低信噪比下对角交替的酉空时码

Diagonal Alternating Unitary Space-Time Codes at Low Signal-to-Noise Ratio

在低信噪比情况下,提出了一种基于循环对角码的改进的酉空时码设计.该方案不同于循环对角码的是,所构造的码符号星座集中的酉矩阵在主对角线和次对角线上交替出现非零元素.理论分析表明,低信噪比下新提出的酉空时码的误符号率联合界小于循环对角码.以误符号率联合界为准则,通过进一步优化参数来提高新的酉空时码的性能.仿真结果表明,在相当大的信噪比范围内该酉空时码的性能显著优于循环对角码.

Based on cyclic diagonal codes, an improved design of unitary space-time codes （USTC） at low SNR is proposed. What makes the new design different from cyclic diagonal codes is that the nonzero entries of unitary matrices in the signal constellations appear at the leading diagonal and the minor diagonal alternately. Theoretical analysis shows that the union bound （UB） on symbol error probability （SER） of the proposed USTC is smaller than that of cyclic diagonal codes. To further improve performance of the proposed design, its parameters are optimized to minimize UB on SER. Simulation results demonstrate superiority of the proposed method over cyclic diagonal codes in a wide range of SNR.