1. A parallel symbol cancellation method for canceling an influence of symbols transmitted from a single transmit antenna on signals from a received signal in a Multiple Input Multiple Output (MIMO) system that supports spatial multiplexing, the method comprising: (a) selecting one quadrant among four quadrants including all points on a constellation having normalization distribution; (b) selecting a single reference point in the selected quadrant and generating a reference value corresponding to the single reference point; (c) generating addition values for representing points other than the single reference point in the selected quadrant using a size difference of each of the points other than the reference point having the normalization distribution; and (d) summing up the reference value and the addition values.