QRI Beam Indication for Beam-Specific Uplink Power Control
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Solution Overview
Problem
In the context of 5G NR communications, there is a challenge in efficiently managing beam-specific uplink power control due to the need for multiple reference signals, such as SS Blocks, periodic CSI-RS, aperiodic CSI-RS, and semi-persistent CSI-RS, without requiring additional signaling for path loss estimation and power control loop selection.
Innovation Solution
The proposed solution involves associating each QRI (QCL Reference Indicator) with an uplink power control loop, where path loss estimation is based on the corresponding reference signal, and the QRI is indicated in downlink control messages (DCI or MAC-CE) to implicitly or explicitly select the appropriate power control loop for PUSCH, PUCCH, or SRS transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple reference signals are used for beam-specific uplink power control, then path loss estimation accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent makes existing downlink reference signals (SSB, CSI-RS) serve dual purposes: beam management and uplink power control path loss estimation. By configuring these reference signals with both downlink beamforming and uplink power control parameters, the system eliminates the need for separate dedicated reference signals, thereby reducing signaling overhead while maintaining accurate path loss estimation for multiple beams
Solution Approach 2:
The patent combines beam management functions and uplink power control functions into a unified framework. The QRI (QCL Reference Indicator) field in DCI messages simultaneously indicates the downlink beam and selects the corresponding uplink power control loop, merging what were previously separate control mechanisms into a single integrated system that reduces overall signaling requirements
2Reliability
If beam switching frequency is increased to maintain high performance, then link quality is improved, but system complexity increases
Solution Approach 1:
The patent implements dynamic beam switching through the QRI field in DCI messages, allowing the network to rapidly switch between different downlink beams and corresponding uplink power control loops based on channel conditions. This dynamic mechanism enables fast adaptation to maintain link quality without requiring complex dedicated control procedures for each beam switch
Solution Approach 2:
The QRI (QCL Reference Indicator) serves as an intermediary that links downlink beam selection with uplink power control loop selection. By using the QRI as a common reference point, the system can coordinate beam switching and power control adjustments without requiring separate complex signaling mechanisms, thereby reducing overall system complexity while maintaining fast beam switching capability
3Ease of operation
If QRI is indicated in DCI or MAC-CE messages, then beam-specific power control loop selection is improved, but additional signaling overhead is introduced
Solution Approach 1:
The QRI field in DCI and MAC-CE messages serves multiple functions simultaneously: it identifies the downlink reference signal for spatial quasi-co-location, indicates the downlink beam to be used, and selects the corresponding uplink power control loop. This multi-functionality eliminates the need for separate fields or messages for power control loop selection, thereby improving ease of operation without introducing additional signaling overhead
Solution Approach 2:
The patent merges beam indication and power control loop selection into a single QRI indicator. Instead of requiring separate signaling for downlink beam selection and uplink power control loop selection, the system uses the QRI to jointly indicate both, thereby simplifying the control mechanism and avoiding additional signaling overhead while maintaining precise power control
Data Source
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AI summary
A user equipment (UE) being configured to receive a downlink, DL, information; determine a spatial association for an uplink, UL, transmission based on the DL information; and determine UL power control, PC, parameters based on the DL information.