Effects of Quantization on Channel-Orthogonalized STBCs with Different Orthogonization Schemes

In this paper, we exploit the channel-orthogonal space-time block codings (CO-STBCs) in multiple-input multiple-output (MIMO) system. First we provide principles for designing CO-STBC schemes with angle feedback and propose two CO-STBC schemes (scheme A and scheme B) based on quasi-orthogonal STBC (QO-STBC) with different orthogonality strategies. Then we analyze the quantization of the feedback angle information and deduct its errors in the proposed CO-STBC schemes. Simulations verify the effectiveness of the proposed CO-STBCs, and the quantization process brings different errors to these schemes. It is demonstrated that the scheme A outperforms scheme B with the same number of feedback bits, and scheme B always needs one more bit for feedback than scheme A in order to reach the same performance.