Balanced QPSK space-time trellis codes
All the best known space-time trellis codes (STTCs) belong to the balanced STTC class. The first method to design balanced STTCs is proposed. The exhaustive code search of optimal codes can then be reduced to this class. Finally, the proposed method is used to construct new QPSK codes for three and four transmit antennas, which outperform the best previously published codes of the same complexity.