Method comprises determining a first HARQ timing wherein an association determines which UL subframes in the TDD carrier that are defined for transmitting HARQ on an UL control channel for an associated set of DL subframes in the FDD carrier, determining a second HARQ timing, wherein an association determines which UL subframes that are defined for transmitting HARQ on an UL shared channel for an associated set of DL subframes in the FDD carrier, resulting in a first set of UL subframes for which the physical UL shared channel is enabled to comprise HARQ, and a second set of UL subframes is not comprising HARQ, and assigning UL channel resources for the HARQ feedback on the physical UL shared channel in said first set of UL subframes, according to said second DL HARQ timing, when there is no UL control channel assigned according to said first DL HARQ timing.