UE Reestablishment Handling for Integrity Check Failure Loops
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Solution Overview
Problem
Ambiguity in UE actions upon integrity check failures during reestablishment procedures in LTE and NR leads to unpredictable behavior and potential infinite loops or failure to change cells, especially in non-radio related issues, causing UEs to get stuck in failing cells.
Innovation Solution
Implement methods for UEs to monitor integrity check failures and transition to RRC_IDLE upon specific conditions, triggering recovery procedures and defining countermeasures to avoid infinite reestablishment loops, including cell reselection and NAS recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE initiates reestablishment procedure upon integrity check failure, then the connection can be recovered, but the UE may enter an infinite loop by repeatedly initiating reestablishment
Solution Approach 1:
The patent applies preliminary action by having the UE monitor and detect integrity check failures before initiating reestablishment. The UE tracks the number of integrity check failures and only initiates reestablishment when a threshold is reached, preventing premature or redundant reestablishment attempts that could cause infinite loops.
Solution Approach 2:
The patent implements feedback mechanisms where the UE monitors integrity check results and uses this information to control reestablishment behavior. The UE counts failure occurrences and adjusts its actions based on the accumulated feedback, transitioning to RRC_IDLE when a threshold is exceeded to break potential infinite loops.
2Reliability
If the UE repeatedly initiates reestablishment upon integrity check failure, then connection recovery attempts are made, but the UE gets stuck in the same failing cell
Solution Approach 1:
The patent applies dynamics by making the UE's state transitions conditional rather than fixed. The UE dynamically adjusts its behavior based on the number of integrity check failures, transitioning from repeated reestablishment attempts to RRC_IDLE state and cell reselection when a threshold is exceeded, enabling adaptation to persistent failure conditions.
Solution Approach 2:
The patent converts the harmful effect of repeated reestablishment failures into a beneficial cell reselection mechanism. By counting integrity check failures and triggering RRC_IDLE transition upon reaching a threshold, the UE transforms the problem of stuck-in-cell behavior into an opportunity to select a better cell, turning failure into a recovery opportunity.
3Device complexity
If the UE transitions to RRC_IDLE upon integrity check failure, then infinite loops are prevented, but connection recovery may be delayed
Solution Approach 1:
The patent applies parameter changes by introducing a configurable threshold parameter that controls when to transition to RRC_IDLE. This threshold can be adjusted to balance between preventing infinite loops and minimizing recovery time, allowing optimization based on network conditions and failure patterns without sacrificing predictability.
Data Source
AI summary
Embodiments described herein relate to methods and apparatuses for performing a re-establishment procedure. A method in a user equipment comprises: receiving a re-establishment message; upon reception of the re-establishment message, monitoring for an indication of an integrity check failure received from lower layers, wherein the indication relates to a first message or a second message received by the UE after transmitting a re-establishment request; responsive to the indication of the integrity check failure, performing actions upon going into an RRC_IDLE mode of operation; indicating a connection failure to upper layers; and based on the indication, upper layers triggering a recovery procedure.