Space-time block codes from co-ordinate interleaved orthogonal designs

We present space-time block codes called 'co-ordinate interleaved orthogonal designs' (CIOD). These codes have low decoding complexity; the same as that of the codes from complex orthogonal designs (COD). Rate 1 CIOD exist for two, three and four transmit antennas and rate 3/4 CIOD exist for five, six, seven and eight transmit antennas while COD exists only for two antennas and generalized COD (GCOD) of rate 3/4 are known to exist for three and four transmit antennas only. The maximum mutual information of these codes is also calculated.