Random access design in a multiple component carrier communication network

1. A method for wireless communication, comprising:

receiving a request for a random access procedure at a user equipment in a wireless communication network, wherein the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers of the wireless communication network, wherein the plurality of component carriers include a primary uplink component carrier and one or more secondary uplink component carriers, and wherein the request is received on a first downlink component carrier of the plurality of component carriers;

selecting an uplink component carrier from among the plurality of component carriers for transmitting a random access message based on an association between the uplink and downlink component carriers, the selecting comprising either (a) selecting an uplink component carrier based on user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, selecting an uplink component carrier based on an association between the selected uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment;

transmitting the random access message on the selected uplink component carrier; and

receiving a response to the transmitted random access message.

2. The method of claim 1 , wherein selecting an uplink component carrier based on an association between the selected uplink component carrier and the first downlink component carrier as specified by SIB2 signaling comprises selecting the primary uplink component carrier, wherein the association is between the primary uplink component carrier and the first downlink component carrier.

3. The method of claim 1 , wherein the first downlink component carrier is associated with the primary uplink component carrier.

4. The method of claim 1 , wherein the selected uplink component carrier is a secondary uplink component carrier.

5. The method of claim 4 , wherein selecting an uplink component carrier further comprises:

selecting a secondary uplink component carrier with an uplink timing advance value that is substantially the same as an uplink timing advance value associated with the primary uplink component carrier.

6. The method of claim 4 , wherein selecting an uplink component carrier further comprises:

selecting a secondary uplink component carrier with a different uplink timing advance value than an uplink timing advance value of the primary uplink component carrier; and wherein the method further comprises:

acquiring uplink synchronization for the primary uplink component carrier to enable proper transmissions of uplink control information.

7. The method of claim 1 , wherein

the request comprises information corresponding to the association between the first downlink component carrier and an indicated uplink component carrier; and

the selected uplink component carrier is the indicated uplink component carrier.

8. The method of claim 7 , wherein receiving the response comprises:

receiving the response to the transmitted random access message on a second downlink component carrier that is linked to the indicated uplink component carrier in accordance with SIB2 signaling.

9. The method of claim 7 , wherein receiving the response comprises:

receiving the response to the transmitted random access message on the first downlink component carrier.

10. The method of claim 7 , wherein the received response is a scrambled response, the method further comprising:

descrambling the response according to a special signature sequence number or a reserved random access radio network temporary identifier (RA-RNTI) to ascertain a particular uplink component carrier.

11. A method for wireless communication, comprising:

configuring a plurality of component carriers for use by a user equipment in a wireless communication network, wherein the plurality of component carriers comprise uplink and downlink component carriers, the plurality of component carriers including a primary uplink component carrier and one or more secondary uplink component carriers, and wherein each uplink component carrier is associated with at least one downlink component carrier;

selecting a downlink component carrier and transmitting a request for a random access procedure to the user equipment on the selected downlink component carrier;

receiving a random access message from the user equipment on an uplink component carrier of the plurality of component carriers, wherein the uplink component carrier is identified by the user equipment either (a) based on user-equipment-specific signaling that links the selected downlink component carrier to the identified uplink component carrier, or otherwise (b) based on an association between the identified uplink component carrier and the selected downlink component carrier as specified by system information block 2 (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment; and

transmitting a response to the user equipment.

12. The method of claim 11 , wherein

the selected downlink component carrier is the primary downlink component carrier; and

the random access message is received on the primary uplink component carrier.

13. A user equipment, comprising:

a processor; and

a memory, comprising processor executable code which, when executed by the processor, configures the user equipment to:

receive a request for a random access procedure at the user equipment in a wireless communication network, wherein the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers of the wireless communication network, the plurality of component carriers including a primary uplink component carrier and one or more secondary uplink component carriers, and wherein the request is received on a first downlink component carrier of the plurality of component carriers;

select an uplink component carrier from among the plurality of component carriers for transmitting a random access message based on an association between the uplink and downlink component carriers, the selecting comprising either (a) selecting an uplink component carrier based on user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, or otherwise, (b) selecting an uplink component carrier based on an association between the selected uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment;

transmit the random access message on the selected uplink component carrier; and

receive a response to the transmitted random access message.

