UE Fallback Handling for CHO and DAPS HO Failures
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Solution Overview
Problem
In wireless communication technologies, existing handover procedures, such as DAPS HO, CHO, and CPAC, face challenges in handling failures effectively, especially when configured simultaneously, requiring improved methods to ensure high reliability and zero interruption time, particularly for services like online gaming and extended reality/virtual reality, where cell quality and radio link failures complicate fallback and re-establishment processes.
Innovation Solution
A user equipment (UE) processor is configured to receive RRC reconfiguration messages with CHO and DAPS HO indications, allowing it to perform handover procedures, fallback to the source cell based on cell quality and radio link status, and maintain configurations, while also handling SCG and MCG failures by transmitting relevant failure information, enabling robust recovery mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CHO and DAPS HO are configured simultaneously to the UE, then handover reliability and zero interruption time are both improved, but the complexity of handling handover failure increases
Solution Approach 1:
The patent segments the failure handling process into distinct scenarios: DAPS HO failure, CHO failure, and their combination. Each scenario has specific handling procedures defined, allowing the UE to systematically manage complexity by addressing each failure type separately rather than as a monolithic problem.
Solution Approach 2:
The patent establishes preliminary failure handling rules and procedures before actual failures occur. The UE is pre-configured with specific actions to take in different failure scenarios, such as when to perform RRC re-establishment, when to fallback to source cell, and how to manage CHO configurations, thereby reducing the cognitive load during actual failure events.
2Reliability
If CHO configurations are maintained after fallback to source cell, then handover reliability is improved, but the loss of time for configuration management increases
Solution Approach 1:
The patent maintains CHO configurations in the UE even after fallback to the source cell, allowing the configurations to remain valid and potentially reusable. This continuity avoids the need to重新generate and manage CHO configurations from scratch, thereby reducing time loss while maintaining reliability.
Solution Approach 2:
The patent implements a mechanism where CHO configurations are discarded only when necessary (e.g., when explicitly released by the network) but recovered/maintained when they can still be useful. This selective discarding and recovering approach optimizes the balance between reliability and time management.
Data Source
AI summary
The present application relates to methods and apparatuses for handling failure. According to some embodiments of the present application, a user equipment (UE), includes a processor; and a receiver coupled to the processor, the receiver being configured to receive a radio resource control (RRC) reconfiguration message from a source node which manages a source cell, the RRC reconfiguration message including both conditional handover (CHO) configurations and per data radio bearer (DRB) dual active protocol stack (DAPS) HO indication for each candidate cell of one or more candidate cells; wherein the processor configured to: perform a first handover procedure to a first target cell selected from the one or more candidate cells; and in response to a failure of the first handover procedure, perform fallback to the source cell when at least one of the following conditions is met: a cell quality of the source cell is higher than or equal to that of each candidate cell of the one or more candidate cells, and there is no radio link failure (RLF) in the source cell; the source cell is selected by a cell selection procedure with configurations of the source cell maintained; the cell quality of the source cell is higher than a threshold; or an indication indicating that the UE is to perform fallback to the source cell is received.