Methods and apparatuses for HARQ in a non-terrestrial network are disclosed. An operation method of a first node may comprise receiving a transport block (TB) from a second node; classifying total soft bits for the TB into information values and sign values; configuring the information values of the total soft bits into one or more subsets; performing a compression operation on each of the one or more subsets; and performing a compression operation on the sign values. Therefore, performance of the communication system can be improved.