14. The user equipment of claim 13 , wherein the selected uplink component carrier is the primary uplink component carrier.

15. The user equipment of claim 13 , wherein the selected uplink component carrier is a secondary uplink component carrier.

16. The user equipment of claim 15 , wherein the processor executable code, when executed by the processor, configures the user equipment to select a secondary uplink component carrier with an uplink timing advance value that is substantially the same as an uplink timing advance value associated with the primary uplink component carrier.

17. The user equipment of claim 15 , wherein the processor executable code, when executed by the processor, configures the user equipment to

select a secondary uplink component carrier with a different uplink timing advance value than an uplink timing advance value of the primary uplink component carrier; and

to acquire uplink synchronization for the primary uplink component carrier to enable proper transmissions of uplink control information.

18. The user equipment of claim 13 , wherein

the request comprises information corresponding to the association between the first downlink component carrier and an indicated uplink component carrier; and

the selected uplink component carrier is the indicated uplink component carrier.

19. The user equipment of claim 18 , wherein the processor executable code, when executed by the processor, configures the user equipment to receive the response to the transmitted random access message on a second downlink component carrier that is linked to the indicated uplink component carrier in accordance with SIB2 signaling.

20. The user equipment of claim 18 , wherein the processor executable code, when executed by the processor, configures the user equipment to receive the response to the transmitted random access message on the first downlink component carrier.

21. The user equipment of claim 18 , wherein

the received response is a scrambled response; and

the processor executable code, when executed by the processor, configures the user equipment to descramble the response according to a special signature sequence number or a reserved random access radio network temporary identifier (RA-RNTI) to ascertain a particular uplink component carrier.

22. A wireless communication device, comprising:

a processor; and

a memory, comprising processor executable code which, when executed by the processor, configures the wireless communication device to:

configure a plurality of component carriers for use by a user equipment in a wireless communication network, wherein the plurality of component carriers comprise uplink and downlink component carriers, the plurality of component carriers including a primary uplink component carrier and one or more secondary uplink component carriers, and wherein each uplink component carrier is associated with at least one downlink component carrier;

select a downlink component carrier and transmit a request for a random access procedure to the user equipment on the selected downlink component carrier;

receive a random access message from the user equipment on an uplink component carrier of the plurality of component carriers, wherein the uplink component carrier is identified by the user equipment either (a) based on user-equipment-specific signaling that links the selected downlink component carrier to the identified uplink component carrier, or otherwise (b) based on an association between the identified uplink component carrier and the selected downlink component carrier as specified by system information block 2 (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment; and

transmit a response to the user equipment.

23. The wireless communication device of claim 22 , wherein

the selected downlink component carrier is the primary downlink component carrier; and

the random access message is received on the primary uplink component carrier.

24. A wireless communication device, comprising:

means for receiving a request for a random access procedure at a user equipment in a wireless communication network, wherein the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers of the wireless communication network, wherein the plurality of component carriers include a primary uplink component carrier and one or more secondary uplink component carriers, and wherein the request is received on a first downlink component carrier of the plurality of component carriers;

means for selecting an uplink component carrier from among the plurality of component carriers for transmitting a random access message based on an association between the uplink and downlink component carriers, the selecting comprising either (a) selecting an uplink component carrier based on user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, selecting an uplink component carrier based on an association between the selected uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment;

means for transmitting the random access message on the selected uplink component carrier; and

means for receiving a response to the transmitted random access message.

