A base station (BS) and a user equipment (UE) for a mobile communication system are provided. The BS generates first downlink information (DCI) related to a first service type and transmits the first DCI indicating a first physical uplink control channel (PUCCH) resource to the UE. The BS further generates second DCI related to a second service type and transmits the second DCI indicating a second PUCCH resource to the UE. The first service type and the second service type have different priorities. The starting symbol of the first PUCCH resource is located within a first type assigned sub-slot of a plurality of first type sub-slots of a slot, and the starting symbol of the second PUCCH resource is located within a second type assigned sub-slot of a plurality of second type sub-slots of the slot.