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Orthogonal time-frequency space modulation for underwater mobile acoustic communications
Yukang Xue1, Xiyuan Zhu1, Y Rosa Zheng1
1Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
The Journal of the Acoustical Society of America
|February 21, 2025
Summary
A new turbo decision feedback equalizer and decoder (TDFED) improves underwater acoustic communications. This orthogonal time-frequency space (OTFS) system excels in challenging multipath and Doppler conditions.
Area of Science:
- Underwater acoustic communications
- Signal processing for wireless systems
Background:
- Underwater mobile acoustic communication channels face severe multipath and Doppler effects.
- Existing orthogonal frequency division modulation (OFDM) and single-carrier coherent modulation (SCCM) struggle with these channel impairments.
Purpose of the Study:
- To propose a novel turbo decision feedback equalizer and decoder (TDFED) for orthogonal time-frequency space (OTFS) systems.
- To enhance the performance of underwater mobile acoustic communications under challenging channel conditions.
Main Methods:
- Developed a time-domain TDFED for OTFS, utilizing feedforward and feedback filters.
- Implemented a low-complexity channel estimation in the delay-Doppler domain.
- Designed practical OTFS modulation for acoustic transmission (115 kHz center frequency, 11.5 ksps symbol rate).
Main Results:
- The proposed OTFS receiver demonstrated reduced accuracy requirements for Doppler compensation compared to SCCM and OFDM.
- The TDFED algorithm achieved a significantly better bit error rate (BER) in the presence of long multipath fading and severe Doppler shifts.
- Experimental results from lake tests validated the effectiveness of the proposed OTFS system.
Conclusions:
- The novel TDFED for OTFS is highly effective for underwater mobile acoustic communications.
- This approach offers superior performance over existing methods in mitigating multipath and Doppler effects.
- The study validates the practical applicability of OTFS in challenging underwater environments.
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