25. A wireless communication device, comprising:

means for configuring a plurality of component carriers for use by a user equipment in a wireless communication network, wherein the plurality of component carriers comprise uplink and downlink component carriers, wherein the plurality of component carriers include at least one primary uplink component carrier and one or more secondary component carriers, and wherein each uplink component carrier is associated with at least one downlink component carrier;

means for selecting a downlink component carrier;

means for transmitting a request for a random access procedure to the user equipment on the selected downlink component carrier;

means for receiving a random access message from the user equipment on an uplink component carrier of the plurality of component carriers, wherein the uplink component carrier is identified by the user equipment either (a) based on user-equipment-specific signaling that links the selected downlink component carrier to the identified uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the identified uplink component carrier and the selected downlink component carrier as specified by system information block 2 (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment; and

means for transmitting a response to the user equipment.

26. A computer program product, embodied on a non-transitory computer-readable medium, comprising:

program code for receiving a request for a random access procedure at a user equipment in a wireless communication network, wherein the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers of the wireless communication network, wherein the plurality of component carriers includes a primary uplink component carrier and one or more secondary uplink component carriers, and wherein the request is received on a first downlink component carrier of the plurality of component carriers;

program code for selecting an uplink component carrier from among the plurality of component carriers for transmitting a random access message based on an association between the uplink and downlink component carriers, the selecting comprising either (a) selecting an uplink component carrier based on user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, selecting an uplink component carrier based on an association between the selected uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment;

program code for transmitting the random access message on the selected uplink component carrier; and

program code for receiving a response to the transmitted random access message.

27. A computer program product, embodied on a non-transitory computer-readable medium, comprising:

program code for configuring a plurality of component carriers for use by a user equipment in a wireless communication network, wherein the plurality of component carriers comprise uplink and downlink component carriers, wherein the plurality of component carriers include a primary uplink component carrier and one or more secondary uplink component carriers, and wherein each uplink component carrier is associated with at least one downlink component carrier;

program code for selecting a downlink component carrier and

program code for transmitting a request for a random access procedure to the user equipment on the selected downlink component carrier;

program code for receiving a random access message from the user equipment on an uplink component carrier of the plurality of component carriers, wherein the uplink component carrier is identified by the user equipment based on either (a) user-equipment-specific signaling that links the selected downlink component carrier to the selected uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the selected uplink component carrier and the selected downlink component carrier as specified by system information block 2 (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment; and

program code for transmitting a response to the user equipment.

28. A method for wireless communication, comprising:

selecting an uplink component carrier for transmitting a random access request by a user equipment in a wireless communication network, wherein the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers, wherein the plurality of component carriers include a primary uplink component carrier and one or more secondary uplink component carriers;

transmitting the random access request on the selected uplink component carrier; and

receiving a response to the random access request on a first downlink component carrier in the plurality of component carriers, wherein the first downlink component carrier is linked with the selected uplink component carrier either (a) based on user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the selected uplink component carrier and the first downlink component carrier as specified by system information block (SIB2)) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment.

29. The method of claim 28 , wherein the user equipment is configured to use a random access channel on the selected uplink component carrier.

30. The method of claim 28 , wherein selecting the uplink component carrier comprises identifying the first downlink component carrier in an active subset of the plurality of component carriers configured for use by the user equipment.

31. The method of claim 28 , wherein the user equipment identifies the first downlink component carrier in accordance with a random access channel (RACH) resource selected from a group consisting of:

a time resource;

a frequency resource; and

a signature space resource.

32. The method of claim 28 , wherein

the selected uplink component carrier is the primary uplink component carrier; and

the first downlink component carrier is the primary downlink component carrier.

33. The method of claim 28 , wherein

the selected uplink component carrier is the primary uplink component carrier; and

the first downlink component carrier is a secondary downlink component carrier.

34. The method of claim 28 , wherein selecting the uplink component carrier comprises selecting a secondary uplink component carrier with substantially the same uplink timing advance value as the primary uplink component carrier.

