Serving Cell Change via L1/L2 Signaling With HARQ-ACK Timing

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Solution Overview

Problem

Current serving cell changes in wireless communications involve L3 signaling, leading to longer latency, larger overhead, and longer interruption times due to complete L2 and L1 resets during cell transitions.

Innovation Solution

Implementing L1 and L2 signaling-based mobility by using DCI or MAC CE to indicate a serving cell change command, allowing for faster transitions by activating unified TCI states associated with candidate target cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If L3 signaling is used for serving cell change, then the cell transition is triggered by RRC measurements and reconfiguration, but the latency and interruption time increase due to complete L2 and L1 resets

Engineering Contradiction:

Improveserving cell change reliabilityVSAvoidmobility latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the mobility procedure into separate L1/L2 signaling operations rather than requiring complete L3 RRC reconfiguration. By using DCI and MAC CE for serving cell change indication, the patent divides the monolithic handover process into smaller, faster signaling steps that can be executed without full protocol stack resets, thereby reducing latency while maintaining reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by pre-configuring TCI states and measurement resources before the actual serving cell change occurs. The UE is pre-prepared with candidate target cell information and measurement configurations, allowing for faster execution of the cell change command without requiring time-consuming reconfiguration during the transition

Inventive Principle:

Principle #10Preliminary action

2Reliability

If L3 signaling with RRC reconfiguration is used, then the serving cell change is properly managed, but the overhead increases due to complete L2 and L1 resets

Engineering Contradiction:

Improveserving cell change managementVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent extracts the essential serving cell change function from the bulky L3 RRC reconfiguration procedure. By isolating the cell change indication to L1/L2 signaling elements (DCI fields, MAC CE commands), the patent removes unnecessary overhead while preserving the core functionality of serving cell management, thereby reducing signaling quantity without compromising reliability

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If complete L2 and L1 resets are performed during serving cell change, then the cell transition is ensured, but the interruption time becomes longer

Engineering Contradiction:

Improvecell transition assuranceVSAvoidinterruption time

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent applies dynamics by enabling flexible, conditional protocol resets rather than mandatory complete L2/L1 resets. The system dynamically determines the extent of resets needed based on the specific cell change scenario, allowing for shorter interruption times when full resets are not necessary while still ensuring reliable cell transitions when required

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20260089657A1Support of l1 and l2 signaling based mobility

Publication Date: 2026.03.26 LENOVO (BEIJING) LTD

AI summary

Methods and apparatuses for support of L1 and L2 signaling based mobility are disclosed. In one embodiment, a UE comprises a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to receive, via the transceiver, a DCI or a MAC CE indicating a serving cell change command for a target cell; and apply the target cell as the new serving cell after sending, via the transceiver, HARQ-ACK information for the DCI or the MAC CE.