Abstract—Amicable Complex Orthogonal Design (ACOD),

which is the complex version of Amicable Orthogonal Design first reported in [1], is proposed and its existence is proven. Using ACOD, new orthogonal space-time block codes (O-STBC) for four and eight transmit antennas are constructed. Their maximum achievable code rates are proven to be as high as the existing O-STBC designs. In addition, the new O-STBCs are shown to have better practical implementation features than the existing O-STBCs, as they do not require any transmit antenna to be turned off intermittently (which is beneficial for the power amplifier design), and they do not have irrational-number coefficients inside the codeword (which simplifies the hardware implementation). I