Design of quasi-orthogonal STBCs with delay optimality

Proposed is a systematic structure for producing quasi-orthogonal space-time block codes (QO-STBCs) to achieve delay optimality for any even number of transmit antennas. These codes are simple extensions of the conventional ABBA code with four transmit antennas, but they are based on a different symbol pairing that uses an independent cyclic-shifting operation for each input sub-vector. When compared to the conventional QO-STBCs, the proposed codes have significant benefits for receive decoding complexity, or in their averaged error performances.