In this paper we study spacetime coding schemes for a novel OFDM-based MIMO system which performs adaptive signal combining in radio-frequency (RF). Assuming perfect channel knowledge at the receiver and statistical channel state information at the transmitter, we consider the problem of selecting the transmit and receive RF weights (beamformers), as well as the time and frequency linear precoders, under the assumption of Rayleigh channels. The transmission scheme is based on orthogonal beam division multiplexing (OBDM) and minimum mean-square error (MMSE) receive beamforming, i.e., the data is transmitted by means of several transmit beamformers matched to the spatial correlation matrix, whereas the receive beamformers are selected to minimize the MSE of the linear MMSE receiver. Finally, the performance of the proposed scheme is evaluated by means of Monte Carlo simulations.
- Analog combining
- Multiple-input multiple-output (MIMO)
- Orthogonal beam division multiplexing (OBDM)
- Orthogonal frequency division multiplexing (OFDM)
- Pre-FFT beamforming