Generalized RAKE receivers for MIMO systems

Recently, a variety of multiple-input multiple-output (MIMO) antenna techniques have been proposed for inclusion in the WCDMA standard. We develop two novel, multi-antenna receiver structures for MIMO operating in frequency-selective fading environments that offer a significant reduction in complexity compared to other MIMO equalizer structures. Both receivers are extensions of the generalized RAKE receiver (GRAKE) for single antenna systems; which receiver to use depends on the degree of dispersion in the channel. However, the two receivers together provide an attractive adaptive solution whereby the receivers are switched as the degree of dispersion changes. Moreover, it is shown that the combined solution is able to achieve performance close to the matched filter bound in a wide variety of frequency-selective fading environments.