A space-time block-coded OFDM scheme for unknown frequency-selective fading channels

We introduce a space-time block-coded orthogonal frequency-division multiplexing (MC-OFDM) scheme for frequency-selective fading channels which does not require channel knowledge either at the transmitter or at the receiver. The decoding algorithm is based on generalized maximum-likelihood sequence estimation. Due to the assumed orthogonality structure of STBC, the decoding rule reduces to a single step. Its form also allows the derivation of a recursive expression, which can be easily implemented by a Viterbi-type algorithm. We investigate the performance of the proposed scheme over two-tap Rayleigh fading channels. Simulation results show the performance of the proposed recursive-type receiver to be near optimum