An operation method of a relay node may include: receiving, from a first communication node, first data composed of n bits; receiving, from a second communication node, second data composed of m bits; in response to determining that n is greater than m, generating first T-data of m bits excluding (n-m) bits from the n-bits of the first data and first R-data of (n-m) bits; generating third data by performing a network coding operation on the first T-data and the second data; transmitting the third data to the first communication node; and transmitting the third data and the first R-data to the second communication node.