Wireless Terminal Failure Reporting in NES Conditional Handover
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Solution Overview
Problem
Existing technologies face challenges in handling handover failures and radio link failures associated with delayed CHO condition evaluation in Network Energy Saving (NES) type conditional handovers, unclear UE reporting of such failures, and unclear UE behavior during RRC connection reestablishment in such scenarios.
Innovation Solution
The proposed solution involves a radio terminal that stores failure information indicating the elapsed time from the start of CHO execution condition evaluation until a handover or radio link failure occurs, and transmits this information to the network, along with specific handling procedures for cell selection and execution of conditional handovers based on NES mode and failure types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the network enters NES mode to reduce energy consumption, then energy efficiency is improved, but handover failure handling and radio link failure reporting become unclear and complex
Solution Approach 1:
The patent segments the CHO evaluation process into distinct phases: pre-NES mode evaluation, post-NES mode evaluation, and failure handling phases. By dividing the complex failure handling into specific scenarios (handover failure before NES mode, radio link failure during NES mode, etc.), the patent makes each scenario manageable with clear predefined behaviors, reducing overall system complexity despite the energy saving requirements.
Solution Approach 2:
The patent establishes preliminary rules and configurations for CHO evaluation before NES mode is activated. The network configures the UE with specific CHO parameters and evaluation conditions in advance, so that when NES mode is entered, the failure handling procedures are already defined and don't require complex real-time decisions, thus reducing operational complexity while maintaining energy efficiency.
2Loss of energy
If CHO condition evaluation is delayed in NES mode to save energy, then network activity is reduced, but failure detection and reporting time increases
Solution Approach 1:
The patent implements periodic CHO condition evaluation during NES mode instead of continuous evaluation. The UE evaluates CHO conditions at specific intervals or triggered events (such as when exiting NES mode or upon receiving specific network signals), reducing energy consumption while ensuring timely failure detection at these periodic checkpoints. This periodic approach balances energy saving with acceptable failure detection timing.
Solution Approach 2:
The patent establishes feedback mechanisms where the network monitors CHO evaluation status and can trigger evaluations or adjust NES mode operation based on network conditions. When failure risk is detected or network conditions change, the network can signal the UE to perform CHO evaluation or exit NES mode, ensuring timely response to failures while maintaining energy efficiency during normal operation.
3Reliability
If the network maintains continuous CHO evaluation to ensure quick failure response, then reliability is improved, but energy consumption increases
Solution Approach 1:
The patent makes CHO evaluation dynamic by adjusting its activity level based on network conditions and NES mode status. During NES mode, CHO evaluation is suspended or reduced, and the system dynamically transitions between evaluation and non-evaluation states based on triggers such as network signals, cell quality changes, or exit from NES mode. This dynamic approach maintains reliability when needed while conserving energy during stable low-activity periods.
Solution Approach 2:
The patent changes the evaluation parameters and thresholds based on whether the network is in NES mode or not. Different measurement thresholds, evaluation frequencies, and triggering conditions are applied depending on the operational mode. This allows the system to maintain adequate handover reliability with relaxed parameters during NES mode, reducing energy consumption while still providing reliable service when the network is fully active.
Data Source
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AI summary
A radio terminal receives a first message containing configuration information for a conditional handover from a network. The radio terminal stores failure information indicating an elapsed time from a start of evaluation of an execution condition for the conditional handover to a given point in time in response to detecting a handover failure or a radio link failure after receiving the first message. The radio terminal transmits a second message containing the failure information to the network. For example, this helps improve a failure report provided by a radio terminal to a network regarding a radio link failure or a handover failure detected in relation to a conditional handover.