Improved transmission scheme for orthogonal space time codes

The major drawback of the orthogonal space time codes (OSTC) is the limited rate achieved by this family of codes. The known answer to this problem is the quasi-orthogonal space time codes (QSTC) which enables full rate with the penalty of high complexity decoding. Both degrades the performance of a system with high data rate demand due to the use of large constellation size to compensate the low symbol rate for the OSTC and the use of non-optimal but tractable decoding scheme for the QSTC. In this paper we present a way to increase the OSTC code rate while maintaining its orthogonal property which results in low complex decoding and improved performance for high data rate systems.