Improvements to MIMO systems

Processing a plurality of multiple-input multiple-output (MIMO) signals for transmission over a plurality of communication channels, comprising: precoding the plurality of signals prior to transmission, the precoding incorporating channel state information (CSI) in relation to the plurality of communication channels, the precoding further incorporating: a priority ranking of a first channel of the plurality of communication channels relative to a second channel of the plurality of communication channels; and/or an error rate required by a channel of the plurality of communication channels; and/or an amount of noise experienced by a channel of the plurality of communication channels. The CSI may be contained within a channel matrix and the channel matrix may be modified to generate a modified channel matrix subsequently used in precoding operations.