The present invention relates to a wireless communication system and particularly to a method and a device therefor, the method comprising the steps of: monitoring control channel candidates in a common search space and a UE-specific search space on subframe #n so as to receive downlink control information; and transmitting, in subframe #n+k, an uplink signal associated with the downlink control information, wherein the value of k is determined based on the search space in which the downlink control information is detected, and the common and UE-specific search spaces correspond to different values of k.