Unitary Space-Time Modulation for Multiple-Antenna Communications in
Rayleigh Flat Fading
Bertrand M. Hochwald
Thomas L. Marzetta
Abstract:
We propose a signalling scheme called unitary space-time modulation
for multiple-antenna communication 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
where T represents the coherence interval during which the fading is
approximately constant, and M < T is the number of transmitter antennas. The
columns of each signal are orthonormal. When the receiver does not know
the propagation coefficients, which between pairs of transmitter and
receiver antennas are modeled as statistically independent, this modulation
performs well either when the SNR is high or when T >> 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.
Status:
TM, Bell Laboratories, Lucent Technologies, 1998. To appear in IEEE
Transactions on Information Theory, March 2000.
Files:
Compressed PostScript (.ps.gz) (157K),
PostScript (.ps) (717K),
PDF v3.0 (.pdf) (395K).
Bert Hochwald <hochwald@bell-labs.com>