Method and apparatus for communicating downlink control information in an asymmetric multicarrier communication network environment

1. A method for communicating Downlink Control Information (DCI) in an asymmetric communication network, the method comprising:

generating unicast DCI for transmitting the unicast DCI to a mobile station;

identifying whether the unicast DCI includes control information for which carrier of a primary carrier, a symmetric secondary carrier and an asymmetric secondary carrier;

transmitting the unicast DCI through a first downlink control channel on the primary carrier in a first time resource, when the unicast DCI includes control information on the primary carrier or the symmetric secondary carrier; and

transmitting the unicast DCI through a second downlink control channel on the primary carrier in a second time resource, when the unicast DCI includes control information on the asymmetric secondary carrier,

wherein each of frequencies of the primary carrier and the symmetric secondary carrier is lower than a frequency of the asymmetric secondary carrier, and

wherein the symmetric secondary carrier is a carrier with a frame structure and operational parameters same as the primary carrier, and the asymmetric secondary carrier is a carrier with a frame structure and operational parameters different than the primary carrier.

2. The method of claim 1 , further comprising:

signaling information of at least one of the first time resource in which the unicast DCI including control information on one of the primary carrier or the symmetric secondary carrier is transmitted through the first downlink control channel; or

signaling information of at least one of the second time resource in which the unicast DCI including control information on the asymmetric secondary carrier is transmitted through the second downlink control channel.

3. The method of claim 1 , wherein the unicast DCI indicates information on resources allocated to the mobile station for a carrier type.

4. The method of claim 3 , wherein the generating of the unicast DCI comprises:

encoding the unicast DCI in a first set of fields of a DCI format when a carrier type of the unicast DCI is one of the primary carrier or the symmetric secondary carrier; and

encoding the unicast DCI in a second set of fields of the DCI format when the carrier type of the unicast DCI is the asymmetric secondary carrier.

5. The method of claim 1 , wherein a sum of sizes of fields in a DCI format encoding the unicast DCI including control information on the asymmetric secondary carrier is equal to a sum of sizes of fields in the DCI format encoding the unicast DCI including control information on the primary carrier or the symmetric secondary carrier.

6. The method of claim 1 , wherein the first downlink control channel is physical downlink control channel (PDCCH) and the second downlink control channel is secondary-PDCCH (S-PDCCH).

7. The method of claim 1 , wherein the unicast DCI transmitted through the first downlink control channel is transmitted in a legacy physical downlink control channel (PDCCH) of the first time resource, and the unicast DCI transmitted through the second downlink control channel is transmitted in a legacy PDCCH of the second time resource.

8. An apparatus comprising:

a transceiver; and

at least one processor coupled to the transceiver,

wherein the at least one processor is configured to:

generate unicast downlink control information (DCI) for transmitting the unicast DCI to a mobile station, identify whether the unicast DCI includes control information for which carrier of a primary carrier, a symmetric secondary carrier and an asymmetric secondary carrier,

transmit the unicast DCI through a first downlink control channel on the primary carrier in a first time resource, when the unicast DCI includes control information on the primary carrier or the symmetric secondary carrier, and

transmit the unicast DCI through a second downlink control channel on the primary carrier in a second time resource, when the unicast DCI includes control information on the asymmetric secondary carrier,

wherein each of frequencies of the primary carrier and the symmetric secondary carrier is lower than a frequency of the asymmetric secondary carrier, and

wherein the symmetric secondary carrier is a carrier with a frame structure and operational parameters same as the primary carrier, and the asymmetric secondary carrier is a carrier with a frame structure and operational parameters different than the primary carrier.

9. The apparatus of claim 8 , wherein the at least one processor is further configured to:

signal information of at least one of the first time resource in which the unicast DCI including control information on one of the primary carrier or the symmetric secondary carrier is transmitted through the first downlink control channel, or

signal information of at least one of the second time resource in which the unicast DCI including control information on the asymmetric secondary carrier is transmitted through the second downlink control channel.

10. The apparatus of claim 8 , wherein the unicast DCI indicates information on resources allocated to the mobile station for a carrier type.

11. The apparatus of claim 10 , wherein the at least one processor is further configured to:

encode the unicast DCI in a first set of fields of a DCI format when a carrier type of the unicast DCI is one of the primary carrier or the symmetric secondary carrier, and

encode the unicast DCI in a second set of fields of the DCI format when the carrier type of the unicast DCI is the asymmetric secondary carrier.

12. The apparatus of claim 8 , wherein a sum of sizes of fields in a DCI format encoding the unicast DCI including control information on the asymmetric secondary carrier is equal to a sum of sizes of fields in the DCI format encoding the unicast DCI including control information on the primary carrier or the symmetric secondary carrier.

13. The apparatus of claim 8 , wherein the first downlink control channel is physical downlink control channel (PDCCH) and the second downlink control channel is secondary-PDCCH (S-PDCCH).

14. The apparatus of claim 8 , wherein the unicast DCI transmitted through the first downlink control channel is transmitted in a legacy physical downlink control channel (PDCCH) of the first time resource, and the unicast DCI transmitted through the second downlink control channel is transmitted in a legacy PDCCH of the second time resource.

15. A method for communicating Downlink Control Information (DCI) in an asymmetric communication network, the method comprising:

receiving, from a base station, a first unicast DCI through a first downlink control channel on a primary carrier in a first time resource, wherein the first unicast DCI includes control information on the primary carrier or a symmetric secondary carrier; and

receiving, from the base station, a second unicast DCI through a second downlink control channel on the primary carrier in a second time resource, wherein the second unicast DCI includes control information on an asymmetric secondary carrier,

wherein each of frequencies of the primary carrier and the symmetric secondary carrier is lower than a frequency of the asymmetric secondary carrier, and

wherein the symmetric secondary carrier is a carrier with a frame structure and operational parameters same as the primary carrier, and the asymmetric secondary carrier is a carrier with a frame structure and operational parameters different than the primary carrier.

16. The method of claim 15 , wherein the unicast DCI indicates information on resources allocated to a mobile station for a carrier type.

17. The method of claim 16 ,

wherein the unicast DCI is encoded in a first set of fields of a DCI format when a carrier type of the unicast DCI is one of the primary carrier or the symmetric secondary carrier, and

wherein the unicast DCI is encoded in a second set of fields of the DCI format when the carrier type of the unicast DCI is the asymmetric secondary carrier.

18. The method of claim 15 , wherein a sum of sizes of fields in a DCI format encoding the unicast DCI including control information on the asymmetric secondary carrier is equal to a sum of sizes of fields in the DCI format encoding the unicast DCI including control information on the primary carrier or the symmetric secondary carrier.

19. The method of claim 15 , wherein the first downlink control channel is physical downlink control channel (PDCCH) and the second downlink control channel is secondary-PDCCH (S-PDCCH).

20. The method of claim 15 , wherein the unicast DCI transmitted through the first downlink control channel is transmitted in a legacy physical downlink control channel (PDCCH) of the first time resource, and the unicast DCI transmitted through the second downlink control channel is transmitted in a legacy PDCCH of the second time resource.