Study On Technology Of Discrete Multitone Modulated WDM-PON

Passive optical network (PON) has become interactive due to its operational cost, huge bandwidth offering, and longevity. Given the exponentially increasing number of users and ever increasing demand of bandwidth hungry applications, the current single-channel PON is likely to be upgraded in order to satisfy the growing traffic demand in future. Single-channel PON may be upgraded by deploying multiple-wavelength channels in the installed fiber infrastructure, both in the upstream and downstream directions, resulting in wavelength division multiplexing (WDM)-PON.In order to increase the bandwidth while maintaining an acceptable cost of deployment, recent research in access network has been being focusing on advanced modulation formats. One of them is the Discrete Multi Tone (DMT). Due to the high spectral efficiency of M-QAM (Quadrature Amplitude Modulation) in each sub-carrier of the DMT symbols, it is possible to increase the bit rate transmitted by low bandwidth components. In addition to its inherent robustness to fiber chromatic dispersion and nonlinear optics impairments, this modulation is attractive for access network since it can be implemented using digital signal processing (DSP) on fast and low-cost embedded devices. Furthermore, it offers the prospect of integrating forward error correcting code (FEC) for improved transmission.Therefore, WDM systems with DMT modulation, has successes to both technologies, become a promising low-cost high-speed large-capacity PON system solutions. Combining theory study and simulation, the writer has done the following work: 1. The internal and abroad development instances of optical access network have been researched in details, especially the international trends and key technology of WDM-PON. The advantage of WDM-PON beyond TDM-PON has been analyzed.2. For the DMT modulated WDM-PON system, the key technologies, subcarrier adaptive algorithm, constellation mapping has been studied. The WDM channel bit loading algorithm has been proposed and studied. It has been proved that the WDM system is likely to have larger capacity.3. It has been experimentally demonstrated that 10Gbit/s transmission over 20km single-mode fiber (SMF) can be achieved by using DMT modulation in WDM-PON, with a total power budget of 24dBm. Multi-tone modulation signal has high spectral efficiency and strong resistance to fiber dispersion and nonlinear optics impairments. It is therefore a promising solution for low-cost, robust, and high capacity PON systems.This article is summary of the writer's theory study and practical research during being a graduate student, including follow parts:The 1st part introduces knowledge background and the writer's research content and achievements.The 2nd part introduces PON systems, especially the international trends and key technology of WDM-PON, and also analyzes the advantage of WDM-PON beyond TDM-PON.The 3rd part studies the key technologies of DMT modulated WDM-PON system, proposes the WDM channel bit loading algorithm. It has been proved that the WDM system is likely to have larger capacity from the algorithm model.The 4th part demonstrates that 10Gbit/s transmission over 20km single-mode fiber (SMF) can be achieved by using DMT modulation in WDM-PON. WDM systems with DMT modulation, have successes to both technologies, and become a promising low-cost high-speed large-capacity PON system solution.The 5th part summarized the existing work and gives an expectation for the next step.