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 COSTBC 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 COSTBC 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.