5G Multicast Session Setup with MBS QoS Flow Configuration

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Solution Overview

Problem

The unclear specification of which NGAP message the core network should utilize for multicast session context establishment in 5G NR systems, and the lack of sufficient information for base stations to properly configure multicast session quality of service (QoS) flows, leading to inefficiencies in multicast service delivery.

Innovation Solution

A base station receives or retrieves MBS QoS flow configurations from the core network prior to configuring a distributed unit (DU), ensuring proper setup of multicast sessions by transmitting these configurations to the DU during the session establishment process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the core network sends an NGAP message to trigger multicast session context establishment, then the multicast session can be established, but it is unclear which specific NGAP message should be used and sufficient configuration information is not conveyed

Engineering Contradiction:
Improvemulticast session establishment reliabilityVSAvoidMBS QoS flow configuration information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent applies preliminary action by having the base station receive or retrieve MBS QoS flow configurations from the core network prior to the CU configuring the DU with multicast session context. This ensures that all necessary configuration information is available before the actual session establishment, preventing information loss and ensuring reliable multicast service delivery.

Inventive Principle:
Principle #10Preliminary action

2Device complexity

If the base station configures multicast session without receiving MBS QoS flow configurations in advance, then the session establishment process is simpler, but the configuration accuracy and service delivery effectiveness deteriorate

Engineering Contradiction:
Improvesession establishment procedure complexityVSAvoidMBS session configuration accuracy
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent resolves this contradiction by performing preliminary action - the base station receives or retrieves MBS QoS flow configurations before the CU configures the DU. This timing ensures configuration accuracy is maintained while the procedural complexity remains manageable through standardized NGAP message exchanges.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4544794B1Managing multicast session establishment
Publication Date: 2026.04.01 GOOGLE LLC
  • EP4544794B1 patent drawingFigure 1A
  • EP4544794B1 patent drawingFigure 1B~2A
  • EP4544794B1 patent drawingFigure 2B

AI summary

A central unit (CU) of a distributed base station transmits, to a core network (CN), a distribution setup request message; receives, from the CN, a distribution setup response message including a first MBS QoS flow configuration; and transmits, to a distributed unit (DU) of the distributed base station, a multicast context setup request message including a second MBS QoS flow configuration based on the first MBS QoS flow configuration, to establish a multicast context for an MBS session.