Performance prediction of passive time reversal communications

Area of Science:

• Underwater acoustics
• Signal processing
• Communications engineering

Background:

• Theoretical performance bounds for time reversal communications were previously established.
• Time reversal (TR) is a technique used to focus acoustic energy in complex environments.

Purpose of the Study:

• To evaluate the performance of time reversal communications using at-sea experimental data.
• To compare experimental results with theoretical predictions for two TR approaches.
• To assess the validity of theoretical performance bounds in practical scenarios.

Main Methods:

• Collected at-sea experimental data for time reversal communications.
• Analyzed performance of (1) time reversal alone and (2) time reversal with channel equalization.
• Compared experimental data against theoretical performance bounds.

Main Results:

• Time reversal alone demonstrated good agreement between experimental data and theoretical predictions.
• Time reversal combined with channel equalization showed experimental data 3-5 dB below theoretical predictions.
• Discrepancies in the second approach are attributed to ideal assumptions in the theory (perfect channel knowledge, infinite taps, no phase tracking).

Conclusions:

• Theoretical performance bounds serve as a useful upper limit for predicting time reversal communication performance.
• Channel equalization in practical TR systems may introduce performance limitations not fully captured by ideal theoretical models.
• Further research may be needed to refine theoretical models for TR systems incorporating channel equalization.