NSF Project: In Band Full Duplex Underwater Acoustic Networks

NSF underwater IBFD project internal webpage (click here)

Synopsis

Wireless communication technologies in the ocean are critical to scientific, commercial, and national defense operations, and yet are still primitive, especially with respect to their data rates and reliability. This project develops new underwater acoustic communications and networking strategies to improve network efficiency in the harsh ocean environment, through underwater in-band full-duplex (IBFD) acoustic networks. The project creates a vertically integrated research experience for both undergraduate and graduate students by exposing them to interdisciplinary research. Through partnerships with local communities, the project investigators develop outreach programs to attract future students, especially those from minority and under-represented communities, to STEM disciplines. This project is a collaboration between the University of Delaware (UD) and the University of Alabama (UA).

Research  Methodology

The major hurdle to achieve underwater acoustic IBFD communications is the presence of strong acoustic self-interference. Therefore, the challenge is how to achieve adequate suppression of the self-interference in the dynamic ocean environment. We take an experiment-based approach in research. A series of field experiments have been conducted in an indoor tank, local rivers, and a large lake. The main objective of these experiments is to collect self-interference measurements at different acoustic frequencies, different transmitter-receiver geometries, different transmitter orientations, etc. Different physical isolation methods have been tested. Based on these field measurements, we analyze the characteristics of the self-interference channel and develop effective signal processing methods for underwater acoustic IBFD receivers.

Efforts and Outcomes

  • Characterization of the acoustic self-interference. A series of field experiments were conducted to analyze the self-interference channel for different transmitter-receiver geometries and different acoustic frequencies. Channel dynamics and their impacts on interference cancellation were investigated in the IBFD context. We proposed a new metric, channel variability ratio (CVR), to measure the fluctuation rates of the acoustic communication channel. Its impacts on channel estimation quality were analyzed in analytic and numerical ways.
  • Development of advanced methods for channel estimation and interference cancellation and assessing their performance. For example, we developed a multi-layered recursive least squares (m-RLS) algorithm to estimate time-varying channels. This m-RLS algorithm applies especially to acoustic IBFD communications, where the interference channel is often much stronger than the intended channel.
  • Development of acoustic transceivers for acoustic IBFD. We have developed different strategies to cope with the residual interference in acoustic IBFD systems based on the new channel estimation algorithms. Adaptive DFE algorithms were developed to address self-interference and multi-path effects jointly. The new receiver algorithm showed substantial improvements when compared with traditional receivers.
  • MAC protocols for underwater acoustic IBFD. A multi-targeted MAC protocol was developed to adjust the acoustic transmission power based on the noise level and communication range. This IBFD MAC protocol significantly reduces energy consumption. At the same time, it achieves the same throughput results as a fixed power transmission mode.

Link to Data Repositories

We are striving to share experimental data and processing tools to the research community. Segments of acoustic IBFD measurements have been organized and are ready for sharing, see the user guide below of our shared data from our 2019 lake experiment. Please visit to IEEE Dataport to retreive the shared dataset: https://ieee-dataport.org/open-access/band-full-duplex-underwater-acoustic-communication-measurements-self-interference.

2019-lake-exp-userguideDownload

Educational  and Outreach Activities

Our project outreach activities fall into the following four categories. During these activities, the PI pays special attention to promote female student participation in STEM disciplines.

  • Interactions with K-12 students through classroom visits by the PI or lab visits by the young students during community events.
  • Involvement of undergraduate students through the REU program.
  • Graduate and REU students supporting the MATHCOUNTS Tuscaloosa competition.
  • Partnership with a sororities group, Alpha Omega Epsilon, to attract female students to STEM disciplines.

Publications

Journal publications/submissions:
Mohammad Towliat, Zheng Guo, Leonard Cimini, Xiang-Gen Xia, and Aijun Song, “Joint Equalization and Self-Interference Cancellation in Underwater Acoustic In-Band Full-Duplex Communication,” IEEE J. Ocean. Eng., accepted, 2023.

Z. Guo, A. Song, M. Towliat, L. J. Cimini, and X.-G. Xia, “Lake Experimentation of in-Band Full-Duplex Underwater Acoustic Communications with a Receiving Array,” IEEE Access, 2023. DOI: 10.1109/ACCESS.2023.3250444.

Z. Guo, A. Song, M. Towliat, L. J. Cimini, and X.-G. Xia, “Impacts of Channel Fluctuations on Channel Estimation in Underwater Acoustic Communications,” J. Acoust. Soc. Am., 149 (6), Jun. 2021. DOI: https://doi.org/10.1121/10.0005087.

M. Towliat, Z. Guo, L. J. Cimini, X. -G. Xia and A. Song, “Multi-Layered RLS Channel Estimation in Underwater Acoustic In-Band Full-Duplex Communication,”submitted, IEEE Transactions on Wireless Communications, Feb. 2021.

Conference papers:
M. Towliat, Z. Guo, L.J. Cimini, X-G. Xia, A. Song. “Enhanced Accuracy of Self-Interference Cancellation in Underwater Acoustic Full-Duplex Communication,” MILCOM, Nov 28-Dec 2. 2022, Rockville, MD.

Z. Guo, A. Song, M. Towliat, L. J. Cimini, X.-G. Xia, Lake experimentation of in-band full-duplex underwater acoustic communications, 182nd meeting of ASA, May 23-26, 2022, Denver, CO.

M. Towliat, Z. Guo, L. J. Cimini, X. -G. Xia and A. Song, “Self-Interference Channel Characterization in Underwater Acoustic In-Band Full-Duplex Communications Using OFDM,” Global Oceans 2020: Singapore – U.S. Gulf Coast, 2020, pp. 1-7.

M. Towliat, Z. Guo, L. J. Cimini, X. -G. Xia and A. Song, “An Adaptive Receiver for Underwater Acoustic Full-Duplex Communication with Joint Tracking of the Remote and Self-Interference Channels,” Global Oceans 2020: Singapore – U.S. Gulf Coast, 2020, pp. 1-7.

Z. Guo, A. Song, M. Towliat, L. Cimini, and X.-G. Xia, and C.-C. Shen, “Self-interference Characterization for In-Band Full Duplex Underwater Acoustic Communications,” The 14th International Conference on Underwater Networks & Systems, Atlanta, Oct 23-25, 2019.

Z. Guo and A. Song, “Impact of channel fluctuations on channel estimation performance in the underwater acoustic environment,” Proceedings of Meetings on Acoustics (for 178th ASA meeting, December 2-6, 2019, San Diego, CA), accepted, June 2020.

REU Posters:
Daniel Williams, Connor Webb, Cari Staats, “NSF REU: Acoustic Channel Probing Using Linear Frequency Modulated Signals,” The 14th International Conference on Underwater Networks & Systems, Atlanta, Oct 23-25, 2019.

Project personnel at the University of Delaware

Dr. Leonard J. Cimini, Jr., Project PI
Dr. Chien-Chung Shen (co-PI)
Dr. Xiang-Gen Xia (co-PI)
Mohammad Towliat (PhD student, graduated in May 2023)

Project Personnel at the University of Alabama

Dr. Aijun Song (PI)
Zheng Guo (PhD student, graduated in Dec 2021)
Daniel Williams (MS graduate student, graduated in May 2022)
Emily Briggs (REU awardee)
Kayla Hamilton (REU awardee)