Reporting power headroom for aggregated carriers

1. A method implemented in a user agent comprising a processor and a memory device storing instructions executable by the processor to implement the method, the method comprising:

transmitting in a media access control (MAC) control element power headroom-related information for a number of a plurality of aggregated carriers that is less than or equal to a total number of the aggregated carriers, the aggregated carriers comprising a first carrier and a second carrier; and

transmitting in the MAC control element a bitmap, each of the aggregated carriers corresponding to a bit in the bitmap, a first value in the bitmap indicating that the power headroom-related information for the first carrier is included in the MAC control element, and a second value in the bitmap indicating that the power headroom-related information for the second carrier is not included in the MAC control element.

2. The method of claim 1 , wherein the power headroom-related information is power headroom information, and wherein the user agent transmits the MAC control element to an access node.

3. The method of claim 1 , wherein each of the aggregated carriers is associated with a carrier index.

4. The method of claim 1 , wherein the transmission of the power headroom-related information is triggered by one of:

a change in the path loss of a reporting carrier among the aggregated carriers being greater than a pre-defined amount since a previous power headroom report;

addition of a third carrier to the aggregated carriers; or

expiration of a timer that controls periodic power headroom reports.

5. The method of claim 1 , wherein, when a physical uplink control channel (PUCCH) is not transmitted in the same subframe in which PUCCH-related power headroom is transmitted, the PUCCH-related power headroom is calculated based on an estimated transmit power of the PUCCH.

6. The method of claim 1 , wherein the bitmap includes at least five bits.

7. The method of claim 1 , further comprising receiving power control commands for at least a subset of the aggregated carriers.

8. A user agent (UA) comprising a memory device and a processor configured to execute instructions stored on the memory device such that when executed, cause the UA to:

transmit in a media access control (MAC) control element power headroom-related information for a number of a plurality of aggregated carriers that is less than or equal to a total number of the aggregated carriers, the aggregated carriers comprising a first carrier and a second carrier; and

transmit in the MAC control element a bitmap, each of the aggregated carriers corresponding to a bit in the bitmap, a first value in the bitmap indicating that the power headroom-related information for the first carrier is included in the MAC control element, and a second value in the bitmap indicating that the power headroom-related information for the second carrier is not included in the MAC control element.

9. The UA of claim 8 , wherein the power headroom-related information is power headroom information, and wherein the UA transmits the MAC control element to an access node.

10. The UA of claim 8 , wherein each of the aggregated carriers is associated with a carrier index.

11. The UA of claim 8 , wherein the transmission of the power headroom-related information is triggered by one of:

a change in the path loss of a reporting carrier among the aggregated carriers being greater than a pre-defined amount since a previous power headroom report;

addition of a third carrier to the aggregated carriers; or

expiration of a timer that controls periodic power headroom reports.

12. The UA of claim 8 , wherein, when a physical uplink control channel (PUCCH) is not transmitted in the same subframe in which PUCCH-related power headroom is transmitted, the PUCCH-related power headroom is calculated based on an estimated transmit power of the PUCCH.

13. The UA of claim 8 , wherein the bitmap includes at least five bits.

14. The UA of claim 8 , wherein the UA is further configured to receive power control commands for at least a subset of the aggregated carriers.

15. A non-transitory computer medium storing computer readable instructions executable by a processor to implement a method, the method comprising:

transmitting in a media access control (MAC) control element power headroom-related information for a number of a plurality of aggregated carriers that is less than or equal to a total number of the aggregated carriers, the aggregated carriers comprising a first carrier and a second carrier; and

transmitting in the MAC control element a bitmap, each of the aggregated carriers corresponding to a bit in the bitmap, a first value in the bitmap indicating that the power headroom-related information for the first carrier is included in the MAC control element, and a second value in the bitmap indicating that the power headroom-related information for the second carrier is not included in the MAC control element.

16. The computer medium of claim 15 , wherein the power headroom-related information is power headroom information, and wherein a user agent transmits the MAC control element to an access node.

