Multicast PTM Configuration for Continuous Reception Across RRC States
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Solution Overview
Problem
Existing wireless communication systems face issues such as service interruption, data loss, and large delays during transitions between RRC states for multicast reception, particularly when a user equipment (UE) moves from RRC_CONNECTED to RRC_INACTIVE or RRC_IDLE states, as multicast reception is currently only supported in RRC_CONNECTED state in NR R17.
Innovation Solution
A UE in RRC non-connected states like RRC_INACTIVE can transmit requests for PTM configuration information or provide associated multicast reception information during state transitions to assist the network in determining the subsequent RRC state, allowing updates without entering RRC_CONNECTED state, using messages like RRC resume request and release to facilitate PTM configuration updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multicast reception is supported only in RRC_CONNECTED state, then the network can maintain simple control procedures, but service interruption and data loss occur during RRC state transitions
Solution Approach 1:
The patent applies preliminary action by preparing and storing PTM configuration information in the UE before RRC state transition. The UE retains the necessary multicast reception parameters (PTM configuration) in its memory during RRC_INACTIVE or RRC_IDLE states, so that when the UE needs to receive multicast services, it can immediately use the pre-stored configuration without needing to re-establish the complete RRC connection first. This eliminates service interruption and data loss during state transitions.
2Adaptability or versatility
If UE enters RRC_CONNECTED state to receive updated PTM configuration, then configuration can be updated, but communication latency and signaling overhead increase
Solution Approach 1:
The patent extracts the essential PTM configuration information from the full RRC connection context and separates it as independent, retainable parameters. These extracted configuration elements (PTM configuration information) can be stored and reused during RRC non-connected states, allowing configuration updates without requiring complete RRC connection establishment. This reduces the scope of what needs to be re-transmitted and re-processed during state transitions.
Solution Approach 2:
The patent introduces RRC resume procedure as an intermediary mechanism between RRC_INACTIVE and full RRC_CONNECTED states. Through the resume procedure, the UE can quickly restore its RRC connection with minimal signaling, serving as a bridge that allows PTM configuration updates without requiring complete connection establishment. This intermediary path reduces the time and overhead associated with full state transitions.
3Adaptability or versatility
If frequent RRC state transitions are used for configuration updates, then configuration can be updated, but service interruption and latency increase
Solution Approach 1:
The network applies preliminary action by proactively updating PTM configuration information in the UE before the UE actually needs to receive multicast services. The network can send configuration updates to the UE in RRC_INACTIVE or RRC_IDLE states through paging or other notification mechanisms, so that when the UE activates multicast reception, the configuration is already ready. This eliminates the need for frequent RRC state transitions just for configuration updates.
Solution Approach 2:
The patent implements dynamic adaptability by allowing the UE to flexibly choose its RRC state based on actual needs. The UE can remain in RRC_INACTIVE or RRC_IDLE states for most time, transitioning to RRC_CONNECTED only when multicast reception is actually required. This dynamic state management reduces unnecessary transitions and optimizes the balance between configuration update capability and reception efficiency.
Data Source
AI summary
Embodiments of the present application are related to methods and apparatuses for point-to-multipoint (PTM) configuration for multicast service. An embodiment of the present application provides a user equipment (UE) including: receive multicast in a radio resource control (RRC) non-connected state; and a transmitter configured to: transmit a request of PTM configuration information for multicast reception in the RRC non-connected state; or transmit information associated with multicast reception of the UE after an initiation of state transition from the RRC non-connected state to a RRC connected state to assist deciding a subsequent RRC state used for the multicast reception.