面向海洋信息的动态水声协作传输方法研究

The complex and variability of marine environment lead to poor reliability of underwater acoustic communication link, which is the bottleneck problem in the practical application of underwater acoustic communication. Cooperative communication theory provides an opportunity for a breakthrough of this bottleneck. This project intends to investigate the dynamic underwater acoustic cooperative transmission mechanism for ocean information. The dynamic is reflected in the dynamic adjustment of the structure of detector, the weighted combining coefficients of multi-branch, the number of cooperating nodes and the modulation mode. Firstly, in view of the inherent characteristics of underwater acoustic channel, we investigate the corresponding cooperative strategy, in which the relay cooperative mode and the relay selection mechanism are jointly designed. Secondly, aiming at the cooperative transmission framework constructed by the proposed cooperative strategy, we research the corresponding joint multi-branch weighted combining and detection mechanism based on robust criterion to achieve better cooperative transmission performance. Then, on the basis of above, considering the frequency band limitation of underwater acoustic channel, to improve the spectrum utilization, the adaptive modulation mechanism for underwater acoustic cooperative transmission is studied. Finally, the real underwater acoustic data is measured and obtained, based on the real measured data, the validity of the investigated approaches is verified. The purpose of this project is to fully exploit the potential advantages of underwater acoustic cooperative transmission and improve the transmission performance to a greater extent, and simultaneously take into account the spectrum efficiency of the system, so as to provide a valuable reference for future underwater acoustic cooperative transmission.

海洋环境的复杂多变性，导致水声通信链路可靠性差，是制约水声通信实际应用的瓶颈问题，协作通信理论为这一瓶颈的突破提供了契机。本项目拟对面向海洋信息的动态水声协作传输机制展开研究，动态性体现在检测器结构、多分支加权合并系数、参与协作的节点数和调制方式等的动态调整上。首先，针对水声信道固有特性，研究相适应的协作策略，联合设计了中继协作模式和中继选择机制；其次，针对提出的协作策略所构建的协作传输框架，研究了相应的、基于鲁棒标准的联合多分支加权合并与检测机制，以获得更好的协作传输性能；而后，在之上的基础上，考虑水声信道的频带有限性，研究水声协作传输下的自适应调制机制，以提高频谱利用率；最后，实测水声数据，并以之验证所研究的内容。本项目旨在充分挖掘水声协作传输的潜在优势，更大程度地提高传输性能，并兼顾系统频谱效率，从而为未来的水声协作传输提供一种有价值的参考方案。

本项目针对复杂多变水声信道下通信链路可靠性差的瓶颈问题，借助协作通信理论优势，开展了以下研究内容：根据水声信道固有特性设计相适应的协作策略；多分支合并与检测联合实现机制；对水声信道有限带宽的有效利用方法。经过近四年的深入探索研究，取得的主要成果包括：. (1) 为尽可能减少传输延迟时间及兼顾中继性能，在中继选择时考虑传输时延和稳态均方误差两个指标，提出了一种基于多属性决策的中继选择方法。. (2) 考虑尽可能减少端到端延迟时间，且能适用于多用户及存在干扰的情况，提出了一种水下解码交织转发(UDIF)协作模式，并相应提出了一种联合多分支合并与Turbo均衡检测器。. (3) 针对各节点间信道质量不同的问题，提出了一种多分支加权合并与均衡检测联合实现算法，以进一步提高检测性能。. (4) 针对信道不同对均衡性能的影响，提出了一种可调观察窗口长度盲时域均衡算法，该算法能根据信道不同自适应调整观察窗口长度，以获得更好的检测性能。. (5) 为了充分利用有限的水声信道带宽，提出一种基于稳态均方误差的自适应调制算法，该算法的实现并不需要传统方法中所需的水声信道状态信息；而后，从另一种思路出发，提出了一种基于无速率编码的水声传输方案，在其实现中，提出了一种变抽头长度盲频域均衡及联合盲频域均衡与无速率译码算法，该方案能根据信道质量好坏自适应调整传输速率。. 综合上述结果可见，本项目的研究为可靠水声通信技术的发展做出了有意义的探索，在海洋资源开发、海洋权益维护等领域具有广泛的应用前景。