A data communication method, applied to a system that comprises an office side device and at least two user side devices connected to the office side device via digital subscriber lines, DSL lines, wherein the office side device comprises at least one arbitration function, AF, module, and in the at least two user side devices, a first user side device comprises a network terminal, and a second user side device comprises a power line communication, PLC, device; and the method comprises: monitoring , by the AF module, a first interference value and a second interference value of the network terminal in the first user side device, wherein the first and the second interference value are signal-to-noise ratio value or a quiet-line-noise values, the first interference value is an interference value that is of the network terminal in the first user side device , and the second interference value is a value of interference of the PLC device in the second user side device to the network terminal in the first user side device; determining , by the AF module based on the detected first interference value and second interference value of the network terminal in the first user side device, whether the network terminal in the first user side device is interfered with by the PLC device in the second user side device; and when the AF module determines that the network terminal in the first user side device is interfered with by the PLC device in the second user side device, controlling the interference of the PLC device in the second user side device to the network terminal in the first user side device by reducing, by the AF module based on the first interference value and on the second interference value, transmit power spectral density, PSD, of the PLC device in the second user side device; wherein the first interference value is detected after PLC devices in all user side devices are disabled; characterized in that the DSL lines are G.fast lines; wherein the method further comprises: compensating for a rate loss caused by the reduction of the PSD by power control performed during linear predictive coding of G.fast. monitoring , by the AF module, a first interference value and a second interference value of the network terminal in the first user side device, wherein the first and the second interference value are signal-to-noise ratio value or a quiet-line-noise values, the first interference value is an interference value that is of the network terminal in the first user side device , and the second interference value is a value of interference of the PLC device in the second user side device to the network terminal in the first user side device; determining , by the AF module based on the detected first interference value and second interference value of the network terminal in the first user side device, whether the network terminal in the first user side device is interfered with by the PLC device in the second user side device; and when the AF module determines that the network terminal in the first user side device is interfered with by the PLC device in the second user side device, controlling the interference of the PLC device in the second user side device to the network terminal in the first user side device by reducing, by the AF module based on the first interference value and on the second interference value, transmit power spectral density, PSD, of the PLC device in the second user side device; wherein the first interference value is detected after PLC devices in all user side devices are disabled; characterized in that the DSL lines are G.fast lines; wherein the method further comprises: compensating for a rate loss caused by the reduction of the PSD by power control performed during linear predictive coding of G.fast. <EOS>