Orthogonally constructed space-time codes

Space-time coding is a promising technique for high data-rate wireless communications. But the difficulty of constructing good space-time codes increases rapidly with the number of transmit antennas. We propose an constructing method called orthogonal construction, which can be used to obtain new space-time codes for more transmit antennas from old codes. We find the symmetry in the branch metrics of orthogonally constructed codes, which leads to lower decoding complexity. Simulation results show that orthogonally constructed codes even outperform the optimum convolutional code from exhaustive computer search with the same code rate and similar decoding complexity.