35. The method of claim 33 , further comprising:

acquiring uplink synchronization for each secondary uplink component carrier within an active subset of the plurality of component carriers configured for use by the user equipment when an uplink timing advance value associated with said each secondary uplink component carrier is different from an uplink timing advance value associated with the primary uplink component carrier.

36. The method of claim 33 , further comprising:

acquiring uplink synchronization for a one or more secondary uplink component carriers within an active subset of the plurality of component carriers configured for use by the user equipment when an uplink timing advance value associated with the one or more secondary uplink component carriers is different from the uplink timing advance value associated with the primary uplink component carrier, and

wherein the one or more secondary uplink component carriers are identified by an entity in the wireless network other than the user equipment.

37. The method of claim 28 , wherein the selected uplink component carrier is the primary uplink component carrier, the method further comprising:

determining that the first downlink carrier is not reliable; and

selecting a secondary uplink component carrier with substantially the same uplink timing advance value as the primary uplink component carrier for the transmission of the random access request.

38. The method of claim 28 , wherein

the selected uplink component carrier is the primary uplink component carrier;

the first downlink carrier is not reliable, and

further comprising receiving an indication of a new primary uplink component carrier, associated with a reliable downlink component carrier.

39. The method of claim 28 , wherein the selected uplink component carrier is the primary uplink component carrier, the method further comprising:

determining that the first downlink carrier is not reliable; and

receiving a contention-free random access request on a reliable downlink component carrier, the contention-free random access request comprising an indication as to an association between the primary uplink component carrier and the reliable downlink component carrier.

40. The method of claim 28 , wherein the selected uplink component carrier is the primary uplink component carrier, the method further comprising:

declaring a radio link failure when the primary uplink component carrier is detected as being unreliable.

41. The method of claim 28 , further comprising:

selecting a secondary uplink component carrier for transmitting the random access request.

42. The method of claim 41 , wherein

determining that the selected uplink component carrier is unreliable;

determining that the first downlink component carrier is reliable; and

acquiring uplink synchronization for an uplink component carrier that is linked to the first downlink component carrier.

43. The method of claim 41 , wherein

determining that the selected uplink component carrier is unreliable;

determining that the first downlink component carrier is reliable; and

attempting to acquire uplink synchronization for each uplink component carrier within an active subset of the plurality of component carriers configured for use by the user equipment in an iterative manner until uplink synchronization for at least one uplink component carrier is successfully attained.

44. The method of claim 43 , further comprising declaring a radio link failure if none of the attempts to acquire uplink synchronization are successful.

45. A method for wireless communication, comprising:

configuring a plurality of component carriers for use by a user equipment in a wireless communication network, wherein the plurality of component carriers comprise uplink and downlink component carriers, wherein the plurality of component carriers include a primary uplink component carrier and one or more secondary uplink component carriers, and wherein each uplink component carrier is associated with at least one downlink component carrier;

receiving a random access request from the user equipment on a first uplink component carrier of the plurality of component carriers, wherein the first uplink component carrier is identified by the user equipment, the user equipment identifying the first uplink component carrier by either (a) selecting the first uplink component carrier based on user-equipment specific signaling that links the first downlink component carrier to the identified uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, selecting the first uplink component carrier based on an association between the first uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment;

transmitting a response on a first downlink component carrier of the plurality of component carriers, wherein the first downlink component carrier is linked to the first uplink component carrier.

46. A user equipment, comprising:

a processor; and

a memory, comprising processor executable code, which when executed by the processor, configures the user equipment to:

select an uplink component carrier for transmitting a random access request by the user equipment from a plurality of component carriers comprising uplink and downlink component carriers, wherein the plurality of component carriers include a primary uplink component carrier and one or more secondary uplink component carriers;

transmit the random access request on the selected uplink component carrier; and

receive a response to the random access request on a first downlink component carrier in the plurality of component carriers, wherein the first downlink component carrier is linked with the selected uplink component carrier either (a) based on user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the selected uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment.

