UICC Scan Control Table for Roaming PLMN Priority
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Solution Overview
Problem
Devices experience poor battery life and user experience when roaming due to frequent searches for higher priority public land mobile networks (PLMNs) that may not be available in a particular area, leading to unnecessary battery drain.
Innovation Solution
A system and method that control the frequency of network identifier scans by determining scan control data based on the user equipment's location and priority of available network identifiers, enabling or disabling searches based on a ranked list of PLMN IDs stored on the SIM card, thereby optimizing battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device performs periodic PLMN searches for higher priority PLMNs, then the device can switch to higher priority networks when available, but the battery life is degraded due to unnecessary scans in areas where higher priority PLMNs do not exist
Solution Approach 1:
The patent applies preliminary action by pre-configuring the device with a scan control table that contains information about which PLMNs are available in different areas before the device actually needs to scan. This table is populated with data about PLMN availability by area, allowing the device to make informed decisions about whether to perform scans without exhaustively searching all possible PLMNs, thus saving battery life while maintaining reliable network selection.
Solution Approach 2:
The patent implements local quality by making the scan behavior adaptive to the specific area where the device is located. Instead of uniformly scanning for all higher priority PLMNs regardless of location, the device checks the scan control table to determine which PLMNs are actually available in its current area, and only scans for those. This localized approach prevents unnecessary scans in areas where higher priority PLMNs don't exist, conserving battery energy.
2Reliability
If the device scans for all higher priority PLMNs regardless of area, then the device ensures it finds the highest priority network, but the user experience is degraded due to unnecessary scans consuming battery resources
Solution Approach 1:
The system pre-populates the scan control table with information about PLMN availability by area before the device needs to perform scans. This preliminary configuration allows the device to use the table to guide its scanning behavior, ensuring it only scans for PLMNs that are actually available in its current area, thereby maintaining accurate network selection while improving user experience by avoiding unnecessary scans.
Solution Approach 2:
The patent implements feedback by using the scan control table to continuously guide and adjust the scanning process. The table provides feedback information about which PLMNs are available in different areas, allowing the device to adapt its scanning behavior in real-time. This feedback mechanism ensures the device maintains accurate network selection by focusing scans only on relevant PLMNs, enhancing user experience through reduced battery consumption.
Data Source
AI summary
Battery life of a user equipment (UE) can be extended when the UE is roaming internationally in a country that has multiple carrier networks each utilizing multiple public land mobile network (PLMN) identifiers. Scan control tables, stored in a universal integrated circuit card (UICC) of the UE, are populated with the identifiers of a PLMN having the highest priority in a defined area (e.g., Circle). A roaming control applet of the UICC can compare serving cell data with the scan control tables to determine if the UE is to perform a higher priority (HP) PLMN search. Utilization of the scan control table avoids unnecessary searches for HPPLMNs that are unavailable in the UE's current location and accordingly extends battery life of the UE.