Research Of Carrier Phase Recovery For Coherent Optical Communication System

With the advent of the era of large data,the rapid development of the Internet +,a variety of high-definition video,remote conversations,electronic transactions and other multimedia business continues to emerge,a large number of data storage,transmission,sharing increased demand,high-speed transmission and high-capacity to meet people's needs.The traditional optical communication receiver adopts the intensity modulation direct detection,can only transmit the intensity modulation signal,resulting in the system transmission rate is relatively low,if the increase transmission rate,causes the system structure is complex,the cost is enhanced,the close communication often uses the traditional optical communication system The Coherent optical communication system can achieve high-speed and long-distance transmission,but its structure is complex and cost is high.With the continuous development of technology,higher order modulation can improve the transmission speed of the system.The coherent detection technology can improve the sensitivity of the receiver to the optical signal,and can also use the digital signal processing technology to eliminate noise,compensate for dispersion nonlinear effects and phase recovery,based on high-order modulation of the coherent optical communication system using coherent detection technology and digital signal processing technology for data transmission,to achieve high-speed,large-capacity and long-distance transmission,which is the future trend of communication development.In the coherent optical communication,the link damage caused by the transmission medium and the noise in the transmission affect the transmission of the data information,and the recovery of the original data is the key to the optical communication.In view of these problems,Carrier phase recovery has been studied,mainly from the following aspects of related research:1.The background of the research,the status quo and development of coherent optical communication systems,the research status of carrier phase recovery,and the learning and use of Opti System optical software and Matlab software,pave the way for the study of subsequent carrier phase recovery.2.Through the traditional optical communication system and coherent optical communication system in the structure of comparison,highlighting the coherent optical communication system in the communication advantage.The problem of link damage in coherent optical communication system is studied,and the compensation method is proposed to improve the system performance degradation caused by optical fiber transmission.The simulation system is used to simulate the real system function.3.In this paper,the estimation techniques of carrier phase are studied,and the optical phase estimation and carrier phase estimation are studied.The optical phase-locked loop technology is studied in optical phase estimation,such as structural principle and existing defects and insufficient.The influence of phase noise on the system performance is studied.The phase noise is eliminated by M-power phase estimation algorithm.The phase noise is eliminated by simulation.The influence of noise on phase estimation and the phase estimation after algorithm compensation are analyzed by simulation.4.In this paper,several common carrier phase recovery techniques are studied,and the algorithms used in these techniques are studied theoretically.A new blind phase search algorithm is proposed by reducing the computational complexity of the blind phase search algorithm.In the digital signal processing,the use of new blind phase search algorithm to eliminate the impact of phase noise.In the software simulation,the construction of DP-QPSK and QAM two types of coherent optical communication system,the system data into the digital signal processing program for phase recovery,in the simulation process while fiber transmission link damage was compensated.