大於兩根傳送天線具有全散度以及碼率為一的複數正交時空編碼已被證明出並不存在。在本研究中，我們結合Jafarkhani 學者所提出的四根傳送天線準正交時空編碼並利用Twin-QPSK 調制產生新的時空編碼。此時空編碼為正交，且具有全散度 (full diversity) 的特性，雖然其碼率 (code rate) 為一，但因其利用Twin-QPSK 調制達到正交以及全散度的特性，每傳輸十二個位元中，有十個為傳送訊號的位元，而另外二個則是為了編碼所傳送的位元。由於Twin-QPSK 正交編碼傳送訊號必須兩兩相依的特性，因此解碼時需要成對地來解。

It has been shown that more than two antennas complex orthogonal space-time block code with full diversity and full code rate does not exist. Here, combining Twin-QPSK modulation with quasi-orthogonal space-time block code which was presented by Jafarkhani, we encode a new four antennas orthogonal space-time block code. This orthogonal code achieves full diversity and full code rate. There are twelve transmitting bits in this new code, ten of them are information bits and rests are redundancy. According to the characteristic of the orthogonal space-time block code by
using Twin-QPSK, the receiver has to decode the transmitted signals in pairs.