Constructions of Asymptotically Optimal Space–Frequency Codes for MIMO-OFDM Systems

Constructions of space–frequency (SF) codes for multiple-input multiple-output (MIMO)–orthogonal frequency-division multiplexing (OFDM) systems with $n_t$ transmit antennas and $Q$ subcarriers are considered in this paper. Following the pairwise-error-probability analysis, it is known that in addition to the conventional rank distance criterion, the minimum column distance of $(n_t \times Q)$ SF codes serves as another benchmark in code design. SF codes with larger minimum column distance are expected to have better performance. Following this principle, the rate–diversity tradeoff for the MIMO–OFDM channels as well as two SF code constructions are presented.