QoS-enabled underwater acoustic communications

For enabling efficient operation of untethered underwater vehicles, error-free underwater communication of command-and-control and telemetry data is a necessity. In contrast, the communication requirements for the sensor data of these vehicles are often less stringent, i.e., a few bad pixels in a SONAR image might be tolerated. To maximize bandwidth utilization of underwater acoustic communication links, the MSFRSS (Multi-Stream Frequency-Repetition Spread Spectrum) modulation that supports transmission of data with distinct Quality-of-Service (QoS) demands within a single transmission is explained in detail. Real-time MSFRSS performance is assessed for remote-monitoring applications in two challenging environments (Port of Scheveningen and Trondheim Fjord). Recordings and channel soundings in the Port of Scheveningen were used to improve the equalization of the MSFRSS modulation scheme. Eventually, the updated transmitter and receiver were used in Trondheim Fjord to demonstrate real-time transmission of telemetry and image data from a ship to a bottom node.