User equipment and operation method thereof

An operation method of a user equipment performing narrowband Internet of Things-based communication, the operation method comprising:

• receiving, from a cell, a downlink signal comprising a plurality of subframes;
• determining a residual frequency offset between the cell and the user equipment based on a signal-to-noise ratio of the downlink signal;
• determining a delayed distance for a target subframe from among the plurality of subframes based on the residual frequency offset;
• estimating, with respect to a time axis, a channel of the target subframe based on a channel estimation technique established using reference signals up to an end subframe corresponding to the delayed distance after the target subframe;
• and
• decoding the target subframe based on the estimated channel.