Secondary Cell Group Failure Detection Using Downlink Timing
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Solution Overview
Problem
In dual connectivity scenarios, there is a need for efficient secondary cell group (SCG) failure detection and reporting techniques to support SCG activation and deactivation in user equipment (UE), as conventional methods lead to performance degradation due to inadequate RRM measurements on deactivated or suspended SCGs, causing potential activation of unsuitable SCGs and increased latency.
Innovation Solution
The UE is configured to identify SCG failures based on downlink timing issues and report these failures to the primary node, using signaling techniques such as SCG failure type indications, measurement reports, and UE assistance information, to facilitate efficient SCG deactivation and activation, thereby mitigating performance degradation and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the UE performs conventional failure detection on deactivated SCG, then the detection process is simplified, but the detection accuracy deteriorates due to inadequate RRM measurements
Solution Approach 1:
The UE performs RRM measurements on the deactivated SCG before formal failure detection is required. By conducting measurements in advance while the SCG is still deactivated, the UE accumulates timing information that can be used for accurate failure detection without requiring complex active measurement procedures during failure conditions.
Solution Approach 2:
The patent uses downlink timing measurements as an intermediary indicator to detect SCG failure. Instead of directly measuring complex failure conditions, the UE monitors timing advances and timing difference values (Tdiff) as intermediate parameters that reflect the health status of the SCG, enabling accurate failure detection through simpler timing-based metrics.
2Measurement precision
If the UE continuously monitors SCG status, then failure detection accuracy is improved, but power consumption increases
Solution Approach 1:
The UE performs RRM measurements periodically on the deactivated SCG rather than continuously. The measurement frequency is optimized to balance detection accuracy with power consumption, allowing the UE to capture timing variations that indicate failure while minimizing unnecessary measurement operations that would consume additional power.
Solution Approach 2:
The UE utilizes existing downlink timing measurement capabilities that are already maintained for other purposes (such as uplink timing alignment) to simultaneously detect SCG failure. By repurposing existing measurement functions, the UE achieves accurate failure detection without requiring additional dedicated measurement resources that would increase power consumption.
3Loss of time
If the UE reports SCG failure immediately, then network response time is reduced, but false reporting increases due to measurement uncertainties
Solution Approach 1:
The UE performs preliminary timing measurements and accumulates measurement results before declaring SCG failure. By gathering timing advance values and Tdiff measurements in advance and analyzing trends, the UE can distinguish between temporary timing variations and actual failure conditions, reducing false reports while maintaining timely failure notification.
Solution Approach 2:
The UE uses feedback from accumulated timing measurements to validate failure conditions before reporting. The measurement results are analyzed against thresholds and trends, and only when the feedback indicates consistent failure conditions does the UE report the failure, thereby reducing false positives while maintaining responsive failure notification.
Data Source
AI summary
A user equipment (UE) receives an indication that a secondary cell group (SCG) state is to be changed from an activated state to a deactivated state, when the SCG is in the deactivated state, identifies a SCG failure based on downlink timing associated with the SCG and reports the SCG failure to a primary node.