Improved design criteria and new trellis codes on space-time trellis coded modulation in fast fading channels

Design criteria on space-time trellis codes (STTC´s) in fast fading channels have been derived by Tarokh, Seshadri and Calderbank (1998): the distance criterion and the product criterion. The design criteria of Tarokh et al. are based on optimizing the pairwise error probability (PWEP). However, a frame error rate (FER) of STTCs depends on the distance spectrum. We propose new design criteria on STTCs based on the distance spectrum in fast fading channels. The proposed design criteria are based on the product distance distribution for a high signal-to-noise ratio (SNR) and the trace distribution for a low SNR, respectively. Moreover, we propose new STTCs by the computer search based on the proposed design criteria in fast fading channels. By the computer simulation, we show that the proposed design criteria are more useful than the product criterion of Tarokh et al. in fast fading channels. We also show that the proposed STTCs achieve better FER than the conventional STTCs in fast fading channels.