Inter-RAT Handover With Selective Lower-Layer Reconfiguration
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Solution Overview
Problem
Existing inter-RAT handover procedures in telecommunications result in unnecessary reconfigurations and service interruptions due to treating all handovers as inter-system, even when they are intra-system, leading to inefficient handover processes.
Innovation Solution
A method for inter-RAT handover that prepares a reconfiguration message based on RAT and system combinations, allowing the UE to reconfigure lower-layer configurations and keep upper-layer configurations, reducing unnecessary reconfigurations and service interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full reconfiguration is performed during inter-RAT handover, then security is improved, but service interruption time increases
Solution Approach 1:
The patent segments the configuration into lower-layer (RLC, MAC, PHY) and upper-layer (PDCP, SDAP) components. During inter-RAT handover, only lower-layer configurations are reconfigured while upper-layer configurations are retained, eliminating unnecessary full reconfigurations and reducing service interruption time while maintaining security through proper key derivation
Solution Approach 2:
The patent introduces dynamic behavior where the UE determines whether to reconfigure based on the handover type (inter-system vs. intra-system). For intra-system handovers, upper-layer configurations are kept; for inter-system handovers, full reconfiguration is performed. This dynamic approach optimizes the balance between security and service continuity
2Reliability
If full configuration is applied during handover, then handover reliability is improved, but handover efficiency deteriorates
Solution Approach 1:
The patent applies partial reconfiguration action by selectively reconfiguring only the necessary lower-layer configurations during intra-system handovers, rather than performing excessive full reconfiguration. This partial action maintains handover reliability while significantly improving handover efficiency by reducing unnecessary reconfiguration overhead
3Reliability
If all protocol sublayers are reconfigured during inter-RAT handover, then security key freshness is improved, but configuration complexity increases
Solution Approach 1:
The patent segments the protocol stack into lower-layer and upper-layer configurations, applying different reconfiguration strategies to each segment. This segmentation reduces configuration complexity by eliminating the need to reconfigure upper layers during intra-system handovers, while still ensuring security key freshness through appropriate key derivation in the lower layers
Data Source
AI summary
A method for inter-Radio Access Technology (RAT) handover comprises preparing, at a target node, a reconfiguration message based on that the target node is inter-RAT and intra-system to a source node, and sending, to the source node, the reconfiguration message for forwarding the reconfiguration message to a user equipment (UE). The reconfiguration message comprises configuration for reconfiguring lower layer at the UE and further keeps the UE from reconfiguring upper-layer configuration. The target node disclosed in the method prepares a reconfiguration message specific to different types of RAT combination and system between the source node and the target node to provide loss-less and in-order data delivery during and after the handover.