Uplink Default Beam Selection in Multi-TRP NR Transmission

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Solution Overview

Problem

Existing 3GPP NR Release 16 specifications do not provide clear guidelines for determining default spatial relations and pathloss reference signals for uplink transmissions in multi-TRP scenarios, leading to confusion and inefficiencies in UE behavior.

Innovation Solution

Methods and apparatuses are developed to determine default spatial relations and pathloss reference signals for uplink resources in multi-TRP scenarios by utilizing the QCL-TypeD RS corresponding to the lowest TCI state codepoint or the activated TCI state with the same CORESETPoolIndex value, even when spatial and pathloss reference signals are not configured.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple TCI states are indicated for multi-TRP PDSCH transmission, then the system supports multiple TRPs and enhanced downlink transmission, but the UE cannot determine a unique default spatial relation for uplink transmission

Engineering Contradiction:

Improvemulti-TRP supportVSAvoiddefault spatial relation determination

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent segments the multiple TCI states by introducing CORESETPoolIndex values to group them into distinct sets. Each uplink resource is associated with a specific CORESETPoolIndex, and the default spatial relation is determined only from TCI states within that same group, effectively dividing the problem into manageable segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces CORESETPoolIndex as an intermediary parameter that mediates between the multiple TCI states and the uplink resource. This intermediary establishes a clear mapping relationship, allowing the UE to select the appropriate default spatial relation through the intermediate step of matching CORESETPoolIndex values.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If default beam is enabled for uplink resources without configured spatial relation, then uplink transmission can proceed without explicit spatial relation configuration, but transmission ambiguity occurs in multi-TRP scenarios

Engineering Contradiction:

Improveuplink transmission without explicit configurationVSAvoidtransmission accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent performs preliminary grouping of TCI states by CORESETPoolIndex before the UE needs to determine the default spatial relation. This pre-organization of TCI states into distinct groups based on CORESETPoolIndex values eliminates ambiguity when the UE later selects the default spatial relation for uplink transmission.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by allowing different default spatial relation determination rules for different uplink resources based on their associated CORESETPoolIndex values. Each uplink resource gets a locally appropriate default spatial relation from its corresponding TCI state group, rather than applying a uniform rule to all resources.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12470281B2Default beam determination for uplink signal transmission

Publication Date: 2025.11.11 EDGEWOOD IP

AI summary

Methods and apparatuses for determining default spatial relation and default PL-RS are disclosed. A method comprises determining a default spatial relation and a default pathloss reference RS (PL-RS) for transmission of uplink resource on a serving cell without configured CORESET, the uplink resource is configured with neither higher layer parameter related to spatial relation nor higher layer parameter related to PL-RS, and the higher layer parameter related to enable default beam for the uplink resource is set to ‘enable’, and transmitting the uplink resource according to the determined default spatial relation and the power determined by the determined default PL-RS.