1. A method for detecting a plurality, M, of transmitted signals transmitted across a channel by respective transmitting antenna elements in a multiple-input multiple-output communications system, the method comprising the steps of: (a) collecting a plurality of received signals from respective receiving antenna elements in said communications system; (b) determining a channel matrix H of estimated channel coefficients based on said plurality of received signals; (c) computing an estimate of a selected one of said transmitted signals, said estimate based on said plurality of received signals and on an intermediate matrix Q, thereby resulting in detection of the selected one of said transmitted signals, wherein said intermediate matrix Q is a function of the channel matrix H; and (d) repeating at least step (c) one or more times to detect an additional one or more of said transmitted signals, wherein said intermediate matrix Q as used in step (c) for each such repeated execution thereof is re-computed based on a function of an inverse of a Schur complement of an element in the inverse of a modified version of the intermediate matrix Q used in the previous execution of step (c).