Cell Selection Indication for MBMS Session Termination
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Solution Overview
Problem
In multimedia broadcast/multicast service systems, when a session is stopped in a frequency layer convergence situation, preferred frequency layer cells become congested, leading to degraded quality of service and increased congestion in non-preferred frequency layer cells due to user equipment dispersion.
Innovation Solution
A method and apparatus that explicitly notify user equipments about the need for cell selection after determining the start time of a new session and load levels of cells, allowing them to disperse or stay based on probability values and timer settings to manage congestion and reduce unnecessary signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If user equipments disperse from preferred frequency layer cells when a session is stopped, then cell congestion is reduced, but service continuity is degraded because UEs may not return to PL cells when new sessions start
Solution Approach 1:
The RNC sends cell selection indication information to UEs based on cell load conditions, creating a feedback mechanism that guides UEs to select appropriate cells. This feedback loop allows the system to dynamically adjust UE distribution based on current congestion levels while maintaining service continuity through informed cell selection decisions.
Solution Approach 2:
The system performs preliminary cell selection indication before UEs need to reconnect to PL cells for new sessions. By providing cell selection information in advance (through the cell selection indication information sent by RNC), UEs are prepared to return to appropriate PL cells when sessions resume, ensuring service continuity while managing congestion.
2Reliability
If cell selection indication information is always transmitted to user equipments, then service quality is maintained, but signal transmission load increases
Solution Approach 1:
The RNC evaluates local cell load conditions and sends cell selection indication information only when necessary (when cell selection is required based on current congestion levels). This localized, condition-based approach maintains service quality where needed while reducing unnecessary signal transmission load in less congested areas.
Solution Approach 2:
Instead of always transmitting cell selection indication information (excessive action), the system transmits it partially - only when cell load conditions warrant intervention. This partial action approach maintains adequate service quality while minimizing unnecessary signal transmission overhead.
Data Source
AI summary
A multimedia broadcast/multicast service (MBMS) service and a method and apparatus for maintaining congestion and a signal transfer load of a cell at a suitable level when a session of the MBMS service is terminated in a frequency layer convergence (FLC) situation in which the MBMS service is provided in a preferred frequency layer (PL). When a session of the MBMS service is terminated, a radio network controller (RNC) determines if a cell selection is required in UEs, desiring to receive the MBMS service located in the PL cell, by using a start time of a new session and load levels of a current cell and other cells, and sends, to the UEs, explicit cell selection indication information along with session stop information according to a determination result. Therefore, the congestion and signal transfer load of the cell can be maintained in the suitable level.