New quasi-orthogonal differential detection for differential space-time modulation

In this paper, we propose a new complex pair-wise differential detection for quasi-orthogonal differential space-time modulation (QO-DSTM) using four transmit antennas. Since the new detection allows independent joint ML detection of two complex symbol pairs, the decoding complexity is the same as or lower than conventional differential detection. Furthermore, the new detection exhibits better performance than the conventional complex pair-wise detection despite identical decoding complexity. Although the error performance of new detection is lower than that of improved differential detection (IDD), the loss is acceptable considering the decoding complexity.