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针对海洋激光通信信道复杂多变的问题,利用理论分析和蒙特卡洛模拟方法详细研究了水下光通信链路的信道特性。采用波长为532 nm的蓝绿激光,分析了典型海水中的信道脉冲响应,研究了接收光强与海水类型、衰减长度、发散角、波束宽度、接收视角及孔径等重要参数的关系,并通过蒙特卡洛仿真实验进行验证。理论分析与仿真结果表明:清澈海域中,传输距离<40 m时,可认为无码间干扰信道,接收端不需要复杂的信号处理算法;但在海港浑浊海域,时延扩展随着接收视角和发散角的增大而增大,从而降低信道的传输效率。当衰减长度小于等于漫射长度时,接收光强随接收孔径的增大而减小;但当衰减长度大于漫射长度时,接收光强随着接收视角的增大呈现先增后恒的趋势。因此,研究结果将对建立准确的水下无线光通信信道模型具有重要的参考价值。
Aiming at the complex and changeable issue of ocean laser communication channel, the channel characteristics of underwater optical communication link are studied in detail by using theoretical analysis and Monte Carlo simulation method. The channel impulse response in a typical seawater is analyzed by using a blue-green laser at a wavelength of 532 nm. The relationship between the received light intensity and important parameters such as seawater type, attenuation length, divergence angle, beamwidth, viewing angle and aperture is studied. Monte Carlo simulation experiment to verify. The theoretical analysis and simulation results show that in the clear sea area, when the transmission distance is less than 40 m, it can be considered that there is no intersymbol interference channel, and the receiving end does not need complicated signal processing algorithms. However, in the harbor haziness, the delay spread increases with the reception angle and divergence The angle increases and increases, thus reducing the channel transmission efficiency. When the attenuation length is less than or equal to the diffusion length, the received light intensity decreases with the increase of the receiving aperture. However, when the attenuation length is greater than the diffusion length, the received light intensity increases first and then increases with the receiving angle . Therefore, the research results will have important reference value for establishing accurate underwater optical communication channel model.