A transmitter in a frequency division multiple access communication system, the transmitter comprising: a pilot controller for generating a plurality of pilot symbols, and grouping the pilot symbols into a plurality of B groups according to a location of a subcarrier, wherein pilot symbols of subcarriers having the same remainder b when the location of the subcarrier is divided by a predetermined integer B are allocated to the same group; an inverse fast Fourier transform unit for inverse fast Fourier transforming the pilot symbols in each group, and outputting a first pilot symbol sequence corresponding to each group; wherein the inverse fast Fourier transform unit is adapted to perform an L size inverse fast Fourier transform operation for the pilot symbol corresponding to each group and generates the first pilot symbol sequence { d n, n = 0,1,..., L - 1} corresponding to each group, wherein L denotes the length of a pilot block, and wherein L is less that the length N of a data/control block; and a parallel/serial converter for generating a plurality of B pilot blocks respectively corresponding to the B groups and serializing the first pilot symbol sequence { d n, n = 0,1,..., L - 1}, having L symbols, of each group into a second pilot symbol sequence { d n, n = 0,1,..., N - 1}, having N time domain pilot symbols, of a corresponding pilot block among the pilot blocks, wherein the second pilot symbol sequence is formed by repeating the first pilot symbol sequence B times and wherein a pilot symbol d n + mL of the second pilot symbol sequence is obtained by multiplying the corresponding symbol d n of the first pilot symbol sequence with a constant according to the formula d n + mL = d n · e j 2 πbm L/N where n = 0,1,..., L - 1, m = 0,1,..., B - 1, to generate a cyclic prefix for the first pilot sequence, wherein the predetermined integer B corresponds to a ratio of N and L; and wherein the plurality of B pilot blocks are included when forming a frame for transmission, the frame further including a plurality of data/control blocks such that the pilot blocks are scattered with data/control blocks. a pilot controller for generating a plurality of pilot symbols, and grouping the pilot symbols into a plurality of B groups according to a location of a subcarrier, wherein pilot symbols of subcarriers having the same remainder b when the location of the subcarrier is divided by a predetermined integer B are allocated to the same group; an inverse fast Fourier transform unit for inverse fast Fourier transforming the pilot symbols in each group, and outputting a first pilot symbol sequence corresponding to each group; wherein the inverse fast Fourier transform unit is adapted to perform an L size inverse fast Fourier transform operation for the pilot symbol corresponding to each group and generates the first pilot symbol sequence { d n, n = 0,1,..., L - 1} corresponding to each group, wherein L denotes the length of a pilot block, and wherein L is less that the length N of a data/control block; and a parallel/serial converter for generating a plurality of B pilot blocks respectively corresponding to the B groups and serializing the first pilot symbol sequence { d n, n = 0,1,..., L - 1}, having L symbols, of each group into a second pilot symbol sequence { d n, n = 0,1,..., N - 1}, having N time domain pilot symbols, of a corresponding pilot block among the pilot blocks, wherein the second pilot symbol sequence is formed by repeating the first pilot symbol sequence B times and wherein a pilot symbol d n + mL of the second pilot symbol sequence is obtained by multiplying the corresponding symbol d n of the first pilot symbol sequence with a constant according to the formula d n + mL = d n · e j 2 πbm L/N where n = 0,1,..., L - 1, m = 0,1,..., B - 1, to generate a cyclic prefix for the first pilot sequence, wherein the predetermined integer B corresponds to a ratio of N and L; and wherein the plurality of B pilot blocks are included when forming a frame for transmission, the frame further including a plurality of data/control blocks such that the pilot blocks are scattered with data/control blocks.