Multicast Reception in RRC Inactive State Using PTM Updates
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Solution Overview
Problem
Existing 3GPP specifications limit multicast reception in user equipment (UE) to the Radio Resource Control (RRC) connected state, which can lead to inefficiencies and power wastage when transitioning to the RRC inactive state.
Innovation Solution
The UE is configured to receive multicast sessions in the RRC inactive state by determining conditions for multicast reception based on paging messages and acquiring updated configuration information through multicast control channels, allowing seamless transition and continuous reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multicast reception is limited to RRC connected state, then configuration management is simplified, but power consumption increases and service continuity is interrupted during state transitions
Solution Approach 1:
The network pre-configures PTM (Point-to-Multipoint) parameters including RNTI, physical resource blocks, and modulation schemes while the UE is in RRC connected state. These configurations are stored and activated when the UE transitions to RRC inactive state, enabling multicast reception without requiring full connection management overhead.
Solution Approach 2:
The system dynamically adapts multicast reception capabilities based on RRC state. In RRC connected state, full configuration management is available. In RRC inactive state, pre-configured parameters are used with simplified monitoring of paging messages for configuration updates, allowing flexible operation across different power states.
2Device complexity
If multicast reception is limited to RRC connected state, then configuration control is simplified, but service continuity is interrupted during state transitions
Solution Approach 1:
Multicast configuration parameters are pre-established before state transition occurs. The network provides PTM-RNTI, resource allocation, and modulation coding schemes in advance, ensuring that when the UE transitions to RRC inactive state, multicast reception can continue seamlessly without service interruption.
Solution Approach 2:
The system maintains continuous multicast service across RRC state transitions by keeping PTM configurations active in inactive state. The UE continues to monitor multicast channels using pre-configured parameters, and can receive configuration update notifications via paging messages, ensuring uninterrupted service delivery.
3Use of energy by moving object
If the UE transitions to RRC inactive state for power saving, then power consumption is reduced, but multicast reception capability is lost
Solution Approach 1:
The network configures all necessary PTM parameters including physical resource blocks, RNTI, and modulation schemes before the UE enters RRC inactive state. This preliminary configuration enables the UE to maintain multicast reception capability in the lower-power inactive state without needing to transition back to connected state.
Solution Approach 2:
The system implements feedback mechanisms where the network can notify the UE of configuration updates through paging messages even when the UE is in RRC inactive state. This allows the UE to maintain power-saving mode while still receiving multicast services and configuration updates, preserving adaptability without sacrificing energy efficiency.
Data Source
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AI summary
A communication method performed by a user equipment in a mobile communication system that provides a multicast/broadcast service (MBS) includes receiving a first PTM configuration from a network, the first PTM configuration being used for reception of a multicast session in a Radio Resource Control (RRC) inactive state, and holding the first PTM configuration, determining, in the RRC inactive state, whether the first PTM configuration needs to be updated in response to reception of a paging message from the network, the paging message including a session identifier of the multicast session, and acquiring, in the RRC inactive state, a second PTM configuration used for reception of the multicast session by receiving a multicast control channel (MCCH) for multicast communication in response to determination that the first PTM configuration needs to be updated.