The Research Of WDM Optical And Wireless Access System

The development of information technology in recent years is continuing to fuel the rise of people’s demands in access applications and the performance of access network, of which the most significant challenge is how to guarantee high bandwidth and flexibility simultaneously, namely the integration of wired and wireless access. RoF (Radio Over Fiber) has been extensively studied among researchers with its advantages of flexible access and huge system capacity, whereas WDM-PON has gained great attention from both communication experts and communication operators as one of the key technologies for next generation optical access network.Consequently, the integration of RoF with WDM-PON to realize hybrid optical wired and wireless access in WDM channel has become the trend of future access network. RoF, WDM-PON and the hybrid system are proposed and detailed researched in this thesis. The results [accomplishments] achieved are:1) WDM-ROF system based on super continuous spectrumIn this paper, super continuous spectrum technology is utilized to realize the multi-wavelength source of the proposed WDM-ROF system. Optical pulses with high power is input into high nonlinear fiber, spectrum of which is broadened as the result of the nonlinear effects in fiber including chromatic dispersion, SPM, XPM, FWM and SRS.The broadened spectrum is then filtered by comb filter implement by SSFBG, yielding multi-wavelength optical source with coherence properties.WDM-ROF system based on super continuous spectrum is designed and experimentally demonstrated in this paper. With comb filtered super continuous spectrum as the multi-wavelength optical source of WDM channel, high frequency microwave is achieved by optical heterodyne. In the experiment,2.5Gbit/s baseband signal is transmitted in WDM channel for 25km,and 40GHz millimeter wave carried baseband signal is generated.2) WDM-PON systemIn this paper,.A Novel WDM-PON system based on DPSK-OOK is proposed, which realizes 4×10Gbps symmetrical access.In the system, ODPSK, with its high dispersion and nonlinearity tolerance, is utilized in down link while OOK in up link.The two signals are orthogonal, which can be achieved by some simple optical devices, ensuring the realization of colourless ONU based on passive technology. Simulation is performed based on the system, and the results prove that the system is feasible.3) WDM-RoF-PON systemSeveral key technologies of WDM-RoF-PON system are emphasized in this paper, including:1) achieve high frequency millimeter wave for wireless access 2) realize low interference co-transmission of wired and wireless signals 3)generate multi-wavelength optical source for WDM channel in CS or OLT 4)Use colourless ONU in ONU or BS to simplify system implementation. System scheme is designed based on the technologies above and simulation system is constructed. Hybrid transmission of lOGbps wired signal and 2.5Gbps wireless signal in a single channel for down link, and 10Gbps transmission based on passive colourless ONU for up link are realized in this system.