1. A method for performing uplink transmission by a communication device in a wireless communication system, the method comprising:receiving downlink control information (DCI) for downlink scheduling, the DCI comprising resource indication information (RI);
receiving downlink data indicated by the DCI; and
transmitting uplink control information (UCI) including hybrid automatic repeat request acknowledgement (HARQ-ACK) information for the downlink data using a PUCCH resource corresponding to the RI in a physical uplink control channel (PUCCH) resource set, wherein the PUCCH resource set is selected from a plurality of PUCCH resource sets based on a size of the UCI,
wherein, based on a UCI size supported by the PUCCH resource set being less than or equal to X (>=1) bits, the PUCCH resource is determined using one of a first scheme and a second scheme, and
wherein, based on the UCI size supported by the PUCCH resource set being greater than X bits, the PUCCH resource is determined using only the second scheme:
the first scheme: the PUCCH resource in the PUCCH resource set is determined based on both the RI and an index of a resource used for reception of the DCI; and
the second scheme: the PUCCH resource in the PUCCH resource set is determined based on the RI only.