A Multiple Input Multiple Output (MIMO) system in a radio access network (RAN) comprises a virtualized baseband unit, an antenna array; and a fronthaul network that connects the virtualized baseband unit to the antenna array. For a first set of antennas in the antenna array, the virtualized baseband unit generates a first MIMO matrix from channel state information (CSI); computes a sparse update matrix corresponding to an update to the first set of antennas; sums the sparse update matrix with the first MIMO matrix to produce a second MIMO matrix corresponding to a second set of antennas in the antenna array; determines which of the MIMO matrices results in a better CSI, MIMO condition number, peak-to-average-power ratio, or quality metric of spatial subchannels; and based on the determination, selects the first set of antennas or the second set of antennas to transmit or receive signals in the RAN.