MAC Reset Control for L1/L2-Centric Cell Mobility

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Solution Overview

Problem

Existing communication technologies face challenges in reducing latency and overhead during high-speed vehicular scenarios by relying on RRC signaling for inter-cell mobility, which is inefficient and increases interruption time.

Innovation Solution

Implementing L1/L2 centric inter-cell mobility by allowing the network to indicate a TCI state associated with a non-serving cell, enabling MAC reset conditionally based on specific criteria to minimize unnecessary resets and reduce latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If RRC signaling is used for inter-cell mobility, then mobility management is achieved, but latency and interruption time increase

Engineering Contradiction:
Improvelatency and interruption timeVSAvoidsignaling overhead
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent extracts the MAC reset operation from the RRC signaling path and implements it at the L1/L2 layer through MAC control elements. This separation allows mobility management to occur at lower layers without requiring higher-layer RRC intervention, thereby reducing latency and interruption time while maintaining appropriate signaling overhead

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent pre-configures multiple TCI states at the UE before handover occurs. These pre-configured states include associations with different PCIs, allowing the UE to quickly switch beams and cells without requiring time-consuming RRC reconfiguration during the actual handover execution

Inventive Principle:
Principle #10Preliminary action

2Reliability

If MAC reset is performed during every inter-cell mobility, then mobility robustness is improved, but unnecessary resets increase latency

Engineering Contradiction:
Improvemobility robustnessVSAvoidlatency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements dynamic MAC reset behavior where the decision to perform a MAC reset during inter-cell mobility depends on the specific scenario. The network can configure different behaviors through RRC parameters, allowing the system to adapt between aggressive reset (for robustness) and conservative reset (for latency reduction) based on deployment requirements and mobility conditions

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4260609B1Media access control reset for layer 1/layer 2 centric mobility
Publication Date: 2025.09.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4260609B1 patent drawingFigure 1~3
  • EP4260609B1 patent drawingFigure 4
  • EP4260609B1 patent drawingFigure 5

AI summary

A communication device can be configured with a plurality of physical cell identifiers, PCIs, for a mobility procedure, a plurality of transmission configurations, and one or more cells. Each cell can be operating in a same serving frequency and each cell can be associated with one or more PCIs. The communication device can receive an indication of a transmission configuration to be activated, from the plurality of transmission configurations, that is associated with a non-serving cell or a non-serving PCI, from a network node. The communication device can determine to perform a media access control, MAC, reset operation based on the transmission configuration to be activated.