关键词: G.fast, 信道模型, 数字信号反射, 信噪比, 超宽带网络, 智慧家庭

Abstract: Based on the reflection principle of digital signal propagation theory, a mathematical model of G.fast channel is established when the impedance of digital subscriber line is not matched.The reflection coefficient is used to describe the line impedance mismatch and the channel data (direct channel, far-end crosstalk channel and near-end crosstalk channel) measured when line impedance matching are used in the model.When the terminal is disconnected, the channel data calculated by the model is consistent with the actually measured data, which proves the accurateness of the model.Since the reflection coefficient is used to describe the degree of impedance mismatch, the model can simulate the influence of the terminal equipment on the signal noise ratio of the communication system under different impedances.Therefore, we propose a maximum allowable variation range of the terminal impedance which provides some theoretical guidance for terminal manufacturer for designing terminal impedance.

Key words: G.fast, channel model, digital signal reflection, signal noise ratio, ultra-wideband network, smart home