Transmit Diversity Scheme for TDS-OFDM Systems with Reduced Complexity

To reduce the complexity of existing transmit diversity solutions for time domain synchronous OFDM (TDS-OFDM), a simple transmit diversity scheme is proposed in this paper. The space shifted constant amplitude zero autocorrelation (CAZAC) sequence is used for time-domain channel estimation. Two types of flexible frame structures are investigated for cyclicity reconstruction of the received inverse discrete Fourier transform (IDFT) block. Regarding to channel estimation and cyclicity reconstruction, the complexity of the proposed scheme is only about 7% of the conventional solutions. With the penalty of small loss in spectral efficiency, the proposed scheme achieves better bit error rate performance over doubly selective channels, which is demonstrated by the simulation results.