LTE RRC Connection Reject De-prioritization Handling
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Solution Overview
Problem
Current mobile network technologies face challenges in efficiently managing frequency or radio access technology (RAT) de-prioritization, leading to prolonged reselection times to higher priority frequencies, continued de-prioritization after PLMN changes, and potential service outages due to inadequate handling of congestion and priority conflicts, especially in CSG cells and MBMS scenarios.
Innovation Solution
Implementing a method where user equipment (UE) regularly attempts to find suitable cells on non-de-prioritized frequencies, modifies cell selection processes to exclude de-prioritized frequencies, and manages de-prioritization requests based on PLMN changes and CSG cell interactions, ensuring faster reselection and appropriate priority handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a de-prioritization request is sent to a UE for a current frequency or RAT to alleviate network congestion, then network congestion is reduced, but the UE takes a long time to reselect to a higher priority layer
Solution Approach 1:
The patent makes the de-prioritization mechanism dynamic by allowing the UE to adaptively adjust its behavior based on whether it is in idle or connected mode. In connected mode, the UE can access de-prioritized frequencies immediately when needed, while in idle mode, it respects the de-prioritization. This dynamic adaptation resolves the contradiction by enabling fast access when necessary while maintaining congestion relief during normal operation.
Solution Approach 2:
The patent changes the priority parameter of de-prioritized frequencies conditionally based on the UE's operational state. When the UE is in connected mode and needs to access the frequency, the priority parameter is temporarily elevated, allowing immediate access. This parameter change resolves the contradiction between maintaining de-prioritization for congestion relief and enabling fast reselection when necessary.
2Adaptability or versatility
If a de-prioritized frequency is reused in a new PLMN, then the UE can connect to the new PLMN, but the frequency remains de-prioritized causing continued congestion issues
Solution Approach 1:
The patent applies local quality by making de-prioritization PLMN-specific rather than frequency-specific. When a UE changes PLMN, the de-prioritization request is cleared only for the new PLMN, allowing the UE to access frequencies in the new PLMN without congestion restrictions. This resolves the contradiction by maintaining PLMN adaptability while preventing congestion in the new network environment.
3Reliability
If a UE attempts to access a de-prioritized RAT or frequency after connection release or radio link failure, then the UE can re-establish connection, but it may worsen the congestion on already overloaded frequencies
Solution Approach 1:
The patent applies preliminary action by pre-configuring the UE with de-prioritization information before connection release or failure occurs. The network includes de-prioritization requests in RRC connection release messages or reestablishment reject messages, so the UE is already aware of which frequencies to avoid when attempting to re-establish connection. This resolves the contradiction by preventing congestion-worsening access attempts while ensuring reliable reconnection to appropriate frequencies.
Data Source
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AI summary
A method and apparatus for enhancements for de-prioritization by RRC connection reject, where the enhancements relate, in one aspect, to faster cell reselection to prevent possible service outages. In a further aspect the enhancements relate to release, suspension or resumption of de-prioritization upon PLMN selection. In a further aspect, the enhancements relate to conflict handling with a CSG cell priority. In a further aspect, the enhancements relate to connected mode UE handling. In a further aspect, the enhancements relate to cancellation of a de-prioritization request.