A system comprising two base stations for a base station group, wherein the two base stations serve one user equipment in a distributed 4x2 MIMO networking scenario, each base station comprising: a processing unit, configured to perform packet assembly, code modulation, and multi-antenna processing on downlink channel data, so as to form antenna port signals, where a quantity of antenna port signals is equal to a quantity of antenna ports and the quantity of antenna ports formed or obtained by the base station is a total antenna port quantity of the base station group, wherein the processing unit is further configured to perform orthogonal transform on the antenna port signals according to a preset matrix used for orthogonal transform, wherein each base station performs the same transformation on all antenna ports; and a setting unit, configured to set, according to an antenna quantity and an antenna port quantity, a row quantity and a column quantity of the matrix used for orthogonal transform, so as to generate the matrix used for orthogonal transform, wherein each element in the matrix has an equal modulus value, the row quantity of the matrix used for orthogonal is the antenna quantity, and the column quantity is the antenna port quantity and wherein the matrix is an orthogonal matrix and the matrix is A = [ a 00, a 01, a 02, a 03 a 10, a 11, a 12, a 13 a 20, a2 1, a 22, a 23 a 30, a3 1, a 32, a33], wherein after orthogonal transform is performed on the signals of antenna port0 to antenna port3, the following is obtained: a linearly superposed signal OUT0=(a00 ∗ port0+a01 ∗ port1+a02 ∗ port2+a03 ∗ port3); a linearly superposed signal OUT1=(a10 ∗ port0+a11 ∗ port1+a12 ∗ port2+a13 ∗ port3); a linearly superposed signal OUT2=(a20 ∗ port0+a21 ∗ port1+a22 ∗ port2+a23 ∗ port3); a linearly superposed signal OUT3=(a30 ∗ port0+a31 ∗ port1+a32 ∗ port2+a33 ∗ port3, wherein port0 and port1 are the signals of antenna ports of one of the two base stations and port2 and port3 are the signals of antenna ports of the other of the two base stations; and a sending unit, configured to simultaneously send orthogonally transformed antenna port signals to the user equipment by using different antennas, wherein the one of the two base stations sends out the linearly superposed signal OUTO and the linearly superposed signal OUT1 and the other of the two base stations sends out the linearly superposed signal OUT2 and the linearly superposed signal OUT3. a processing unit, configured to perform packet assembly, code modulation, and multi-antenna processing on downlink channel data, so as to form antenna port signals, where a quantity of antenna port signals is equal to a quantity of antenna ports and the quantity of antenna ports formed or obtained by the base station is a total antenna port quantity of the base station group, wherein the processing unit is further configured to perform orthogonal transform on the antenna port signals according to a preset matrix used for orthogonal transform, wherein each base station performs the same transformation on all antenna ports; and a setting unit, configured to set, according to an antenna quantity and an antenna port quantity, a row quantity and a column quantity of the matrix used for orthogonal transform, so as to generate the matrix used for orthogonal transform, wherein each element in the matrix has an equal modulus value, the row quantity of the matrix used for orthogonal is the antenna quantity, and the column quantity is the antenna port quantity and wherein the matrix is an orthogonal matrix and the matrix is A = [ a 00, a 01, a 02, a 03 a 10, a 11, a 12, a 13 a 20, a2 1, a 22, a 23 a 30, a3 1, a 32, a33], wherein after orthogonal transform is performed on the signals of antenna port0 to antenna port3, the following is obtained: a linearly superposed signal OUT0=(a00 ∗ port0+a01 ∗ port1+a02 ∗ port2+a03 ∗ port3); a linearly superposed signal OUT1=(a10 ∗ port0+a11 ∗ port1+a12 ∗ port2+a13 ∗ port3); a linearly superposed signal OUT2=(a20 ∗ port0+a21 ∗ port1+a22 ∗ port2+a23 ∗ port3); a linearly superposed signal OUT0=(a00 ∗ port0+a01 ∗ port1+a02 ∗ port2+a03 ∗ port3); a linearly superposed signal OUT1=(a10 ∗ port0+a11 ∗ port1+a12 ∗ port2+a13 ∗ port3); a linearly superposed signal OUT2=(a20 ∗ port0+a21 ∗ port1+a22 ∗ port2+a23 ∗ port3); a linearly superposed signal OUT3=(a30 ∗ port0+a31 ∗ port1+a32 ∗ port2+a33 ∗ port3, wherein port0 and port1 are the signals of antenna ports of one of the two base stations and port2 and port3 are the signals of antenna ports of the other of the two base stations; and a sending unit, configured to simultaneously send orthogonally transformed antenna port signals to the user equipment by using different antennas, wherein the one of the two base stations sends out the linearly superposed signal OUTO and the linearly superposed signal OUT1 and the other of the two base stations sends out the linearly superposed signal OUT2 and the linearly superposed signal OUT3.