A Time Domain Iteration-Based Channel Estimation Method in OFDM Systems with Null Subcarriers

In orthogonal frequency division multiplexing (OFDM) systems, some subcarriers are often retained as null subcarriers for easier filter implementation. In this case, the performance of conventional Discrete Fourier Transform (DFT)-based channel estimation will be degraded dramatically due to dispersive distortion of actual channel impulse response (CIR). To solve this problem, in the present paper, we analyze the effect of null subcarriers on channel estimation and propose a novel channel estimation scheme. The proposed scheme, whose basic principle is the joint iteration of correlation operation and interference cancellation in time domain, can hold most energy of actual CIR and suppress noise effectively. Finally, simulation results show that the proposed method outperforms Least Square (LS) channel estimator, conventional DFT-based channel estimator and IDFT-Zero-Forcing(ZF) channel estimatior, especially in low signal-to-noise ratio (SNR).