An Adaptive Routing Protocol for Underwater Acoustic Sensor Networks With Ocean Current

Long-term underwater acoustic sensor networks (UASNs) are widely deployed for marine scientific and industrial applications. The widespread ocean currents lead to variations in the communication range of location-fixed nodes equipped with nonomnidirectional transducers, which will reduce the successful packet relaying probability. In order to reduce the impact of ocean currents on packet relaying, we propose an adaptive routing protocol for UASNs with ocean currents (OCAR). By adaptively selecting candidate nodes based on communication range, OCAR improves the successful packet relaying probability in poor communication conditions caused by ocean currents. First, the impact of ocean currents on communication range is demonstrated by constructing a communication range model and a sea trial. Second, successful packet relaying probability is improved by selecting the communicable nodes under ocean currents as the candidate nodes. Next, the transmitter-based adaptive routing scheme reduces the number of nodes responding to the relay packet and adaptively reselects the destination node per hop. Therefore, energy consumption is reduced, and the packet delivery ratio (PDR) is improved. Finally, routing recovery and candidate set dynamic update are achieved to improve successful packet relaying probability. Simulation results show that, compared with the flood, OCAR can achieve a maximum 98.29% reduction in energy consumption and 37.05% reduction in average end-to-end delay while maintaining close to 100% PDR. In addition, compared with vector-based forwarding (VBF), OCAR can achieve close to 100% PDR when the PDR of VBF is 0, maximum energy consumption reduction of 84.41%, and average end-to-end delay reduction of 96.34%.