L1 Measurement-Based Inter-Cell Mobility for Wireless Handover

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Solution Overview

Problem

Existing wireless communication systems face challenges in minimizing delay during inter-cell mobility decisions, as they rely on layer 3 (L3) reports which provide a long-term view of channel conditions but incur increased delay.

Innovation Solution

Implementing a method where inter-cell mobility of a user equipment (UE) across serving and non-serving cells is based on layer 1 (L1) measurements, which are faster and more immediate, by configuring the UE to perform L1 measurements on reference signals from non-serving cells and reporting these measurements back to the serving cell.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If L3 measurements are used for inter-cell mobility decisions, then long-term channel condition view is obtained, but delay is increased

Engineering Contradiction:
Improvechannel condition accuracyVSAvoidmobility decision delay
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the measurement process into two distinct layers: L3 measurements for long-term channel condition assessment and L1 measurements for immediate mobility decisions. This segmentation allows each layer to perform its specialized function without being constrained by the other, resolving the contradiction between obtaining long-term channel views and minimizing decision delay.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces L1 measurements as an intermediary mechanism that bridges the gap between L3 measurement accuracy and real-time mobility decision requirements. L1 measurements provide immediate channel quality indicators that enable fast handover decisions while L3 measurements continue to provide long-term trends, thus mediating between the two conflicting requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of time

If L1 measurements are used for inter-cell mobility decisions, then delay is minimized, but measurement reliability may be reduced

Engineering Contradiction:
Improvemobility decision delayVSAvoidmeasurement reliability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent merges L1 and L3 measurement results to make mobility decisions. L1 measurements provide immediate feedback for fast decision-making, while L3 measurements provide long-term reliability validation. By combining both measurement types, the system achieves both low delay and high reliability simultaneously.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements a feedback mechanism where L3 measurement results are used to validate and adjust L1 measurement-based decisions. The L3 layer provides continuous feedback on channel conditions, allowing the system to verify the reliability of L1 measurements and make more accurate mobility decisions by incorporating both time scales of information.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4190007B1Inter-cell mobility across serving and non-serving cells
Publication Date: 2025.05.07 QUALCOMM INC
  • EP4190007B1 patent drawingFigure 1
  • EP4190007B1 patent drawingFigure 2A~2D
  • EP4190007B1 patent drawingFigure 3

AI summary

Inter-cell mobility across serving and non-serving cells based on layer 3 measurements is accomplished at the cost of increased delay. Inter-cell mobility across serving and non-serving cells based on layer 1 measurements minimized delay. A user equipment (UE) apparatus that is served by a serving cell of a base station receives, from the serving cell, a configuration to perform layer 1 (L1) measurements based on one or more reference signals from a non-serving cell. The UE also receives the one or more reference signals from the non-serving cell. The UE performs the L1 measurements on the one or more reference signals received from the non-serving cell based on the configuration received from the base station. The UE may perform the L1 measurements on a synchronization signal block (SSB), a channel state information reference signal (CSI-RS), or a positioning reference signal (PRS) from the non-serving cell.