The Active Multi-line Channel Simulation Method And Implementation

With the continuous development of digital business, the demand of high rate is increasing. Though optical fiber technology is evolving rapidly, it is still relatively expensive than copper wire(CAT-x) technology; and since CAT-x cables have been deployed widely especially in urban areas, digital subscriber line(xDSL) technologies are still the best choice due to new advanced high-speed systems and technologies proposed – like vectoring and G.fast, xDSL technology is still of great market value.Although xDSL devices have been widely adopted, they can be under various scenarios with different cable length, bandwidth and data-rate requirement, which are not predefined. XDSL devices must pass tests for at least a set of typical scenarios, including cable length line(in sections), the strength of noise/interference, logarithmic, etc. Analogue simulation technology cannot meet the existing requirements of simulation, the test is usually carried out by manually changing cables of different length, and changing noise/interference setting, the test cycle and process is complex and difficult to control, with a high bandwidth, digital simulation is programmable and easy to upgrade and expand. Under the MATLAB/Simulink framework, the xDSL channel simulator was built in this thesis to verify the structure of the channel simulation, assisted by theoretical analysis and MATLAB simulation. The main work is as follows:Firstly, the characteristics of twisted pair and principles and advantages of the existing twisted-pair communication system were introduced in the thesis. The components of the DSL system and several common DSL technologies were introduced in detail. The transmission line theory was briefly reviewed, which provided full preparations for the proposing of the channel simulation model.Secondly, the twisted-pair transmission model and far-end crosstalk model under 30 MHz bandwidth were studied. In view of the problem of inapplicability of the traditional RLCG model and the ABCD model in modeling the twisted pair with over 10 MHz bandwidth, a new transmission model was proposed: Wideband model. The near-end crosstalk and far-end crosstalk model proposed in DSL standards were introduced in detail, and on this basis the 99% extended far-end crosstalk model we used was introduced.Finally, for the elected transmission model and far-end crosstalk model, the overall structure of 4-line twisted-pair channel was designed. And according to the overall design, the implementation of the channel simulator was completed, including the interception of groups of filter coefficients and the construction of filter Simulink. The far-end attenuation filter and the far-end crosstalk filter were tested and verified, and then the concrete realization of the xDSL transceiver was described. Therefore, the Simulink module of the whole communication system was written. The program of the system simulation console for the simulated control of each module was written for the convenience of users. The implementation of Simulink of the channel simulator can provide the basis for the simulation of real-time transmission of Xilinx FPGA, which is of great practical value.