In this paper, we first show equivalence of OFDM channel estimation using time-domain windowing and using frequency-domain interpolation. Based on this equivalence, a new frequency-domain channel interpolator featuring the advantage of time-domain channel impulse response windowing is proposed. Furthermore, the proposed raised-cosine channel interpolator can adaptively adjust its coefficients to accommodate various channel power delay profiles. Both theoretical and simulation results verify that the proposed interpolator achieves more accurate channel estimation performance than other existing solutions.