Enhanced DFT-Based Channel Estimator for Leakage Effect Mitigation in OFDM Systems

The leakage effect occurs in a DFT-based channel estimator (CE) due to the presence of guard bands, where the energy of the channel impulse response (CIR) is dispersed to other estimated taps. Furthermore, some of the CIR energy leaks outside of the estimation range and fails to be captured in the channel estimation. This letter presents an enhanced DFT-based CE for orthogonal frequency-division multiplexing (OFDM) systems. The proposed method is composed of two techniques (spectral extrapolation and circular shift) to mitigate the leakage effect, followed by a denoising post-processing to enhance the estimation accuracy. Through performance analysis, it is demonstrated that the spectral extrapolation eliminates the leakage effect corresponding to the first CIR tap, and the circular shift improves estimation accuracy by incorporating the leaked CIR energy in the channel estimation. The simulation results show that the proposed method has superior performance compared with conventional CEs. In addition, the proposed method is feasible from a computational complexity perspective.