A method for transmitting an uplink signal by a device in a wireless communication system, the method includes receiving a downlink control channel (DCI) format defined for uplink (UL) multi-antenna transmission mode, the DCI format including a resource allocation (RA) field; and transmitting an uplink signal using the RA field, wherein a size of the RA field is represented by the following expression: MAX (RASizeA, RASizeB), wherein RASizeA is a first number of bits required for representing a resource indication value (RIV) corresponding to a starting resource block (RB) and a length of contiguously allocated RBs within a given uplink bandwidth, and wherein RASizeB is a second number of bits required for representing a combinatorial index r corresponding to 4 indexes, and the 4 indexes are used to indicate a start resource block group (RBG) index and an end RBG index of a first RB set and a start RBG index and an end RBG index of a second RB set within the given uplink bandwidth.