Uplink power headroom reporting for carrier aggregation
A method for reporting power headroom is disclosed. Power headroom may be reported across all carriers (wideband), for a specific carrier, or for a carrier group. The formula used to calculate the power headroom depends on whether the carrier (or a carrier in the carrier group) has a valid uplink grant. If the carrier or carrier group does not have a valid uplink grant, the power headroom may be calculated based on a reference grant. The power headroom is calculated by a wireless transmit/receive unit and is reported to an eNodeB.
1. A wireless transmit/receive unit (WTRU) comprising, the WTRU comprising:
a processor configured to:
determine a carrier that does not have a physical uplink shared channel (PUSCH) transmission in a subframe i from a plurality of aggregated carriers;
calculate a power headroom for the carrier according to the formula:
PH ( k,i )= P CMAX _ carrier ( k )− P PUSCH _ REF ( k,i )
where PH(k,i) is the power headroom for the carrier, k is the carrier, P CMAX _ carrier (k) is a maximum power for the carrier, and P PUSCH _ REF (k,i) is a transmit power determined according to a reference grant; and
report the power headroom for the carrier.
2. The WTRU of claim 1 , wherein the processor is configured to report the power headroom for the carrier by sending a power headroom report to an eNodeB.
3. The WTRU of claim 2 , wherein the power headroom report is a type 1 power headroom report.
4. The WTRU of claim 1 , wherein the reference grant is a pre-defined allocation.
5. The WTRU of claim 4 , wherein the pre-defined allocation is a pre-defined number of resource blocks.
6. The WTRU of claim 1 , wherein the carrier does not have a valid uplink grant.
7. The WTRU of claim 1 , wherein the carrier is a first carrier and wherein the processor is configured to report the power headroom for the first carrier by reporting the power headroom for the first carrier to a second carrier.
8. The WTRU of claim 2 , wherein the carrier is a first carrier, the power headroom for the carrier is a first power headroom for the first carrier, and the power headroom report comprises the first power headroom for the first carrier and a second power headroom for a second carrier that has a valid uplink grant.
9. The WTRU of claim 1 , wherein the processor is configured to report the power headroom for the carrier by reporting the power headroom for the carrier via medium access control (MAC) signaling.
10. A wireless transmit/receive unit (WTRU), the WTRU comprising:
a processor configured to:
determine a carrier that does not have a physical uplink shared channel (PUSCH) transmission in a subframe from a plurality aggregated carriers;
determine a maximum power for the carrier;
calculate a power headroom for the carrier using the maximum power for the carrier and a reference grant; and
send a power headroom report that includes the power headroom for the carrier.
11. The WTRU of claim 10 , wherein the processor is configured to send the power headroom report by sending the power headroom report to an eNodeB.
12. The WTRU of claim 10 , wherein the power headroom report is a type 1 power headroom report.
13. The WTRU of claim 10 , wherein the power headroom report is a type 2 power headroom report.
14. The WTRU of claim 10 , wherein the reference grant is a pre-defined allocation.
15. The WTRU of claim 14 , wherein the pre-defined allocation is a pre-defined number of resource blocks.
16. The WTRU of claim 10 , wherein the carrier does not have a valid uplink grant.
17. The WTRU of claim 10 , wherein the processor is further configured to calculate a reference transmit power using the reference grant.
18. The WTRU of claim 10 , wherein the processor is further configured to calculate the power headroom for the carrier using the maximum power for the carrier and the reference grant by:
calculating a reference transmit power using the reference grant; and
calculating the power headroom for the carrier using the maximum power for the carrier and the reference transmit power.
19. The WTRU of claim 18 , wherein the processor is further configured to calculate the power headroom for the carrier using the maximum power for the carrier and the reference grant by determining a difference between the maximum power for the carrier and the reference transmit power.
20. The WTRU of claim 10 , wherein the carrier is a first carrier and wherein the processor is configured to send the power headroom report by sending the power headroom report to a second carrier.
