A method of performing a Hybrid Automatic Repeat request, HARQ, procedure by a communication device in a wireless communication system, comprising: receiving information on uplink-downlink, UL-DL, configuration, wherein a subframe, SF, pattern based on the UL-DL configuration is represented as Table 1 including a plurality of UL-DL configurations, and DL SF and UL SF are configured with a plurality of short-Transmission Time Intervals, TTIs; transmitting/receiving HARQ-acknowledgement, ACK, information in a short-TTI of SF #n for data received/transmitted in a short-TTI of SF #n-a; and re-receiving/retransmitting the data in a short-TTI of SF #n+b, wherein a+b is equal to the SF number corresponding to a shortest period among DL-to-UL switching periods of the plurality of UL-DL configurations, [Table 1] Uplink-downlink configuration Subframe number 0 1 2 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D where D, S and U indicate DL SF, special, S, SF and UL SF, respectively and the S SF is a SF configured to include a resource for downlink reception, a Guard Period, GP, and a resource for uplink transmission in one SF, wherein the S SF comprises at least one UL short-TTI; and transmitting HARQ-ACK information in a UL short-TTI of S SF #m for data received in a short-TTI of SF #m-c; and re-receiving the data in a short-TTI of SF # m+d, wherein if SF #m-a is DL SF, c has a value equal to a, wherein if the SF #m-a is UL SF, the SF #m-c is a DL SF having a biggest interval with the S SF #m among at least one DL SF of which interval with S SF #m is smaller than a SFs, and wherein c+d is equal to a+b. receiving information on uplink-downlink, UL-DL, configuration, wherein a subframe, SF, pattern based on the UL-DL configuration is represented as Table 1 including a plurality of UL-DL configurations, and DL SF and UL SF are configured with a plurality of short-Transmission Time Intervals, TTIs; transmitting/receiving HARQ-acknowledgement, ACK, information in a short-TTI of SF #n for data received/transmitted in a short-TTI of SF #n-a; and re-receiving/retransmitting the data in a short-TTI of SF #n+b, wherein a+b is equal to the SF number corresponding to a shortest period among DL-to-UL switching periods of the plurality of UL-DL configurations, [Table 1] Uplink-downlink configuration Subframe number 0 1 2 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U D where D, S and U indicate DL SF, special, S, SF and UL SF, respectively and the S SF is a SF configured to include a resource for downlink reception, a Guard Period, GP, and a resource for uplink transmission in one SF, wherein the S SF comprises at least one UL short-TTI; and transmitting HARQ-ACK information in a UL short-TTI of S SF #m for data received in a short-TTI of SF #m-c; and re-receiving the data in a short-TTI of SF # m+d, wherein if SF #m-a is DL SF, c has a value equal to a, wherein if the SF #m-a is UL SF, the SF #m-c is a DL SF having a biggest interval with the S SF #m among at least one DL SF of which interval with S SF #m is smaller than a SFs, and wherein c+d is equal to a+b. where D, S and U indicate DL SF, special, S, SF and UL SF, respectively and the S SF is a SF configured to include a resource for downlink reception, a Guard Period, GP, and a resource for uplink transmission in one SF, wherein the S SF comprises at least one UL short-TTI; and transmitting HARQ-ACK information in a UL short-TTI of S SF #m for data received in a short-TTI of SF #m-c; and re-receiving the data in a short-TTI of SF # m+d, wherein if SF #m-a is DL SF, c has a value equal to a, wherein if the SF #m-a is UL SF, the SF #m-c is a DL SF having a biggest interval with the S SF #m among at least one DL SF of which interval with S SF #m is smaller than a SFs, and wherein c+d is equal to a+b.