Grassmannian beamforming on correlated MIMO channels

Abstract

The diversity gains available from multiple-input multiple-output (MIMO) wireless systems are well documented. These gains are realizable through the use of transmit beamforming and receive combining. Transmit beamforming relies on the assumption of channel knowledge at the transmitter, an assumption that is often unrealistic. Limited feedback beamformers have been designed over the past few years, but they concentrate primarily on the assumption of a spatially uncorrelated Rayleigh fading channel matrix. The paper addresses the design of limited feedback beamformers for transmit and receive correlated MIMO channels. In particular, we use a technique where the receiver chooses the beamforming vector from a codebook of possible vectors and conveys this vector over a limited feedback channel. We show how this method obtains full diversity order. Monte Carlo simulations show performance close to optimal beamforming.