A Reliability-Driven Topology Restoration Strategy for Underwater Wireless Sensor Networks in Dynamic Ocean Environments

In ocean environments, underwater sensor nodes (USNs) are susceptible to failure due to various factors, such as seawater corrosion, hardware failure, depleted battery, harsh deployment scenarios, and intentional sabotage. This article focuses on the topology restoration problem of disconnected subnetworks (TR-DSNs) caused by large-scale USN failures in underwater wireless sensor networks (UWSNs). The existing research cannot be well adapted to dynamic ocean environments because they ignore the effects of underwater communication channel and current movement on the cost and reliability of network restoration. It would consequently lead to high restoration cost and unreliable data transmission for UWSNs. To solve the mentioned problem, we first build a reliability evaluation model of topology restoration that considers the link quality, network connectivity, and data transmission of UWSNs in dynamic ocean environments. Then, a reliability-driven topology restoration strategy (called RDTRS) based on underwater relay node (URN) placement is designed. RDTRS comprises three key algorithms: 1) URN placement path generation; 2) URN location determination; and 3) URN location adjustment. By RDTRS, the number of URNs can be reduced on the premise of ensuring the restoration reliability of UWSNs. In the end, we validate the performance of RDTRS in terms of network restoration cost, packet delivery ratio, and transmission latency.