DCT-based channel estimator for OFDM systems: threshold setting and leakage estimation

This paper addresses the problem of the discrete cosine transform (DCT)-based channel estimator for orthogonal frequency-division multiplexing (OFDM) systems in the presence of virtual subcarriers. We focus on the following two problems. The first issue is the threshold setting. Traditional methods to set the threshold are reasonable but based on heuristics. We propose a new threshold based on the analytical expression of the channel impulse response (CIR) in the DCT domain. The second issue is the leakage estimation for DCT-based channel estimators. Recently, we have proposed the leakage estimation for discrete Fourier transform (DFT)-based channel estimators. It is well known that there is the channel leakage in the high frequency region of the DCT domain, and the leakage causes the error floor. In order to eliminate the error floor, we propose to estimate the leakage in the high frequency region. Simulation results show that the DCT-based channel estimator with the proposed threshold achieves better performance and the error floor is mitigated after leakage estimation.