Transmit diversity over quasi-static fading channels using multiple antennas and random signal mapping

We introduce a scheme that achieves a diversity gain for coded systems under static fading conditions by using multiple antennas and random signal mapping. In a two-antenna system, the bit-error rate performance of the proposed scheme approaches that of Alamouti´s scheme when the channel is perfectly known. In the presence of channel mismatch, the proposed scheme outperforms Alamouti´s scheme significantly. It is shown that, as the number of transmit antennas N goes to infinity, the effective channel for the introduced scheme behaves as if it were perfectly interleaved (i.e., as if the fading was independent). When N is small, further performance gain can be achieved by expanding the original signal constellation.