A method, comprising: determining by a base station a first set of physical uplink control channel resources to use for a first set of user equipment to send acknowledgment information to the base station for a first group of downlink subframes, wherein the first set of physical uplink control channel resources starts at a first index; determining by the base station a second set of physical uplink control channel resources to use for a second set of user equipment to send acknowledgment information to the base station for a second group of downlink subframes, wherein the user equipment in the first and second sets of user equipment are different, the second set of physical uplink control channel resources starts at a second index, the user equipment in the first set of user equipment only use the first set of physical uplink control channel resources to send the acknowledgment information to the base station for the first group of downlink subframes, and the user equipment in the second set of user equipment use the first set of physical uplink control channel resources to send the acknowledgment information to the base station for the first group of downlink subframes and use the second set of physical uplink control channel resources to send acknowledgment information to the base station for the second group of downlink subframes, wherein the first group of downlink subframes is limited to legacy downlink subframes, and the second group of downlink subframes is limited to non-legacy downlink subframes, and wherein the legacy downlink subframes correspond to those subframes that are defined as downlink or special subframes by downlink hybrid automatic repeat request reference configuration and that are associated with a same uplink subframe and a same subframe offset as a system information block-1 configured downlink or special subframes, and the non-legacy downlink subframes correspond to other downlink, special or flexible subframes according to downlink hybrid automatic repeat request reference configuration than the legacy downlink subframes.; and for an uplink reception by the base station, receiving acknowledgement information from the first user equipment using the first set of physical uplink control channel resources and receiving acknowledgement information from the second user equipment using the first and second sets (520-1, 530-1) of physical uplink control channel resources. determining by a base station a first set of physical uplink control channel resources to use for a first set of user equipment to send acknowledgment information to the base station for a first group of downlink subframes, wherein the first set of physical uplink control channel resources starts at a first index; determining by the base station a second set of physical uplink control channel resources to use for a second set of user equipment to send acknowledgment information to the base station for a second group of downlink subframes, wherein the user equipment in the first and second sets of user equipment are different, the second set of physical uplink control channel resources starts at a second index, the user equipment in the first set of user equipment only use the first set of physical uplink control channel resources to send the acknowledgment information to the base station for the first group of downlink subframes, and the user equipment in the second set of user equipment use the first set of physical uplink control channel resources to send the acknowledgment information to the base station for the first group of downlink subframes and use the second set of physical uplink control channel resources to send acknowledgment information to the base station for the second group of downlink subframes, wherein the first group of downlink subframes is limited to legacy downlink subframes, and the second group of downlink subframes is limited to non-legacy downlink subframes, and wherein the legacy downlink subframes correspond to those subframes that are defined as downlink or special subframes by downlink hybrid automatic repeat request reference configuration and that are associated with a same uplink subframe and a same subframe offset as a system information block-1 configured downlink or special subframes, and the non-legacy downlink subframes correspond to other downlink, special or flexible subframes according to downlink hybrid automatic repeat request reference configuration than the legacy downlink subframes.; and for an uplink reception by the base station, receiving acknowledgement information from the first user equipment using the first set of physical uplink control channel resources and receiving acknowledgement information from the second user equipment using the first and second sets (520-1, 530-1) of physical uplink control channel resources.