UE PLMN Selection Using SA Cell Caching and Targeted NR Scans
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Solution Overview
Problem
PLMN selection in user equipment (UE) is a source of latency and inefficiency, leading to prolonged access times and power drain, particularly when distinguishing between standalone (SA) and non-standalone (NSA) operations for 5G New Radio (NR) networks.
Innovation Solution
The UE maintains a database (SA PLMN database) to store indications of SA-capable cells, allowing it to prioritize frequency scans and reduce latency by differentiating between SA and NSA cells using system information blocks (SIBs) and master information blocks (MIBs, without relying solely on SIB1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs a full PLMN search procedure including frequency scan to ensure reliable network connection, then the reliability of network access is improved, but the time required for PLMN selection increases
Solution Approach 1:
The UE performs preliminary actions by maintaining a cached database of SA PLMN information from previous measurements and registrations. When selecting a PLMN, the UE first checks this cached information to identify potential SA cells before performing a full frequency scan, thereby reducing the time required while maintaining reliability through verification steps.
Solution Approach 2:
The PLMN selection process is segmented into multiple stages: first checking cached SA PLMN information, then performing targeted frequency scans only on relevant frequencies, and finally verifying SA capability through system information block checks. This segmentation allows the UE to quickly eliminate obvious candidates and focus resources on promising options.
2Measurement precision
If the UE performs comprehensive PLMN selection operations including full frequency scans to ensure accurate network selection, then the accuracy of PLMN selection is improved, but the power consumption increases
Solution Approach 1:
The UE performs partial frequency scans rather than exhaustive scans of all possible frequencies. By using cached SA PLMN information to identify likely candidates and scanning only those specific frequencies, the UE achieves sufficient selection accuracy with significantly reduced power consumption compared to comprehensive scanning.
Solution Approach 2:
The UE utilizes its own previously stored measurement results and cached PLMN information to assist in the current selection process. This self-service approach allows the UE to leverage historical data to reduce the amount of new measurement activity required, thereby lowering power consumption while maintaining accuracy.
3Adaptability or versatility
If the UE performs full PLMN search procedures to ensure complete network service availability, then the completeness of service access is improved, but the latency increases
Solution Approach 1:
The UE performs preliminary checks using cached SA PLMN information to quickly identify potential network candidates before initiating full PLMN search procedures. This preliminary action allows the UE to access services faster by leveraging previously gathered intelligence about available networks in the area.
4Measurement precision
If the UE performs detailed PLMN selection operations to ensure correct network identification, then the precision of network identification is improved, but the computational resources and time required increase
Solution Approach 1:
The network identification process is segmented into efficient stages: first using cached SA PLMN information for quick candidate identification, then performing targeted verification only on promising candidates. This segmentation maintains high identification precision while improving overall selection efficiency by avoiding exhaustive analysis of all possible networks.
Data Source
AI summary
A computer readable storage medium comprising a set of instructions to operate a processor, a user equipment (UE) and an integrated circuit configured to perform operations. The operations include receiving a signal broadcast by a cell of new radio (NR) network, determining whether the cell is configured for a standalone (SA) operation for NR based on the received signal, when the cell is configured for the SA operation for NR, storing a first indication locally at the UE that the cell is configured for the SA operation for NR, when the cell is not configured for the SA operation for NR, storing a second indication locally at the UE that the cell is configured for a non-standalone (NSA) operation for NR and initiating a public land mobile network (PLMN) search procedure, wherein the PLMN search procedure includes a frequency scan based on the first indication or the second indication.