Unitary Space-Time Modulation for Multiple-Antenna Communications in Rayleigh Flat Fading

Motivated by information-theoretic considerations, we propose a signalling scheme, unitary space-time modulation, for multiple-antenna communications links. This modulation is ideally suited for Rayleigh fast-fading environments, since it does not require the receiver to know or learn the propagation coefficients. Unitary space-time modulation uses constellations of T x M space-time signals {PHI sub t, l = 1,....L}, where T represents the coherence interval during which the fading is approximately constant, and M M. We design some multiple-antenna signal constellations and simulate their effectiveness as measured by bit error probability with maximum likelihood decoding. We demonstrate that two antennas have a 6 dB diversity gain over one antenna at 15 dB SNR.