Method and device for random access in wireless communication system supporting multi-carrier wave

1. A method for performing a random access procedure on a first secondary serving cell (SCell) in a user equipment comprising a plurality of serving cells, the method comprising:

transmitting a random access preamble on the first SCell to a base station;

receiving a random access response on a primary serving cell (PCell) from the base station;

transmitting uplink data to the base station on the PCell by using an uplink grant included in the random access response; and

receiving a contention resolution message from the base station on the first SCell, on which scheduling information on the first SCell is transmitted,

wherein the user equipment determines that contention resolution is successful only if physical downlink control channel (PDCCH) transmission is received on the first SCell, on which the scheduling information on the first SCell is transmitted,

wherein the user equipment determines that contention resolution is not successful if PDCCH transmission is received on a serving cell other than the first SCell among the plurality of serving cells,

wherein an identifier of the user equipment includes a cell-radio network temporary identifier (C-RNTI) or a temporary C-RNTI, and

wherein the first SCell belongs to a timing advance group (TAG) that includes SCells only, the SCells being from the base station and from neighboring base stations.

2. The method according to claim 1 , wherein the physical downlink control channel (PDCCH) transmission is addressed by the identifier of the user equipment.

3. The method according to claim 1 , wherein the physical downlink control channel (PDCCH) transmission includes the uplink grant.

4. The method according to claim 1 , wherein the user equipment initiates a contention resolution timer if the uplink data is transmitted.

5. The method according to claim 1 , wherein the contention resolution message is received before a contention resolution timer expires.

6. The method according to claim 1 , wherein the user equipment that has received the contention resolution message determines that the random access procedure is successful.

7. A user equipment for performing a random access procedure on a first secondary serving cell (SCell) the user equipment comprising:

a reception module configured to receive a downlink signal from a base station;

a transmission module configured to transmit an uplink signal to the base station; and

a processor configured to control the user equipment that includes the reception module and the transmission module,

wherein a plurality of serving cells are configured for the user equipment, and

wherein the processor is further configured to:

transmit a random access preamble on the first SCell to the base station through the transmission module,

receive a random access response on a primary serving cell (PCell) from the base station through the reception module,

transmit uplink data to the base station on the PCell by using an uplink grant included in the random access response through the transmission module, and

receive a contention resolution message from the base station on the first SCell, on which scheduling information on the first SCell is transmitted, through the reception module,

wherein the user equipment determines that contention resolution is successful only if physical downlink control channel (PDCCH) transmission is received on the first SCell, on which the scheduling information on the first SCell is transmitted,

wherein the user equipment determines that contention resolution is not successful if PDCCH transmission is received on a serving cell other than the first SCell among the plurality of serving cells,

wherein an identifier of the user equipment includes a cell-radio network temporary identifier (C-RNTI) or a temporary C-RNTI, and

wherein the first SCell belongs to a timing advance group (TAG) that includes SCells only, the SCells being from the base station and from neighboring base stations.