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基于光载波抑制调制的ROF系统的研究
Investigations on ROF System Based on Optical Carrier Suppression Modulation
【作者】 赵银川；
【导师】 夏光琼；
【作者基本信息】 西南大学 ， 信号与信息处理， 2010， 硕士
【摘要】 光纤无线通信(ROF:Radio-over-Fiber)技术是指利用光纤代替大气作为传输宽带射频信号的一种传输技术。输入ROF系统的电信号可以是基带数字信号、中频信号和射频信号。这些信号调制到光载波上,然后光信号再通过光纤网络传输到远端基站。在远端基站,通过光电探测器得到电信号从而提取传送的信息。ROF技术以其充分结合光纤和高频无线电波传输的特点,充分利用40-60GHz的频段资源,为大容量、低成本的射频信号有线传输和超宽带无线接入提供了理想的解决方案。光毫米波的产生和传输是实现光纤无线通信的关键技术。本文讨论了几种主要产生光毫米波的方法,着重介绍利用外部调制器产生光毫米波的方案,提出了一种改进的基于光载波抑制调制的ROF系统,对光毫米波的产生及其在光纤中的传输特性进行深入的理论分析和系统仿真。研究表明：这种改进的ROF系统不但可以降低中心站副载波的频率,而且能减少光毫米波在光纤中传输时光纤色散对传输信号的影响,大大延长信号的传输距离。同时,该系统还实现中心站光载波的重用,有利于简化基站的结构。
【Abstract】 ROF (Radio-over-Fiber) is a broadband radio-frequency signal transmission technique using fiber instead of atmosphere. The input electrical signal in ROF system may be base-band digital signal, intermediate-frequency signal or radio-frequency signal. These signals are used to modulate the optical carrier, and then the optical signal is transmitted to the remote base station by optical net. At the base station, the information can be extracted from the electrical signal obtained by the photo detector. ROF technique has provided an ideal scheme for large capacity and low cost wire transmission and ultra-broadband wireless access, as it has the characteristics of combining fiber with high-frequency radio wave, and making the best of the frequency resource between 40GHz and 60 GHz.The generation and transmission of optical mm-wave is one of key techniques in the ROF communication system, In this paper, it have been discussed that several main methods of optical mm-wave generation, in which external modulation technique is focused on. Furthermore, a scheme of an improved radio-over-fiber communication system based on optical carrier suppression modulation is proposed and the generation and transmission characteristics of optical mm-wave are analyzed and simulated. The results show that the scheme can not only reduce the sub-carrier frequency in the central office, but also reduce the influence of fiber dispersion on the signal, which is helpful for extending the transmission distance. Meanwhile, this system can also realize the reuse of the central optical carrier, which can simplify the structure of the base station.