A space-frequency-time diversity scheme for MIMO-OFDM systems

In this paper, a new coding scheme, for MIMO-OFDM systems that tends to exploit both space, time, and frequency diversity is introduced. The code, partially based on the well-known Alamouti scheme, works with a configuration of two transmit and n_r receive antennas and requires a channel with coherent impulse response during two OFDM signaling intervals. Monte Carlo simulations have been run to compare the new scheme with other designs. Simulations have shown that this scheme performs better than direct MIMO-OFDM transposition of space-time codes (e.g. transpositions of Alamouti scheme). Despite the reduced code rate 1/2 of this scheme, its performances show a superior diversity order characterized by a steeper slope of the bit error rate curves. Simulations were also run to gauge the effects of errors on channel parameters estimation. These errors were simulated through, a model derived from a MIMO-OFDM channel estimation technique