Robustness of space-time turbo codes

We consider the performance of a turbo code with 2 transmit antennas and 2 receive antennas for flat fading channels. We consider robustness within and among families of channels with the same singular values (SVs). When the two SVs are similar, the bit error rate performance is robust in terms of proximity to the channel capacity. When the 2 SVs differ significantly, robust performance can be achieved by a time-varying linear transformation (TVLT). Iterative decoding is the same as for standard parallel concatenated convolutional codes, except that the extrinsic information about encoder outputs are also exchanged.