Improved diagonally weighted space-time trellis codes with two transmit antennas

Thus far, most work on space-time trellis codes (STTCs) has assumed that the transmitter has no knowledge about the channel. In certain situations, however, it is reasonable to assume that the channel information at the transmitter is available. In this paper, we consider diagonally weighted space-time trellis codes with two transmit antennas. We derive performance criteria for designing STTCs and a feedback scheme in a perfect feedback channel. A simple modification of the conventional STTC is proposed, based on the performance criteria, and some modified STTCs are found through computer search. Simulation results show that the modified STTCs achieve improved performance over a wide range of feedback channel conditions.