Uplink power headroom reporting for carrier aggregation

• US 8,315,320 B2
• Filed: 12/03/2009
• Issued: 11/20/2012
• 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: Zhang, Guodong, Bala, Erdem, Pietraski, Philip J., Shin, Sung-Hyuk, 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:
  US12/630,562
• Publication Number:
  US 20100158147A1
• Time in Patent Office: 1,083 Days
• Field of Search: 375/260, 375/267, 455/452.1, 455/452.2, 455/522
• US Class Current: 375/260
• 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 for reporting a carrier-specific power headroom for aggregated carriers, the method comprising:

determining a first carrier from a plurality of aggregated carriers that has a physical uplink shared channel (PUSCH) transmission in a subframe i;

determining a second carrier from the plurality of aggregated carriers that does not have a PUSCH transmission in a subframe i;

calculating a first power headroom according to the formula;

PH(k₁,i)=P_CMAXcarrier(k₁)−

P<sub>PUSCH—

UG</sub>(k₁,i)

where k₁ is the first carrier, and P<sub>PUSCH—

UG</sub>(k₁,i) is a transmit power for the first carrier in subframe i prior to imposing maximum power limitations; and

calculating a second power headroom for the second carrier according to the formula;

PH(k₂,i)=P<sub>CMAX—

carrier</sub>(k₂)−

P<sub>PUSCH—

REF</sub>(k₂,i)

where k₂ is the second carrier, and P<sub>PUSCH—

REF</sub>(k₂,i) is a transmit power determined according to a reference grant allocation.

2. The method according to claim 1, wherein:

3. The method according to claim 2, wherein the sum of P_CMAX—

_carrier(k) for all carriers k is limited by P_CMAX such that

4. The method according to claim 1, wherein:

5. The method according to claim 4, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

is limited by P_CMAX such that

6. The method according to claim 1, wherein:

7. The method according to claim 6, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

_m is limited by P_CMAx(m) such that

8. The method according to claim 1, wherein:

9. The method according to claim 8, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

_m is limited by P_CMAX(m) such that

10. The method of claim 1, further comprising reporting the first power headroom and the second power headroom.

11. The method of claim 1, wherein P_PUSCH—

UG(k,i) is defined for k carrier according to the formula;

10 log₁₀(M_PUSCH(i)+α

(j)×

PL+Δ

_TF(i)+f(i)

12. The method of claim 11, wherein P_CMAX—

_carrier(k) is a maximum WTRU transmit power of the k carrier.

13. The method of claim 1, wherein the sum of P_CMAX—

_carrier(k₂) and P<sub>CMAX—

carrier</sub>(k₁) is less than or equal to a P_CMAX for the plurality of aggregated carriers.

14. The method of claim 1, further comprising determining a third carrier that does not have a PUSCH transmission in a subframe i.

15. The method of claim 14, further comprising calculating a third power headroom for the third carrier according to the formula:

PH(k₃, i)=P<sub>CMAX—

carrier</sub>(k₃, i)

where k₃ is the third carrier, and P<sub>PUSCH—

REF</sub>(k₃, i) is a transmit power determined according to a reference grant allocation.

16. The method of claim 15, further comprising reporting the first power headroom, the second power headroom, and the third power headroom.

17. A method for reporting a carrier-specific power headroom, comprising:

calculating a maximum power per carrier, P<sub>CMAX—

carrier</sub>;

on a condition that the carrier does not have a valid uplink grant, calculating a power headroom using a reference grant according to the formula;

PH(k,i)=P<sub>CMAX—

carrier</sub>(k)−

P<sub>PUSCH—

REF</sub>(k,i)

where k is a carrier number, i is a subframe for which the power headroom is to be reported, and P<sub>PUSCH—

REF</sub>(k,i) is defined as

P<sub>PUSCH—

REF</sub>(k,i)=f<sub>1—

REF</sub>(P<sub>PUSCH—

REF</sub>(n,i))+α

×

(PL(k)−

f<sub>2—

REF</sub>(PL(n)))

where f<sub>1—

REF</sub>(*) is a function of a reference carrier-specific wireless transmit/receive unit transmit power, n≠

k and carrier n belongs to the set of carriers with a valid uplink grant, α

is a cell-specific parameter, PL(k) is a pathloss estimate on carrier k, and f<sub>2—

REF</sub>(*) is a function of a reference carrier-specific pathloss; and

reporting the calculated power headroom.

