Method and device for monitoring control channel in a wireless communication system

1. A method for monitoring a control channel in a wireless communication system, the method comprising:

receiving a control format indicator (CFI) on a physical control format indicator channel (PCFICH) in a subframe including a control region and a data region, the CFI on the PCFICH indicating a number of orthogonal frequency division multiplexing (OFDM) symbols for the control region of the subframe,

wherein remaining OFDM symbols are used for the data region;

determining whether an extended control region is present in the remaining OFDM symbols used for the data region of the subframe based on whether the CFI on the PCFICH indicates a maximum number of OFDM symbols or not,

wherein if the CFI on the PCFICH indicates the maximum number of OFDM symbols used for the control region, the extended control region is determined to be present in the remaining OFDM symbols used for the data region of the subframe; and

if the extended control region is determined to be present in the remaining OFDM symbols used for the data region of the subframe, monitoring a physical downlink control channel (PDCCH) in the control region and the extended control region; and

receiving extended control information regarding the extended control region in the subframe through a second downlink control channel.

2. The method of claim 1 , wherein the extended control information includes resource allocation information regarding a resource to which the extended control region is allocated.

3. The method of claim 1 , wherein the extended control information includes a cross-CFI indicating a size of a control region in a subframe of a component carrier.

4. The method of claim 1 , wherein the extended control information regarding the extended control region in the subframe is received through the second downlink control channel if the CFI indicates a specific value.

5. The method of claim 1 , wherein if the CFI indicates a specific value, it is determined that the extended control region is present in the subframe.

6. The method claim 1 , wherein the second downlink control channel is detected by blind decoding.

7. A user equipment configured for monitoring a control channel in a wireless communication system, the user equipment comprising:

a radio frequency (RF) unit configured to transmit and receive a radio signal; and

a processor coupled to the RF unit, wherein the processor is configured to:

receive a control format indicator (CFI) on a physical control format indicator channel (PCFICH) in a subframe including a control region and a data region, the CFI on the PCFICH indicating a number of orthogonal frequency division multiplexing (OFDM) symbols for the control region of the subframe,

wherein remaining OFDM symbols are used for the data region;

determine whether an extended control region is present in the remaining OFDM symbols used for the data region of the subframe based on whether the CFI on the PCFICH indicates a maximum number of OFDM symbols or not,

wherein if the CFI on the PCFICH indicates the maximum number of OFDM symbols used for the control region, the extended control region is determined to be present in the remaining OFDM symbols used for the date region of the subframe; and

if the extended control region is determined to be present in the remaining OFDM symbols used for the data region of the subframe, monitor a physical downlink control channel (PDCCH) in the control region and the extended control region,

wherein the processor is further configured to receive extended control information regarding the extended control region in the subframe through a second downlink control channel.

8. The user equipment of claim 7 , wherein the extended control information includes resource allocation information regarding a resource to which the extended control region is allocated.

9. The user equipment of claim 7 , wherein the processor is further configured to receive the extended control information regarding the extended control region in the subframe through the second downlink control channel if the CFI indicates a specific value.

10. The user equipment of claim 7 , wherein if the CFI indicates a specific value, the processor is further configured to determine that the extended control region is present in the subframe.

11. The user equipment of claim 7 , wherein the extended control information includes a cross-CFI indicating a size of a control region in a subframe of a component carrier.

12. The user equipment of claim 7 , wherein the second downlink control channel is detected by blind decoding.