密集型波分复用RoF系统的外差式信道选取与上变频研究

发布时间：2018-01-12 15:12

本文关键词：密集型波分复用RoF系统的外差式信道选取与上变频研究　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：光载无线通信(RoF)技术是满足未来无线接入容量和频带资源需求的有效途径。而在RoF系统中,结合密集型波分复用技术(DWDM)可以将调制到不同波长的信号复用到一根光纤中进行传输,极大地提高通信容量。因此,本文围绕密集型波分复用光载无线通信(DWDM-RoF),利用光外差探测实现下行链路中密集型波分复用信道的精准选取以及频率上变换。进而针对OOK、QPSK、16QAM三种调制格式下ROF系统,分别进行了数值研究和实验研究。本论文的主要研究内容如下:(1)理论推导了 MZM外调制器的工作原理及单边带调制方式下的参数设置,进而分析了外差探测中激光器间相位噪声影响,并简单介绍消除激光器间相位噪声的方法。(2)针对OOK调制格式下的密集型波分复用RoF系统方案,在基站处利用外差探测和电滤波器,同时实现上变频和DWDM信道选取。在此方案下,研究了两种信号接收方案(包络检波非相干接收方案、电混频相干接收方案),并对比分析了它们的性能。在此基础上,分别研究了在单/多信道下,不同传输距离或不同传输速率下NRZ和RZ信号接收端眼图及误码特性。最后,通过实验验证了光信道间隔为15.25GHz的两信道下,数据速率为1.25Gbit/sOOK信号经过10km光纤传输,在接收端通过调节本振光实现信道选择及上变频功能。(3)在高阶调制格式下的密集型波分复用RoF系统中,研究了外差探测过程中激光器间拍频产生相位噪声消除的方法。单信道下传输速率为1Gbit/s、中频为3GHz的QPSK和16QAM信号通过单边带调制到光载波上,经过10km光纤传输后,在接收端利用平方律检波下变频方案消除信号光和本振光之间的相位噪声。接收端仿真得到的星座图显示该方案有效地消除了相位噪声。进而,在多信道传输仿真中设置:信道间隔为10GHz的四个光载波、数据传输速率为1Gbit/s、中频为3GHz的QPSK/16QAM的信号。经过10km光纤传输,结果显示在多信道下该方法同样能够消除激光器之间的相位噪声影响。此外,方案通过合理设计信道带宽,可以有效提高系统频谱利用率。
[Abstract]:Optical wireless communication (RoF) technology is an effective way to meet the future wireless access capacity and bandwidth resource requirements, while in the RoF system. Combined with intensive wavelength division multiplexing (DWDM), signals modulated to different wavelengths can be multiplexed into an optical fiber for transmission, which greatly improves the communication capacity. This paper focuses on dense wavelength division multiplexing optical wireless communication (DWDM-RoF). Optical heterodyne detection is used to accurately select the dense wavelength division multiplexing channel and transform the frequency in the downlink. Then the ROF system is designed in three modulation formats: OOKO QPSKO 16QAM. The main contents of this thesis are as follows: 1) the working principle of MZM external modulator and the parameter setting under single sideband modulation are derived. Furthermore, the effect of phase noise between lasers in heterodyne detection is analyzed, and the method of eliminating phase noise between lasers is introduced briefly. The scheme of intensive wavelength division multiplexing (RoF) system based on OOK modulation format is introduced. At the base station, heterodyne detection and electric filter are used to realize both up-conversion and DWDM channel selection. In this scheme, two signal reception schemes (envelope detection incoherent reception scheme) are studied. Their performances are compared and analyzed. On the basis of this, the single / multiple channel is studied separately. The receiver of NRZ and RZ signals with different transmission distance or different transmission rate has the characteristics of eye diagram and error code. Finally, the experimental results show that the optical channel spacing is 15.25GHz. The data rate is 1.25 Gbit / s OOK signal transmitted through 10km fiber. The channel selection and up-conversion function of the receiver are realized by adjusting the local oscillator at the receiving end in a high-order modulation format intensive wavelength division multiplexing (RoF) system. In this paper, the method of eliminating phase noise generated by laser beat frequency during heterodyne detection is studied. The transmission rate is 1 Gbit / s in single channel. If 3GHz QPSK and 16QAM signals are modulated to the optical carrier by single sideband and transmitted through 10km optical fiber. The phase noise between the signal light and the local oscillator is eliminated by the square law demodulation down-conversion scheme at the receiver. The constellation diagram obtained by the receiver simulation shows that the scheme effectively eliminates the phase noise. In the multi-channel transmission simulation, four optical carriers with 10GHz channel spacing are set, and the data transmission rate is 1Gbit / s. The signal of if 3 GHz QPSK/16QAM is transmitted by 10km fiber. The results show that the method can also eliminate the phase noise between lasers in multi-channel. The scheme can effectively improve the spectral efficiency of the system by reasonably designing the channel bandwidth.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

【相似文献】