基于改进Gardner算法的水下无线光OQPSK系统性能分析  

Performance analysis of underwater wireless optical communication system based on improved Gardner algorithm of OQPSK modulation

作　　者：杨祎 刘雯 阴亚芳 贺锋涛 张建磊 YANG Yi;LIU Wen;YIN Yafang;HE Fengtao;ZHANG Jianlei(School of Electronic Engineering,Xi’an University of Posts and Telecommunications,Xi’an 710121,China)

机构地区：[1]西安邮电大学电子工程学院,陕西西安710121

出　　处：《量子电子学报》2022年第3期467-476,共10页Chinese Journal of Quantum Electronics

基　　金：国家自然科学基金,61805199;国防基础科研计划实验室稳定支持专题项目,JCKY2020207CD02;陕西省技术创新引导专项资助项目,2020TG-001;西安邮电大学研究生联合培养工作基地资助项目,YJGJ201905。

摘　　要：针对水下无线光通信(UWOC)中海水信道的衰减特性和系统自噪声对调制性能的影响,提出了一种改进的Gardner定时同步算法,建立了基于偏移正交相移键控(OQPSK)调制的UWOC系统模型,仿真分析了OQPSK调制系统中水质和传输距离对误码率(BER)性能的影响规律。结果表明,与正交振幅调制(QAM)、四相相对移相键控(QDPSK)、开关键控(OOK)调制的系统相比,当系统BER达到10^(-3)时,采用OQPSK调制可分别获得2.2、4.4、6.2 dB左右的增益。与OOK调制相比,采用OQPSK调制可获得2.3~8.2 m的距离增益。在衰减较大的水下信道中,提出的Gardner算法较好地改善了OQPSK调制信号的同步性能,与传统算法相比,BER明显降低,可获得约12.5~14.2 dB左右的增益。Considering the attenuation characteristics of the seawater channel in underwater wireless optical communication(UWOC)and the influence of system self-noise on the modulation performance,an improved Gardner timing synchronization algorithm is proposed,and an UWOC system model is established based on offset quadrature phase shift keying(OQPSK)modulation,then the influence of water types and transmission distance on the bit error rate(BER)performance in the OQPSK modulation system is simulated and analyzed.The simulation results show that compared with quadrature amplitude modulation(QAM),quadrature differential phase shift keying(QDPSK)and on off keying(OOK)modulation systems,when the BER of the system reaches 10^(-3),OQPSK modulation can obtain the gains of about 2.2,4.4 and 6.2 dB respectively.And compared with OOK modulation,OQPSK modulation can obtain a distance gain of 2.3-8.2 m.In addition,in the underwater channel with large attenuation,the proposed Gardner algorithm can improve the synchronization performance of the OQPSK modulation signal,and compared with the traditional algorithm,the bit error rate of the proposed algorithm is significantly reduced,and a gain of about 12.5-14.2 dB can be obtained.

关 键 词：光通信 水下无线光通信系统 定时同步 偏移正交相移键控调制 GARDNER算法 

分 类 号：TN929.1[电子电信—通信与信息系统]