Handover Management Using Backup Resources for Beam Failure
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Solution Overview
Problem
Random access free handovers in multi-beam wireless communication systems face challenges such as incorrect beam selection due to movement and signal strength variations, leading to potential handover failures, especially in conditional handovers where delays increase the risk of radio channel changes and resource inefficiencies.
Innovation Solution
The system employs backup resources, such as contention-based or grant-free uplink resources, to establish a connection with the target cell if none of the candidate beams are usable, and initiates a radio link recovery process before the handover timer expires, ensuring a stable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If random access free handover is implemented using candidate beams, then handover speed is improved, but reliability deteriorates when beams become unusable due to movement or signal variations
Solution Approach 1:
The system pre-configures backup resources (contention-based random access resources or grant-free uplink resources) before handover is needed. When candidate beams become unusable, the terminal can immediately switch to pre-configured backup resources without delay, maintaining both fast handover and high reliability.
Solution Approach 2:
The system prepares fallback mechanisms in advance by configuring backup resources that can be used if candidate beams fail. This cushioning ensures that handover reliability is maintained by having predetermined alternative paths ready before failures occur.
2Reliability
If conditional handover with delays is used, then handover reliability is improved by allowing beam selection, but the risk of radio channel changes increases
Solution Approach 1:
The system performs beam measurement and selects candidate beams in advance before the actual handover execution. This preliminary beam selection is stored and can be quickly executed when handover is triggered, reducing the delay between handover decision and execution, thereby minimizing radio channel changes while maintaining reliability.
Solution Approach 2:
The system dynamically adapts by monitoring the usability of candidate beams and having the ability to switch to backup resources if conditions change. This dynamic adjustment allows the system to maintain reliability while responding quickly to channel changes.
3Reliability
If multiple backup resources are configured for fallback, then handover reliability is improved, but resource overhead increases
Solution Approach 1:
The system configures backup resources selectively based on local conditions and requirements. Instead of uniformly configuring multiple backup resources for all scenarios, the system adjusts the number and type of backup resources according to specific deployment needs, terminal capabilities, and channel conditions, optimizing the balance between reliability and overhead.
Data Source
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AI summary
According to an example aspect of the present invention, there is provided an apparatus comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to receive, from a target cell via a source cell, information concerning at least one beam of the target cell, the at least one beam being at least one candidate beam for random access free handover, determine that none of the at least one beam is usable for the random access free handover, and exactly one of establish a connection to the target cell using a backup resource, and initiate a radio link recovery process.