Designs of Differential Space-Time and Space-Frequency Coded OFDM Schemes

The simple differential designs on both space-time coded OFDM (STC-OFDM) and space-frequency coded OFDM (SFC-OFDM) are introduced when neither the transmitter nor the receiver has the channel state information. In the differential STC-OFDM (DSTC-OFDM) and the differential SFC-OFDM (DSFC-OFDM) systems, the block differential encodings are adopted in the time dimension and the frequency dimension, respectively. We give the detailed description and theoretical analysis of the two schemes. The effectiveness in achieving the transmitter diversity is illustrated by simulations in both slow and fast fading environments. By taking the advantage of the characteristics of the OFDM frame structure, the computational complexity of the introduced schemes is greatly reduced.