Two-Stage Cell Reselection for Unlicensed Spectrum
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Solution Overview
Problem
In New Radio-Unlicensed (NR-U) systems, user equipment (UE) faces challenges in performing robust cell reselection in unlicensed bands, especially when neighbor cells belong to different public land mobile networks (PLMNs), leading to failed reselections due to lack of registration.
Innovation Solution
A two-stage cell reselection procedure is implemented, where the UE first measures and selects candidate cells based on signal metrics and then performs a pre-check of the PLMN associated with the target cell before initiating reselection, ensuring compatibility and improving success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If UE performs cell reselection in unlicensed band without PLMN verification, then reselection speed is improved, but reselection failure rate increases due to PLMN incompatibility
Solution Approach 1:
The patent applies preliminary action by performing PLMN verification before completing the cell reselection process. The UE measures and identifies candidate cells first, then verifies PLMN compatibility as a preliminary check before finalizing reselection. This prevents failed reselections due to PLMN incompatibility while maintaining efficient cell selection based on signal metrics.
2Reliability
If UE performs PLMN verification before cell reselection, then reselection success rate is improved, but reselection process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the cell reselection process into distinct stages: (1) cell measurement and candidate identification based on signal metrics, (2) PLMN verification of candidate cells, and (3) final reselection decision. This segmented approach organizes the complex procedure into manageable steps, making the PLMN verification process systematic and integrated into the existing reselection framework.
3Reliability
If UE performs PLMN search in between paging occasions, then PLMN compatibility is ensured, but time consumption increases
Solution Approach 1:
The patent performs PLMN verification as a preliminary check during the cell reselection process, utilizing existing measurement opportunities and signaling resources. By integrating PLMN verification into the cell selection procedure rather than performing separate PLMN searches, the solution ensures PLMN compatibility while minimizing additional time consumption.
Data Source
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AI summary
The present application relates to wireless devices and components including apparatus, systems, and methods for two-stage cell reselection in New Radio (NR) systems operating on unlicensed spectrum. In some embodiments, a user equipment may be perform a pre-check of a public land mobile network associated with a target cell prior to cell reselection.