A method for a terminal to receive downlink data, comprising: receiving resource allocation information from a base station; and demodulating the downlink data transmitted through a sub-resource allocation unit allocated based on the resource allocation information, wherein a resource allocation unit includes the sub-resource allocation unit and an additional sub-resource allocation unit, wherein the resource allocation unit is a physical resource block, PRB, wherein the PRB includes seven orthogonal frequency division multiplexing, OFDM, symbols and 12 subcarriers, wherein the sub-resource allocation unit includes a resource for a first demodulation reference signal, DM-RS, and the additional sub-resource allocation unit includes a resource for a second DM-RS, wherein the first DM-RS is generated based on a first DM-RS sequence, wherein the second DM-RS is generated based on a second DM-RS sequence, wherein the pattern of the first DM-RS is determined based on the first DM-RS sequence, wherein the pattern of the second DM-RS is determined based on the second DM-RS sequence, and wherein the initial value of a pseudo random sequence for generating each of the first DM-RS sequence and the second DM-RS sequence is determined as follows: c init = ⌊ n s / 2 ⌋ + 1 ⋅ 2 n ID, i EPDCCH + 1 ⋅ 2 16 + n SCID EPDCCH + k, where the n SCID EPDCCH = 2; the n ID, i EPDCCH is determined by an upper layer; the ns is a slot index; and the k is determined by an index of the sub-resource allocation unit when the initial value of the pseudo random sequence is for the first DM-RS, and the k is determined by an index of the additional sub-resource allocation unit when the initial value of the pseudo random sequence is for the second DM-RS. receiving resource allocation information from a base station; and demodulating the downlink data transmitted through a sub-resource allocation unit allocated based on the resource allocation information, wherein a resource allocation unit includes the sub-resource allocation unit and an additional sub-resource allocation unit, wherein the resource allocation unit is a physical resource block, PRB, wherein the PRB includes seven orthogonal frequency division multiplexing, OFDM, symbols and 12 subcarriers, wherein the sub-resource allocation unit includes a resource for a first demodulation reference signal, DM-RS, and the additional sub-resource allocation unit includes a resource for a second DM-RS, wherein the first DM-RS is generated based on a first DM-RS sequence, wherein the second DM-RS is generated based on a second DM-RS sequence, wherein the pattern of the first DM-RS is determined based on the first DM-RS sequence, wherein the pattern of the second DM-RS is determined based on the second DM-RS sequence, and wherein the initial value of a pseudo random sequence for generating each of the first DM-RS sequence and the second DM-RS sequence is determined as follows: c init = ⌊ n s / 2 ⌋ + 1 ⋅ 2 n ID, i EPDCCH + 1 ⋅ 2 16 + n SCID EPDCCH + k, where the n SCID EPDCCH = 2; the n ID, i EPDCCH is determined by an upper layer; the ns is a slot index; and the k is determined by an index of the sub-resource allocation unit when the initial value of the pseudo random sequence is for the first DM-RS, and the k is determined by an index of the additional sub-resource allocation unit when the initial value of the pseudo random sequence is for the second DM-RS.