UE Cell Reselection Filtering for Roaming-Aware Network Handover
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Solution Overview
Problem
User equipment (UE) experiences service interruptions and loss of coverage when moving between networks with different radio access technologies (RATs) due to lack of roaming agreements, leading to unnecessary reselection rejections and delays.
Innovation Solution
The UE manages cell reselection by storing allowed frequency bands and PLMN identifiers based on operator agreements, decoding system information blocks (SIBs) to identify relevant neighboring cells, and triggering reselection only to cells that meet the criteria, ensuring seamless transitions without service disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE measures all neighboring cells regardless of roaming agreements, then the UE can identify all available cells, but the UE experiences reselection rejections and service interruptions
Solution Approach 1:
The UE performs preliminary filtering of neighboring cells based on stored roaming agreement information (allowed frequency bands and PLMN identifiers) before initiating reselection measurements and procedures. This preliminary action prevents the UE from attempting reselection to cells without roaming agreements, thereby avoiding reselection rejections and service interruptions while reducing unnecessary measurement overhead.
2Reliability
If the UE filters neighboring cells based on roaming agreements before measurement, then reselection rejections are reduced, but the UE requires additional storage and processing of agreement information
Solution Approach 1:
The UE pre-stores frequency band and PLMN identifier information from roaming agreements in its memory before needing to perform cell reselection. This preliminary storage of filtering criteria enables efficient real-time filtering of neighboring cells without requiring complex processing during the reselection event itself, thus improving reselection success rate while keeping processing complexity manageable.
3Speed
If the UE attempts reselection to cells without checking roaming agreements, then reselection speed is faster, but service interruptions occur due to reselection rejections
Solution Approach 1:
The UE performs preliminary filtering of neighboring cells based on stored roaming agreement information (allowed frequency bands and PLMN identifiers) before initiating reselection measurements and procedures. This preliminary action prevents the UE from attempting reselection to cells without roaming agreements, thereby avoiding reselection rejections and service interruptions while reducing unnecessary measurement overhead.
4Measurement precision
If the UE stores detailed roaming agreement information, then filtering accuracy is improved, but the UE requires more memory resources
Solution Approach 1:
The UE extracts and stores only the essential filtering criteria from roaming agreements - specifically frequency band identifiers and PLMN identifiers - rather than storing complete agreement details. This extraction of critical information maintains sufficient filtering accuracy to prevent reselection to non-roaming cells while minimizing memory resource consumption.
Data Source
AI summary
A method for managing cell reselection by a user equipment (UE) is provided. The method includes storing, at the UE, a set of allowed frequency bands supported by a first operator. The set of allowed frequency bands are determined based on a first set of frequency bands supported by the first operator, and a second set of frequency bands associated with a second operator and permitted for use by the first operator. The method includes decoding a first system information block (SIB) comprising frequency information and frequency band information associated with corresponding neighbouring cells. The method includes determining one or more relevant neighbouring cells based on the corresponding first SIB and the set of allowed frequency bands, and further, determining, based at least on cell measurements associated with the one or more relevant neighbouring cells, at least one of a neighbouring cell for reselection.