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Joint equalization and decoding with per-survivor processing based on super-trellis in time-varying underwater
Xu Kou1,2,3, Yanbo Wu1,2,4, Min Zhu1,2,4
1Ocean Acoustic Technology Laboratory, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
JASA Express Letters
|June 14, 2024
Summary
This study introduces a new reception scheme for underwater acoustic communications, improving signal recovery in challenging, fast-changing conditions. The method offers a significant performance advantage over existing techniques.
Area of Science:
- Electrical Engineering
- Ocean Engineering
- Signal Processing
Background:
- Underwater acoustic communication channels are characterized by fast time-varying conditions and intersymbol interference.
- Maximum likelihood sequence estimation (MLSE) is desirable for reliable data recovery but is computationally complex.
- Existing reception schemes struggle to maintain performance under dynamic channel conditions.
Purpose of the Study:
- To propose a low-complexity joint equalization and decoding reception scheme for high-order underwater acoustic communications.
- To enable the application of MLSE in fast time-varying underwater acoustic channels.
- To improve the performance and robustness of underwater communication systems.
Main Methods:
- A novel super-trellis per-survivor processing (PSP) approach is developed.
- The scheme integrates trellis-coded modulation (TCM) states with intersymbol interference (ISI) states.
- PSP is utilized to dynamically track channel parameters, adapting to time variations.
- A general trellis configuration is provided for arbitrary order quadrature amplitude modulation (QAM) signals with a truncated channel model for ISI states.
Main Results:
- The proposed scheme demonstrates superior performance compared to conventional methods.
- Sea trials confirmed a performance gain exceeding 1.4 dB.
- The low-complexity design makes MLSE feasible for practical high-order underwater acoustic systems.
Conclusions:
- The developed joint equalization and decoding scheme effectively handles fast time-varying underwater acoustic channels.
- The super-trellis PSP approach offers a significant performance improvement and computational efficiency.
- This technique enhances the reliability and applicability of high-order QAM in challenging underwater environments.
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