Collaborative Ocean Acoustic Sensing Technology

Project Summary

P.I.: Young H. Cho, University of Southern California


Despite the fact that the human civilization has heavily depended on the bodies of water covering over 71% of the Earth, we know more about the surfaces of planets millions of miles away than about what lies down on the ocean floor.  However, several recent studies on marine ecology and their important role in sustaining the rest of the Earth seem to urge immediate need for more and better underwater capabilities.  Furthermore, in the wake of several recent naval incidents in the waters of the Korean Peninsula as well as the massive oil spill in the Gulf of Mexico, we recognize the mounting need for high resolution, in-situ underwater monitoring technology.

Therefore, our team at USC/ISI has been conducting research and development for scalable and practical technologies toward global underwater sensing since 2006.  Our approach differs from the main stream techniques in that we seek to monitor the underwater physical phenomena accurately at higher resolution using a network of collaborative, low-cost, general purpose underwater sensor nodes.  Unlike most underwater systems that are in existence, we also adhere to a central philosophy behind wireless sensor network to enable global sensing.  Although there have been much research on wireless sensor network in terrestrial environments, changing the deployment environment from ground to water introduces several research challenges that did not manifest themselves in most prior works.

The source of most of these new challenges is the differences in the physics of how the preferred forms of wireless signals in corresponding environments work.  The solution to this problem is fundamental in nature with potential for far reaching impacts in various future underwater research.  Recognizing the large scope of this project, we will approach the problem by incrementally solving specific problems that we encounter during the development of useful underwater sensing applications.

Therefore, we propose to adapt one of the most elegant concepts of underwater monitoring called Ocean Acoustic Tomography onto our underwater testbed and extend its capability with new research ideas of our own.  Through this research, we will build one of the first minimally invasive, marina-scale in-situ underwater temperature and current sensor using underwater wireless acoustic sensor network.  This proposal seeks to make new intellectual contributions in the field of ocean acoustic tomography, underwater sensor network, and underwater time synchronization.

We have three concrete objectives, each with tasks that depict new contributions in the field while providing support and validation to the subsequent tasks.  They are (1) Marina-scale ocean acoustic tomography (micro-tomography), (2) Micro-tomography without time synchronization, and (3) Underwater time synchronization without Global Positioning System.

The intellectual merit of the proposed research lies in making new contributions in global underwater sensing by appropriately applying prior research works in wireless sensor networks and ocean acoustic tomography to marina-scale underwater sensing.  During our preliminary studies, we discovered a number of opportunities for optimizations and novel research in in-situ underwater monitoring.  Our proposal seeks to explore these opportunities to enable least invasive and practical in-situ monitoring for marina-scale shallow bodies of water.  Furthermore, additional merits of this proposal are predicted by the estimated results of our new algorithms and technologies that may be applied back to the ocean scale tomography systems to not only improve their performance and accuracy but enable new applications in extreme depth.

This project will have broad impacts in a number of fields.  Our proposal can have significant benefit for environmental science community as it has the potential to make minimally invasive underwater monitoring very practical.  For industrial community and military, our work can be used to rapidly detect problems in the underwater infrastructure with high precision.  Such monitoring capability can be used to trigger faster response to prevent unrecoverable damage.  Beyond its impact on technology, our philosophical adherence to inexpensive sensor network will allow more researchers to participate in research endeavors to sense underwater environment.  As a part of the broader education effort, our project results will also be incorporated into networking and distributed system course at USC.  Finally, the infrastructural components resulting from our research (hardware, software, models) will be made available to the broader education and research community to promote collaboration and synergy.