基于改进型曼彻斯特编码的UWOC解调算法设计  

Design of a Demodulation Algorithm for UWOC based on Improved Manchester Coding

作　　者：张优 胡芳仁[1] 赵晓燕 周军 王启龙 ZHANG You;HU Fangren;ZHAO Xiaoyan;ZHOU Jun;WANG Qilong(College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology),Nanjing University of Posts and Telecommunications,Nanjing 210023,China;Nanjing Advanced Technology Laser Research Institute,Nanjing 210038,China)

机构地区：[1]南京邮电大学电子与光学工程学院、柔性电子(未来技术)学院,南京210023 [2]南京先进激光技术研究院,南京210038

出　　处：《光通信研究》2025年第2期52-59,共8页Study on Optical Communications

摘　　要：【目的】为了满足高速水下无线光通信(UWOC)技术工程化的要求,改善高速率通信时开关键控(OOK)等依赖阈值解调的调制方式在水下信道较差时通信误码率(BER)较高的问题,文章对常用的水下光通信调制方式进行了对比仿真分析,提出了一种脉冲位置调制(PPM)和曼彻斯特编码相结合的、无阈值判决的改进型调制解调算法。【方法】文章通过滑动均值滤波提高系统信噪比(SNR);对PPM帧头进行并行多路无阈值判决实现帧同步,为曼彻斯特编码解调提供时间校准基础;最后在数据部分使用曼彻斯特编码副帧头和里德-所罗门(RS)纠错码实现低BER的高速通信。在现场可编程门阵列(FPGA)上对该算法进行了设计实现,搭建了使用该方法的UWOC系统,在不同环境和距离下进行了BER测试。【结果】测试结果表明,基于文章所提解调算法的UWOC系统在通信速率为50 Mbit/s、通信距离为10 m时,在室内清澈水池中的BER为10-5,近岸湖水中的BER为10^(-3)。【结论】在10 m距离的近岸湖水中,相较于OOK和PPM等调制方法,使用文章所提改进型曼彻斯特编码调制可以实现更可靠的50 Mbit/s通信。【Objective】To meet the requirements of the engineering of high-speed Underwater Wireless Optical Communication(UWOC)technology,and to address the issue of high Bit Error Rate(BER)in underwater channels when using modulation methods such as On/Off Keying(OOK)that rely on threshold demodulation for high-speed communication,this paper conducts comparative simulation analysis of commonly used underwater optical communication modulation methods and proposes an improved modulation and demodulation algorithm that combines Pulse Position Modulation(PPM)with Manchester encoding and does not require threshold decision-making.【Methods】The paper uses sliding mean filtering to improve the Signal to Noise Ratio(SNR).The frame synchronization is then achieved by parallel multi-path threshold-free decision-making on the PPM frame header,providing a time calibration basis for Manchester encoding and demodulation.Finally,high-speed communication system with low BER is realized by using Manchester encoding sub-frame headers and Reed-Solomon(RS)error-correcting codes in the data part.The algorithm is designed and implemented on a Field Programmable Gate Array(FPGA),and a UWOC system using this method is built to conduct BER tests under different environments and distances.【Results】The test results show that the UWOC system based on this demodulation algorithm has an BER of 10-5 in indoor clear water pools and 10^(-3)in nearshore lake water at a communication speed of 50 Mbit/s and a communication distance of 10 m.【Conclusion】The proposed algorithm in this paper is applied in nearshore lake water with a distance of 10 meters,compared to modulation methods such as OOK and PPM,using modified Manchester encoding modulation can achieve more reliable 50 Mbit/s communication.

关 键 词：曼彻斯特编码 水下无线光通信 脉冲位置调制 并行无阈值解调 

分 类 号：TN929.1[电子电信—通信与信息系统]