MAC CE Pathloss Reference Signal Configuration for SRS

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Solution Overview

Problem

The current configuration of pathloss reference signal (PL-RS) for Sounding Reference Signal (SRS) in NR Release 15 is not efficient for reducing UL beam management latency and overhead, as RRC signaling is slow and may not reflect changes in pathloss reference signals in a timely manner.

Innovation Solution

Configuring PL-RS for SRS resource sets using a MAC Control Element (CE) and transmitting a Physical Downlink Shared Channel (PDSCH) carrying the MAC CE, allowing for faster configuration and updating of PL-RS compared to traditional RRC signaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RRC signaling is used to configure pathloss reference signal for SRS, then configuration reliability is ensured, but configuration latency increases and responsiveness to changing conditions deteriorates

Engineering Contradiction:

Improveconfiguration reliabilityVSAvoidconfiguration latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent introduces MAC CE as an intermediary mechanism between RRC signaling and SRS transmission. RRC signaling configures the MAC CE parameters in advance, while MAC CE dynamically indicates the actual pathloss reference signal to be used. This two-layer approach ensures both reliability (through RRC configuration) and low latency (through MAC CE indication), resolving the contradiction between configuration reliability and configuration latency.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If RRC signaling is used to configure pathloss reference signal, then configuration completeness is achieved, but signaling overhead increases

Engineering Contradiction:

Improveconfiguration completenessVSAvoidsignaling overhead

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent segments the configuration process into two parts: RRC signaling provides the configuration framework and available options, while MAC CE provides the specific selection指示. This segmentation allows RRC to maintain configuration completeness while MAC CE reduces the actual signaling overhead needed for dynamic pathloss reference signal indication, as MAC CE only needs to indicate the selection rather than reconfigure everything.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If RRC signaling updates pathloss reference signal, then configuration accuracy is maintained, but update speed decreases

Engineering Contradiction:

Improveconfiguration accuracyVSAvoidupdate speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent applies preliminary action by having RRC signaling pre-configure multiple pathloss reference signal options and the MAC CE structure in advance. When dynamic updates are needed, the system only needs to indicate the selection from pre-configured options via MAC CE, rather than performing complete reconfiguration. This preliminary preparation maintains configuration accuracy while enabling fast update speed through simple indication messages.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12316565B2Media Access Control (MAC) Control Element (CE) for configuring pathloss reference signal for Sounding Reference Signal (SRS)

Publication Date: 2025.05.27 LENOVO (BEIJING) LTD

AI summary

Methods and apparatuses for configuring pathloss reference signal to SRS resource set(s) are disclosed. A method comprises configuring pathloss reference signal for one or more SRS resource sets by using a MAC CE and transmitting a PDSCH carrying the MAC CE.