Removing error floor for bit interleaved coded modulation MIMO transmission with iterative detection

We present a method to remove the error floor of an iterative bit interleaved coded modulation MIMO (multiple-input multiple-output) system when Gray mapping is used without shifting the position of the turbo cliff to higher SNR. To do so, code doping is applied by introducing an additional rate 1 inner encoder. We optimize doping rate and outer code by using the EXIT chart. Simulations reveal transmission without error floor for a rate 1/2, 4 × 4 MIMO system with 16-QAM per antenna, resulting in a transmission of 8 information bits per channel use, with a turbo cliff position that is 2 dB smaller compared to state of the art.