The invention relates to methods and apparatuses implementing a novel three-phase closed-loop CSI feedback scheme, in which receiver stations exchange local channel state information for optimal feedback design. One or more transmission stations transmit a sounding signal to a group of receiver stations via a channel using an antenna array, so as to enable the receiver stations to obtain local channel state information representing the instantaneous channel state. The channel state information of the receiver stations is shared so that at least one master station has the global channel state and can obtain based on the knowledge of the instantaneous global channel state and on some given optimization criterion an optimum feedback on the channel that allows one or more of the transmitting stations to select a transmission scheme for transmitting signals to the receiver stations. The optimized feedback is sent back to one or more of the transmission stations.
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