Apparatus and method for estimating channel in communication system supporting OFDM/OFDMA

1. An apparatus for estimating a channel in a communication system supporting Orthogonal Frequency Division Multiplexing/Orthogonal Frequency Division Multiple Access (OFDM/OFDMA), the apparatus comprising:

a phase estimation/compensation unit configured to estimate and compensate phase change of a channel by using pilots included in a Partial Usage of Sub-Channels (PUSC) mode signal input by a sub-channel; and

a channel estimation unit configured to estimate the channel by using the pilots of the PUSC mode signal of which the phase is compensated.

2. The apparatus of claim 1 , wherein the phase estimation/compensation unit comprises:

a pilot extraction unit configured to extract the pilots from each tile constituting the sub-channel in the PUSC mode signal input by the sub-channel;

a phase change estimation unit configured to estimate the phase change by the sub-channel by using the extracted pilots; and

a phase compensation unit configured to compensate the phase of the extracted pilots by using the estimated phase change.

3. The apparatus of claim 1 , wherein the channel estimation unit comprises:

an averaging unit configured to calculate representative values of the respective tiles by summing the phase-compensated pilots by the tile and averaging the sum; and

a phase reflection unit configured to estimate the channel for data compensation by using the representative values of the respective tiles and the phase change.

4. The apparatus of claim 2 , wherein the phase change estimation unit is configured to estimate the phase change by conjugation-multiplying two pilots constituting the same symbol among the pilots in each tile by a pilot distanced by a predetermined number of sub-carriers, respectively, obtaining an arctan value by adding the values conjugation-multiplied by the tile, for one sub-channel, and dividing the arctan value by a value corresponding to a difference of sub-carrier position between the two pilots.

5. A computer-implemented method for estimating a channel in a communication system supporting OFDM/OFDMA, the computer-implemented method comprising:

estimating and compensating, using a computer processor, phase change of the channel by using pilots included in a Partial Usage of Sub-Channels (PUSC) mode signal input by a sub-channel; and

estimating, using a computer processor, the channel by using the pilots of the PUSC mode signal of which the phase change is compensated.

6. The computer-implemented method of claim 5 , wherein the estimating and compensating of the phase change comprises:

extracting, using a computer processor, the pilots from each tile constituting the sub-channel in the PUSC mode signal input by the sub-channel;

estimating, using a computer processor, the phase change by the sub-channel by using the extracted pilots; and

compensating, using a computer processor, the phase of the extracted pilots by using the phase change.

7. The computer-implemented method of claim 5 , wherein the estimating of the channel comprises:

calculating, using a computer processor, representative values of the respective tiles by summing the phase-compensated pilots by the tile and averaging the sum; and

estimating, using a computer processor, the channel for data compensation by using the representative values of the respective tiles and the phase change.

8. The computer-implemented method of claim 7 , wherein the phase change is estimated by conjugation-multiplying two pilots constituting the same symbol among the pilots in each tile by a pilot distanced by a predetermined number of sub-carriers, respectively, obtaining an arctan value by adding the values conjugation-multiplied by the tile, for one sub-channel, and dividing the arctan value by a value corresponding to a difference of sub-carrier position between the two pilots.

9. An apparatus for estimating a channel in a communication system supporting OFDM/OFDMA, comprising:

a Radio Frequency (RF) module configured to convert an RF band Partial Usage of Sub-Channels (PUSC) mode signal received from a terminal via an antenna to a low-frequency band signal;

a Fast Fourier Transform (FFT) module configured to convert the low-frequency band signal to a frequency-domain signal;

a derandomizer configured to offset a random number included in the PUSC mode signal being transmitted by the terminal, with respect to the frequency-domain signal;

a depermutation module configured to depermutate and output the frequency-domain signal in which the random number is offset, by the sub-channel;

a channel estimator configured to estimate and compensate phase change of the channel by using pilots included in the frequency-domain signal by the sub-channel, and estimate the channel by using the phase-compensated signal.

10. The apparatus of claim 9 , wherein the channel estimator comprises:

a pilot extraction unit for extracting the pilots from each tile constituting the sub-channel in the signal input by the sub-channel;

a phase change estimation unit for estimating the phase change by the sub-channel by using the extracted pilots;

a phase compensation unit for compensating the phase of the extracted pilots by using the estimated phase change;

an averaging unit for calculating representative values of the respective tiles by summing the phase-compensated pilots by the tile and averaging the sum; and

a phase reflection unit for estimating the channel for data compensation by using the representative values of the respective tiles and the phase change.

11. The apparatus of claim 10 , wherein the phase change estimation unit is configured to estimate the phase change by conjugation-multiplying two pilots constituting the same symbol among the pilots in each tile by a pilot distanced by a predetermined number of sub-carriers, respectively, obtaining an arctan value by adding the values conjugation-multiplied by the tile, for one sub-channel, and dividing the arctan value by a value corresponding to a difference of sub-carrier position between the two pilots.

12. The apparatus of claim 10 , wherein the channel estimator estimates the channel by reflecting the phase change to the representative values of the respective tiles, according to positions of the sub-carriers constituting each tile.

13. A computer-implemented method for estimating a channel in a communication system supporting OFDM/OFDMA, the computer-implemented method comprising:

converting, using a computer processor, an RF band Partial Usage of Sub-Channels (PUSC) mode signal received from a terminal via an antenna to a low-frequency band signal;

converting, using a computer processor, the low-frequency band signal to a frequency-domain signal;

offsetting, using a computer processor, a random number included the PUSC mode signal being transmitted by the terminal, with respect to the frequency-domain signal;

combining, using a computer processor, the frequency-domain signal in which the random number is offset, by the sub-channel; and

estimating and compensating, using a computer processor, phase change of the channel by using pilots included in the frequency-domain signal by the sub-channel, and estimating the channel by using the phase-compensated signals.

14. The computer-implemented method of claim 13 , wherein the estimating of the channel comprises:

extracting, using a computer processor, the pilots from each tile constituting the sub-channel in the signals input by the sub-channel;

estimating, using a computer processor, the phase change by the sub-channel by using the extracted pilots;

compensating, using a computer processor, the phase of the extracted pilots by using the phase change;

calculating, using computer processor, representative values of the respective tiles by summing the phase-compensated pilots by the tile and averaging the sum; and

estimating, using a computer processor, the channel for data compensation by using the representative values of the respective tiles and the phase change.

15. The computer-implemented method of claim 14 , wherein the phase change is estimated by conjugation-multiplying two pilots constituting the same symbol among the pilots in each tile by a pilot distanced by a predetermined number of sub-carriers, respectively, obtaining an arctan value by adding the values conjugation-multiplied by the tile, for one sub-channel, and dividing the arctan value by a value corresponding to a difference of sub-carrier position between the two pilots.

16. The computer-implemented method of claim 14 , wherein the channel is estimated by reflecting the phase change to the representative values of the respective tiles, according to positions of the sub -carriers constituting each tile.