Performance comparison of two space-time trellis-coded modulation schemes

In Tarokh´s space-time trellis-coded modulation (STTCM), diversity gain is relatively easy to control by the rank of the code distance matrix. However, it is difficult to perfectly optimize coding gain. Meanwhile, by concatenating orthogonal space-time block codes with traditional trellis-coded modulation, we may obtain full diversity with large coding gain at the price of possible rate loss. In this paper, a coding gain expression is derived to analyze the performance of the two schemes at the same bandwidth efficiency. By assigning optimum codes on Tarokh´s STTCM and the concatenated orthogonal STTCM with two transmit antennas and one receive antenna, our analysis and simulation results show that the orthogonal scheme outperforms Tarokh´s scheme 1.0 dB ∼2.0 dB at the given bandwidth efficiencies.