A method for a BS for processing multiplexed UCI received from a UE is disclosed. The method includes grouping PUCCH resources for CSI and an SR with a low priority and PUCCH resources for a slot-based HARQ-ACK into a first group of PUCCH resources; grouping PUCCH resources for CSI and an SR with a high priority and PUCCH resources for a sub-slot based HARQ-ACK into a second group of PUCCH resources; determining a first set of PUCCH resources in a slot from the first group; obtaining first multiplexed UCI of a first PUCCH resource by a first UCI multiplexing procedure for UCI corresponding to the first set; determining a second set of PUCCH resources in a sub-slot of the slot from the second group; and obtaining second multiplexed UCI of a second PUCCH resource by a second UCI multiplexing procedure for UCI corresponding to the second set.