NG Handover Capability Checks for Unsupported UE Configurations
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Solution Overview
Problem
In Next Generation (NG) handover procedures, handover failures occur due to unsupported user equipment (UE) capabilities, particularly in subcarrier spacing (SCS) and bandwidth configurations, without clear cause values indicating the rejection, leading to unnecessary handover attempts and increased signaling overhead.
Innovation Solution
Implementing methods at network nodes to proactively prevent handover rejections by explicitly or implicitly knowing the target RAN node's capabilities, such as supported SCS and bandwidth, allowing the source node to avoid incompatible handover attempts and reduce signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network node proactively checks UE capabilities and prevents incompatible handovers, then handover failure rate is reduced, but device complexity and signaling overhead increase
Solution Approach 1:
The network node performs capability checking and compatibility assessment before initiating the handover procedure. By proactively determining whether the target cell supports the UE's capabilities (such as subcarrier spacing and bandwidth), the system prevents incompatible handovers from occurring, thereby reducing handover failure rates without requiring complex runtime adjustments during the handover process itself.
2Loss of energy
If the network node proactively checks UE capabilities and prevents incompatible handovers, then signaling overhead is reduced, but device complexity and processing time increase
Solution Approach 1:
The capability verification is performed in advance during the handover preparation phase, before any handover signaling is exchanged with the UE. This preliminary check prevents unnecessary handover attempts that would generate redundant signaling traffic, thereby reducing overall signaling overhead while concentrating the processing complexity in a single preparatory step rather than distributing it across multiple failed handover attempts.
3Reliability
If the network node performs detailed capability checking, then handover compatibility is improved, but processing time and latency increase
Solution Approach 1:
The patent extracts and checks only the critical capability parameters that are most likely to cause handover failures, such as subcarrier spacing (SCS) and bandwidth support. By focusing on these essential parameters rather than performing a comprehensive check of all UE capabilities, the system achieves sufficient compatibility verification while minimizing the processing time required during handover preparation.
Data Source
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Figure 2
AI summary
A method performed by a target network node includes receiving, from a source network node, a handover request associated with a wireless device. The target network node transmits, via a core network node, a handover reject message to the source network node. The handover reject message comprises a cause value for rejecting the handover request.