Should MIMO orthogonal space-time coding be preferred to non-orthogonal coding with iterative detection?

In order to propose practical solutions to the future communication systems employing MIMO structures, we compare the performances obtained by using orthogonal and non-orthogonal space-time codes. For the latter case, we propose to use a simple iterative detector based on parallel interference cancellation. The choice of an orthogonal or a non-orthogonal code with iterative detection is then studied for several space-time coding schemes and for two or three antennas at transmitter. We show that when frames are long enough so that we can estimate properly the detector parameters, non-orthogonal codes can provide considerable gain over orthogonal designs at the price of a more complex detector