QR-decomposition-based linear and decision-feedback detections for D-STTD systems over time-selective fading channels

In this paper, we propose QR-decomposition-based unordered/ordered decorrelating decision-feedback detection (D-DFD) schemes with linear or D-DFD symbol estimators for a double space-time transmit diversity (D-STTD) system. The time-selective fading mobile channel severely degrades the performance of conventional detectors, since the time-selectivity of the fading channel destroys the orthogonality of the space-time codeword. Moreover, the complexity of the known symbol-by-symbol detectors is too high to be implemented, due to the multiple channel inversions. In contrast, through the block-by-block QR-decomposition, our proposed methods can decorrelate the two STTD units while preserving the Alamouti-like codeword structure and exploit this structure to efficiently estimate the symbols corrupted by the severe time-selective fading channels