| 水声通信系统中双向turbo均衡算法 |
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| 引用本文： | 奚钧壹,鄢社锋,徐立军,田婧.水声通信系统中双向turbo均衡算法[J].声学学报,2018,43(5):771-778. |
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| 作者姓名： | 奚钧壹 鄢社锋 徐立军 田婧 |
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| 作者单位： | 1. 中国科学院声学研究所 北京 100190; |
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| 基金项目： | 国家自然科学基金项目(61725106,61431020)资助 |
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| 摘 要： | 提出了一种水声通信系统中直接自适应双向turbo均衡算法。摒弃了信道估计步骤,采用基于直接自适应的turbo均衡器,并利用内嵌数字锁相环的判决反馈均衡器结构跟踪时变信道,采用最速优化算法自适应调整迭代步长,使得收敛速度和算法性能得到很好折中。此外,利用最小均方误差准则,得到最优权重因子,对正向与反向turbo均衡结果加权求和,消除误差传播效应。仿真和湖上实验验证了方法的正确性,双向均衡的性能优于单向均衡。湖上实验结果表明,基于直接自适应算法相比于基于信道估计的算法,对时变信道不敏感,能获得更低的误比特率。
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| 关 键 词： | 均衡算法通信系统水声最小均方误差准则判决反馈均衡器自适应调整TURBO均衡信道估计 |
| 收稿时间： | 2017-05-10 |
Bidirectional turbo equalization for underwater acoustic communications |
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| Affiliation: | 1. Institute of Acoustics, Chinese Academy of Sciences Beijing 100190;2. University of Chinese Academy of Sciences Beijing 100049 |
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| Abstract: | A direct-adaptation based bidirectional turbo equalizer for underwater acoustic communications is proposed. Abandoning the channel estimation process, the direct-adaptation based turbo equalizer embedded with digital phase- locked loop is adopted to track time-varying channel. The fast self-optimized algorithm is used to adjust the step size, so a good tradeoff between the convergence speed and performance has been made. Frthermore, by minimizing the mean squared error, an optimal weighting factor is derived to exploit bidirectional diversity gain. The forward turbo equalizer is combined with the backward turbo equalizer to eliminate error propagation effect. Simulated and experimental results demonstrate that the bidirectional turbo equalizer outperforms the single directional one. Seen from the experimental results, compared to the channel estimation based equalization algorithm, the direct-adaptation based algorithm is less sensitive to the time-varying channel and has a lower bit error rate. |
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