Apparatus and method for detecting the ack/nack signal in a wireless communication system

An apparatus and a method for detecting ACK/NACK information in a wireless communication system are provided to reduce the error of ACK/NACK detection, thereby retransmitting data efficiently and minimizing average cost. An apparatus for detecting ACK/NACK information in a wireless communication system comprises an RF(Radio Frequency) receiving unit(410), an ADC(Analog to Digital Converter) unit(420), a demultiplexer(430), an equalization unit(450), a correlation coefficient estimator(460), an information determination unit(480), a channel/noise power estimator(440), and a threshold value calculator(470). The correlation coefficient estimator calculates a correlation coefficient with a receiving signal including ACK or NACK(Acknowledgement or Non-Acknowledgement) information by using at least one of an ACK code vector and an NACK code vector. The threshold value calculator calculates a threshold value and a criterion of the ACK/NACK information. The information determination unit compares the correlation coefficient with the threshold value to determine whether the receiving signal is ACK information or NACK information. The channel/noise power estimator calculates a channel estimation value by using a pilot subcarrier or a pilot and a data subcarrier included into the receiving signal, estimates signal volume and noise power, the parameters of the receiving signal on the basis of the calculated channel estimation value, and transmits the estimated signal volume and noise power to the threshold value calculator. The equalization unit compensates the volume and phase of the data subcarrier by using the channel estimation value transmitted from the channel/noise power estimator, and transmits the compensated receiving signal to the correlation coefficient estimator.