UE Cell Reselection Using MBS Availability and Load Status
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Solution Overview
Problem
Existing wireless communication systems face challenges in maintaining the continuity of Multicast/Broadcast Service (MBS) for User Equipment (UE) during cell reselection, particularly in RRC_INACTIVE state, due to issues like selecting target gNBs that are outside the MBS service area or overloaded, without the ability to receive necessary configuration information.
Innovation Solution
The UE receives load and MBS information from the serving base station to select a new serving cell based on load status and MBS service availability, ensuring the UE avoids overloaded or unsuitable cells, thereby maintaining MBS service continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the UE autonomously performs cell reselection in RRC_INACTIVE state without network control, then the control plane footprint is reduced and power efficiency is improved, but the UE may select a target gNB that is outside the MBS service area or overloaded, causing loss of MBS service continuity
Solution Approach 1:
The network provides MBS service area information and load information to the UE before the UE performs cell reselection. This preliminary provision of information enables the UE to autonomously select a suitable target gNB that supports MBS service and is not overloaded, thereby maintaining MBS service continuity while operating in RRC_INACTIVE state without frequent transitions to RRC_CONNECTED state.
Solution Approach 2:
The network provides feedback information to the UE about the MBS service area and load status of candidate gNBs. This feedback mechanism allows the UE to make informed decisions during cell reselection, selecting target gNBs that can support MBS service, thus resolving the contradiction between autonomous operation and service continuity.
2Reliability
If the UE transitions to RRC_CONNECTED state to receive MBS configuration information during cell reselection, then MBS service continuity is maintained, but the control plane footprint increases and power efficiency decreases
Solution Approach 1:
The network provides MBS configuration information and service area information to the UE in advance, while the UE is in RRC_INACTIVE state. This allows the UE to perform cell reselection autonomously and select a target gNB that supports MBS service without needing to transition to RRC_CONNECTED state, thereby maintaining service continuity while preserving power efficiency.
3Speed
If the UE selects any available cell during reselection, then cell selection speed is improved, but the UE may select an overloaded cell causing data loss and service interruption
Solution Approach 1:
The network provides load information about candidate gNBs to the UE before the cell reselection process. This preliminary information allows the UE to quickly identify and select a suitable target gNB that is not overloaded, thereby maintaining fast cell selection speed while avoiding data loss and service interruption that would occur with random selection.
Solution Approach 2:
The network provides feedback regarding the load status of candidate gNBs to the UE. This feedback enables the UE to make rapid informed decisions during cell reselection, selecting target gNBs with appropriate load capacity, thus resolving the contradiction between selection speed and reliability.
Data Source
AI summary
A method for reselecting, by a User Equipment, UE, a new serving cell of a wireless communication system is disclosed. The method at the UE comprises receiving, from a serving base station of the UE as part of a Multicast Broadcast Service, MBS, procedure for receiving a multicast MBS session, multicast MBS information for one or more candidate cells, selecting one of the one or more candidate cells as a new serving cell for the UE based on the received multicast MBS information. The UE may be operating in a non-connected RRC state and participating in one or more Multicast Broadcast Service, MBS, sessions.