47. The user equipment of claim 46 , wherein the user equipment is configured to use a random access channel on the selected uplink component carrier.

48. The user equipment of claim 46 , wherein the processor executable code, when executed by the processor, configures the user equipment to select the uplink component carrier by identifying the first downlink component carrier from an active subset of the plurality of component carriers configured for use by the user equipment.

49. The user equipment of claim 46 , wherein the processor executable code, when executed by the processor, configures the user equipment to identify the first downlink component carrier in accordance with a random access channel (RACH) resource selected from a group consisting of:

a time resource;

a frequency resource; and

a signature space resource.

50. The user equipment of claim 46 , wherein

the selected uplink component carrier is the primary uplink component carrier; and

the first downlink component carrier is the primary downlink component carrier.

51. The user equipment of claim 46 , wherein

the selected uplink component carrier is the primary uplink component carrier; and

the first downlink component carrier is a secondary downlink component carrier.

52. The user equipment of claim 46 , wherein the processor executable code, when executed by the processor, configures the user equipment to select a secondary uplink component carrier with substantially the same uplink timing advance value as the primary uplink component carrier.

53. The user equipment of claim 51 , wherein the processor executable code, when executed by the processor, further configures the user equipment to:

acquire uplink synchronization for each secondary uplink component carrier within an active subset of the plurality of component carriers configured for use by the user equipment when the uplink timing advance value associated with each secondary uplink component carrier is different from the uplink timing advance value associated with the primary uplink component carrier.

54. The user equipment of claim 51 , wherein the processor executable code, when executed by the processor, further configures the user equipment to:

acquire uplink synchronization for a one or more secondary uplink component carriers within an active subset of the plurality of component carriers configured for use by the user equipment when the uplink timing advance value associated with of the one or more secondary uplink component carriers is different from the uplink timing advance value associated with the primary uplink component carrier, and

wherein the one or more secondary uplink component carriers are identified by an entity in the wireless network other than the user equipment.

55. The user equipment of claim 46 , wherein

the selected uplink component carrier is the primary uplink component carrier;

the first downlink carrier is not reliable; and

the processor executable code, when executed by the processor, configures the user equipment to newly select a secondary uplink component carrier with substantially the same uplink timing advance value as for transmitting the random access request.

56. The user equipment of claim 46 , wherein

the selected uplink component carrier is the primary uplink component carrier;

the first downlink carrier is not reliable; and

a new primary uplink component carrier, associated with a reliable downlink component carrier, is configured for the user equipment.

57. The user equipment of claim 46 , wherein

the selected uplink component carrier is the primary uplink component carrier;

the first downlink carrier is not reliable; and

the processor executable code, when executed by the processor, configures the user equipment to receive a contention-free random access request on a reliable downlink component carrier, the request comprising an indication as to an association between the primary uplink component carrier and the reliable downlink component carrier.

58. The user equipment of claim 46 , wherein

the selected uplink component carrier is the primary uplink component carrier; and

the processor executable code, when executed by the processor, configures the user equipment to declare a radio link failure when the primary uplink component carrier is unreliable.

59. The user equipment of claim 46 , wherein the processor executable code, when executed by the processor, configures the user equipment to select a secondary uplink component carrier for transmitting the random access request.

60. The user equipment of claim 59 , wherein

the selected uplink component carrier is determined to be unreliable;

the first downlink component carrier is determined to be reliable; and

the processor executable code, when executed by the processor, further configures the user equipment to acquire uplink synchronization for an uplink component carrier that is linked to the first downlink component carrier.

61. The user equipment of claim 58 , wherein

the selected uplink component carrier is determined to be unreliable;

the first downlink component carrier is determined to be reliable; and

the processor executable code, when executed by the processor, configures the user equipment to acquire uplink synchronization for each uplink component carrier within an active subset of the plurality of component carriers configured for use by the user equipment until uplink synchronization for at least one uplink component carrier is successfully attained.

