Related Experiment Video
Updated: Jun 5, 2026
09:36
Continuous-Wave Propagation Channel-Sounding Measurement System - Testing, Verification, and Measurements
Published on: June 25, 2021
Long-range multi-carrier acoustic communications in shallow water based on iterative sparse channel estimation
Taehyuk Kang1, H C Song, W S Hodgkiss
1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0238, USA. tedkang@ucsd.edu
The Journal of the Acoustical Society of America
|January 12, 2011
Summary
Long-range acoustic communications using orthogonal frequency division multiplexing (OFDM) achieved error-free 10 kb/s transmission over 8 km in shallow water. This study demonstrates robust underwater communication despite environmental challenges.
Area of Science:
- Underwater acoustics
- Digital communications
- Signal processing
Background:
- Underwater acoustic communication faces challenges due to signal scattering and multipath propagation.
- Orthogonal frequency division multiplexing (OFDM) offers potential for robust underwater acoustic communication.
Purpose of the Study:
- To demonstrate long-range OFDM acoustic communication in a shallow water environment.
- To investigate the effectiveness of iterative sparse channel estimation and diversity combining.
Main Methods:
- Utilized data from the Kauai Acomms MURI 2008 (KAM08) experiment.
- Applied iterative sparse channel estimation with low-density parity-check decoding.
- Investigated diversity combining techniques in an inhomogeneous underwater environment.
Main Results:
- Achieved error-free transmission at 10 kb/s over an 8 km distance.
- Demonstrated successful 16-quadrature amplitude modulation (QAM) in a challenging acoustic channel.
- Showcased the benefits of diversity combining for improved communication reliability.
Conclusions:
- Long-range OFDM acoustic communication is feasible in shallow water environments.
- Advanced signal processing techniques enhance underwater communication performance.
- OFDM acoustic systems can achieve high data rates for underwater applications.
Related Concept Videos
01:18Uniform Depth Channel Flow: Problem Solving
To calculate the flow rate for a trapezoidal channel, first, identify the bottom width, side slope, and flow depth of the channel. The cross-sectional area (A) corresponding to the depth of flow (y), channel bottom width (B), and side slope (θ) is determined by:Next, calculate the wetted perimeter, which includes the bottom width and the sloped side lengths in contact with the water. Using the values of the cross-sectional area and the wetted perimeter, determine the hydraulic radius by...
01:27Uniform Depth Channel Flow
Uniform depth channel flow keeps fluid depth consistent along channels such as irrigation canals. In natural channels, such as rivers, approximate uniform flow is often assumed. This condition occurs when the channel’s bottom slope matches the energy slope, balancing potential energy lost from gravity with head loss due to shear stress. This balance prevents depth changes along the channel length, resulting in a steady, uniform flow.Uniform flow in open channels with a constant cross-section...
01:26Linear Approximation in Frequency Domain
Linear systems are characterized by two main properties: superposition and homogeneity. Superposition allows the response to multiple inputs to be the sum of the responses to each individual input. Homogeneity ensures that scaling an input by a scalar results in the response being scaled by the same scalar.
In contrast, nonlinear systems do not inherently possess these properties. However, for small deviations around an operating point, a nonlinear system can often be approximated as linear.
In contrast, nonlinear systems do not inherently possess these properties. However, for small deviations around an operating point, a nonlinear system can often be approximated as linear.
01:07Propagation of Waves
When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second medium. In such a case, the interface of the two mediums can be considered as a boundary that is neither fixed nor free.
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
01:11Buoyancy and Stability for Submerged and Floating Bodies
In fluid mechanics, buoyancy and stability are key concepts for understanding the behavior of submerged and floating bodies. When a stationary body is fully or partially submerged in a fluid, the fluid exerts a force on the body known as the buoyant force. This force acts vertically upward through a point called the center of buoyancy, which is the center of the displaced fluid volume. According to Archimedes' principle, the magnitude of the buoyant force is equal to the weight of the fluid...
01:21Linear Approximation in Time Domain
Nonlinear systems often require sophisticated approaches for accurate modeling and analysis, with state-space representation being particularly effective. This method is especially useful for systems where variables and parameters vary with time or operating conditions, such as in a simple pendulum or a translational mechanical system with nonlinear springs.
For a simple pendulum with a mass evenly distributed along its length and the center of mass located at half the pendulum's length, the...
For a simple pendulum with a mass evenly distributed along its length and the center of mass located at half the pendulum's length, the...