Space-time OFDM with adaptive beamforming: performance in spatially correlated channels

Space-time block coding (STBC) has proved to be an effective means of exploring diversity branches and improving system performance. In a previous work we proposed an extension to that where the STBC was combined with adaptive eigenbeamforming, an approach that takes an advantage of spatial channel correlation and can provide further improvement for the overall system performance. In this paper, we investigate this new transmission structure for broadband orthogonal frequency division multiplexing (OFDM) systems in frequency-selective channels. Numerical analysis showed that systems employing this scheme would not undergo any diversity losses as it maintains the maximum achievable diversity advantage of space-time (ST) codes in realistic channel conditions. Simulation results showed that the proposed structure has a significant improvement in bit/symbol error rate performance in a spatially correlated channel over systems that utilize only space-time coding.