PLMN Selection on Unlicensed Spectrum via Wake-Up Signal Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems, particularly in next-generation 5G NR, face inefficiencies in PLMN selection and cell reselection procedures when operating on unlicensed spectrums, leading to increased delay and complexity due to the need to search for the strongest cell across multiple PLMNs, which may not belong to the registered or equivalent PLMN.
Innovation Solution
A method for User Equipment (UE) to perform PLMN selection and cell reselection on unlicensed spectrums by reading system information from multiple cells, prioritizing cells belonging to the selected PLMN, and deprioritizing non-compatible cells, thereby optimizing the process and reducing unnecessary searches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE searches for the strongest cell across multiple PLMNs on unlicensed spectrum, then the UE can find available cells, but the search delay and complexity increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-obtaining PLMN information from wake-up signals before performing full cell selection. The UE reads PLMN IDs from WUS in advance, filters candidate cells by PLMN compatibility, and only then performs detailed cell selection procedures. This preliminary filtering reduces the search space and avoids unnecessary delays in cell selection.
Solution Approach 2:
The patent segments the cell selection process into distinct phases: (1) receiving wake-up signals with PLMN information, (2) filtering cells based on PLMN matching, (3) performing cell selection on filtered candidates. This segmentation allows the UE to eliminate incompatible cells early without performing full selection procedures on all cells, thereby reducing overall search time.
2Reliability
If the UE reads system information from multiple cells to check PLMN compatibility, then the UE can identify suitable cells, but the power consumption and processing complexity increase
Solution Approach 1:
The patent applies preliminary action by extracting PLMN identification information from wake-up signals before the UE performs full system information reading. The network broadcasts PLMN IDs in WUS, allowing the UE to pre-filter candidate cells and only read detailed system information from cells that match the UE's registered PLMN, thereby reducing power consumption.
Solution Approach 2:
The patent extracts the essential PLMN identification information from the complete system information blocks and places it in the compact wake-up signal format. This extraction allows the UE to perform quick PLMN matching without reading entire system information from all cells, significantly reducing processing complexity and power consumption.
3Productivity
If the UE prioritizes cells belonging to the selected PLMN on unlicensed spectrum, then the network access efficiency improves, but the device complexity increases due to additional filtering logic
Solution Approach 1:
The patent applies preliminary action by performing PLMN filtering based on information received from wake-up signals before the UE engages in full cell selection procedures. The network provides prioritization information in advance, allowing the UE to simply follow pre-determined filtering rules rather than implementing complex real-time decision logic.
Solution Approach 2:
The patent uses the wake-up signal as an intermediary that carries PLMN identification and prioritization information from the network to the UE. This intermediary structure simplifies the UE's device complexity by offloading the filtering logic to the network side, where the network determines and communicates the prioritization rules.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A method of wireless communication is provided. The method includes reading, by a User Equipment (UE), system information of a plurality of cells on a first carrier frequency to obtain identification information of a plurality of Public Land Mobile Networks (PLMNs). The first carrier frequency is an unlicensed carrier frequency. The method further includes reporting, by an Access Stratum (AS) entity of the UE, the identification information of the plurality of PLMNs to a Non-Access Stratum (NAS) entity of the UE, selecting, by the NAS of the UE, one of the plurality of PLMNs as a selected PLMN, searching for the plurality of cells on the first carrier frequency during a cell selection procedure, and selecting a suitable cell belonging to the selected PLMN from the plurality of cells on the first carrier frequency as an outcome of the cell selection procedure.