Proc. IEEE Int. Global
Nov. 29-Dec. 3, 2004, Dallas, TX, accepted for publication.
Comparison of Space-Time Water-filling and Spatial Water-filling for
MIMO Fading Channels
Robert W. Heath, Jr.,
Jeff Andrews, and
Brian L. Evans
Wireless Networking and Communications Group,
Dept. of Electrical and Computer Engineering,
The University of Texas at Austin,
Austin, TX 78712-1084 USA
In this paper, the capacities achieved by spacetime
water-filling and spatial water-filling for MIMO fading
channels are compared.
Both the effects of fast fading and shadowing are considered.
It is found that for Rayleigh fast fading MIMO channels, the
spectral efficiency per antenna achieved by one-dimensional
spatial water-filling is close to two-dimensional space-time
However, with log-normal shadowing, space-time water-filling
achieves significantly higher capacity per antenna than spatial
water-filling at low to moderate SNR regimes.
Furthermore, space-time water-filling has lower computational
complexity than spatial water-filling.
It is also shown that space-time water-filling requires a priori
knowledge of the channel gain distribution, and for Rayleigh
channels with lognormal shadowing, the spectral efficiency
advantage over spatial water-filling comes with an increased
channel outage probability.
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Last Updated 11/24/04.