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 BER 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.