Investigations On ROF System Based On Optical Carrier Suppression Modulation

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.