MBS Multicast for Inactive UEs via Central Unit
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Solution Overview
Problem
Providing Multicast and Broadcast Services (MBS) via multicast to user equipment (UEs) in RRC inactive state is challenging, especially with distributed base station units, due to lack of accurate information about the number of inactive UEs and their interest in MBS sessions.
Innovation Solution
The method involves receiving information from a central unit about MBS sessions to be provided via multicast in a cell, and using this information to manage point-to-multipoint transmissions for UEs in an inactive state, even after cell reselection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If distributed base station units are used to provide MBS via multicast to UEs in RRC inactive state, then service coverage and flexibility are improved, but the system cannot accurately determine the number of inactive UEs and their interest in MBS sessions, leading to inefficient resource allocation
Solution Approach 1:
The patent introduces the central unit as an intermediary between distributed units and UEs in inactive state. The central unit collects and maintains information about inactive UEs and their MBS session interests, then provides this information to distributed units via F1AP messages. This mediator resolves the information asymmetry problem where distributed units otherwise cannot directly access UE state information.
Solution Approach 2:
The system performs preliminary actions by establishing MBS sessions and collecting UE interest information in advance, while UEs are still in connected state or before they transition to inactive state. The central unit pre-processes and stores this information so that when UEs transition to inactive state, the distributed units can immediately provide continuous multicast service without needing to re-query or re-establish sessions.
2Loss of energy
If multicast transmission is used for MBS sessions, then resource efficiency is improved by serving multiple UEs simultaneously, but service continuity cannot be maintained during cell reselection for inactive UEs
Solution Approach 1:
The patent implements a feedback mechanism where UEs in inactive state periodically report their cell reselection status and MBS session reception quality to the network via the central unit. The central unit uses this feedback to determine whether to maintain, switch, or release multicast sessions. This feedback loop ensures service continuity by allowing the network to adapt to changing UE locations and conditions while maintaining resource-efficient multicast transmission.
Solution Approach 2:
The system dynamically adjusts the multicast transmission parameters and session management based on real-time conditions. When UEs perform cell reselection, the system dynamically updates the multicast session configuration, switches between different distributed units as needed, and adjusts resource allocation. This dynamic behavior maintains service continuity while preserving the resource efficiency benefits of multicast transmission.
3Reliability
If the system maintains detailed information about each inactive UE's MBS session interest, then service personalization and continuity are improved, but system complexity and information management overhead increase
Solution Approach 1:
The patent merges the management of multiple inactive UEs' MBS session information into a centralized data structure at the central unit. Instead of each distributed unit maintaining separate information for each UE, the system combines all inactive UE information and their MBS session interests into unified tables and data structures at the central unit. This consolidation reduces overall system complexity while maintaining the ability to provide personalized service continuity for each UE.
Data Source
AI summary
A communication system is disclosed in which Multicast and Broadcast Services (MBS) may be provided via multicast, for user equipment (UE) in an inactive state. A distributed unit of a base station apparatus receives, from a central unit of the base station apparatus, information identifying at least one MBS session and information identifying that the at least one MBS session is to be provided in a cell via multicast for the UE in the inactive state.