Network Apparatus Signaling for PTM Continuity During Cell Reselection
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Solution Overview
Problem
Existing mobile communication systems face challenges in enabling User Equipment (UE) to receive multicast sessions in a Radio Resource Control (RRC) inactive state, leading to disruptions in Point-to-Multipoint (PTM) transmission during cell reselection and transitions between network apparatuses.
Innovation Solution
A communication method and network apparatus that allow for the continuation or discontinuation of PTM transmission by transmitting specific messages between network apparatuses, such as CU and DU, or gNBs, to manage UE transitions in RRC inactive state, ensuring seamless multicast reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If UE transitions to RRC inactive state during multicast reception, then power consumption is reduced and mobility is improved, but PTM transmission continuity is disrupted and multicast reception reliability deteriorates
Solution Approach 1:
The network apparatus sends a notification message to neighboring gNBs in advance when UE transitions to RRC inactive state, informing them of the UE's inactive status and multicast session information. This preliminary action enables neighboring gNBs to prepare for potential handover and maintain PTM transmission continuity, preventing multicast reception disruptions during cell reselection.
2Duration of action of stationary object
If PTM transmission is maintained during cell reselection, then multicast reception continuity is improved, but network complexity and signaling overhead increase
Solution Approach 1:
The patent extracts and transmits only essential information (UE inactive state notification, multicast session identification, and gNB identification) in a compact notification message format. This selective extraction of critical parameters minimizes signaling overhead while enabling neighboring gNBs to maintain PTM transmission for the specific UE without requiring complex full-state synchronization.
3Reliability
If notification mechanism is implemented for UE inactive state, then PTM transmission continuity is improved, but signaling overhead increases
Solution Approach 1:
The notification mechanism is applied locally and selectively only when UE transitions to RRC inactive state during multicast reception, rather than being a continuous or universal mechanism. The notification message contains targeted information specific to the affected UE and its multicast sessions, reducing overall signaling overhead compared to blanket notification approaches.
Data Source
AI summary
A communication method to be used in a mobile communication system that provides a multicast and broadcast service (MBS) includes transmitting, by a first network apparatus, a message for requesting continuation or discontinuation of Point-to-Multipoint (PTM) transmission to a second network apparatus that performs the PTM transmission of a multicast session.