海洋湍流对水下激光通信的影响及其抑制方法研究

Underwater laser communication has the advantages of high data rate, low power consumption, high security etc. It is an efficient method to achieve high-data-rate communication and break through the bottleneck of underwater acoustic communication. Most of the previous studies on the validity and reliability of underwater laser communication were only concerned with the absorption and scatter characteristics of the sea water, seldom considering the effect of oceanic turbulence. But, in fact, oceanic turbulence can lead to random variations in the intensity, phase, and transmission direction of the transmitted laser beam, eventually to the severe channel fading and deteriorate the communication quality. To this end, this project is going to study the effects of oceanic turbulence on underwater laser communication and efficient mitigation methods. The main content include: developing probability density function model for irradiance fluctuations under arbitrary turbulence strength conditions, quantitatively analyze the performance of underwater laser communication for laser beams propagating along a horizontal or a slant path; studying the characteristics of oceanic turbulence-induced fading for large receive aperture and multiple transmission/multiple receiving, evaluating the performance of aperture averaging and space diversity techniques in mitigating the detrimental effect of oceanic turbulence; according to the typical underwater network topology, designing turbulence mitigation method based on cooperative diversity technique and analyzing the performance. The formulation of this project is with the close combination of national marine development strategy, the research results will provide the theoretical basis for mitigating the adverse effects of oceanic turbulence on underwater laser communication, and serve for building China into a great naval power.

水下激光通信具有速率高、功耗低和隐蔽性强等优点，是解决水声通信瓶颈、实现高速通信的有效手段。以往关于水下激光通信有效性和可靠性的研究大都只考虑了海水的吸收和散射特性，很少考虑海洋湍流的影响。但实际上，海洋湍流会引起激光光强、相位和传输方向的随机变化，导致严重的信道衰落，使通信质量劣化。为此，本项目拟研究海洋湍流对水下激光通信的影响以及抑制不利影响的有效方法。建立不同湍流强度下的光强起伏概率密度模型，定量分析激光束沿水平或斜程路径传输时的水下激光通信性能；研究大孔径接收和多光束发射/接收所对应的海洋湍流信道衰落特性，评估孔径平均和空间分集的湍流抑制效果；结合典型的水下网络拓扑结构，设计基于协作分集的湍流抑制方案并进行性能分析。本项目的制定紧密结合国家海洋发展战略，研究成果将为抑制海洋湍流对水下激光通信的影响提供理论依据，服务于“海洋强国”建设。

水下激光通信具有速率高、功耗低和隐蔽性强等优点，是解决水声通信瓶颈、实现高速通信的有效手段。以往关于水下激光通信有效性和可靠性的研究大都只考虑了海水的吸收和散射特性，很少考虑海洋湍流的影响。但实际上，海洋湍流会引起激光光强、相位和传输方向的随机变化，导致严重的信道衰落，使通信质量劣化。为此，本项目研究海洋湍流对水下激光通信的影响以及抑制不利影响的有效方法。建立不同湍流强度下的光强起伏概率密度模型，定量分析激光束沿水平或斜程路径传输时的水下激光通信性能；研究大孔径接收和多光束发射/接收所对应的海洋湍流信道衰落特性，评估孔径平均和空间分集的湍流抑制效果；结合典型的水下网络拓扑结构，设计基于协作分集的湍流抑制方案并进行性能分析。项目的主要成果包括：一个新的符合实验结果的水平路径海洋湍流空间功率谱模型；基于所提出模型进行的光束漂移、光强闪烁等光束传播特性分析；孔径平均、空间分集等湍流抑制技术的性能评估。本项目的制定紧密结合国家海洋发展战略，研究成果为抑制海洋湍流对水下激光通信的影响提供理论依据，服务于“海洋强国”建设。