An improved method to design QPSK Balanced Space-Time Trellis Codes

Recently, a new class of Space-Time Trellis Codes was proposed as having the best performance. These codes are ‘balanced’ because they use the points of the constellation with the same probability. In this correspondence, we propose a new and simpler method than exisiting method to design these class for QPSK modulation and several transmit antennas. New and better balanced codes for 3 and 4 transmit antennas are also proposed.