Differential Space-Time Spreading with Segment Selective Repeat-Based Automatic Repeat Request

In this paper, we first propose differential space- time spreading (DSTS) with multiple transmit antennas. With the assumption of no channel state information at either the transmitter or the receiver, the DSTS signal is differentially encoded and decoded. The proposed method achieves full transmit diversity gains. As compared to the coherent space-time spreading (CSTS) method, the proposed scheme has 3-dB performance degradation, but avoids the demand of perfect channel estimation. We then combine DSTS with segment selective repeat (SSR)-based automatic repeat request (ARQ). By utilizing the estimated channel gain of DSTS at the receiver, only the worse corrupted portion of the data is retransmitted upon error to improve efficiency. It is shown that the proposed DSTS with SSR-based ARQ achieves higher throughput than DSTS with Type-I ARQ while maintaining similar bit error rate (BER).