Research On Coded Modulation And Equalization Algorithm In Multi-core And Few-mode Optical Fiber Transmission

With the rise and popularization of big data Internet services such as 4K video,"smart home",on-board Internet of things and virtual reality technology,network data traffic is growing rapidly.According to the latest report released by Cisco,the IP data traffic of global network system in 2022 will exceed the total traffic from 1995 to 2016,and the demand of users for data transmission rate is growing rapidly,The information capacity of optical communication transmission system based on single-mode fiber has gradually approached the limit of Shannon capacity.Therefore,the long-distance high-speed information transmission carrier of optical fiber communication system is facing huge capacity growth pressure.By increasing the number of cores and mode,the capacity of optical fiber communication system can be significantly improved and the transmission capacity of single-mode optical fiber can be broken.Therefore,it is of great significance to study the key technologies of space division multiplexing transmission system based on few mode multi-core fiber.Focusing on the key problems in the few mode multi-core optical fiber system,this paper first analyzes the theoretical model of the space division multiplexing optical fiber transmission system,and studies the transmission characteristics of the space division multiplexing optical fiber.Based on the analysis of the system model based on the seven core three mode fiber,the MIMO algorithm of the receiver in the few mode multi-core optical fiber transmission system is studied in this paper.In addition,the performance of the few mode multi-core optical fiber transmission system based on OFDM modulation technology is studied,and the simulation and analysis of the few mode multi-core optical fiber communication system based on OFDM modulation are carried out.The research work of this paper mainly includes the following three parts(1)the channel theoretical model of the low modulus multi-core optical fiber is studied,and the seven core three mode optical fiber transmission system is built by using the MATLAB simulation software.Through the reasonable optimization design of the parameters of the space division multiplexing channel,the transmission distance of the 70km optical fiber link is achieved,and the BER of the 25dB link is lower than the FEC threshold threshold 1 e-3.(2)in view of the influence of damage factors such as mode coupling and differential mode delay in the low modulus multi-core optical fiber transmission system,this paper proposes a VSS-SCA and VSS-SCA-CMMA joint equalization algorithm with low complexity and fast convergence.The new algorithm achieves approximately 3dB SNR gain in the equalization process of the seven core three mode fiber link model compared with the traditional equalization algorithm.A good equalization effect is achieved.(3)The performance of the few mode multi-core optical fiber transmission system based on OFDM modulation technology is studied.By combining OFDM modulation technology with the few mode multi-core optical fiber communication system,the spectrum efficiency of the system can be doubled,and the transmission efficiency and performance of the optical fiber communication system can be effectively improved.