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The Alamouti space-time code for transmission diversity is extended recursively to 2/sup n/ /spl times/ 2/sup n/ antenna elements as well as to unsymmetrical arrays of size m /spl times/ n. The proposed schemes exhibit two significant advantages: they allow for higher diversity (of degree 2/sup n/ for the symmetrical case) and at the same time can be implemented as zero-forcing or MMSE type at low complexity avoiding any matrix inversion due to the structure in the transmission matrices as well as low complexity ML.