ENHANCED DFT INTERPOLATION-BASED CHANNEL ESTIMATION FOR OFDM SYSTEMS WITH VIRTUAL SUBCARRIERS

In practical OFDM systems, some virtual subcarriers are reserved for easing the requirements on the filter. In this case, the channel impulse response (CIR) estimated by DFT approaches appears a spectral leakage, which results in an error floor for the MSE performance. This paper proposes two enhanced DFT interpolation-based channel estimation methods, termed as EDFTI-CE-A and EDFTI-CE-B, based on the robust Wiener filtering, which can eliminate most of the leakage effect owning to the absence of pilot symbols in the virtual subcarriers and further suppress the effect of additive noise. The analysis and simulation results show that the proposed EDFTI-CE-A can almost eliminate the MSE floor of conventional DFTI-CE with small complexity increase and the proposed EDFTI-CE-B can achieve the same performance as linear MMSE channel estimator but with much lower computational complexity.