62. The user equipment of claim 61 , wherein the processor executable code, when executed by the processor, configures the user equipment to declare a radio link failure if none of the synchronization acquisition attempts are successful.

63. A device, comprising:

a processor; and

a memory, comprising processor executable code, which when executed by the processor, configures the device to:

configure a plurality of component carriers for use by a user equipment in a wireless communication network, wherein the plurality of component carriers comprise uplink and downlink component carriers, wherein the plurality of component carriers comprise a primary uplink component carrier and one or more secondary uplink component carriers, and wherein each uplink component carrier is associated with at least one downlink component carrier;

receive a random access request from the user equipment on a first uplink component carrier of the plurality of component carriers, wherein the first uplink component carrier is identified by the user equipment;

transmit a response on a first downlink component carrier of the plurality of component carriers, wherein the first downlink component carrier is linked to the first uplink component carrier either (a) based on user-equipment specific signaling that links the first downlink component carrier to the first uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the first uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment.

64. A device, comprising:

means for selecting an uplink component carrier for transmitting a random access request by a user equipment in a wireless communication network, wherein the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers, wherein the plurality of component carriers include a primary uplink component carrier and one or more secondary uplink component carriers;

means for transmitting the random access request on the selected uplink component carrier; and

means for receiving a response to the random access request on a first downlink component carrier in the plurality of component carriers, wherein the first downlink component carrier is linked with the selected uplink component carrier either (a) based on user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the selected uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment.

65. A wireless communication device, comprising:

means for configuring a plurality of component carriers for use by a user equipment in a wireless communication network, wherein the plurality of component carriers comprise uplink and downlink component carriers, wherein the plurality of component carriers include a primary uplink component carrier and one or more secondary uplink component carriers, and wherein each uplink component carrier is associated with at least one downlink component carrier;

means for receiving a random access request from the user equipment on a first uplink component carrier of the plurality of component carriers, wherein the first uplink component carrier is identified by the user equipment;

means for transmitting a response on a first downlink component carrier of the plurality of component carriers, wherein the first downlink component carrier is linked to the first uplink component carrier either (a) based on user-equipment specific signaling that links the first downlink component carrier to the first uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the first uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment.

66. A computer program product, embodied on a non-transitory computer-readable medium, comprising:

program code for selecting an uplink component carrier for transmitting a random access request by a user equipment in a wireless communication network, wherein the user equipment is configured to operate with a plurality of component carriers comprising uplink and downlink component carriers, the plurality of component carriers including a primary uplink component carrier and one or more secondary uplink component carriers;

program code for transmitting the random access request on the selected uplink component carrier; and

program code for receiving a response to the random access request on a first downlink component carrier in the plurality of component carriers, wherein the first downlink component carrier is linked with the selected uplink component carrier either (a) based on user-equipment specific signaling that links the first downlink component carrier to the first uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the first uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment.

67. A computer program product, embodied on a non-transitory computer-readable medium, comprising:

program code for configuring a plurality of component carriers for use by a user equipment in a wireless communication network, wherein the plurality of component carriers comprise uplink and downlink component carriers, wherein the plurality of component carriers include a primary component carrier and one or more secondary component carriers, and wherein each uplink component carrier is associated with at least one downlink component carrier;

program code for receiving a random access request from the user equipment on a first uplink component carrier of the plurality of component carriers, wherein the first uplink component carrier is identified by the user equipment;

program code for transmitting a response on a first downlink component carrier of the plurality of component carriers, wherein the first downlink component carrier is linked to the first uplink component carrier either (a) based on user-equipment specific signaling that links the first downlink component carrier to the first uplink component carrier, or otherwise, (b) in the absence of user-equipment specific signaling that links the first downlink component carrier to the selected uplink component carrier, based on an association between the first uplink component carrier and the first downlink component carrier as specified by system information block (SIB2) signaling, wherein whether (a) or (b) is used is dependent upon signaling received by the user equipment.