Research For WDM-PON And ROF Integration System

In recent years, the core part of the communication network has changed very much,either the way of exchange or in the transmission capacity. But as transmission’s last mile,the access network has become a very seriously question to restrict the communicationnetwork developing into the broadband and operational network. People begin to turn theirattention to the integration of the wireless and optical fiber to solve the problem of theaccess network, providing voice, data, images and other multimedia services to the terminaluser. Because of the huge bandwidth, seamless coverage, high capacity as well as thelow-loss characteristics, ROF technology becomes the promising method in the wirelessaccess network. Meanwhile in the optical access network, the WDM-PON technologyprovides each user exclusive a wavelength bandwidth as well as the excellent full-servicecarrying capacity. Therefore, integrated the ROF technology with the WDM-PONtechnology has become the development tendency in the future network architectures.The current research program can be divided into two parts: one integration systems isbased on a single carrier. The integration signals are transmitting on the same wavelength ofthe optical fiber. In the practical application, they can not meet the needs of more users,meanwhile they also lack of flexibility. The other one of the system is usually focused onone frequency of the optical fiber. However the users’ needs are usually distributed indifferent frequency, we have to employ more systems to meet the users’ needs in eachfrequency, the solution will increase the cost of construction. This paper proposes anddemonstrates two types of integration systems for simultaneous generation and transmissionof wired and wireless signal, in the base station, we use the carrier reuseable technology toachieve the uplink signal’s transmission. The research contents as follows:First, against for the single-carrier question, we proposed the integration system forwired and wireless signal transmission based on the orthogonal modulation. The wirelesssignals are modulated in phase modulation. The wired signals are modulated by theintensity modulator. The two signals are based on orthogonal modulation, so theinterference between the signals will not occur. The orthogonal signals are transmittedthrough the fiber to base station for demodulation, and use carrier reuse technology foruplink signals’ re-modulate. Then employ the software of optisystem7.0to analysis thesystem’s validity and reliability. The simulation shows that, after the optical fibertransmission, the signals can be accurately received at the receiving end.Second, combination of sub-carrier modulation technology, propose a system totransmit the high and low frequency signals simultaneously. The wireless signal ismodulated on the local RF signal with high frequency, the wired baseband signal is modulated on the RF signal with low frequency. Through the optical fiber transmission, thesignals are demodulated by the multi-frequency signal receiver in the base station.Meanwhile a part of the high frequency signals are reused for uplink signal remodulation.After the simulation software’s verification, the low frequency signal and the highfrequency signal can be received very well on the base station, the uplink signal can also bedemodulated accurately on the central station. The results demonstrate the effectiveness andfeasibility of the proposed scheme.