Inter-RAT Conditional Handover for User Plane Data Continuity
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Solution Overview
Problem
Inter-RAT handovers in mobile communication networks often result in data loss due to the inability to utilize the UE context of the previous source RAT during the creation of a new UE context in the target RAT, leading to a lack of continuity in user plane data.
Innovation Solution
Implementing a conditional handover (CHO) mechanism that allows user equipment to prepare for handovers between nodes using different radio access technologies by providing configuration information and core network compatibility indications, enabling seamless transitions without data loss by deriving security keys and maintaining user plane data continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover procedure is used between different RATs, then handover can be performed, but data loss occurs and user plane continuity is broken
Solution Approach 1:
The patent applies preliminary action by preparing the target node with full configuration information (including security keys, context, and routing parameters) before the actual handover occurs. The source node provides all necessary configuration data to the target node in advance, enabling the target node to immediately take over without requiring a full context re-creation process that would cause data loss.
Solution Approach 2:
The patent introduces an intermediary mechanism where the source node acts as a mediator to transfer complete UE context and configuration information to the target node during the handover process. This intermediary transfer ensures that security keys and user plane data routing information are preserved across the handover boundary, preventing data loss and maintaining continuity.
2Speed
If conditional handover with configuration information is provided, then handover speed and efficiency are improved, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the target node with complete handover parameters, security keys, and routing information before the handover trigger occurs. This advance preparation eliminates the need for complex real-time configuration negotiation during the handover event, significantly reducing handover latency while managing complexity through pre-computed configurations.
Solution Approach 2:
The patent implements feedback mechanisms where the user equipment reports handover conditions (such as signal quality thresholds being met) to the network, which then triggers the conditional handover. This feedback-based approach simplifies the handover management by using clear, measurable triggers rather than complex real-time decision-making algorithms.
3Reliability
If core network compatibility indication is provided, then data continuity is ensured, but signaling overhead increases
Solution Approach 1:
The patent applies local quality by providing core network compatibility information at the specific handover context level rather than requiring system-wide compatibility checks. The compatibility indication is localized to the particular UE and target node combination, allowing data continuity to be ensured only where needed without adding unnecessary signaling overhead for incompatible configurations.
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting the handover procedure based on the core network compatibility indication. When compatibility is detected, the system activates data continuity modes and preserves security keys; when incompatibility is detected, the system automatically selects alternative handover paths or notifies the user. This parameter-based approach ensures data continuity only when possible, minimizing unnecessary signaling.
Data Source
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AI summary
An apparatus, configured to operate in a mode such that the apparatus is communicating with a first and second node using different radio access technologies RAT. The apparatus being configured to respond to receipt of conditional handover information from the first node, the conditional handover information comprising configuration information for the second node and a core network indication indicating whether the first and second node provide access to a same, a compatible or an incompatible core network; to determine whether at least one handover condition is fulfilled; and where so to generate a handover confirmation report comprising an indication of the at least one handover condition that was determined to be fulfilled; to transmit the report to the second node; and to perform a handover such that the apparatus is no longer connected to the first node and the apparatus is connected to the second node.