A method in which a base station transmits pilot signals in a multiple-antenna communication system is provided. The base station includes some of the plurality of pilot signals distinguished by at least one of time domain symbols, subcarriers, and orthogonal codes in a first set to which a first random number is applied. The base station includes the remaining pilot signals, excluding the pilot signals that are included in the first set, in a second set that uses the same resources as used by the first set and to which a second random number different from the first random number is applied. The base station transmits at least one of the pilot signals that belong to the first set and the second set.