A method executed by a terminal in a wireless communication system, the method comprising: determining that a downlink transmission for a subframe with a physical downlink control channel, PDCCH, is indicated through the PDCCH or a downlink assignment for the subframe with the PDCCH is configured through the PDCCH, wherein the subframe with the PDCCH is included in an active time and the subframe with the PDCCH is not part of a configured measurement gap, and wherein the active time is a period that the terminal operating in discontinuous reception, DRX, mode monitors the PDCCH; and starting a hybrid automatic repeat request, HARQ, round trip time, RTT, timer, in case that the downlink transmission is indicated through the PDCCH for the subframe or the downlink assignment is configured through the PDCCH for the subframe, wherein in case that a serving cell associated with the downlink transmission or the downlink assignment is included in a secondary cell group, SCG, and a primary secondary cell, PSCell, in the SCG is associated with time division duplex, TDD, the HARQ RTT timer is set to a first interval plus 4 subframes, and the first interval is an interval between the downlink transmission and a transmission of associated HARQ feedback and the first interval is determined based on TDD configuration information associated with the PSCell in the SCG, wherein in case that the serving cell associated with the downlink transmission or the downlink assignment is included in a master cell group, MCG, and a primary cell, PCell, in the MCG is associated with TDD, the HARQ RTT timer is set to a second interval plus 4 subframes, and the second interval is determined based on TDD configuration information associated with a primary cell, PCell, in the MCG, wherein in case that the serving cell associated with the downlink transmission or the downlink assignment is included in the SCG and the PSCell in the SCG is associated with frequency division duplex, FDD, the HARQ RTT timer is set to 8 subframes, wherein in case that the serving cell associated with the downlink transmission or the downlink assignment is included in the MCG and the PCell in the MCG is associated with FDD, the HARQ RTT timer is set to 8 subframes, and wherein the PSCell is configured with a resource for a physical uplink control channel, PUCCH, and PUCCH associated with the SCG is transmitted on the resource for the PUCCH of the PSCell. determining that a downlink transmission for a subframe with a physical downlink control channel, PDCCH, is indicated through the PDCCH or a downlink assignment for the subframe with the PDCCH is configured through the PDCCH, wherein the subframe with the PDCCH is included in an active time and the subframe with the PDCCH is not part of a configured measurement gap, and wherein the active time is a period that the terminal operating in discontinuous reception, DRX, mode monitors the PDCCH; and starting a hybrid automatic repeat request, HARQ, round trip time, RTT, timer, in case that the downlink transmission is indicated through the PDCCH for the subframe or the downlink assignment is configured through the PDCCH for the subframe, wherein in case that a serving cell associated with the downlink transmission or the downlink assignment is included in a secondary cell group, SCG, and a primary secondary cell, PSCell, in the SCG is associated with time division duplex, TDD, the HARQ RTT timer is set to a first interval plus 4 subframes, and the first interval is an interval between the downlink transmission and a transmission of associated HARQ feedback and the first interval is determined based on TDD configuration information associated with the PSCell in the SCG, wherein in case that the serving cell associated with the downlink transmission or the downlink assignment is included in a master cell group, MCG, and a primary cell, PCell, in the MCG is associated with TDD, the HARQ RTT timer is set to a second interval plus 4 subframes, and the second interval is determined based on TDD configuration information associated with a primary cell, PCell, in the MCG, wherein in case that the serving cell associated with the downlink transmission or the downlink assignment is included in the SCG and the PSCell in the SCG is associated with frequency division duplex, FDD, the HARQ RTT timer is set to 8 subframes, wherein in case that the serving cell associated with the downlink transmission or the downlink assignment is included in the MCG and the PCell in the MCG is associated with FDD, the HARQ RTT timer is set to 8 subframes, and wherein the PSCell is configured with a resource for a physical uplink control channel, PUCCH, and PUCCH associated with the SCG is transmitted on the resource for the PUCCH of the PSCell.