The present invention relates to a wireless communication system, and, particularly, to a method and a device therefor, the method comprising the steps of: receiving first uplink resource allocation information from a base station, wherein the first uplink resource allocation information includes information indicating a subframe set and TPC range indicating information; transmitting second uplink resource allocation information to the base station, wherein the second uplink resource allocation information includes a TPC value selected by a user equipment in the TPC range determined on the basis of the TPC range indicating information; and transmitting uplink data to the base station in the subframe set, wherein the transmission power for the uplink data is set on the basis of the TPC value, the subframe set includes multiple subframe groups, and the TPC range is changed in a unit of subframe groups according to the predefined pattern.