METHODS, APPARATUS AND SYSTEMS FOR HANDLING ADDITIONAL POWER BACKOFF

• US 20120178494A1
• Filed: 01/06/2012
• Published: 07/12/2012
• Est. Priority Date: 01/07/2011
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Inventors: TERRY, Stephen E., HAIM, John W., STERN-BERKOWITZ, Janet A., COMSA, Virgil, SHIN, Sung-Hyuk H.
• Granted Patent: US 9,020,556 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• CPC Class Codes: H04W 52/365 Power headroom reporting
• CPC Class Codes: H04W 72/0473 the resource being transmission power
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

Methods, apparatus and systems are described for a wireless transmit/receive unit (WTRU) to manage its transmission power. A power headroom report (PHR) may be triggered based on changes to backoff or the impacts of backoff. Additional backoff may be used to calculate a maximum output power of the WTRU and may be indicated by a domination indicator to network resources. The WTRU may be configured to eliminate triggers caused by virtual PHRs. Furthermore, the WTRU may be configured to respond to rapid changes to backoff.

Claims

1. A method of managing power headroom reporting associated with a wireless transmit/receive unit (WTRU), the method comprising:

determining a Power Management Power Reduction (P-PR);

determining a backoff value for reducing a value of maximum transmission power for the WTRU; and

reporting power headroom in accordance with the determined backoff value.

2. The method of claim 1, wherein the determining of the backoff value includes

determining a further value for reducing a value of maximum transmission power for the WTRU;

selecting between one of the further value and the P-PR, as a selected value; and

calculating the backoff value based on the selected value.

3. The method of claim 2, further comprising:

comparing the further value to the P-PR; and

responsive to the further value being less than the P-PR, calculating the backoff value in accordance with the P-PR, exclusive of the further value.

4. The method of claim 2, wherein the further value is based on a Maximum Power Reduction (MPR), and an Additional MPR (A-MPR).

5. The method of claim 2, wherein:

the calculating of the backoff value based on the selected value includes calculating a maximum output power using the maximum of the further value and the P-PR; and

the P-PR, the backoff value, the power headroom reporting and the maximum output power are each associated with an individual component carrier of the WTRU.

6. The method of claim 1, further comprising:

configuring maximum output power between an upper bound and a lower bound where the lower bound is set by the following equation;

P<sub>CMAX—

L</sub>=MIN{P_EMAX,−

Δ

T_C,P_PowerClass−

MAX(MPR+A-MPR,P-PR)−

Δ

T_C,}

where P_EMAX is a quantity signaled to the WTRU, Δ

T_C, is a power reduction that is based on the WTRU transmission frequency, P_PowerClass is the maximum power of the WTRU'"'"'s power class, MPR is a Maximum power reduction for the WTRU, A-MPR is a additional MPR, and P-PR is a power management power reduction.

7. The method of claim 1, further comprising:

configuring maximum output power for an individual component carrier between an upper bound and a lower bound where the lower bound is set by the following equation;

P<sub>CMAX—

L,c</sub>=MIN{P_EMAX,c−

Δ

T_C,c,P_PowerClass−

MAX(MPR+A-MPR,P-PR)−

Δ

T_C,c}

where P_EMAX,c is a quantity signaled to the WTRU, Δ

T_C,c, is a power reduction that is based on the WTRU transmission frequency for the individual component carrier, P_PowerClass is the maximum power of the WTRU'"'"'s power class, MPR is a Maximum power reduction for the WTRU, A-MPR is a additional MPR, and P-PR is a power management power reduction.

8. The method of claim 1, further comprising:

determining whether the WTRU applies a backoff value based on the P-PR; and

reporting to a network resource that the WTRU has applied the backoff value based on the P-PR.

9. The method of claim 8, wherein the reporting that the WTRU has applied the backoff value based on the P-PR includes:

setting a domination indicator when the backoff is based on the P-PR; and

sending the domination indicator to the network resource.

10. The method of claim 9, further comprising including the domination indicator in a power headroom (PH) report.

11. The method of claim 9, wherein the sending of the domination indicator includes sending a power headroom report including the domination indicator to the network resource in a medium access control (MAC) control element (CE).

12. The method of claim 9, wherein the setting of the domination indicator includes setting one of:

(1) a respective domination indicator for each component carrier impacted by a corresponding P-PR;

or (2) a single domination indicator associated with the WTRU.

13. The method of claim 9, wherein the setting of the domination indicator includes setting the domination indicator to one of:

(1) a first logic level responsive to the backoff value being impacted by the P-PR;

or (2) a second logic level responsive to the power backoff not being impacted by the P-PR.

14. A method of managing power headroom reports (PHRs) associated with a wireless transmit/receive unit (WTRU), the method comprising

determining whether a real transmission is to occur for a component carrier (CC) at a first period;

determining a previous period when a real transmission occurred for the CC;

comparing the P-PR of the CC associated with the first period with the P-PR of the CC associated with the previous period; and

triggering a PHR in accordance with a comparison result.

15. The method of claim 14, wherein the triggering of the PHR includes triggering the PHR in response to the P-PR of the CC associated with the first period differing from the P-PR of the CC associated with the previous period by a threshold.

16. The method of claim 14, wherein the determining of whether the real transmission is to occur for the CC at the first period includes determining whether any UL resources are to be used for the CC at the first period.

