【作者】 刘婷；

【导师】 潘炜；

【作者基本信息】 西南交通大学 ， 微电子与固体电子学， 2010， 硕士

【摘要】 射频微波链路系统是将射频通信与光纤通信相结合,使得通信既具备有线传输中低损耗高容量的特性,又拥有无线传输中移动便利的特性,因此越来越受到人们的重视。本论文中系统模型的模拟和数据的测试结果是使用Optiwave Optisystem光通信系统模拟软件来完成的。文中首先介绍了射频微波链路系统的工作原理,分别对调制一个射频副载波和调制两个射频副载波的两种情况进行分析,利用频谱图比较单边带调制、双边带调制和载波抑制调制三种强度调制方式,并对相应的解调方式进行说明。其次,简单介绍了信道间隔大于两倍的副载波带宽和信道间隔小于一倍的副载波带宽两种情况下的波分复用方式,详细分析了信道间隔在一倍到两倍副载波带宽之间,即交叉波分复用的情况下的系统,通过研究相应的性能参数,比较了单边带调制波分复用、双边带调制波分复用和载波抑制调制波分复用三种系统的优劣。最后,结合副载波复用和波分复用,设计了一种在载波抑制调制方式下的射频微波链路传输方案,通过与载波抑制调制传输系统,载波抑制调制副载波复用系统和载波抑制调制波分复用系统的比较,讨论相应的性能参数,分析该方案的可行性。研究结果表明：第一,对于单边带调制交叉波分复用系统来说,误码率性能具备复用前的特点,即在一定范围内系统性能稳定,随着光纤传输距离的增加系统衰减逐渐加大,与复用前的系统比较,复用系统的总体性能变差,受消光比影响程度也变深。第二,对于双边带调制交叉波分复用系统来说,解调时所利用的滤波器可以有效改善两个边带在光纤中因传输速度不同而造成的系统性能恶化,同时消光比对复用后系统的影响程度减小。第三,对于载波抑制交叉波分复用系统来说,与复用前相比,复用后系统的稳定性减弱,总体衰减增加,消光比影响程度有所加深。第四,载波抑制调制方式下的副载波复用系统具备复用前系统的特性；从系统的接收端功率来看,载波抑制调制系统性能最好,载波抑制副载波复用系统性能最差；从系统的稳定性来看,载波抑制调制系统以及设计方案系统都很稳定,这两者中前者更优；从系统受消光比值影响程度来看,载波抑制调制波分复用系统受影响程度最小,设计方案受影响程度最大。可见设计方案在接收端功率以及系统的稳定性上都具有一定的优势,证明系统方案可行。更多还原

【Abstract】 Radio-over-fiber system combines radio communication and fiber communication, making it characteristic of the low consumption and high capacity of wire communication and the mobility of wireless communication. Therefore, it draws more and more attention.In this paper, simulation of each system and data testing are accomplished by applying Optiwave Optisystem.In this paper, firstly, the working principle of Radio-over-fiber is introduced, two conditions of modulating one radio sub-carrier and two radio sub-carriers are analyzed, three intensity modulations of Single-Sideband modulation, Double-Sideband modulation and Optical-Carrier-Suppression modulation are compared by applying spectrograms and the corresponding demodulation methods are explained. Secondly, this paper briefly discusses the Wavelength Division Multiplexing methods when the channel spacing is more than two times radio sub-carrier bandwidth and the channel spacing is less than one time radio sub-carrier bandwidth. As for the case of channel spacing between one and two times radio sub-carrier bandwidth—crossing Wavelength Division Multiplexing, through doing research on corresponding performance parameters, the advantages and disadvantages of the three systems, that is, Wavelength Division Multiplexing system of Single-Sideband modulation, Wavelength Division Multiplexing system of Double-Sideband modulation and Optical-Carrier-Suppression modulation of Double-Sideband modulation are compared and explicated. Lastly, by integrating Subcarrier Multiplexing and Wavelength Division Multiplexing, a Radio-over-fiber transmission scheme based on Optical-Carrier-Suppression modulation is designed. By comparing the other three systems which are Optical-Carrier-Suppression modulation transmission system, Optical-Carrier-Suppression modulation of Subcarrier Multiplexing transmission system and Optical-Carrier-Suppression modulation of Wavelength Division Multiplexing transmission system, corresponding performance parameters are discussed and the feasibility of this design scheme is analyzed.The results demonstrate as follows. First, as far as crossing Wavelength Division Multiplexing is concerned, the bit error rate has the same capability characteristics as the system before multiplexing, which means the system has steady performance within a certain range, and attenuation of the system increases as the fiber transmission distance increases. Compared with the system before multiplexing, the overall performance of the multiplexing system deteriorates, and is influenced by the extinction ratio to a larger degree. Second, with regard to the crossing Wavelength Division Multiplexing system of Double-Sideband modulation, the filters used in demodulation process can improve the deterioration of the system performance which is caused by two side bands having different transmission rate in fiber. At the same time, the system after multiplexing is influenced by the extinction ratio to a smaller degree. Third, as for Optical-Carrier-Suppression modulation of Wavelength Division Multiplexing transmission system, the stability of the multiplexing system gets more weakened than before, its overall attenuation is enhanced, and it is influenced by the extinction ratio to a larger extent. Fourth, Optical-Carrier-Suppression modulation of Subcarrier Multiplexing transmission system has the same characteristics with the system before multiplexing; in terms of power of the receiving end, the best is Optical-Carrier-Suppression modulation transmission system and the poorest is Optical-Carrier-Suppression modulation of Subcarrier Multiplexing transmission system; in terms of the stability of system, Optical-Carrier-Suppression modulation transmission system and the design scheme are both stable, and the former is better; in consideration of the degree to which the system is influenced by the extinction ratio, the influence to Optical-Carrier-Suppression modulation of Wavelength Division Multiplexing transmission system is minimal and the influence to the design scheme is the most. Thus it can be concluded that the design scheme possesses certain advantages on power of the receiving end and stability of the system and the design scheme is feasible.更多还原