RNA Update Reject Handling via Wait Timer
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Solution Overview
Problem
There is currently no clear specification for the actions a UE should take upon receiving an RRCReject message, particularly in scenarios involving mobility RNA updates, leading to ambiguity in state mismatch between the UE and the network, and potential reachability issues.
Innovation Solution
The proposed solution defines specific UE behaviors upon receiving an RRCReject message, including setting a reject wait timer and performing area updates upon timer expiry, to ensure clear network actions and avoid state mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no clear specification is provided for UE actions upon receiving RRCReject, then the network has flexibility in handling rejections, but the UE experiences state mismatch and reachability issues
Solution Approach 1:
The patent applies preliminary action by defining specific UE behaviors in advance upon receiving RRCReject messages. The UE is instructed to set a reject wait timer and perform area updates upon timer expiry, which prevents state mismatches and ensures network reachability before problems occur rather than reacting to them later.
Solution Approach 2:
The patent uses parameter changes by introducing a reject wait timer parameter that changes the UE's behavior state. When the timer expires, the UE transitions from a rejected state to an active area update state, thereby resolving the state mismatch issue through controlled parameter evolution.
2Reliability
If the UE performs area updates immediately upon RRCReject, then network reachability is improved, but the network may experience increased signaling load
Solution Approach 1:
The patent applies periodic action by introducing a reject wait timer that delays area update performance. Instead of immediate updates, the UE waits for the timer to expire before performing area updates, thereby distributing signaling load over time and reducing peak network signaling traffic while maintaining reachability.
3Use of energy by moving object
If the UE enters RRC inactive state without clear rejection handling, then energy consumption is reduced, but the UE may enter unreachable states
Solution Approach 1:
The patent uses feedback by implementing a reject wait timer mechanism that provides feedback control to the UE's state transitions. The timer acts as a feedback mechanism that prevents the UE from entering unreachable states while in RRC inactive state, ensuring that the UE will perform area updates at appropriate intervals to maintain network reachability without excessive energy consumption.
Data Source
AI summary
A wireless device handles area update reports. The wireless device initiates a radio network area update, RNAU, responsive to detecting that the wireless device has entered a cell not belonging to a radio network area, RNA, configured for the wireless device. The wireless device receives, from the wireless network, a message indicating that the wireless device's attempt to perform the RNAU has been rejected. The message includes or is accompanied by an indication that a wait time value is applicable. Responsive to the message, the wireless device sets a reject wait timer to the wait time value and performs the RNAU upon expiry of the reject wait timer. In some embodiments, the wireless device sets a periodic RNAU timer to the wait time value, responsive to the message, and performs the RNAU upon expiry of the reject wait timer and the periodic RNAU timer.