A low complexity approach to space-time coding for multipath channels

We consider a low-complexity single-carrier space-time coding scheme for frequency-selective channels based on the concatenation of an outer Trellis-Coded Modulation (TCM) with an inner Time-Reversal Orthogonal Space-Time Block Code (TR-STBC). The TR-STBC reduces the Multi-Input Multi-Output (MIMO) frequency-selective channel to a standard Single-Input Single-Output (SISO) channel affected by Inter-Symbol Interference (ISI). Hence, we apply reduced-state sequence detection based on combined equalization and Viterbi decoding in order to decode the outer TCM code. We motivate this structure via an information theoretic argument, and we show that for sufficiently large interleaving depth it achieves the maximum diversity offered by the channel. Our scheme achieves better spectral efficiency than space-time spreading and much lower complexity with similar/superior performance than other proposed schemes with the same spectral efficiency.