Random Access Channel Resource Selection in Multi-Beam Handover
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Solution Overview
Problem
In next-generation wireless communication networks, particularly in 5G NR, there is a challenge in efficiently selecting random access channel (RACH) resources during handover procedures in multi-beam environments, leading to potential delays and resource wastage due to the uncertainty of beam information validity and the need for beam refinement.
Innovation Solution
The solution involves a method where a source base station initiates a handover procedure based on event-triggered measurement reports, updates beam information proactively, and uses a new information element 'ReportOnBeamInfoChanged' to ensure the UE performs random access using dedicated or common RACH resources effectively, thereby reducing latency and increasing handover success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs beam refinement and selects from multiple beams with dedicated RACH resources, then the handover success rate improves, but the latency increases due to additional beam detection and measurement time
Solution Approach 1:
The source base station proactively updates beam information and triggers measurement reports before handover is actually needed. This preliminary action ensures that the UE already has current beam information when handover is initiated, eliminating the need for time-consuming beam refinement during the handover process itself.
Solution Approach 2:
The system implements event-triggered measurement reports that provide feedback to the source base station about beam quality changes. This feedback mechanism allows the network to proactively identify when beam information needs updating, enabling timely adjustments without waiting for handover to fail or latency to accumulate.
2Loss of time
If the source base station proactively updates beam information and triggers measurement reports, then handover latency is reduced, but the signaling overhead and network resources increase
Solution Approach 1:
Instead of continuous monitoring, the system uses event-triggered measurement reports that are periodically activated based on specific conditions (beam quality thresholds). This periodic action reduces signaling overhead compared to continuous updates while still maintaining current beam information when needed.
Solution Approach 2:
The system changes the parameter of measurement triggering from continuous to event-based. By monitoring beam quality parameters and only triggering updates when thresholds are crossed, the system reduces unnecessary signaling while ensuring updates occur when actually needed for handover optimization.
3Speed
If dedicated RACH resources are reserved for fast access, then access speed improves, but resource wastage occurs when beams become invalid and resources cannot be used
Solution Approach 1:
Event-triggered measurement reports provide feedback about beam validity to the source base station. This feedback allows the network to identify when dedicated RACH resources associated with specific beams are no longer valid, enabling timely reallocation or release of those resources to prevent wastage while maintaining fast access when beams are valid.
Solution Approach 2:
The system dynamically adjusts the validity and allocation of dedicated RACH resources based on current beam information. When beams become invalid, the resources are dynamically reallocated or released, transforming the static resource allocation into a dynamic system that adapts to changing conditions, thereby reducing waste while preserving fast access capability.
Data Source
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AI summary
An apparatus and a method for handover in a wireless communication system are provided. The method is performed by a UE and includes receiving an RRC message from a source base station; and performing a handover procedure to handover from the source base station to a target base station in response to the RRC message, wherein: the RRC message comprises one of a first dedicated random access configuration associated with a CSI-RS of the target base station and a second dedicated random access configuration associated with a first SSB of the target base station, the CSI-RS is configured with a first dedicated random access resource by the first dedicated random access configuration, and the first SSB is configured with a second dedicated random access resource by the second dedicated random access configuration.