An Enhanced Transmit Diversity Scheme for MIMO MC-CDMA Systems using Three Antennas

In this work, an enhanced transmit diversity scheme for downlink scenarios is presented for multi-input multi-output, multicarrier systems. Specifically, orthogonal, full rate operation of Alamouti´s scheme has been utilized in an architecture with three transmit antennas, whereas at each time instant only two of them are active. The antenna switching is based on a predetermined pattern achieving a space diversity increase and at the same time transparency with respect to the receiver structure. The performed analysis and the simulated results indicate a performance increase especially for the cases with variable inter-element spacing. These results become more visible as the channel time variation increases. The evaluation has been based on realistic spatial channel models for various modulation formats and FEC codes.