Combining transmit antenna weights and orthogonal space-time block codes by utilizing side information

Multiple transmit and receive antennas can be used in wireless systems to achieve high data rate communications. Previously, space-time codes have been developed that utilize some of the capacity available. These codes are developed under the assumption that the transmitter has no knowledge about the channel. However we consider the case when the transmitter has partial, but not perfect, knowledge about the channel and how to adjust the antenna weights at the transmitter. A criterion is derived that optimally determines the transmit antenna weights when well known orthogonal space-time block codes are used. Simulation results using eight transmit antennas are included to demonstrate the performance.