Distributed Connectivity Restoration in Underwater Acoustic Sensor Networks via Depth Adjustment

In most applications of Underwater Acoustic Sensor Networks, network connectivity is required for data exchange, data aggregation and relaying the data to a surface station. However, such connectivity can be lost due to failure of some sensor nodes which creates disruptions to the network operations. In this paper, we present two algorithms, namely BMR and DURA, which can detect network partitioning due to such node failures and re-establish network connectivity through controlled depth adjustment of nodes in a distributed manner. The idea is to first identify whether the failure of each node will cause partitioning or not based on localized information. If partitioning is to occur as a result of the possible failure of a particular node, both BMR and DURA designates backup nodes to handle the recovery in the future. While DURA aims to localize the recovery process and minimize the movement overhead on the nodes, BMR strives to reduce the recovery completion time at the expense of increased movement overhead by employing a two-phase block movement. The performance of the proposed approaches is validated through extensive simulations. The results indicated that DURA can provide energy savings as much as a centralized exhaustive approach while BMR provided the fastest recovery time.