基于低密度奇偶校验码和脉冲位置调制的水下长距离光通信系统设计  

Long Distance Underwater Laser Communication System Based on Low-Density Parity Check Codes and Pulse-Position Modulation

作　　者：米乐 胡思奇 周田华[1] 陈卫标[1] Mi Le;Hu Siqi;Zhou Tianhua;Chen Weibiao(Key Laboratory of Space Laser Communication and Detection Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 01800, China ; University of Chinese Academy of Sciences, Beijing 100049, China)

机构地区：[1]中国科学院上海光学精密机械研究所空间激光信息传输与探测技术重点实验室,上海201800 [2]中国科学院大学,北京100049

出　　处：《中国激光》2018年第10期219-225,共7页Chinese Journal of Lasers

基　　金：国家863计划(2014AA093301)

摘　　要：基于蒙特卡罗方法对水下激光脉冲长距离传输进行了模拟仿真。根据激光脉冲在水下的展宽情况及脉冲能量的变化规律,系统采用波长为532 nm、单脉冲能量为1 mJ的全固态脉冲激光器作为发射光源,采用口径为100 mm、接收视场角为15°的望远镜作为接收机。采用现场可编程门阵列(FPGA)进行低密度奇偶校验码(LDPC)编码和脉冲位置调制(PPM),经光电转换及采样后的接收端信号被发送到上位机进行后处理。最后,基于研制的实验系统开展了水池实验,以验证系统性能。理论与实验结果表明,在JerlovⅡ类水质条件下,误码率情况相同时LDPC编码与PPM相结合的通信系统可获得2.34 dB的编码增益。实验证明该系统可以实现水下130 m处误码率低于10^(-5)的可靠通信。The long distance transmission of underwater laser pulse is simulated based on Monte Carlo method. According to the underwater broadening of laser pulse and the variation of pulse energy, the system uses a solid-state laser with the wavelength of 532 nm and the single pulse energy of 1 mJ as the emission source, and uses a telescope with the aperture of 100 mm and the field angle of 15° as the receiver. Low-density parity check codes （LDPC） and pulse-position modulation （PPM） are accomplished based on a field-programmable gate array （FPGA）. The received signal after photoelectric conversion and sampling is transmitted to the host computer for post-processing. Finally, a pool experiment is used to verify the system performance based on the developed experimental system. The theoretical and experimental results demonstrate that the designed system with LDPC and PPM can obtain 2.34 dB coding gain at the same bit error rate （BER） under the condition of Jerlov Ⅱ water quality. Experiment shows that the system can achieve reliable underwater communication with BER of 10-5 and distance of 130 m.

关 键 词：光通信 水下激光通信 低密度奇偶校验码编码 脉冲位置调制 蒙特卡罗法 

分 类 号：TN929.1[电子电信—通信与信息系统]