Provided is a data decoding method of a wireless communication device. The method includes receiving a plurality of sub-frames. The method further includes accumulating data signals respectively included in each of the plurality of sub-frames. The method further includes updating a channel estimation value based on reference signals included in a most recent sub-frame of the plurality of sub-frames. The method further includes calculating a log likelihood ratio (LLR) based on the accumulated data signals and the updated channel estimation value. Furthermore, the method includes decoding data based on the LLR.