Improved space-time trellis codes with three and four transmit antennas

It has been shown that the rank and the determinant of the distance matrices are the design criteria for space-time trellis codes over quasi-static Rayleigh fading channels. Recently, a new design criterion that maximizes only the trace has been proposed for systems with a large product of the numbers of transmit and receive antennas. This criterion is useful and yields superior codes when the product of the numbers of receive and transmit antennas is at least 4. In this paper, new QPSK space-time trellis codes for 3 and 4 transmit antennas with up to 1024 states are presented. Our 64-state codes for 3 and 4 transmit antennas present a larger trace and provide a better error performance than previously published codes with the same number of states. If a smaller error probability is required, a further improvement can be achieved by increasing the number of states at the expense of additional complexity.