The Design And Implementation Of OCDMA Two-Dimensional Electrical Domain Encoding And Decoding System Based On FPGA

With the advent of the Internet,a variety of new business makes the demand of access network bandwidth growing exponentially.The optical fiber communication in China has entered into a relative high-speed period of expansion,and its main goal is to achieve a network with high-bandwidth,large capacity,long-distance transmission and in intelligent all-optical form.The OCDMA(Optical Code Division Multiple Access)technology has several advantages of unique confidentiality,high scalability,random asynchronous access,soft capacity and multi-user shared channel,etc.And it has become the most potential program with the next generation of fiber access network technology.This paper focuses on the key technologies of OCDMA two-dimensional domain coding system.The main contents are as follows:1.The structure and working principle of several common OCDMA optical one-dimensional and two-dimensional codecs are reviewed,and the performance of various kinds of optical codecs is analyzed.Also,an electro-optical combiner with decoding of the spatial domain coding and optical domain FBGs is described.The structure and codec principle are defined in detail,and the advantages of OCDMA system are analyzed.According to the codec technique of time domain and spectral domain 2D OCDMA system,the design of an OCDMA two-dimensional domain codec is made with defining its construction method and codec principle.2.An FPGA-based OCDMA two-dimensional domain codec system is designed.The design principle and function of the main modules of the two-dimensional electronic domain codec module,high-speed serial communication module,frame encapsulation module and assistant channel binding module are expounded in detail,combined with Verilog HDL hardware description language,Modelsim,ISE and other software design tools to Xilinx ML605 FPGA development board as a hardware platform for each sub-module FPGA function.Finally,the whole codec system is cascaded and integrated,and the codec test of two user data is carried out.The test results show that the FPGA-based OCDMA two-dimensional electronic domain codec system can successfully realize the two-Dimensional encoding decoding function.3.The design and implementation of non-coherent OCDMA two-dimensional electronic domain codec system experiment is also successfully examined and explained.The results show that the two-way user data rate is 312.5Mb/s,the system transmission line rate of 3.125Gb/s,4-channel parallel transmission of the total amount of 12.5Gb/s,and the fiber transmission distance is 10KM.In addition,the results also prove that the receiver can correctly decode the desired user data,and through the analysis of the oscilloscope eye diagram.And it can be seen the small system crosstalk,the low noise and the the excellent system performance.On the basis of the hardware of the experimental system,the bit error rate test in the high-speed transmission channel of the IBERT IP check system provided by Xilinx is carried out.The test results also display the design of high-speed transmission channel with good transmission performance and low bit error rate in this paper.