Study Of OFDM-Based Convergence Optical Access Network

The ultimate target of Internet is providing access service anywhere, anytime at any speed. However, with the development of technology and enrichment of Internet's content, the traditional access network architec-ture cannot satisfy customs'demand anymore.Today, custom's demand is changing from original "fixed time, fixed spot and low-speed" to "high-speed, anytime and anywhere" gradually. Basing on the analysis of current Internet broadband demand, it not hard to draw the conclusion that some Internet applications already reach the brass-based transport medium's physical limitation. Once more band-width-sensitive services, such as Virtual Reality, come true, the speed bottleneck problem will be more obvious. In the future, access network users will ask for more personality services, they will need more high-quality videos; they will need to participate multiple real-time conferences. These connection patterns demand large amount of band-width in download direction, and similar bandwidth in upload direction as well.How to providing high-speed and high-convenient access service is current major task that access network technology faced.OFDM is a typical frequency-division multiplexing technology. Its basic theory is dividing one data stream into two or more parallel streams or channels, one for each subcarrier whose frequency is chosen so that every subcarrier is orthogonal to each other. The primary advantage of OFDM is its ability to achieve high-speed transition with low-speed equipment and use frequency resource effectively.During the last decade, many relative papers have been published which is a strong evidence to prove the potential of OFDM in optical communication area theoretically and practically. Moreover, as the core multiplexing technology of the 4th generation mobile communication, OFDM could be the bridge between wire and wireless communication network architecture. Research focused on this topic could contribute to simplify convergence network systems in the future.How to combine OFDM with current optical transmit technologies in order to enhance its performance is a popular academic topic in optical communication research area. Most of all, how to adopt low-cost optical equipment, such as LEDs, to achieve clients'demand and improve its business value is the major research direction.This paper mainly gives a comprehensive research about the realiza-tion, potential and performance about OFDM combining with different communication technologies. Combining theory study and simulation, the major research results and improvements of this paper as fallow:1. Studied the domestic and abroad development of optical access network in detail, and deeply studied the OFDM technology's history and its current trend; furthermore, analyzed the application prospect of the convergence network architecture.2. Did an in-depth analysis and research on relative technologies, mathematics foundations, characters and application prospects, include OFDM, MIMO, colorless ONU, WDM-PON and wireless channel.3. Via simulation, compared the performance of MIMO-OFDM access networks under different circumstances, designed and accom-plished a OFDM-based optical-wireless convergence access network, its major character is adoption of MIMO and OFDM technologies to smooth negative effect caused by dispersion in optical fiber and multiple paths fading in wireless channel.4. Designed and accomplished an OFDM-based spectrum slicing WDM-PON system, its major character is its ability to satisfy customs' access bandwidth demand and improve system performance using low-cost optical equipment.This thesis is organized into six chapters.Part I introduces background information and knowledge about optical access network; PartⅡparticularly introduces and analyses the OFDM technology;PartⅢproposes a novel optical-wireless convergence access network architecture, and describes its major contents;PartⅣdesigns and accomplishes an OFDM-based optical access network, measures its performance under different circumstances;PartⅤdesigns and accomplishes an OFDM-based LED spectrum slicing optical access network, and studies its performance;PartⅥsummarizes the existing work and gives an expectation for the next step.