Multiple input, multiple output (MIMO) systems using singular value decomposition (SVD) require channel state information (CSI) at both the transmitter and the receiver. Operation over a time division multiplexing (TDD) channel avoids the requirement of a feedback channel but the CSI must be updated some 3.36 times faster than the update rate in the feedback mode. Hence, the TDD mode can only be applied to channels facing a very low Doppler frequency, or using very short frames.