Code Design for Combined Space Time Trellis Codes and Beamforming on Slow Fading Channels

The performance of space-time codes can be dramatically improved by weighting transmitted signals. In this paper, we present the performance analysis of the combined space time trellis codes and beamforming, referred to as weighted space time trellis codes (WSTTCs). Contrary to the standard STTC, WSTTCs can achieve a full diversity order regardless of STTCs adopted at the transmitter. A new design criterion for WSTTCs has been proposed and the good codes based on this criterion have been found by computer search. Simulation results show that the proposed 4, 16, and 64-state WSTTCs not only outperform the standard STTCs with the same number of state by more than 2dB, but are also superior by about 0.3dB, 1.1dB and 2dB to the conventional beamforming scheme, which allocates full power in the direction of the eigenvector corresponding to the maximum singular value of the channel matrix.