Reliable Data Delivery in Underwater Acoustic Sensor Networks

Underwater Acoustic Sensor Networks (UASNs) are becoming increasingly promising to monitor aquatic environment. However, reliable data delivery remains challenging due to long propagation delay and high error-rate of underwater acoustic channel, limited energy and inherent mobility of sensor nodes. To address these issues, we propose a data delivery protocol to improve data transfer reliability for delay-tolerant underwater traffic. Data delivery reliability is significantly improved by selecting the next hop forwarder on-the-fly based on its link reliability, reachability to gateways and coverage probability through probabilistic estimation. Data forwarding solution is coupled with delay tolerant networking paradigm to improve delivery with reduced overhead. With the exception of having initial coarse location of sensor nodes, the proposed protocol does not require "active" localization technique to estimate node's updated location. The mobility of anchor-based nodes within the surface-area of a hemisphere is exploited to estimate node movement and location. Mobile message ferries are used to collect stored data from one or more nodes, called gateways. A strategy for gateway selection is devised to maximize their lifetime. Simulation results show that our protocol achieves significant performance improvement over competing protocols using low overhead and less energy.