Apparatus and Method for Estimating Channel in Communication System Supporting Ofdm/Ofdma

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

• a Radio Frequency (RF) module for converting a RF band signal received from a terminal via antenna to a low-frequency band signal;
• a Fast Fourier Transform (FFT) module for converting the low-frequency band signal to a frequency domain signal;
• a derandomizer for offsetting a random number included in the signal being transmitted by the terminal, with respect to the frequency-domain signal;
• a depermutation module for depermutating and outputting the frequency-domain signal in which the random number is offset, by the sub-channel;
• a channel estimator for estimating and compensating 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 signal.

A method for estimating a channel in a communication system supporting OFDM/OFDMA, comprising steps of:

• converting RF band signal received from a terminal via antenna to low-frequency band signal;
• converting the low-frequency band signal to a frequency domain signal;
• offsetting a random number included signal being transmitted by the terminal, with respect to the frequency-domain signal;
• combining the frequency-domain signal in which the random number is offset, by the sub-channel;
• and
• estimating and compensating 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.