In a Time Division Duplex (TDD) system, downlink and uplink communications share the same bandwidth but occupy different subframes. When the downlink has more subframes than the uplink, special treatment on user equipment (UE) ACK/NACK feedback is needed. One uplink may need to ACK multiple downlink subframes. A downlink association without unnecessary ACK/NACK resources sets accounts for subframes for which ACK feedback is not desired. Examples of such subframes include: a blank subframe; an almost blank subframe where only a cell specific Reference Signal (RS) is transmitted; a Time Division Multiplex (TDM) partition in which an evolved NodeB (eNB) only transmits a Physical Downlink Shared Channel (PDSCH) or a Physical Downlink Control Channel (PDCCH) indicating Semi-persistent scheduling (SPS) at certain downlink subframes; a Downlink Pilot Timeslot (DwPTS) with a certain special subframe configuration where an eNB does not send the PDSCH and the UE is not in SPS active mode in the DwPTS; and a Multi-Media Broadcast over a Single Frequency Network (MBSFN) subframe when the UE is not in SPS active mode in the MBSFN subframe.