Research On Novel Access Networks Technology Based On OFOM

Rapid development of informational society leads to the explosive increase of data services. High quality data services, such as high definition video, IPTV, P2P and so on, are urgently required by people and social applications so that the dilatation of current communication networks has no time to delay. Especially under the driving of Triple Play and Internet of Things, access networks, called "final one kilometer", is facing austere challenge. Next generation access networks is going forward to high capacity, high flexibility and more comprehensive. Optical access networks does not decline to shoulder a responsibility in it and is known as the best resolution. Meanwhile, combining with OFDM technology, it can effectively enhance the efficiency of frequency spectrum and restrain channel distortion. However, only increasing capacity is not sensible. How to simultaneously realizing perfect amalgamation of multiple services and providing comprehensive services are the final requirement of access networks.This thesis, aiming amalgamation access networks, made exploration on novel optical access networks based on OFDM and also gave analysis and resolution on how to simplify system architechture and eliminate power attenuation caused by dispersion. The main works are as the following:1) Theory and key technologies about OFDM is studied in the second chapter, comprehending its math model, structure components and principle of restraining channel distortion. Also comparing OFDM with single carrier modulation technology to highlight the superiority of combination of OFDM and optical access networks.2) Research on OFDM-ROF system is done in the chapter3. Research points are mainly focused on generation of high quality optical millimeter-wave signal, comparison of different analog modulation forms, realization of optical frequency doubling with the non-linear modulation of Mach-Zehnder modulator. Also downstream wavelength reuse technique is utilized to save upstream optical source, simplify the construction of base station and realize full duplex communications. In addition, system design and simulation of OFDM-ROF system with odd-sidebands suppression are achieved,2.5Gbps wireless signal successfully completes40km standard SMF transmission and performs well. Periodic power attenuation phenomena due to fiber dispersion is found and analysed.3) Coupling ROF signal into PON, an amalgamation full duplex optical access networks that can provide2.5Gbps wireless/10Gbps wired downstream signals and2.5Gbps upstream signal is designed and simulated in chapter4. The key problems, such as proper modulation form selection, coupling and separating methods of two services signals, are focused and solved. Non-symmetry optical carrier suppression modulation method based on filter is proposed to overcome the periodic power attenuation problem caused by fiber dispersion. And, feasibility experiment about the generation of OFDM signal is done finally.