Resetting Location Registration Timer During Radio Access Technology Transitions
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Solution Overview
Problem
User equipment (UE) faces issues with periodic location registration when transitioning between different radio access technologies (RATs), leading to potential disconnection and inability to receive mobile terminating calls due to expired timers and barred or rejected network access.
Innovation Solution
Resetting the periodic location registration timer when the UE transitions from one RAT to another, using the remaining value of timers like T3412 to ensure timely location updates and prevent implicit detachment by the core network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions between different RATs without resetting the periodic location registration timer, then the timer may expire causing implicit detachment, but resetting the timer ensures continuous pageability
Solution Approach 1:
The patent applies preliminary action by resetting the periodic location registration timer (T3412) before it expires, specifically when the UE transitions between RATs. This proactive timer reset prevents the timer from expiring and causing implicit detachment, ensuring the UE remains pageable throughout the transition process.
2Reliability
If the network bars or rejects access for periodic location registration, then the UE cannot update its location, but resetting the timer upon RAT transition provides another opportunity for successful registration
Solution Approach 1:
The patent resets the periodic location registration timer as a preliminary action when the UE transitions between RATs, providing a fresh time window for successful location registration. This prevents the timer from expiring during transitions when access might be barred or rejected, giving the UE another opportunity to register successfully.
3Use of energy by moving object
If the UE remains in idle state with ISR across RATs, then signaling is reduced, but location registration must still be performed to maintain reachability
Solution Approach 1:
The patent dynamically manages the periodic location registration timer based on RAT transitions. When the UE transitions between different radio access technologies, the timer is reset to appropriate values, allowing the UE to maintain reachability while benefiting from ISR signaling reduction during idle periods in each RAT.
Data Source
AI summary
When at user equipment UE transitions between radio access technology cells, at the transition a timer for controlling when the UE is to send a periodic location registration is reset. This avoids the UE being implicitly detached when it is unable/blocked in the packet-switched PS domain from performing a RAU but would be able to perform a LU, particularly when the UE is in PS/CS modes 1 or 2. Five different embodiments are detailed: the LU timer T3212 is reset with a value of time remaining in a tracking area update TAU timer T3412; T3212 is reset with an initial value for T3212; the RAU timer T3312 is reset with a value of time remaining in the TAU timer T3412; and the T3212 or T3312 reset is conditional on a value of time remaining in a PS backoff timer T3346 exceeding the value of time remaining in the TAU T3412.