MBS Transmission Mode Differentiation for Soft Combining

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Solution Overview

Problem

The challenge is to ensure high reliability of multicast broadcast service (MBS) in new radio (NR) systems, particularly in ensuring that terminal devices can correctly perform soft combining of new and retransmitted data to maximize receiving gain.

Innovation Solution

The solution involves determining the transmission mode of the MBS service, where new transmissions are sent in a point-to-multipoint (PTM) mode and retransmissions are sent in a point-to-point (PTP) mode. This allows the network device to schedule transmissions accordingly, and the terminal device to differentiate between new and retransmitted data based on the transmission mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If new transmission is sent in PTM mode and retransmission is sent in PTP mode, then reliability of MBS service reception is improved, but device complexity increases due to mode differentiation and scheduling complexity

Engineering Contradiction:
Improvereliability of MBS service receptionVSAvoidtransmission mode differentiation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The transmission process is segmented into two distinct phases: initial transmission using PTM mode for efficiency, and retransmission using PTP mode for reliability. This segmentation allows each phase to use the most appropriate transmission mode, resolving the contradiction between reliability and complexity by handling different transmission stages differently.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between PTM and PTP modes based on transmission status. The network device determines whether to use PTM or PTP mode for each transmission instance, allowing flexible adaptation to different reception conditions while maintaining overall system reliability.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the terminal device determines transmission mode to differentiate new and retransmitted data, then receiving gain is maximized, but measurement precision requirements increase for accurate mode identification

Engineering Contradiction:
Improvereceiving gainVSAvoidtransmission mode identification accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The terminal device provides feedback to the network device regarding reception status. This feedback mechanism enables the network device to determine appropriate transmission modes and ensures the terminal can accurately identify whether received data is new or retransmitted, thereby maximizing receiving gain while maintaining identification accuracy.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4228293B1Method and apparatus for improving reliability of MBS, and terminal device and network device
Publication Date: 2025.05.21 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD
  • EP4228293B1 patent drawingFigure 1
  • EP4228293B1 patent drawingFigure 2~3
  • EP4228293B1 patent drawingFigure 4

AI summary

A method and an apparatus for improving reliability of multicast broadcast service (MBS) service, a terminal device, and a network device are provided. The method includes the following. A terminal device determines a transmission mode of an MBS service. The terminal device determines, based on the transmission mode of the MBS service, whether a first transmission is new transmission or is retransmission.