21. The WTRU of claim 10 , wherein the carrier is a first carrier, the power headroom for the carrier is a first power headroom for the first carrier, and the power headroom report comprises the first power headroom for the first carrier and a second power headroom for a second carrier that has a valid uplink grant.
22. The WTRU of claim 10 , wherein the processor is configured to send the power headroom report via medium access control (MAC) signaling.
23. A method for reporting power headroom, the method comprising:
determining a carrier that does not have a physical uplink shared channel (PUSCH) transmission in a subframe i from a plurality of aggregated carriers;
calculating a power headroom for the carrier according to the formula:
PH ( k,i )= P CMAX _ carrier ( k )− P PUSCH _ REF ( k,i )
where PH(k,i) is the power headroom for the carrier, k is the carrier, P CMAX _ carrier (k) is a maximum power for the carrier, and P PUSCH _ REF (k, i) is a transmit power determined according to a reference grant; and
reporting the power headroom for the carrier.
24. The method of claim 23 , wherein reporting the power headroom for the carrier comprises sending a power headroom report to an eNodeB.
25. The method of claim 24 , wherein the power headroom report is a type 1 power headroom report.
26. The method of claim 23 , wherein the reference grant is a pre-defined allocation.
27. The method of claim 26 , wherein the pre-defined allocation is a pre-defined number of resource blocks.
28. The method of claim 23 , wherein the carrier does not have a valid uplink grant.
29. The method of claim 23 , wherein the carrier is a first carrier and wherein reporting the power headroom for the first carrier comprises reporting the power headroom for the first carrier to a second carrier.
30. The method of claim 25 , wherein the carrier is a first carrier, the power headroom for the carrier is a first power headroom for the first carrier, and the power headroom report comprises the first power headroom for the first carrier and a second power headroom for a second carrier that has a valid uplink grant.
31. The method of claim 23 , wherein reporting the power headroom for the carrier comprises reporting the power headroom via medium access control (MAC) signaling.
32. A method for reporting power headroom, the method comprising:
determining a carrier that does not have a physical uplink shared channel (PUSCH) transmission in a subframe from a plurality of aggregated carriers;
determining a maximum power for the carrier;
calculating a power headroom for the carrier using the maximum power for the carrier and a reference grant; and
sending a power headroom report that includes the power headroom for the carrier.
33. The method of claim 32 , wherein sending the power headroom report comprises sending the power headroom report to an eNodeB.
34. The method of claim 32 , wherein the power headroom report is a type 1 power headroom report.
35. The method of claim 32 , wherein the power headroom report is a type 2 power headroom report.
36. The method of claim 32 , wherein the reference grant is a pre-defined allocation.
37. The method of claim 36 , wherein the pre-defined allocation is a pre-defined number of resource blocks.
38. The method of claim 32 , wherein the carrier does not have a valid uplink grant.
39. The method of claim 32 , further comprising calculating a reference transmit power using the reference grant.
40. The method of claim 32 , wherein calculating the power headroom for the carrier using the maximum power for the carrier and the reference grant comprises:
calculating a reference transmit power using the reference grant; and
calculating the power headroom for the carrier using the maximum power for the carrier and the reference transmit power.
41. The method of claim 40 , wherein calculating the power headroom for the carrier using the maximum power for the carrier and the reference grant further comprises determining a difference between the maximum power for the carrier and the reference transmit power.
42. The method of claim 32 , wherein the carrier is a first carrier and wherein sending the power headroom report comprises sending the power headroom report to a second carrier.
43. The method of claim 32 , wherein the carrier is a first carrier, the power headroom for the carrier is a first power headroom for the first carrier, and the power headroom report comprises the first power headroom for the first carrier and a second power headroom for a second carrier that has a valid uplink grant.
44. The method of claim 32 , wherein sending the power headroom report comprises sending the power headroom report via medium access control (MAC) signaling.