AREP: An asymmetric link-based reverse routing protocol for underwater acoustic sensor networks

Abstract

Routing protocol design is one of the fundamental requirements of Underwater Acoustic Sensor Networks (UASNs). However, traditional underwater routing protocols focus on the particularities of underwater environment, while ignoring the features of underwater nodes that influence route establishment. In this study, the impact of the directional beam width of underwater nodes on communication links was fully explored. The presented case studies indicate that for fixed beam width of directional antennas, the relative position change of two geographically adjacent nodes is prone to generate asymmetric links. To ensure bidirectional data communication between source nodes and destination nodes, an asymmetric link-based reverse routing (AREP) is proposed. In AREP, each node maintains a neighbor table in which items are used to analyze the link state. Routing paths are established by prioritizing the utilization of symmetric links. When an asymmetric link is required to be introduced into a routing path, a three-hop-constrained circuitous route will be established for ease of reverse routing search. The routing void problem is addressed in AREP through eliminating void nodes. A routing update is periodically conducted to dynamically adjust previous routing paths to the change of network topology caused by node mobility. Simulation results demonstrated that AREP improves network performance in terms of transmission delay, packet delivery ratio, as well as energy consumption.