Design And Implementation Of Digital Subscriber Line Channel Simulation System

In recent years,the optical fiber communication network develops rapidly,which made a trend of "light forward and copper back" in domestic.However,the distribution of copper twisted pair resources at home and abroad is still very extensive,and the cost is low,so digital subscriber line(DSL)technology in the medium of twisted pair still has a great value to promote.The new generation of digital subscriber line technology G.fast broke the original 30 MHz bandwidth limit,making the bandwidth up to 100 megabytes,which can real match the fiber network in transmission rate and network bandwidth.Therefore,it is very important to test the channel of DSL equipment,including central office and client equipment.At present,the testing methods for DSL device are mainly divided into two kinds.One is through special instruments to obtain twisted pair transmission characteristics,such as signal generators and spectrum measuring instrument.The main drawback of this approach is the cost of the instrument is too high.The other is based on the actual cables,which through the laying of twisted pair,to measure the characteristics of DSL channel transmission.The main drawback of this approach is to spend lots of manpower,material and financial resources,and has a higher demand of project site.Based on this,the xDSL channel simulator of which the project team developed is of great significance,which could simulate the real-time transmission of multi-pair cables,and finally passed the acceptance of Huawei's work.This thesis is based on the theory of digital subscriber line channel transmission,which mainly includes transmission line theory,channel model and noise model,to implement a channel simulation system in Simulink.The system is used to simulate the transmission characteristics of DSL channel,and laid the theory foundation of xDSL channel simulator.The main work is as follows.Firstly,the overall demand of the simulation system is analyzed,and the structure and related parameters of the system are determined.The models of channel and noise are defined in the standard,and the simulation method of channel and noise is analyzed in this thesis.Finally,the entire digital subscriber line channel simulation system's design work is completed.After the design work,the digital subscriber line channel simulation system is implemented in Simulink.Firstly,the relevant channel parameters are analyzed,and then the simulation of channel and noise module is implemented.The next is compared with the theoretical value,and the correctness of the system is verified.Finally,the channel simulation control display platform software is implemented to display the channel transmission characteristics.The last is testing work of the whole system.In this thesis,the test scheme is analyzed,and the far-end attenuation module,the far-end crosstalk module and the whole system are tested respectively,which verified the correctness of the channel simulation system.Finally,after the hardware system testing work,xDSL simulator could achieve the required performance,thus further proof of the correctness of the simulation system.