A vectoring control entity, VCE, wherein the VCE provides N ports that are separately used to connect to different transceiver units at the side of the subscriber end of the loop, FTU-Rs; and the VCE comprises: a downlink far end crosstalk, FEXT, determining module, configured to: for a port i of the N ports, when the port i is activated at a historical moment, determine, when each port j of the other N-1 ports and the port i are activated at the same time, a power value U_dl ( i, j) of downlink FEXT caused to a signal on a line corresponding to the port i by a signal on a line corresponding to the port j, and a downlink receive power value U_dl ( i, i) of an FTU-R connected to the port i, wherein i, j = 1, 2,..., N, and i is not equal to j; and a downlink receive power adjustment module, configured to: when the port i is activated, determine, according to the downlink FEXT power value U_dl ( i, j) and the downlink receive power value U_dl ( i, i) of the FTU-R corresponding to the port i that are determined by the downlink FEXT determining module, a downlink virtual power margin VirtualPwr_dl ( i) corresponding to the port i; and send the downlink virtual power margin VirtualPwr_dl ( i) to the FTU-R connected to the port i, so that the FTU-R connected to the port i performs downlink receive power adjustment according to the downlink virtual power margin VirtualPwr_dl ( i); wherein the downlink receive power adjustment module is specifically configured to determine, according to the following formula, the downlink virtual power margin VirtualPwr_dl ( i) corresponding to the port i: VirtualPwr _ dl i = 10 * log 10 ∑ j = 1 N U _ dl i, j ∑ j = 1, and j ∈ acurrently activated port N U _ dl i, j; and wherein the downlink FEXT determining module is specifically configured to: determine the downlink FEXT power value U_dl ( i, j) and the downlink receive power value U_dl ( i, i) according to an error amount reported by the FTU-R connected to the port i, wherein the error amount is a difference that is between a standard point vector and a sampling point vector determined by a constellation decider in the FTU-R connected to the port i; or wherein the downlink FEXT determining module is specifically configured to: determine the downlink FEXT power value U_dl ( i, j) according to a historical coefficient of downlink crosstalk of the port j to the port i, and determine the downlink receive power value U_dl ( i, i) according to a historical coefficient of downlink crosstalk of the port i to the port i itself. a downlink far end crosstalk, FEXT, determining module, configured to: for a port i of the N ports, when the port i is activated at a historical moment, determine, when each port j of the other N-1 ports and the port i are activated at the same time, a power value U_dl ( i, j) of downlink FEXT caused to a signal on a line corresponding to the port i by a signal on a line corresponding to the port j, and a downlink receive power value U_dl ( i, i) of an FTU-R connected to the port i, wherein i, j = 1, 2,..., N, and i is not equal to j; and a downlink receive power adjustment module, configured to: when the port i is activated, determine, according to the downlink FEXT power value U_dl ( i, j) and the downlink receive power value U_dl ( i, i) of the FTU-R corresponding to the port i that are determined by the downlink FEXT determining module, a downlink virtual power margin VirtualPwr_dl ( i) corresponding to the port i; and send the downlink virtual power margin VirtualPwr_dl ( i) to the FTU-R connected to the port i, so that the FTU-R connected to the port i performs downlink receive power adjustment according to the downlink virtual power margin VirtualPwr_dl ( i); wherein the downlink receive power adjustment module is specifically configured to determine, according to the following formula, the downlink virtual power margin VirtualPwr_dl ( i) corresponding to the port i: VirtualPwr _ dl i = 10 * log 10 ∑ j = 1 N U _ dl i, j ∑ j = 1, and j ∈ acurrently activated port N U _ dl i, j; and wherein the downlink FEXT determining module is specifically configured to: determine the downlink FEXT power value U_dl ( i, j) and the downlink receive power value U_dl ( i, i) according to an error amount reported by the FTU-R connected to the port i, wherein the error amount is a difference that is between a standard point vector and a sampling point vector determined by a constellation decider in the FTU-R connected to the port i; or determine the downlink FEXT power value U_dl ( i, j) and the downlink receive power value U_dl ( i, i) according to an error amount reported by the FTU-R connected to the port i, wherein the error amount is a difference that is between a standard point vector and a sampling point vector determined by a constellation decider in the FTU-R connected to the port i; or wherein the downlink FEXT determining module is specifically configured to: determine the downlink FEXT power value U_dl ( i, j) according to a historical coefficient of downlink crosstalk of the port j to the port i, and determine the downlink receive power value U_dl ( i, i) according to a historical coefficient of downlink crosstalk of the port i to the port i itself. determine the downlink FEXT power value U_dl ( i, j) according to a historical coefficient of downlink crosstalk of the port j to the port i, and determine the downlink receive power value U_dl ( i, i) according to a historical coefficient of downlink crosstalk of the port i to the port i itself.