Periodic PHR Timing in Overlapped Uplink Carrier Aggregation

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Solution Overview

Problem

In 5G NR with uplink carrier aggregation, power headroom reports (PHRs) are often inaccurate due to virtual PH values being reported for secondary component carriers (SCCs) when they are not overlapped with primary component carriers (PCCs, preventing appropriate waveform switching and increasing peak-to-average power ratio (PAPR) and UE power consumption.

Innovation Solution

Wait for a multiple component carrier (multi-CC) uplink slot where PCC and SCC slots overlap to transmit a periodic power headroom report (PHR) with accurate PH values for both carriers, ensuring robust PHR reporting and enabling appropriate waveform switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If periodic PHR is transmitted on non-overlapped uplink slots, then transmission timing is simplified, but PH values become inaccurate (virtual PH values) leading to increased PAPR and power consumption

Engineering Contradiction:

ImprovePHR accuracyVSAvoidUE power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The UE proactively waits for a multi-CC uplink slot before transmitting the periodic PHR, ensuring that accurate PH values can be obtained for both PCC and SCC. This preliminary waiting action prevents the transmission of inaccurate virtual PH values, thereby avoiding unnecessary waveform switching and reducing power consumption.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If periodic PHR is transmitted on non-overlapped uplink slots, then transmission timing is simplified, but waveform switching decisions become inappropriate increasing PAPR

Engineering Contradiction:

ImprovePHR transmission efficiencyVSAvoidPAPR

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The system waits for a multi-CC uplink slot before transmitting the periodic PHR, ensuring that accurate PH values are available for both PCC and SCC. This preliminary action enables the network to make appropriate waveform switching decisions based on accurate power headroom information, thereby avoiding harmful high PAPR conditions.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If the UE waits for multi-CC uplink slot to transmit periodic PHR, then PHR accuracy improves, but transmission delay increases

Engineering Contradiction:

ImprovePHR accuracyVSAvoidPHR transmission delay

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The UE waits for a multi-CC uplink slot within the current PHR period, which may extend the transmission timing beyond the original schedule. However, this partial delay is acceptable and necessary to obtain accurate PH values for both PCC and SCC, ensuring that the PHR information is reliable for waveform switching decisions.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250261131A1Periodic power headroom report for uplink carrier aggregation

Publication Date: 2025.08.14 QUALCOMM INC

AI summary

Certain aspects of the present disclosure provide a method for wireless communications by a user equipment (UE). The method generally includes waiting for a multiple component carrier (multi-CC) uplink slot in which an uplink slot on a first component carrier (CC) overlaps with an uplink slot of a second CC in order to transmit a periodic power headroom report (PHR) in a current PHR period and transmitting, in the multi-CC uplink slot, the periodic PHR with power headroom (PH) values for the first CC and the second CC.