In-Network Collaboration for CDMA-Based Reliable Underwater Acoustic Communications

Achieving high throughput and reliability in underwater acoustic networks for transmitting distributed and large volume of data is a challenging task due to the bandwidth-limited and unpredictable nature of the acoustic channel. In a multinode network, such as in the Internet of Underwater Things, communication link efficiency varies dynamically: if the channel is not in good condition, e.g., when in deep fade, channel coding techniques may fail to deliver the information even with multiple retransmissions. Hence, an efficient and agile collaborative strategy is required to allocate appropriate resources to the communication links based on their statuses. The proposed solution adjusts the physical- and link-layer parameters collaboratively for a code-division multiple-access (CDMA)-based underwater network. An adaptive hybrid automatic repeat request solution is employed to guarantee reliable communications against errors in poor links. Results were validated using data collected from the LOON testbed-hosted at the North Atlantic Treaty Organization Science and Technology Organisation Centre for Maritime Research and Experimentation in La Spezia, Italy-and from the REP18-Atlantic sea trial conducted in September 2018 in Portuguese water.