A method for receiving an uplink signal by a base station in a wireless communication system, and the base station therefore are discussed. The method according to one embodiment includes transmitting, by the base station, a physical downlink control channel (PDCCH) via one or more resource units; transmitting, by the base station, a physical downlink shared channel (PDSCH) corresponding to the transmitted PDCCH; and receiving, by the base station, a physical uplink control channel (PUCCH) using a PUCCH resource in response to the transmitted PDSCH. In addition, an index of the PUCCH resource is determined by adding a first index offset and a second index offset to a lowest index of the one or more resource units. Additionally, the first index offset is signaled via the PDCCH and the second index offset is signaled via higher layer signaling.