EURASIP Journal on Wireless Communications and Networking 
Volume 2006 (2006), Article ID 16281, 8 pages
doi:10.1155/WCN/2006/16281

Space-Time Water-Filling for Composite MIMO Fading Channels

Zukang Shen, Robert W. Heath Jr., Jeffrey G. Andrews, and Brian L. Evans

 Department of Electrical and Computer Engineering, University of Texas at Austin, Austin 78712, TX, USA
Received 1 September 2005; Revised 14 February 2006; Accepted 13 March 2006

Abstract

We analyze the ergodic capacity and channel outage probability for a composite MIMO channel model, which includes both fast fading and shadowing effects. The ergodic capacity and exact channel outage probability with space-time water-filling can be evaluated through numerical integrations, which can be further simplified by using approximated empirical eigenvalue and maximal eigenvalue distribution of MIMO fading channels. We also compare the performance of space-time water-filling with spatial water-filling. For MIMO channels with small shadowing effects, spatial water-filling performs very close to space-time water-filling in terms of ergodic capacity. For MIMO channels with large shadowing effects, however, space-time water-filling achieves significantly higher capacity per antenna than spatial water-filling at low to moderate SNR regimes, but with a much higher channel outage probability. We show that the analytical capacity and outage probability results agree very well with those obtained from Monte Carlo simulations.