Researches On Electronic Dispersion Compensation And Network Element Manegement Adaption Solution In High Speed Optical Transmission System

With the increase of transmission distance and channel capacity and the decrease of channel spacing, optical signal noise ratio (OSNR), chromatic dispersion (CD), polarization mode dispersion (PMD), nonlinear effects and spectral efficiency become the main bottleneck of further improving performance of high speed optical transmission system. Since the remarkable development on high speed electronic circuit, the technology of electronic dispersion compensation (EDC) attracted more attention for their high performance and low cost. The electronic signal processing technology adopted in optical digital transmission system, such as advanced error correction coding, coded modulation technology and electronic equalization techniques at the receive side, demonstrates remarkable performance in fiber impairment.Network intellectualization is a major trend of the development of optical transmission networks. The selection of network devices or components is always based on network scale, user demand and cost efficiency during network construction. There are multi-vendor and multi-type devices working together in today’s optical network. Without unified detail items of network management standards, each manufacturer would like use their private protocols, which block the network management information exchanging between the equipments from different manufacturers. As the quantity of devices and the scale of DWDM network, uniform network management and maintenance between different vendors will be very difficult.In addition, the structure of optical transmission network changed from the static point to point transmission to an efficient and flexible structure in business processing. Multi-degree Reconfigurable optical add-drop multiplexer (ROADM) technology become a key node device in WDM system, which supports remote wavelength network reconfiguration, simplifies service planning, implements end-to-end management through integration of automated control plane technologies. It also supports for multiple data rates, different modulation formats and protocols in one network.The research work is supported by863Program "High-speed Optical Fiber Communication Signal Transmission System in The Dynamic Combination of Optical Damage Equalization Technology","Emergency Recovery for DWDM System ", and "Multi-Degree ROADM System". This dissertation concentrates on the application of electronic dispersion compensation and intelligent adaption technology for element management in high speed optical transmission system. The main contents and innovations of this dissertation are as follows:1. The optical fiber channel characteristics is throughout studied and the structure of MLSE (maximum likelihood sequence estimator) equalizer is demonstrated, including the channel estimate method and Viterbi decoder. A novel MLSE equalizer technology combined with linear equalization is proposed, which shows a superior performance over an uncompensated span of300km (～5000ps/nm dispersion), and reduces requirements for number of states Viterbi decoder, making complexity simplification.2. The key algorithms for coherent detection are realized. Based on coherent detection in DWDM system,112Gbit/s signal combined with43Gbit/s signal or10Gbit/s signal is proved for considerable tolerance to linear and nonlinear effect even after very long haul transmission, which indicates the feasibility of100G overlaying existing10G/40G commercial systems.3. The element management system model and common protocol in DWDM systems are investigated. A novel adaptive solution for element management in DWDM system is designed and implemented based on throughout investigation and analysis on the management system of an unknown manufacturer. This adaptive solution and demo system is proved to be able to be identified by the management system and can work as a substitution of the original device. The feasibility and validity of proposal is proved by field experimental result. 4. Multi-Degree ROADM Systems is investigated and designed. The implementation methods and key techniques are explored, including the reconfigurable optical switching technology over multi-directional wavelength control; automatically signal monitoring in optical domain, dynamic gain equalization, adaptive impairment compensation technology and the advanced embedded network management. The Multi-Degree ROADM is not only with better self-adaptive and self-organization ability, but also with the flexibility in allocation of wavelength resources, which satisfies the requirement of dynamic business in the future.5. Based on the optical fiber communication network for power-grid enterprises, the application of DWDM technology in the existing SDH network is designed a new type of information and communication system for power-grid. Performance of the chain and loop networking modes is analyzed in wavelength assignment, routing and protection switching. The upgrading schemes with low-cost and high-utility are designed to resolve the bottleneck of bandwidth in communication network of Jiangxi power grid, and approved by specialist group authenticate.