Abstract: Receiver diversity for Orthogonal Frequency Division Multiplexing system in high-speed wireless data transmission is investigated. An improved channel estimate method that calculates the correlation of the channel impulse response and a reference signal to extract the channel information from its noisy version is proposed. It is demonstrated by theoretical analysis and computer simulation that for QPSK modulated OFDM systems with one transmitter antenna and four receiver antennas, the performance of the improved channel estimator outperforms Least Square and Discrete Fourier Transform-based channel estimator greatly.