1. A signal detection apparatus for a single receiver unit equipped with a plurality of antennas in a system having at least one transmitter unit configured to transmit data streams by spatial multiplexing, the signal detection apparatus comprising: a partial linear coefficient generator unit configured to generate a linear weighting matrix by using a preset algorithm on a channel matrix formed between the transmitter unit and the single receiver unit; a partial symbol remover unit configured to generate a first symbol vector by removing all transmittable symbols for each transmitting antenna from all received data streams; and a partial symbol detector unit configured to generate a transmission symbol candidate vector by using the linear weighting matrix and the first symbol vector, wherein the partial linear coefficient generator unit generates the linear weighting matrix using at least one of a ZF (zero-forcing) algorithm and an MMSE (minimum mean square error) algorithm.