Comparative study of open-loop transmit diversity schemes with four antennas in DFT-precoded OFDMA using turbo FDE and iterative channel estimation

This paper compares the block error rate (BLER) performance of open-loop (OL) transmit diversity schemes with four antennas in the uplink for discrete Fourier transform (DFT)-precoded orthogonal frequency division multiple access (OFDMA). One candidate is a quasi-orthogonal (QO) - space-time block code (STBC) in which four-branch minimum mean-square error combining (MMSEC) is achieved at the cost of residual inter-code interference (ICI). Another candidate is a combination of STBC and selection diversity called time switched transmit diversity (TSTD) or frequency switched transmit diversity (FSTD). We assume a turbo frequency domain equalizer (FDE) associated with iterative decision-feedback channel estimation (DFCE) at a receiver to reduce the influences of the residual ICI and channel estimation (CE) error. From the extensive link-level simulation results, we show that a combination of STBC and TSTD (FSTD) is suitable as four-antenna OL transmit diversity scheme for DFT-precoded OFDMA using turbo FDE and iterative DFCE.