A mobile device in an OFDM system receives an OFDM signal comprising RS tones and data OFDM symbols. The received RS tones are extracted for channel estimation using a masking operation. Masking parameters are determined by matching channel time variance using corresponding time domain samples of the extracted RS tones. As approximated channel impulse responses of transmission channels, the time samples are masked to perform the channel estimation. The channel time variance comprising inter-carrier interference and delay spread are measured, respectively. A mean of differences in power between neighbor adjacent subcarriers of the extracted RS tones is used for the inter-carrier interference measurement. The delay spread measurement such as root-mean-squared (RMS) delay spread is calculated using the approximated channel impulse responses. Masking parameters are determined based on the inter-carrier measurement and the RMS-DS measurement for generating channel estimates by masking the approximated channel impulse responses.