【摘要】 讨论了几种准正交空时码的编码及解码问题;分析了准正交空时码编码矩阵的缺秩问题及最大似然解码时至少有两个符号相关联的现象,即分析了准正交空时码的分集增益减小特性与最大似然解码复杂度的增加问题;阐释了通过星座图旋转固然可以保证准正交空时码的分集增益但却无法克服其最大似然解码复杂度的增加,因此,必须从编码矩阵本身出发来解决算法复杂度,为研究以"面向单符号"的最大似然解码算法奠定基础。最后给出了一定的计算机模拟结果以说明理论分析的有效性。更多还原

【Abstract】 A detail analysis of several quasi-orthogonal space-time coding and decoding schemes are provided.Both the quasi-orthogonal space-time coding matrices with rank deficiency and the maximum likelihood decoding being related to with at least two symbols are analyzed,i.e.,quasi-orthogonal space-time codes reduce the diversity gain and increasing the maximum likelihood decoding complexity.Rotating the constellation could guarantee the diversity gain but can not overcome the increasing complexities of the maximum likelihood decoding.Therefore,it is necessary to research "symbol orientated" decoding algorithm for the quasi-orthogonal space-time coding.Some results of computer simulations are given to illustrate the validity of theoretical analysis.更多还原