Trellis-coded differential unitary space-time modulation in slow flat fading channels with interleaver

This paper considers trellis-coded differential unitary space-time modulation for multiple-antenna systems when neither the transmitter nor the receiver has access to channel state information. The channel is assumed to be slowly time-varying flat Rayleigh fading with ideal interleaver. We derive the metric for maximum likelihood differential decoding and the Chernoff bound for pair-wise error probability. We show that performance is dominated by the minimum Hamming distance which contributes linearly to the order of diversity. Code construction is described for rate m/(m + 1) trellis codes. Several code examples are provided based on diagonal cyclic group constellations for two transmit antennas with data rate 1 and 2 bits/s/Hz. Simulation results show that the proposed trellis-coded differential scheme can achieve high data rate communications by medium signal-to-noise ratio without channel estimation