18. The method according to claim 17, wherein calculating the maximum power per carrier is based on the formula:

19. The method according to claim 18, wherein the sum of P_CMAX—

_carrier(k) for all carriers k is limited by P_CMAX such that

20. The method according to claim 17, wherein calculating the maximum power per carrier is based on the formula:

21. The method according to claim 20, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

is limited by P_CMAX such that

22. The method according to claim 17, wherein calculating the maximum power per carrier is based on the formula:

23. The method according to claim 22, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

_m is limited by P_CMAX(m) such that

24. A method for reporting a carrier group-specific power headroom, comprising:

calculating a maximum power per carrier, P<sub>CMAX—

carrier</sub>(k);

on a condition that at least one carrier in the carrier group has a valid uplink grant, calculating a group power headroom according to the formula;

25. The method according to claim 24, wherein calculating the maximum power per carrier is based on the formula:

26. The method according to claim 25, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

is limited by P_CMAX such that

27. The method according to claim 24, wherein calculating the maximum power per carrier is based on the formula:

28. The method according to claim 27, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

is limited by P_CMAX such that

29. A method for reporting a carrier group-specific power headroom, comprising:

calculating a maximum power per carrier, P<sub>CMAX—

carrier</sub>(k);

on a condition that no carrier in the carrier group has a valid uplink grant, calculating a group power headroom using a reference grant according to the formula;

30. The method according to claim 29, wherein calculating the maximum power per carrier is based on the formula:

31. The method according to claim 30, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

is limited by P_CMAX such that

32. The method according to claim 29, wherein calculating the maximum power per carrier is based on the formula:

33. The method according to claim 32, wherein the sum of P_CMAX—

_carrier(k) for all carriers k in Ω

is limited by P_CMAX such that

34. A method for reporting a carrier group-specific power headroom, comprising:

on a condition that at least one carrier in the carrier group has a valid uplink grant, calculating a group power headroom according to the formula;

35. A method for reporting a earner group-specific power headroom, comprising:

on a condition that no carrier in the carrier group has a valid uplink grant, calculating a group power headroom using a reference grant according to the formula;

36. A method for reporting carrier-specific power headroom for aggregated carriers, the method comprising:

determining a first maximum power for a first carrier;

determining a first transmit power that corresponds to the first carrier;

calculating a first power headroom for the first carrier;

determining a second maximum power for a second carrier from a plurality of aggregated carriers that does not have a physical uplink shared channel (PUSCH) transmission in a subframe i;

calculating a second power headroom for the second carrier using a reference grant; and

reporting the calculated first and second power headroom.

37. The method according to claim 36, wherein the first carrier has a valid uplink grant, and the first transmit power comprises a transmit power for the first carrier prior to imposing maximum power limitations.

38. The method according to claim 36 wherein the second carrier does not have a valid uplink grant, and a second transmit power comprises a reference transmit power.

39. The method according to claim 38, further comprising:

calculating the reference transmit power based on a pathloss estimate on the second carrier, a pathloss on at least one carrier that has a valid uplink grant, and a transmit power for the at least one carrier that has a valid uplink grant.

40. The method according to claim 38, further comprising:

calculating the reference transmit power using a predetermined value reference.

41. The method according to claim 38, further comprising:

calculating the reference transmit power using at least one parameter of at least one carrier that has a valid uplink grant.

42. The method according to claim 36, wherein the first maximum power for the first carrier is pre-defined by higher layer configurations.

43. The method according to claim 36, wherein calculating the first power headroom comprises determining a difference between the first maximum power and the first transmit power.

44. The method according to claim 36, wherein calculating the second power headroom comprises determining a difference between a second maximum power and the second transmit power.