A Link-State Based Adaptive Feedback Routing for Underwater Acoustic Sensor Networks

Underwater Acoustic Sensor Networks (UASNs) have recently been attracted significant attention from both academia and industry for resources exploration and for scientific data gathering in underwater environments. The important characteristic of a UASN is that most underwater acoustic sensor nodes have a certain beam width and a three dimension direction, which is ignored by the existing underwater routing protocols. This characteristic will reduce the network connectivity and cause a large number of asymmetric links, so it will lead to sharp decline of the existing protocol performance. We develop a routing protocol to tackle this problem in UASNs. A link detection mechanism is employed to get link state information (symmetrical link or asymmetric link), and an adaptive routing feedback method is adopted to make full use of the underwater asymmetric link and save energy. We propose a time-based priority forwarding mechanism and utilize downstream node table to prevent flooding, and a credit-based routing table update mechanism is adopted to avoid energy consumption caused by frequent update of routing table. The proposed protocol is compared with a representative routing protocol for UASNs. The simulation results verify the effectiveness and feasibility of the proposed protocol.