1. A receiving-end apparatus in a Multiple Input Multiple Output (MIMO) wireless communication system, the apparatus comprising: a plurality of receivers for receiving training symbol vectors and a data signal vector from a transmitting end through a plurality of corresponding receive (Rx) antennas; and a detector for expanding the training symbol vectors into second- or higher-order polynomials, for generating a weighting parameter vector for multivariate polynomial expansion of the data signal vector by using the polynomials expanded from the training symbol vectors and for expanding the data signal vector into a second- or higher-order multivariate polynomial using the weighting parameter vector, and for detecting Transmit (Tx) values of the data signal vector from the multivariate polynomial.