Uplink power headroom reporting for carrier aggregation

• US 9,426,752 B2
• Filed: 10/04/2012
• Issued: 08/23/2016
• Est. Priority Date: 12/03/2008
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: Shin, Sung-Hyuk, Zhang, Guodong, Bala, Erdem, Pietraski, Philip J., Pan, Kyle Jung-Lin, Levy, Joseph S., Wang, Jin, Wang, Peter S., Stern-Berkowitz, Janet A., Haim, John W.
• Primary Examiner(s): Vo, Don N
• Application Number:
  US13/645,169
• Publication Number:
  US 20130028231A1
• Time in Patent Office: 1,419 Days
• Field of Search: 375/260, 375/267, 455/452.1, 455/452.2, 455/522
• US Class Current: 1/1
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/365 Power headroom reporting
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/0473 the resource being transmission power
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network

Abstract

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.

Claims

1. A method comprising:

determining, via a wireless transmit/receive unit (WTRU), a carrier that does not have a physical uplink shared channel (PUSCH) transmission in a subframe i from a plurality of aggregated carriers; and

calculating, via the WTRU, 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 a carrier number, 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 allocation.

2. The method of claim 1, wherein the reference grant allocation is a pre-defined allocation.

3. The method of claim 2, wherein the pre-defined allocation is a pre-defined number of resource blocks.

4. The method according to claim 1, wherein P_{CMAX_carrier}(k) is less than or equal to a P_CMAX, where P_CMAX is a total maximum transmit power.

5. The method of claim 1, further comprising reporting, via the WTRU, the power headroom for the carrier.

6. The method according to claim 1, wherein the carrier does not have a valid uplink grant.

7. A method for comprising:

determining, via a wireless transmit/receive unit (WTRU), a carrier that does not have a physical uplink shared channel (PUSCH) transmission in a subframe from one or more aggregated carriers;

determining, via the WTRU, a maximum power for the carrier; and

calculating, via the WTRU, a power headroom for the carrier using the maximum power for the carrier and a reference grant.

8. The method of claim 7, wherein the reference grant is a pre-defined allocation.

9. The method of claim 8, wherein the pre-defined allocation is a pre-defined number of resource blocks.

10. The method of claim 7, further comprising reporting, via the WTRU, the power headroom.

11. The method of claim 7, wherein the carrier does not have a valid uplink grant.

12. The method of claim 7, further comprising calculating, via the WTRU, a reference transmit power using the reference grant.

13. The method of claim 12, wherein calculating, via the WTRU, the power headroom for the carrier using the maximum power for the carrier and the reference grant comprises determining, via the WTRU, a difference between the maximum power for the carrier and the reference transmit power.

14. The method of claim 7, further comprising calculating, via the WTRU, a reference transmit power using a predetermined number of resource blocks associated with the reference grant.

15. The method of claim 7, wherein calculating, via the WTRU, the power headroom for the carrier using the maximum power for the carrier and the reference grant comprises:

calculating, via the WTRU, a reference transmit power using the reference grant; and

calculating, via the WTRU, the power headroom for the carrier using the maximum power for the carrier and the reference transmit power.

16. A wireless transmit/receive unit (WTRU) comprising:

a processor configured to;

determine a carrier that does not have a physical uplink shared channel (PUSCH) transmission in a subframe from one or more aggregated carriers;

calculate a maximum power for the carrier; and

calculate a power headroom for the carrier using the maximum power for the carrier and a reference grant.

17. The WTRU of claim 16, wherein the reference grant is a previous grant allocation for the carrier.

18. The WTRU of claim 16, wherein the reference grant is a grant allocation for another carrier.

19. The WTRU of claim 16, wherein the processor is further configured to report the power headroom.

20. The WTRU of claim 16, wherein the carrier does not have a valid uplink grant.

21. The WTRU of claim 16, wherein the processor is further configured to calculate a reference transmit power using the reference grant.

22. The WTRU of claim 21, wherein the processor is 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.

23. The WTRU of claim 16, wherein the processor is 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 a predetermined value associated with the reference grant.

24. The WTRU of claim 16, wherein the processor is 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.

25. The WTRU of claim 18, wherein the processor is further configured to calculate a reference transmit power using a pathloss estimate for the carrier, and a transmit power for another carrier.

26. The WTRU of claim 16, wherein the processor is further configured to calculate a reference transmit power using at least one parameter of at least one carrier that has a valid uplink grant.