when the network quality is considered first. Simulation results show that the proposed network topologies can resist subsequent attacks and meet the actual needs better.