一种全速率准正交空时分组码

空时分组码是发射分集中的一项新技术。通常的空时分组码采用正交设计，虽可以提供全分集增益，却不能保证全速率传输，造成发射端数据的积压。改进的空时分组码采用准正交设计，能够保证数据以全速率传输，但是其性能在低信噪比时优于正交空时分组码，在高信噪比时反而不如前者。提出一种改进的基于准正交设计的空时分组码。通过仿真表明，在不增加译码复杂度的情况下，其性能不论在低信噪比还是高信噪比时都优于正交设计的空时分组码，从而改善了系统性能。

An improved space - time block code based on quasi - orthogonal design

Space-time block codes (STBC) are a new technology of transmitting diversity. Orthogonal codes are a class of space-time block codes that achieve full diversity gain and typically at a loss of code rate. This leads up to the deposit of the data at the transmitting point. The code rate can be made higher by constructing quasi-orthogonal codes. The performance of these codes is better than that of the codes from orthogonal designs at low SNR, but worse at high SNR. This paper proposes an improved space-time block codes based on quasi-orthogonal design. The simulation results demonstrate that the new scheme can improve the performance not only at low SNR but also at high SNR, while the decoding complexity is the same as other quasi-orthogonal codes.