Distributed k-Connectivity Restoration for Fault Tolerant Wireless Sensor and Actuator Networks: Algorithm Design and Experimental Evaluations

Connectivity maintenance is an important requirement in wireless sensor and actuator networks (WSANs) because node failures can, potentially, lead to destructive changes in the network topology, which, in turn, can create a partitioned network. Preserving k-connectivity in a WSAN is important for keeping stable connections. A k-connected network is a network that remains connected after removing any k-1 nodes. Higher k values provide more reliable connectivity and a higher level of fault tolerance. In this article, we present a distributed k-connectivity restoration approach for heterogeneous WSANs where the nodes can be static or mobile. In the proposed algorithm, each node identifies the mobile nodes in the network and its 2-hop local subgraph. After a node is incapacitated, a neighbor of the failed node calls a mobile node with minimum moving cost to the location of the failed node if the failure reduces k. A minimum cost movement path between a neighbor of the failed node and a mobile node is constructed by considering the locations of the nodes, moving costs, and obstacles. Testbed experiments and comprehensive simulations reveal that the proposed distributed algorithm is capable of restoring k-connectivity with up to 35.5% lower sent Bytes and up to 40.9% lower movement cost than the existing algorithms.