A Pragmatic Design of Space-time-frequency Coding

This paper presents a design methodology and resulting schemes for space-time-frequency (STF) coding and linear preceding of downlink multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) modulated wireless systems, based on practical hypotheses. In particular, the design takes into account the fact that the receiver implements STF minimum mean square error (MMSE) detector instead of traditional optimal receivers, which are probably too complex to address high spectral efficiencies. The design also takes into account that long term channel statistics is easily available at the transmitter side, while the receiver reasonably has access to instantaneous channel knowledge. The resulting schemes combine STF coding or linear preceding with long-term eigenbeam selection with a specific power loading. Numerical evaluation on correlated flat fading channel shows that they outperform a state-of-the-art scheme combining spatial multiplexing and space time orthogonal block coding (STOBC) in terms of bit error rate (BER) and other intermediate design criteria. Their low decoding complexity and good performance make them relevant for practical implementation