酉变换准正交空时编码

Unitary conversion quasi-orthogonal space-time code

设计了一种采用预编码方式的准正交空时编码（quasi-orthogonal space time code, QOSTC）,其编码方案是首先对发送信号向量进行与信道状态信息无关的酉变换,然后再进行正交编码.酉变换可将QOSTC信道能转化为并行复用传输信道,实现无符号间干扰的高速率并行传输,且接双端信号的最大似然（maximum likelihood,ML）符号译码可简化成线性译码,从而可采用简单的线性检测降低译码复杂度.仿真结果表明,在高信噪比下,酉变换的QOSTC线性检测比没有酉变换的QOSTC的ML检测差2dB左右,但其分集度几乎相同.

A quasi-orthogonal space-time code （QOSTC） with preceding is proposed. A unitary transform independent of the channel state information is performed on the transmitted signal, followed by a quasi-orthogonal encoding process. Thus QOSTC channels are transformed into parallel multiplexing ones, leading to high data rate non-intersymbol interference transmission. What＇s more, maximum likelihood （ML） decoding at the receiver end can be simplified into linear operation , therefore simple linear detection can be used to reduce decoding complexity. Simulation result shows that at high SNR region, unitary transformed QOSTC with linear detection is only about 2dB inferior to untransformed QOSTC with ML detection, while having almost the same diversity order.