Space-time codes with controllable ML decoding complexity for any number of transmit antennas

We construct a class of linear space-time block codes for any number of transmit antennas that have controllable ML decoding complexity with a maximum rate of 1 symbol per channel use. The decoding complexity for M transmit antennas can be varied from ML decoding of 2^{lceillog2 Mrceil-1} symbols together to single symbol ML decoding. For ML decoding of 2^{lceillog2 Mrceil-n} (n = 1,2,hellip) symbols together, a diversity of min(M, 2^{lceillog2 Mrceil-n+1}) can be achieved. Numerical results show that the performance of the constructed code when 2^{lceillog2 Mrceil-1} symbols are decoded together is quite close to the performance of ideal rate-1 orthogonal codes (that are non-existent for more than 2 transmit antennas).