A base station for wireless communication comprising: a communication unit configured to transmit a Long Term Evolution Advanced, LTE-Advanced, channel state information, CSI, reference signal, CSI-RS; a first multiplication unit configured to multiply transmission data with a first matrix of transmission weights, V1, that is determined based on reception of the CSI reference signal, CSI-RS, by a mobile station; and a second multiplication unit configured to multiply the transmission data with a second matrix of transmission weights, V2, that is determined based on reception of the CSI reference signal, CSI-RS, by the mobile station, wherein determination of the first and the second matrix of transmission weights is based on reception at the mobile station of the LTE-Advanced CSI reference signal that is transmitted by the base station without pre-coding, wherein the first matrix of transmission weights, V1, is applied to the result of multiplying the transmission data with the second matrix of transmission weights, V2, for Multi-User Multiple Input Multiple Output, MU-MIMO, transmissions, said base station characterised in that the communication unit is further configured to transmit a weighted CSI reference signal, V1*CSI-RS, that is obtained by multiplying the LTE-Advanced CSI reference signal, CSI-RS, with the first matrix of transmission weights, V1, after determination of the first matrix of transmission weights, V1, wherein the second matrix of transmission weights, V2, is determined based on the reception of the weighted CSI reference signal, V1*CSI-RS, when the weighted CSI reference signal is transmitted. a communication unit configured to transmit a Long Term Evolution Advanced, LTE-Advanced, channel state information, CSI, reference signal, CSI-RS; a first multiplication unit configured to multiply transmission data with a first matrix of transmission weights, V1, that is determined based on reception of the CSI reference signal, CSI-RS, by a mobile station; and a second multiplication unit configured to multiply the transmission data with a second matrix of transmission weights, V2, that is determined based on reception of the CSI reference signal, CSI-RS, by the mobile station, wherein determination of the first and the second matrix of transmission weights is based on reception at the mobile station of the LTE-Advanced CSI reference signal that is transmitted by the base station without pre-coding, wherein the first matrix of transmission weights, V1, is applied to the result of multiplying the transmission data with the second matrix of transmission weights, V2, for Multi-User Multiple Input Multiple Output, MU-MIMO, transmissions, said base station characterised in that the communication unit is further configured to transmit a weighted CSI reference signal, V1*CSI-RS, that is obtained by multiplying the LTE-Advanced CSI reference signal, CSI-RS, with the first matrix of transmission weights, V1, after determination of the first matrix of transmission weights, V1, wherein the second matrix of transmission weights, V2, is determined based on the reception of the weighted CSI reference signal, V1*CSI-RS, when the weighted CSI reference signal is transmitted.