17. The method of claim 14, wherein the first period is a period associated with a current transmission time interval and the previous period is a period associated with a closest, previous transmission time interval in which the PHR was sent by the WTRU and included a power headroom corresponding to a real transmission for the CC.

18. The method of claim 14, wherein the comparing of the P-PR of the CC associated with the first period with a P-PR of the CC associated with the previous period includes:

obtaining the P-PR of the CC associated with the first period;

obtaining the P-PR of the CC associated with the previous period; and

determining whether the P-PR of the CC associated with the first period differs from the P-PR of the CC associated with the previous period by a threshold.

19. A method of managing transmission power of a wireless transmit/receive unit (WTRU), the method comprising:

determining a Power Management Power Reduction (P-PR);

determining a backoff value for reducing a value of maximum transmission power for the WTRU; and

adjusting transmission power in accordance with the determined backoff value.

20. The method of claim 19, wherein the determining of the backoff value includes:

determining a further value for reducing a value of maximum transmission power for the WTRU; and

selecting between one of the further value and the P-PR, as a selected value.

21. The method of claim 20, further comprising:

comparing the further value to the P-PR; and

responsive to the further value being less than the P-PR, adjusting of the maximum transmission power in accordance with the P-PR, exclusive of the further value.

22. The method of claim 19, further comprising:

determining whether a sum of powers of component carriers (CCs) of the WTRU is to exceed the maximum transmission power, as a determined result; and

scaling a transmission power of the CCs used for transmission by the WTRU such that a composite of the scaled transmission power does not exceed the maximum transmission power in accordance with the determined result.

23. A wireless transmit/receive unit (WTRU) configured to report power headroom, comprising:

a processor configured to;

determine a Power Management Power Reduction (P-PR) and determine a backoff value for reducing a value of maximum transmission power for the WTRU; and

a transmit/receive unit configured to report power headroom in accordance with the backoff value determined by the processor.

24. The WTRU of claim 23, wherein the processor is configured to:

determine a further value for reducing a value of maximum transmission power for the WTRU;

select between one of the further value and the P-PR, as a selected value; and

calculate the backoff value based on the selected value.

25. The WTRU of claim 23, wherein the processor is configured to:

compare the further value to the P-PR; and

responsive to the further value being less than the P-PR, calculate the backoff value in accordance with the P-PR, exclusive of the further value.

26. The WTRU of claim 23, wherein the processor is configured to set a maximum output power between an upper bound and a lower bound where the lower bound is set by the following equation:

P<sub>CMAX—

L</sub>=MIN{P_EMAX,−

Δ

T_C,P_PowerClass−

MAX(MPR+A-MPR,P-PR)−

Δ

T_C,}

where P_EMAX is a quantity signaled to the WTRU, Δ

T_C, is a power reduction that is based on the WTRU transmission frequency, P_PowerClass is the maximum power of the WTRU'"'"'s power class, MPR is a Maximum power reduction for the WTRU, A-MPR is a additional MPR, and P-PR is a power management power reduction.

27. The WTRU of claim 23, wherein the processor is configured to set a maximum output power for an individual component carrier between an upper bound and a lower bound where the lower bound is set by the following equation:

P<sub>CMAX—

L,c</sub>=MIN{P_EMAX,c−

Δ

T_C,c,P_PowerClass−

MAX(MPR+A-MPR,P-PR)−

Δ

T_C,c}

where P_EMAX,c is a quantity signaled to the WTRU, Δ

T_C,c, is a power reduction that is based on the WTRU transmission frequency for the individual component carrier, P_PowerClass is the maximum power of the WTRU'"'"'s power class, MPR is a Maximum power reduction for the WTRU, A-MPR is a additional MPR, and P-PR is a power management power reduction.

28. The WTRU of claim 23, wherein:

the processor is configured to determine whether the WTRU applies the backoff value based on the P-PR; and

the transmit/receive unit is configured to report to a network resource that the WTRU has applied the backoff value based on the P-PR.

29. The WTRU of claim 23, wherein:

the processor is configured to set a domination indicator when the backoff value is based on P-PR; and

the transmit/receive unit is configured to send the domination indicator to a network resource.

30. The WTRU of claim 29, wherein:

the processor is configured to set the domination indicator and to include the domination indicator in a media access controller (MAC) control element (CE); and

the transmit/receive unit is configured to send the MAC CE to the network resource.

31. The WTRU of claim 23, wherein the processor is configured to set one of:

(1) a respective domination indicator for each component carrier impacted by the P-PR;

or (2) a single domination indicator associated with the WTRU.

32. A wireless transmit/receive unit (WTRU) configured to manage power headroom reports (PHRs), comprising:

a processor configured to determine whether a real transmission is to occur for a component carrier (CC) at a first period;

determine a previous period when a real transmission occurred for the CC;

compare the P-PR of the CC associated with the first period with the P-PR of the CC associated with the previous period; and

trigger a PHR in accordance with a comparison result.

33. The WTRU of claim 32, wherein the processor is configured to trigger the PHR in response to the P-PR of the CC associated with the first period differing from the P-PR of the CC associated with the previous period by a threshold.

34. The WTRU of claim 33, wherein:

the previous period is a most recent period a PHR was sent by the WTRU which included a power headroom corresponding to a real transmission for the CC; and

the first period is a period associated with a current transmission time interval.