Universal space-time trellis codes

This correspondence gives practical examples of space–time trellis codes performing as predicted by Root and Varaiya’s compound channel theorem. Specifically, 32-state and 64-state 2 2 space–time trellis codes are presented that provide a bit-error rate (BER) of10 on all2 2 matrix channels with an excess mutual information (MI) within 8% of the excess MI required by standard trellis codes of the same complexity operating only in additive white Gaussian noise (AWGN). Not surprisingly, the universal space–time trellis-coded modulations (ST-TCMs) provide average bitand frame-error rates in quasi-static Rayleigh fading (QRF) that are comparable to those achieved by ST-TCMs designed specifically for QRF as well as standard TCMs followed by the Alamouti space–time block code. However, all of these other schemes require more excess MI in the worst case, and some have a significantly wider variation in the required excess MI. The correspondence also compares the universal and quasi-static Rayleigh fading design approaches analytically and bounds the worst case distance of a trellis code on a 2 2 channel using the distances of the code on singular and unitary channels. This bound is extended to the more general scenario.