A method for a user equipment (UE) to transmit an uplink signal, and which includes receiving a first downlink control channel identified by a temporary cell identifier (Temporary C-RNTI) from a base station, the first downlink control channel including a first uplink grant signal having a new data indicator (NDI) with a first value; receiving a second downlink control channel identified by a cell identifier (C-RNTI) from the base station, the second downlink control channel including a second uplink grant signal having the NDI with a second value; and determining if the NDI with the second value has been toggled compared to the NDI previously received from the base station. Further, the UE ignores the NDI with the first value received through the first downlink control channel identified by the temporary cell identifier (Temporary C-RNTI). The method also includes transmitting the uplink signal based on the determining.