A method of determining hybrid automatic repeat request (HARQ) resource of a UL subframe for an advanced communication device comprises determining a first new association set of the UL subframe according to an association set of the UL subframe of a first UL/DL configuration of a legacy communication device; configuring a mapping between at least one sequence index of the UL subframe of the first UL/DL configuration and the first new association set according to the first UL/DL configuration; and determining the HARQ resource of the UL subframe according to the mapping and the first new association set.