Error statistics of optimal and sub-optimal space-time trellis codes: concatenation requirements

The bit error rate and frame error rate performance of space-time trellis codes are analysed. The analysis shows that for increasing number of states in the trellis codes, the FER performance improves; however, the BER performance does not always do so. By considering error event paths in trellises of different complexities, it is shown that this effect is owed to the increased recovery time from an erroneous decision needed by the trellis code of higher complexity. The results from this study also indicate certain design criteria when space-time trellis codes are concatenated with channel codes.