Ocean-TUNE: A Community Ocean Testbed for Underwater ...

Ocean-TUNE: A Community Ocean Testbed for Underwater Wireless Networks Jun-Hong Cui, Shengli Zhou, Zhijie Shi, James O’Donnell, Zheng Peng

Sumit Roy, Payman Arabshahi University of Washington Seattle, WA

University of Connecticut Storrs/Groton, CT

Mario Gerla, Burkard Baschek

Xi Zhang

University of California Los Angeles, CA

Texas A&M University College Station, TX

ABSTRACT This paper presents collective efforts from four institutions, University of Connecticut, University of Washington, University of California, Los Angeles, and Texas A&M University, on a community Ocean Testbed for Underwater Networks Experiments (Ocean-TUNE). This proposed community testbed will enable a wide range of research in the areas of underwater communications, networking, engineering, and marine science, and hence will promote unprecedented progress towards practical solutions in diverse aquatic applications.

Keywords System, Testbed, Underwater, Network

1.

INTRODUCTION

The need to understand changes in our planet’s environment resulting from its inter-relations with human civilization and other natural ecosystems has never been stronger. These are complex, global issues and the challenges are manyfold, beginning with fundamental scientific questions underpinning environmental processes across multiple scales. Within this context, exploration and monitoring of the oceans (90% of which are still unexplored) is an urgent need as they play a major role in regulating Earth weather and climate. Consequently, expansion of suitably engineered infrastructures is needed for desired levels of monitoring and data collection from bodies of water. What makes the above particularly challenging is not just the vastness but the many variations of aquatic environments, including estuaries, lakes, rivers and coastlines. The needs to monitor/explore such a variety of environments for scientific exploration, commercial exploitation and environ-

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mental protection, requires transformative technologies for underwater networking infrastructure. While ongoing technological advances in platforms and instrumentation have underpinned significant progress in observation and exploration capabilities, these still drastically lag relative to land-based capabilities. The water world is a much more dynamic and harsher physical environment, in turn requiring a mix of in-situ and ad-hoc infrastructures, for observing evolution or changes across various time scales. Driven by these needs, underwater wireless networking (UWN) technology becomes most desired and a rapidly growing interest in this field has been witnessed in the past several years [1, 2, 3, 4, 5]. Underwater wireless networking is extremely challenging, however, from both the theoretical and practical worlds. UWNs have to rely on acoustic channels characterized by long propagation delays, low communication bandwidth, high channel error rates, link asymmetry and anisotropy, and tempo-spatial multi-level dynamics. This creates great challenges for network design, in terms of the physical, medium access and network layers to ensure reliable data transfer. Furthermore, in a UWN with mobile nodes, node mobility poses significant additional challenges with regards to multihop routing, and synchronization/localization. Accordingly, any attempts at optimization of UWNs must recognize the potential of cross-layer approaches whereby the link and multi-access layers are jointly adapted, in response to environmental changes.

2.

THE INFRASTRUCTURE

The final goal of this project is to provide ubiquitous access to an open and versatile field (ocean) testbed to the underwater wireless networking community. To achieve this goal, we consider six feature dimensions: openness, configurability, flexibility, ubiquity, economy, and user-friendliness. By “openness”, we mean that the testbed is accessible to the public; by “configurability”, we mean that the parameters of the modem and network systems used in the testbed can be modified at all layers (including physical layer); by “flexibility”, we mean that the testbed could provide various system/network configurations, such as site choices, topology choices, and (mobile) node choices; by “ubiquity”, we mean that the testbed can be accessed at any time anywhere; and “economy” and “user-friendliness” are more self-explained.

Figure 1: Four Ocean-TUNE Sites

It will leverage the facilities and equipment of the Long Island Sound Integrated Coastal Observing System (LISICOS). The Marine Science and Technology Center (MSTC) at the Avery Point Campus of the University of Connecticut operates ships, diving and laboratory services in support of LISICOS and these will be used extensively in the deployment phase of the testbed. This sea testbed (see Figure 2) will entail five underwater senor nodes (each equipped with acoustic modems), all anchored to the seafloor by bottom frames, three surface gateway nodes or buoys (also equipped with acoustic and RF modems), and two underwater gliders. The fixed bottom nodes will be equipped with complex sensor sets from SBE Microcats for data sampling. Two of the surface buoys will be also installed with a reconfigurable modem (on which various communication algorithms can be implemented and tested). The gliders will embed sensors and OFDM acoustic modems (without housing) in its scientific bay. This kind of hybrid testbed will help to fully demonstrate the challenges encountered in the coordination of the mobile assets and fixed nodes. Networking protocols will be developed based on the networking development kit of OFDM modems, and will coordinate all platforms, including bottom nodes, surface gateways, and gliders.

3.

Figure 2: An illustration of the UCONN testbed.

To satisfy the above desired features, in this project, we unify four groups of researchers from University of Connecticut, University of Washington, University of California Los Angeles, and Texas A&M University, and propose to develop a community ocean testbed (OCEAN-TUNE) for underwater wireless networks. Based on the past rich experiences in underwater networking research, accumulated extensive field (lake to ocean) experiments, and the close interactions with the researchers in the community, the team carefully picks appropriate devices and equipment and representative deployment locations for Ocean-TUNE. Ocean-TUNE consists of four sites, as shown in Figure 1, with each site operating a testbed for several months per year. The aim is to have at least one testbed function at any given time. If each testbed can be operated for six months straight, Ocean-TUNE could provide 24/7 access to two testbeds via a web user interface (note that all sites can be accessed through the Internet). This is achievable through a good scheduling given that the involved four sites have a wide geographic and weather span over the US coasts. In this way, Ocean-TUNE can provide “ubiquitous” access to users through the web. More importantly, these four sites offer different underwater environments and have different network configurations, which allows a wide range of research capabilities to be tested and evaluated. In other words, Ocean-TUNE will provide high “flexibility” to users. Each participating site will design, develop and deploy its own testbed. Take the UCONN testbed for example.

SUMMARY

The Ocean-TUNE is an open testbed “suite” accessible to the public. It consists four testbeds to be deployed at four different sites, namely, Long Island Sound (CT), Hood Canal (WA), Santa Monica Bay (CA), and Galveston Bay (TX), which have a diverse coverage of the US coasts in terms of geography and weather. It will enable a wide range of research within the underwater communications, networking, engineering, and marine science communities.

Acknowledgement This project is supported by the National Science Foundation under grants: CNS-1205665 (UCONN), 1205725 (UW), 1205757 (UCLA), 1205726 (TAMU).

4.

REFERENCES

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