基于空时分组编码的差分检测方法

Differential detection scheme based on space-time block codes

利用正交设计原理提出了通用的差分空时分组码(GDSTBC, general differential space-time block code)。与已有的差分调制方法相比,GDSTBC对信号星图无任何限制,因而可利用幅度和相位同时携带信息提高频谱效率。基于最大似然准则,给出了平坦Rayleigh衰落信道下的非相干译码器。我们将证明:在高信噪比下,GDSTBC能够以线性复杂度和满天线分集恢复数据符号;在PSK调制方式下,没有信道估计时性能下降3dB;Ganesan基于PSK星图的差分空时分组码、Xia基于APSK星图的差分空时调制技术都可看成GDSTBC的特例。

Utilizing the theory of orthogonal design, this paper presents a general differential space-time block code (GDSTBC). Compared with the existing differential modulation designs, GDSTBC imposes no restrictions on underlying signal constellations. This generalization potentially allows the spectral efficiency to be increased by carrying information not only on phases but also on amplitudes. Based on maximum-likelihood criterion, we derive a noncoherent decoder for flat Rayleigh fading channels. We will show that: GDSTBC may recover data symbols with linear complexity and full antenna diversity at high SNR. In the case of PSK modulation, performance degrades by 3dB while channel estimates are not available.Ganesans DSTBC based on PSK constellation and Xias differential space-time modulation technique based on APSK constellation are both the special cases of GDSTBC.