Adaptive Detection for Double STBCs Based on QR Decomposition

This study proposes an efficient detection algorithm for double space-time block codes (DSTBCs) to improve the algorithm of Kim et al. The proposed algorithm applies QR decomposition to the channel matrix of the DSTBC to obtain an upper triangular matrix. The diagonal entries of the upper triangular matrix contain two different values. The proposed algorithm adaptively determines the number of candidates for the DSTBC according to the ratio of these two diagonal values. When their ratio is large, the number of the candidates decreases. Finally, the detection result is searched among the candidates based on a maximum-likelihood criterion. Numerical results demonstrate that the computational complexity for the search process can be reduced by 70% with little performance loss at a bit error rate (BER)of 10^-4.