17. The computer medium of claim 15 , wherein each of the aggregated carriers is associated with a carrier index.

18. The computer medium of claim 15 , wherein the transmission of the power headroom-related information is triggered by one of:

a change in the path loss of a reporting carrier among the aggregated carriers being greater than a pre-defined amount since a previous power headroom report;

addition of a third carrier to the aggregated carriers; or

expiration of a timer that controls periodic power headroom reports.

19. The computer medium of claim 15 , wherein, when a physical uplink control channel (PUCCH) is not transmitted in the same subframe in which PUCCH-related power headroom is transmitted, the PUCCH-related power headroom is calculated based on an estimated transmit power of the PUCCH.

20. The computer medium of claim 15 , wherein the bitmap includes at least five bits.

21. The computer medium of claim 15 , wherein the method further comprises receiving power control commands for at least a subset of the aggregated carriers.

22. A method implemented in an access node comprising a processor and a memory device storing instructions executable by the processor to implement the method, the method comprising:

receiving in a media access control (MAC) control element power headroom-related information for a number of a plurality of aggregated carriers that is less than or equal to a total number of the aggregated carriers, the aggregated carriers comprising a first carrier and a second carrier; and

receiving in the MAC control element a bitmap, each of the aggregated carriers corresponding to a bit in the bitmap, a first value in the bitmap indicating that the power headroom-related information for the first carrier is included in the MAC control element, and a second value in the bitmap indicating that the power headroom-related information for the second carrier is not included in the MAC control element.

23. The method of claim 22 , wherein the power headroom-related information is power headroom information, and wherein the access node receives the MAC control element from a user agent.

24. The method of claim 22 , wherein each of the aggregated carriers is associated with a carrier index.

25. The method of claim 22 , wherein the transmission of the power headroom-related information is triggered by one of:

a change in the path loss of a reporting carrier among the aggregated carriers being greater than a pre-defined amount since a previous power headroom report;

addition of a third carrier to the aggregated carriers; or

expiration of a timer that controls periodic power headroom reports.

26. The method of claim 22 , wherein, when a physical uplink control channel (PUCCH) is not received in the same subframe in which PUCCH-related power headroom is transmitted, the PUCCH-related power headroom is calculated based on an estimated transmit power of the PUCCH.

27. The method of claim 22 , wherein the bitmap includes at least five bits.

28. The method of claim 22 , further comprising transmitting power control commands for at least a subset of the aggregated carriers.

29. An access node comprising a memory device and a processor configured to execute instructions stored on the memory device such that when executed, cause the access node to:

receive in a media access control (MAC) control element power headroom-related information for a number of a plurality of aggregated carriers that is less than or equal to a total number of the aggregated carriers, the aggregated carriers comprising a first carrier and a second carrier; and

receive in the MAC control element a bitmap, each of the aggregated carriers corresponding to a bit in the bitmap, a first value in the bitmap indicating that the power headroom-related information for the first carrier is included in the MAC control element, and a second value in the bitmap indicating that the power headroom-related information for the second carrier is not included in the MAC control element.

30. The access node of claim 29 , wherein the power headroom-related information is power headroom information, and wherein the access node receives the MAC control element from a user agent.

31. The access node of claim 29 , wherein each of the aggregated carriers is associated with a carrier index.

32. The access node of claim 29 , wherein the transmission of the power headroom-related information is triggered by one of:

a change in the path loss of a reporting carrier among the aggregated carriers being greater than a pre-defined amount since a previous power headroom report;

addition of a third carrier to the aggregation of aggregated carriers; or

expiration of a timer that controls periodic power headroom reports.

33. The access node of claim 29 , wherein, when a physical uplink control channel (PUCCH) is not received in the same subframe in which PUCCH-related power headroom is transmitted, the PUCCH-related power headroom is calculated based on an estimated transmit power of the PUCCH.

34. The access node of claim 29 , wherein the bitmap includes at least five bits.

35. The access node of claim 29 , wherein the access node is further configured to transmit power control commands for at least a subset of the aggregated carriers.