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全双工ROF系统的研究

The Rescher of Full-Duplex Rof System

【作者】 詹娱

【导师】 马健新;

【作者基本信息】 北京邮电大学 , 光学工程, 2013, 硕士

【摘要】 随着信息时代的不断前进,人们对海量数据的长距离传输和宽带接入需求日益突显。光纤通信技术的大带宽、低损耗等特点满足了加载高数据速率的光载毫米波信号的长距离传输要求,无线通信技术的灵活接入优势满足了终端用户的接入多样化需求,因此结合光纤通信与无线通信的射频光纤传输RoF (Radio over Fiber)技术应运而生。近年来,RoF技术逐渐向高数据速率、高频光载波的趋势发展。其中,光载毫米波信号的产生、传输以及探测解调等均为RoF技术中的关键技术。如何进一步实现高速率数据的调制、高频光载毫米波信号的产生和光纤的长距离传输,并实现基站的有效接收解调,成为RoF技术中不断探索讨论的热点问题。基于光纤接入的无源光网络PON(Passive Optical Network)能够提供足够带宽以满足目前及未来各种宽带业务的需求,且设备成本和维护成本相对较低,在解决“最后一公里”的接入瓶颈问题中显示出独有的优势,因此PON与RoF的融合技术也逐渐成为研究应用的一大方向。本论文中,首先综合概述RoF技术的产生背景、技术特点、国内外应用、研究前景,以及PON技术的基本特征。分析RoF技术中光载毫米波信号的几种产生方案,着重介绍了目前应用最为广泛的外调制方案,比较外调制方案中的双边带调制DSB、单边带调制SSB和中心载波抑制调制OCS三种调制方式的频谱结构和传输性能。分析基于马赫曾德调制器非线性效应的倍频技术产生高频光载毫米波信号的方案。基于RoF技术的基础研究,提出基于QAM四倍频光载毫米波信号的全双工RoF链路。链路基于马赫曾德调制器的非线性效应产生高阶边带,实现四倍频光载毫米波的产生,Gbit/s级别的数据单载波调制于光载波并实现光纤长距离传输。上行链路中光载波由下行信号中提取,无需额外光源,简化基站结构,完成RoF全双工链路。基于Optisystem仿真平台进行RoF链路搭建,通过眼图、星座图和EVM演化曲线分析信号的传输性能,进行参数优化,得出加载高速率数据的高频光载毫米波的最佳传输方案。进一步融合RoF与PON技术,提出基于RoF无线/PON有线混合接入方案。通过偏振正交实现光载波的复用,产生RoF无线/PON有线的融合光信号,满足用户终端的有线/无线灵活接入。其中上行载波由下行链路中提取,基站无需额外光源,实现全双工RoF链路。基于Optisystem仿真平台搭建全双工链路,仿真结果表明经70km单模光纤传输后信号仍保持良好的传输性能。最后对论文所完成的工作进行总结,并对RoF技术的未来发展进行展望。

【Abstract】 As the development of informational society, the requirement of capacity and quality communication is increasing rapidly, in which the Radio over Fiber (RoF) technology comes to being. RoF technology combines the optical fiber and wireless technology. The low attenuation and almost unlimited bandwidth advantages of optical fiber technology meet the need of high speed, high frequency millimeter-wave’s long distance transmission, and the wireless technology provides a convenient access way in user terminal. Nowadays, RoF technology focuses on the generation of millimeter-wave signal, long distance transmission and demodulation technology more and more. The Passive Optical Network (PON) has its advantages in solving the problem of "Last Kilometre" access, so the combination of RoF and PON technology attacts lots attention of researchers.In this paper, firstly, we introduce the background, features, application and development of RoF technology, and the advantage of PON technology. We highlight the generation of optical millimeter-wave signal, and compare the difference between double sideband modulation (DSB), single sideband modulation (SSB) and optical carrier suppression (OCS) of external modulation technology. Also we investigate frequency multiplication technology in obtaining frequency quadrupling millimeter-wave signal. Secondly, we put forward a full-duplex RoF link with16-ary QAM vector modulation on lOGbit/s binary data and using frequency quadrupling to generate the60GHz millimeter-wave signal. Thirdly, we propose a full-duplex hybrid wired/wireless link with Gbit/s 16-ary QAM format, which can provide wired and wireless access alternately for the user terminal, and the remote base station free from the lightwave source. The simulations for both wired and wireless accesses show the good performance of the hybrid optical signal. Lastly, a conclusion and prospect of this paper are given in the final chapter.

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