UE Aperiodic L1 Measurement Reporting for Faster Cell Handover

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Solution Overview

Problem

Existing communication networks face challenges in efficiently reporting channel state information (CSI) measurements for cells that are not already configured, leading to delays in lower layer mobility and handover processes.

Innovation Solution

The implementation of UE-initiated aperiodic Layer 1 (L1) measurement reports based on Layer 3 (L3) measurements, allowing the UE to trigger and report CSI for detected cells that are not part of the current configuration, using methods such as 2-step RACH, UCI content re-interpretation with CRC masking, and reserved bit indication in CSI reports.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If traditional CSI configuration methods are used for reporting measurements of detected cells, then the network can obtain channel state information for mobility management, but the process involves significant delay and complexity due to requiring full CSI configuration setup

Engineering Contradiction:
Improvedelay in lower layer mobilityVSAvoidCSI configuration overhead
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent extracts only the essential measurement reporting function from the complete CSI configuration process. The UE reports L1 measurements for detected cells using simplified procedures (e.g., PUCCH, PUSCH, or RACH messages) without requiring the full CSI configuration apparatus, thereby reducing time delay and configuration overhead while maintaining the core mobility management capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The network pre-configures the UE with measurement configurations and reporting resources before the UE needs to report measurements of detected cells. This preliminary setup includes providing measurement object configurations, reporting configuration, and uplink resources, so that when the UE detects new cells, it can immediately report measurements without going through the complete CSI configuration process

Inventive Principle:
Principle #10Preliminary action

2Loss of information

If the UE reports measurements for all detected cells, then the network gains comprehensive information for handover decisions, but the reporting overhead and processing burden increase significantly

Engineering Contradiction:
Improveinformation about detected cellsVSAvoidreporting overhead
Core Design Contradiction:
Loss of informationVSQuantity of substance

Solution Approach 1:

The patent applies local quality by having the UE report measurements selectively based on specific conditions rather than uniformly for all detected cells. The UE evaluates criteria such as signal quality thresholds, cell ranking, and mobility events to determine which detected cells warrant reporting, thereby providing the network with locally optimized information about the most relevant cells while reducing overall reporting overhead

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements partial action by having the UE report measurements only for a subset of detected cells that meet specific reporting criteria, rather than reporting for all detected cells. This partial reporting approach provides the network with sufficient information for handover decisions regarding the most promising target cells while avoiding the excessive overhead of reporting measurements for every detected cell

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4515941B1Methods for UE initiated aperiodic l1 measurement report for detected cells based on l3 measurements
Publication Date: 2026.01.28 NOKIA TECHNOLOGIES OY
  • EP4515941B1 patent drawingFigure 1
  • EP4515941B1 patent drawingFigure 2
  • EP4515941B1 patent drawingFigure 3

AI summary

An apparatus includes at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to: receive a configuration from a radio access network, the configuration related to at least one layer 3 measurement; perform the at least one layer 3 measurement; determine, based on the at least one layer 3 measurement, at least one physical cell identifier that has not already been configured with a channel state information layer 1 measurement; and transmit, towards the radio access network, an aperiodic layer 1 measurement report initiated with a user equipment for the determined at least one physical cell identifier, based on the at least one layer 3 measurement.