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Abstract : |
Motivated by information-theoretic considerations, we propose a signalling scheme, unitary spacetime 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 \Theta M space-time signals f\Phi ` ; ` = 1; : : : ; Lg, 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 \Phi ` 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 very well either when the SNR is high or when T AE 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. Index Terms---Multi-element antenna arrays, wireless communications, channel coding, fading channels, transmitter and receiver diversity, space-time modulation 1, |
