Performance of STF Coded OFDM with Transmit Eigenbeamforming in Correlated Fading Channels

A new transmit diversity configuration that combines transmit eigenbeamforming with space-time-frequency (STF) coding for orthogonal frequency division multiplex (OFDM) systems is investigated. Based on the signal angle-of-arrival (AoA) estimates, channel correlation matrix is constructed. It is shown that signal transmission of STF codes in the eigen-modes of this matrix gives an effective array weighting gain which improves system error performance without sacrificing any diversity and coding gain. For imperfect AoA estimation, error probability loss due to incorrect estimation is quantified and the required accuracy of AoA estimation for securing the performance gain is shown for different angular spreads