Multi-RAT Cell Selection During NAS Timer Registration Failure
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Solution Overview
Problem
Existing electronic devices face delays in core network registration due to failed attempts in poor radio access technology (RAT) conditions, leading to prolonged service disruptions as they wait for NAS layer timers to expire.
Innovation Solution
The electronic device identifies events causing RRC connection release, performs a camp-on to a second RAT with a good electric field, and initiates a NAS timer-based scan to quickly register with the core network, prioritizing scans based on service type and RAT priority.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE waits for the NAS timer to expire before attempting registration, then the system follows standardized timer-based retry logic, but the service disconnection time increases and communication reliability deteriorates
Solution Approach 1:
The UE performs cell scanning and identifies available RATs with good electric fields before the NAS timer expires. By preparing alternative cell candidates in advance and initiating registration attempts on these cells during the timer period, the system reduces service disconnection time while maintaining standardized timer operation for fallback scenarios
Solution Approach 2:
The system dynamically adjusts registration behavior based on real-time radio conditions. When the electric field strength of alternative RATs exceeds a threshold, the UE actively seeks and camps on these cells during the timer period, transitioning from passive timer-waiting to active registration attempts, thereby improving reliability without permanently increasing complexity
2Productivity
If the UE performs active cell scanning and camp-on to alternative RATs during the timer period, then service reconnection speed improves, but device complexity increases due to additional scan and selection logic
Solution Approach 1:
The enhanced cell scanning is performed selectively only when specific conditions are met (e.g., timer period elapsed, electric field threshold exceeded, service interruption detected). By localizing the complex scanning behavior to specific time and condition windows rather than making it continuous, the patent improves reconnection speed while containing the increase in device complexity to manageable levels
3Adaptability or versatility
If the UE continuously scans for better RATs, then the ability to find optimal cells improves, but energy consumption increases
Solution Approach 1:
The UE performs cell scanning periodically at defined intervals during the NAS timer period rather than continuously. The scanning occurs at specific time points (e.g., when timer reaches certain thresholds, or at regular intervals within the timer window), allowing the system to maintain adaptability in cell selection while significantly reducing energy consumption compared to continuous scanning
Data Source
AI summary
According to various embodiments, an electronic device includes at least one processor. The at least one processor is configured to: after establishing an RRC connection with a first cell of a first RAT, confirm the occurrence of an event associated with the release of the RRC connection with the first cell; camp on to a second cell of a second RAT different from the first RAT in response to the confirmation of the occurrence of the event; initiate a timer, defined in an NAS, on the basis of a failure to register to a core network corresponding to the second RAT; and perform one of a scan associated with the first RAT or a scan associated with a RAT according to a preset priority, on the basis of the initiation of the timer, according to whether a service performed while connected to the first cell is an IMS call service.