Power reservation for carrier aggregation signaling during shortened transmission time intervals

Patent metadata

Field	Value
Publication number	US-10397886-B2
Application number	US-201816019113-A
Country	US
Kind code	B2
Filing date	Jun 26, 2018
Priority date	Jun 29, 2017
Publication date	Aug 27, 2019
Grant date	Aug 27, 2019

Abstract

Methods, systems, and devices for wireless communication are described. In some cases, a user equipment (UE) may be scheduled to transmit uplink signals on different carriers during transmission time intervals (TTIs) that have different durations. As such, a TTI on a first carrier (e.g., a reference carrier) may overlap with multiple shortened TTIs (sTTIs) on a second carrier (e.g., a non-reference carrier). Using the techniques described herein, the UE may select a calibration point (or a gain index) for uplink transmissions at the beginning of the TTI on the reference carrier based on an amount of power reserved for expected power increases during the TTI. As such, when the UE has to update its transmit power for an uplink transmission during an sTTI on the second carrier, the UE may apply a digital back-off from a power associated with the calibration point.

First claim

What is claimed is:

1. A method for wireless communication at a user equipment (UE), comprising:
identifying, from a plurality of component carriers (CCs) used in carrier aggregation (CA) communication, a first CC having a first transmission time interval (TTI) duration as a reference CC and a second CC having a second TTI duration different from the first TTI duration;
determining, at a first TTI boundary of a first TTI of the reference CC, a first transmit power for the reference CC and a second transmit power for the second CC of the plurality of CCs;
determining an amount of transmit power to be reserved during the first TTI for adjusting the second transmit power at second TTI boundaries of the second CC;
selecting a power amplifier (PA) gain value for a calibration point based at least in part on the amount of transmit power reserved during the first TTI, the first transmit power, and the second transmit power; and
transmitting, during the first TTI, at the first transmit power for the reference CC and at the second transmit power for the second CC, based at least in part on the amount of transmit power reserved, wherein the transmitting comprises digitally backing off from a transmit power corresponding to the PA gain value for the calibration point.

2. The method of claim 1 , wherein determining the amount of transmit power to be reserved during the first TTI comprises:
receiving, from a base station, an indication of the amount of transmit power to be reserved during the first TTI.

3. The method of claim 1 , wherein determining the amount of transmit power to be reserved during the first TTI comprises:
autonomously determining the amount of transmit power to reserve during the first TTI; and
transmitting, to a base station, an indication of the amount of transmit power reserved during the first TTI.

4. The method of claim 3 , wherein the indication is transmitted in a power headroom (PHR) report.

5. The method of claim 1 , further comprising:
identifying an updated second transmit power for the second CC during a duration of the first TTI and at a second TTI boundary of a second TTI on the second CC, the second TTI boundary being unaligned with the first TTI boundary; and
maintaining the PA gain value for the calibration point while transmitting during the first TTI at the first transmit power for the reference CC and at the updated second transmit power for the second CC.

6. The method of claim 5 , wherein maintaining the PA gain value for the calibration point comprises:
adjusting an amount of digital back-off from the transmit power corresponding to the PA gain value for the calibration point.

7. The method of claim 1 , further comprising:
identifying an updated second transmit power for the second CC during a duration of the first TTI and at a second TTI boundary of a second TTI on the second CC, the second TTI boundary being unaligned with the first TTI boundary;
identifying that a sum of the first transmit power and the updated second transmit power exceeds the transmit power corresponding to the PA gain value for the calibration point;
identifying a transient period for a PA gain adjustment;
updating the PA gain value for a different calibration point during the transient period based at least in part on the first transmit power and the updated second transmit power; and
transmitting, during the first TTI of the reference CC and during the second TTI of the second CC, at the first transmit power for the reference CC and at the updated second transmit power for the second CC.

8. The method of claim 7 , wherein the second TTI comprises any one of one or more TTIs of the second CC that overlap with the first TTI of the first CC.

9. The method of claim 1 , wherein the PA gain value for the calibration point is selected based at least in part on a sum of the amount of transmit power reserved during the first TTI, the first transmit power, and the second transmit power.

10. The method of claim 9 , wherein the transmit power corresponding to the PA gain value for the calibration point is equal to or greater than the sum of the amount of transmit power reserved during the first TTI, the first transmit power, and the second transmit power.

11. The method of claim 1 , wherein the amount of transmit power reserved during the first TTI is based at least in part on expected transmit power increases on the second CC during the first TTI of the reference CC.

12. The method of claim 11 , further comprising:
transmitting an indication of an actual amount of power reserved for the expected transmit power increases on the second CC during the first TTI of the reference CC.

13. The method of claim 1 , wherein identifying the reference CC is based at least in part on the first TTI duration being longer than the second TTI duration.

14. The method of claim 1 , wherein the reference CC and the second CC are within a same frequency band.

15. The method of claim 1 , wherein a same PA is used by the UE for transmissions on the reference CC and the second CC.

16. The method of claim 1 , wherein the amount of transmit power reserved is equal to a power headroom (PHR) associated with transmissions on the reference CC and the second CC during the first TTI.

17. The method of claim 1 , wherein the amount of transmit power reserved is less than a power headroom (PHR) associated with transmissions on the reference CC and the second CC during the first TTI.

18. A method for wireless communication, comprising:
identifying, from a plurality of component carriers (CCs) used in carrier aggregation (CA) communication, a first CC as a reference CC;
transmitting, to a user equipment (UE), a first indication of a first transmit power for transmissions on the reference CC during a first transmission time interval (TTI) and a second transmit power for transmissions on a second CC of the plurality of CCs during a second TTI that at least partially overlaps with the first TTI;
identifying a reserved amount of transmit power based at least in part on expected transmit power increases on the second CC during the first TTI of the reference CC;
transmitting, to the UE, a reserved power indication indicating the reserved amount of transmit power to be used by the UE in selecting a power amplifier (PA) gain value for a calibration point;
determining whether a total uplink transmit power for the first CC and the second CC exceeds a transmit power corresponding to the PA gain value for the calibration point; and
communicating with the UE based at least in part on a result of the determining, including allocating a transient period to the UE for selecting an updated calibration point or identifying a phase discontinuity in an uplink transmission from the UE.

19. The method of claim 18 , further comprising:
receiving, from the UE, a PA power indication indicating an actual amount of power reserved for the expected transmit power increases on the second CC during the first TTI of the reference CC; and
determining an updated reserved amount of transmit power for a subsequent TTI on the reference CC based at least in part on receiving the PA power indication.

20. The method of claim 19 , further comprising:
identifying an updated second transmit power used for transmissions on the second CC during a third TTI that at least partially overlaps with the first TTI;
determining that the total uplink transmit power comprising a sum of the first transmit power and the updated second transmit power exceeds the transmit power correspo

Assignees

• Qualcomm Inc

Inventors

• Akula Prashanth
• Farajidana Amir
• Hosseini Seyedkianoush

Classifications

• H04L5/00

  Arrangements affording multiple use of the transmission path · CPC title

• H04W52/367

  Power values between minimum and maximum limits, e.g. dynamic range · CPC title

• H04W52/146

  Uplink power control · CPC title

• H04L5/001

  the frequencies being arranged in component carriers · CPC title

• H04W52/365 Primary

  Power headroom reporting · CPC title