Design And Implementation Of XDSL Channel Simulator Based On FPGA

With the development of digital subscriber line technology(DSL),xDSL technology,represented by VDSL2,G.fast and so on,can provide communication bandwidth similar to passive optical fiber network under the full use of copper resources,and significantly reduce broadband network investment.At the same time,with the improvement of the quality requirements of broadband communication,the research and development of broadband communication equipments has become more and more complicated,and the importance of the system testing of the equipment manufacturers has increased in the whole process of R & D.In order to reduce the development cycle and ensure the quality of the equipments,equipment inspectors need to simulate the transmission characteristics of broadband cable channels in the laboratory.With the emergence of multi-service,high bandwidth,crosstalk and other new features of broadband communication,the traditional channel simulation scheme can not meet the test requirements of the current broadband communication equipments.Based on the above backgrounds,the xDSL channel simulator based on FPGA is presented in this thesis,which has high bandwidth,programmable,easy to upgrade,easy to expand and other advantages.The xDSL channel simulator can play an important role in DSL communications equipments testing.The xDSL channel simulator designed in this thesis uses Xilinx's Virtex-7 family of chips to simulate the 8-wire twisted pair channels.Based on the transmission characteristics of xDSL channel,the transmission model of xDSL channel and the main parameters of channel transmission are analyzed.The characteristics of remote attenuation and far-end crosstalk of channel are analyzed,and the xDSL channel simulator based on FPGA is implemented.Then hardware and software validation is accomplished.Firstly,the transmission characteristics of xDSL channel are studied,and the theoretical model of xDSL channel is analyzed deeply.The characteristics of far-end attenuation and far-end crosstalk of DSL transmission channel are analyzed emphatically.Secondly,the design of the xDSL channel simulator is completed,and the overall architecture of the system based on the xDSL channel simulator is introduced.The hardware's structure of the channel simulator is elaborated.In view of the internal resource allocation of FPGA,the difficulty of implementing the xDSL channel simulator in FPGA is analyzed,and the main function modules are divided.And the data acquisition and adjustment,remote attenuation,inter-chip interconnection,remote crosstalk,UDP communication module's code development and on-board debugging are completed in this thesis.The control communication protocol of the xDSL channel simulator is designed and the PC terminal control software is written.The debugging of the 8-line xDSL channel simulator in FPGA and PC-side software is completed.Finally,the xDSL channel simulator is systematically tested,and the xDSL central and remote devices are used to test the channel characteristics under different transmission bandwidth and different transmission distance.The signal to noise ratio,transmission rate and other parameters are measured on each transmission path of the channel.The test results meet the specified parameters.