The oceans cover 71% of the earth's surface and represent one of the least explored frontiers, yet the oceans are integral to climate regulation, nutrient production, oil retrieval, and transportation. Future scientific and technological efforts to achieve better understanding of oceans and water-related applications will rely heavily on our ability to communicate reliably between instruments, vehicles (manned and unmanned), human operators, platforms, and sensors of all types. The glue of such underwater networks will be the underwater acoustic communication link. Despite recent activity on acoustic physical layer single-links, digital acoustic communication is in its infancy in comparison to comparable efforts for radio-based terrestrial wireless communication. This project exploits the unique features of the underwater acoustic channel to significantly improve performance of underwater networks.
The research focus is on design for the inherently multi-scale, multipath channels in this wideband environment. Surprisingly, transceiver design for the coupled efforts of wideband channels and distinct Doppler scales for practical underwater communication systems does not appear to have been thoroughly investigated. The network is examined from the perspective of individual links up to entire networks of multiple nodes, encompassing novel multi-scale, multi-lag channel modeling, waveform design, equalizer designs, channel estimation, single-link and network capacity evaluation, novel coding to achieve capacity, as well as signaling and routing over large-scale networks. In a principled manner, the fundamental properties of multi-scale, multipath channels are explored in order to design and analyze high performance underwater acoustic networks. Implementable algorithms are designed which endeavor to achieve the fundamental limits. The research outcomes will also impact ultrasound, ultrawideband, wideband radar, sonar, acoustic signal processing, and moderate to high speed vehicle-to-vehicle (V2V) communication and possibly understanding of biosonar.