Study On DQPSK In Optical Label Switching System

With the rapid expansion of transmission capacity as well as the growing demand for communication bandwidth, the transmission and switching technologies which support the communication network are changing an updated development. Due to the high-speed, large-capacity, optical fiber communication technology has become an important information carrier in communication network. In high-speed Internet communications network, data traffic has far exceeded the voice traffic, with the emergence of video conferencing, e-commerce, cloud computing to flourish and the applications of distance education, telemedicine, and video-on-demand network, IP traffic appear "blowout" growth. However, a large number of optical/electrical interfaces greatly limit the switching rate. The low-speed electronic data processing greatly restricts the further upgrade of transmission rate and the utilization of network resource. Therefore, the urgent development needs of the rapid expansion of optical broadband transmission system for switching technology has been proposed.Due to high spectrum efficiency, anti-nonlinear dispersion ability, the good receiver sensitivity, optical differential quadrature frequency shift keying (DQPSK) modulation format has been one hot spot of coded modulation techniques in high capacity, long-distance optical transmission.Based on CSRZ-DQPSK modulation signal, this paper mainly studies two optical label switching systems-orthogonal modulation format and Carrier Suppression and Separation (OCSS) optical label switching technology. The content consists of three main Parts:Firstly, we have solved the optical pulses transmission of the nonlinear Schrodinger equation by using of step Fourier method. The theory analysis and numerical simulation being combined, the individual and comprehensive influence of dispersion and nonlinear effects on high-speed optical communication system are studied. Secondly, we have Studied the mechanism of the differential quadrature frequency shift keyed signal and compare the dispersion and nonlinear resistant ability of three different anti-duty-cycle modulated signal.Thirdly, the CSRZ-DQPSK modulation signal as payload, we have proposed simulation models of the two optical label switching systems. the key parameters for each system have been optimized to analyze the impact on system performance.