UE PLMN Selection Using Access-Specific Signal Thresholds

The patent applies preliminary action by having the UE measure and store signal level information for multiple PLMNs before final selection. The UE measures signal levels during initial network scanning and periodically updates this information, preparing network selection data in advance so that when selection is needed, the UE can immediately use the stored signal level data to make informed decisions about which PLMN to select based on both priority and actual signal quality.

The patent implements feedback by having the UE continuously monitor and report signal level information back to the network selection process. The UE measures current signal levels for available PLMNs and uses this feedback information to dynamically adjust network selection decisions. This feedback mechanism ensures that the network selection algorithm considers actual signal quality conditions and can switch between PLMNs based on real-time signal availability, resolving the contradiction between simple selection process and optimized signal coverage.

The patent applies partial action by implementing a tiered network selection approach where the UE first considers high-priority PLMNs but also evaluates signal level thresholds. Instead of immediately selecting the highest priority PLMN without checking signal quality, the UE partially evaluates multiple criteria (priority and signal level) before making the final selection. This partial evaluation mechanism allows the system to maintain speed by using priority as the primary filter while using signal level as a secondary validation criterion, thus optimizing both speed and signal quality.

The patent changes the selection parameters dynamically based on conditions. The UE adjusts the weight given to priority versus signal level parameters based on the current situation. When signal level thresholds are not met for high-priority networks, the UE changes the selection criterion to favor networks with adequate signal quality even if they have lower priority. This dynamic parameter adjustment allows the system to optimize signal quality without permanently sacrificing selection speed, as the full priority-based fast selection path remains available when signal conditions permit.

The patent applies beforehand cushioning by establishing signal level thresholds and hysteresis margins in advance that prevent frequent network re-selection. The UE is configured with minimum signal level thresholds that must be exceeded to trigger network re-selection, and these thresholds act as a cushion against unnecessary switching. Additionally, the system implements a hysteresis mechanism where the UE waits for signal conditions to improve beyond the threshold by a certain margin before initiating re-selection, providing a cushion that stabilizes communication while still allowing adaptation to genuine changes in network conditions.

The patent implements dynamics by making the network selection criteria adaptive rather than static. The UE dynamically adjusts its network selection behavior based on current signal conditions, user mobility state, and network availability. The system can switch between different selection strategies: when the UE is stationary, it uses stricter signal level criteria to maintain stability; when the UE is mobile, it becomes more adaptive to network changes. This dynamic adaptation resolves the contradiction by allowing frequent re-selection only when necessary, while maintaining stability during normal operation.