Underwater Acoustic Channel Estimation and Statistical Analysis from Experimental Data

OBJECTIVES

• Estimate the channel impulse response (CIR) of the acoustic underwater channel

• Compare the PDF of the channel coefficients to known distributions

• Analyze statistical properties such as the correlation, coherence time, and scattering function

BACKGROUND

• Acoustic communication in shallow water is more complicated than in air radio communication due to the excessive pass loss, scattering, and time varying nature of the channel.

APPROACH

• Experimental data from the Reschedule Acoustic Communications Experiment in March 2008 (RACE08) has been analyzed.

• The CIR of the channel has been estimated many times using the sliding window least squares estimation technique in the time domain.

• The coefficients of the CIRs calculated were used to plot the PDF of the underwater channel and to calculate the other statistical properties

DISCUSSION

• Rayleigh PDF does not describe the experimental PDF

• Channel coherence time is .12 seconds. Therefore, the channel is time invariant for about 470 symbols.

• Doppler spread is very low in this channel since both the receivers and transmitters were fixed.

• Observed Doppler spread is due to the movement of the channel medium, itself.

RESULTS

• The CIR estimation plot shows how the CIR can change with time.

• The autocorrelation function is a measure of how likely the next coefficient values are related to the current coefficient.

FUTURE WORK

• Data from other environments will be analyzed.

• The knowledge gained from this experiment will be used to create a transceiver design that improves upon the speed of current transceivers.

AcknowledgementsNSF grant ECCS-0846486

ONR grant N00014-10-1-0174Intelligent Systems Center

Missouri University of Science and TechnologyDepartment of Electrical and Computer Engineering

Student: Jesse Cross Advisor: Dr. Rosa Zheng

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Underwater Multipath