In this paper, we propose a novel transmit diversity technique in multiple-input multiple-output (MIMO) wireless communication systems. The major difference between our work and other existing MIMO diversity techniques is that we consider the case in which the channel state information (CSI) is perfectly known to a transmitter but unknown to a receiver. This communication scenario may have applications in a time division duplex (TDD) system with periodic channel sounding pilot signals transmitted from the receiver. With this scheme, the complexity of the receiver can be greatly reduced due to the fact that most of signals processing efforts are shifted to the transmitter side. We propose a simplified non-coherent detection method that almost fully utilizes the potential spatial diversity gain in this communication scenario. Numerical results show that the performance of this method is very close to that of the optimum beamforming technique which requires CSIs at both the transmitter and the receiver.