MBS Cell Reselection for Service Continuity in RRC_INACTIVE

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing wireless communication systems face challenges in maintaining multicast and broadcast service (MBS) continuity, particularly for UEs in RRC_INACTIVE state, leading to increased latency and network signaling load due to frequent state transitions and cell reselection during mobility.

Innovation Solution

A method for cell reselection in MBS service continuity, where user equipment (UE) and network nodes utilize MBS indications to prioritize cells based on activated MBS sessions and transmission manners, allowing seamless transitions between cells without additional state changes, using PTM or PTP transmission methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the UE transits to RRC_INACTIVE for power saving and goes back to RRC_CONNECTED for MBS reception, then power consumption is reduced, but service latency increases significantly

Engineering Contradiction:

Improvepower consumptionVSAvoidservice latency

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The network pre-configures MBS service information including neighboring cell lists and MBS indications to the UE before the UE enters RRC_INACTIVE state. This preliminary configuration enables the UE to quickly resume MBS service without full state transition, reducing latency while maintaining power savings.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE autonomously performs cell reselection based on MBS indications received from the network, without requiring network assistance or full RRC connection establishment. The UE can independently identify and camp on neighboring cells that support MBS service, reducing signaling overhead and latency.

Inventive Principle:

Principle #25Self-service

2Device complexity

If the network specifies multicast only for UEs in RRC_CONNECTED state, then MBS service delivery is simplified, but power efficiency deteriorates due to frequent state transitions

Engineering Contradiction:

Improveservice delivery complexityVSAvoidpower efficiency

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The MBS service mechanism is designed to support both RRC_CONNECTED and RRC_INACTIVE states universally. The network can deliver MBS services to UEs regardless of their RRC state by using pre-configured information and MBS indications, eliminating the need for separate service delivery mechanisms for different states.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically adapts MBS service delivery based on UE state. When UE is in RRC_CONNECTED, full MBS service is provided. When UE transitions to RRC_INACTIVE, the system uses pre-configured information and MBS indications to maintain service continuity, allowing flexible state-dependent service delivery.

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If the UE performs cell reselection without MBS service information, then cell reselection process is simplified, but MBS service continuity is lost during cell changes

Engineering Contradiction:

Improvecell reselection simplicityVSAvoidMBS service continuity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The network provides pre-configured MBS service information including neighboring cell lists and MBS indications to the UE before cell reselection. This advance information enables the UE to maintain MBS service continuity during cell changes without complex procedures, as the UE already knows which neighboring cells support MBS service.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If the UE stays in RRC_CONNECTED state for MBS reception, then MBS service continuity is maintained, but network signaling load and latency increase

Engineering Contradiction:

ImproveMBS service continuityVSAvoidnetwork signaling efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent extracts essential MBS service information (neighboring cell lists, MBS indications) from the full RRC connection context and delivers it to the UE in advance. This extracted information enables the UE to maintain MBS service continuity without requiring full RRC connection, reducing network signaling load while preserving service reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20260025641A1Cell reselection method for MBS service continuity, method for providing MBS service continuity, and related devices

Publication Date: 2026.01.22 ESSEN INNOVATION CO LTD

AI summary

A cell reselection method for multicast and/or broadcast service (MBS) service continuity and related devices are provided. The method, performed by a user equipment (UE), includes staying on a first cell for MBS data reception based on an MBS configuration in a power saving state; receiving a signaling from at least one of the first cell or at least one neighboring cell for the power saving UE to prioritize cells for cell reselection, wherein an MBS indication comprised in the signaling is configured to identify whether an MBS session of an associated cell is activated; and selecting a second cell from the at least one neighboring cell based on the MBS indication, and changing from the first cell to the second cell to camp on for the MBS data reception. With this method, MBS service continuity is achieved during the change of serving cell.