NR MBS Session Release via RRC Signaling and Bearer Control

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Solution Overview

Problem

Existing technologies have not adequately addressed efficient multicast/broadcast service reception methods for NR, particularly in the context of 5G core networks, lacking detailed operations for effectively receiving Multimedia Broadcast Multicast Services (MBS) via NR.

Innovation Solution

The solution involves defining terminal and base station apparatuses and methods that facilitate efficient MBS reception using NR, including specific protocol stacks and configurations for both E-UTRA and NR, with detailed flow procedures and ASN.1 notations for RRC connections and MBMS reception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a terminal device camps on a cell with SIB1 scheduling information but fails to receive it within the scheduled time, then the terminal may perform cell reselection, but this causes unnecessary switching to other cells and wastes system resources

Engineering Contradiction:

ImproveSIB1 reception reliabilityVSAvoidSystem resource waste

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The terminal device performs preliminary actions by monitoring the PDCCH for SIB1 scheduling information within the scheduled time window before making any cell reselection decision. This preliminary monitoring action allows the terminal to confirm whether SIB1 is actually transmitted, preventing premature cell reselection and avoiding unnecessary resource waste.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the terminal device continuously monitors PDCCH for SIB1 scheduling information, then the terminal can accurately determine SIB1 availability, but this increases power consumption and processing overhead

Engineering Contradiction:

ImproveSIB1 scheduling detection accuracyVSAvoidTerminal power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The terminal device performs periodic monitoring of the PDCCH for SIB1 scheduling information only during the scheduled time window indicated by system information. This periodic action within a defined time frame ensures accurate detection of SIB1 availability while avoiding continuous monitoring, thereby reducing power consumption and processing overhead.

Inventive Principle:

Principle #19Periodic action

3Reliability

If the terminal device switches to another cell when SIB1 is not received, then the terminal maintains connectivity, but this causes unnecessary cell reselection and increases network switching overhead

Engineering Contradiction:

ImproveConnection reliabilityVSAvoidCell reselection time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The terminal device uses feedback from the PDCCH monitoring result to make an informed cell reselection decision. By checking whether SIB1 scheduling information is actually present in the PDCCH before initiating cell reselection, the terminal receives feedback that prevents unnecessary switching, thereby reducing cell reselection time and network switching overhead while maintaining connection reliability.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP4195715B1Terminal device, base station device, and method

Publication Date: 2026.04.29 SHARP KK

Figure 1
Figure 2(A)~2(B)
Figure 3(A)~3(B)

AI summary

Provided is a terminal apparatus configured to release, based on receiving, via a DCCH from the base station apparatus, an RRC message including a part of session information of an MBS session, an MBS radio bearer used to receive the MBS session.