Dual Stack Handover Source Cell Release Indication
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Solution Overview
Problem
Current mobility management in 5G NR systems lacks clear guidelines on when and how to transition communication from a source cell to a target cell during handover, leading to potential delays and service interruptions in dual active protocol stack (DAPS) based handovers.
Innovation Solution
A method for wireless devices to initiate mobility from a source node to a target node, while maintaining communication with the source node, and upon receiving an indication from the target node, stop communicating with the source node, ensuring seamless handover by explicit control of communication links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If explicit RRC signaling is used to trigger handover in cell level mobility, then mobility control is achieved, but handover delays and service interruptions occur
Solution Approach 1:
The patent applies preliminary action by establishing dual active protocol stacks at both source and target cells before the handover is triggered. The UE configures radio resource control (RRC) connections with both cells simultaneously, preparing the data radio bearers in advance so that when handover occurs, the transition is seamless without service interruption. This is achieved through the dualStackHandoverConfiguration parameter that enables concurrent RRC connections.
Solution Approach 2:
The patent maintains continuity of useful action by keeping both source and target cell connections active during the handover process. The UE continues to receive and transmit data through both cells simultaneously, ensuring uninterrupted service. The dual active protocol stacks allow data flow to continue through the source cell while the target cell is being activated, eliminating handover gaps.
2Reliability
If dual active protocol stack is configured for concurrent transmissions and receptions, then mobility performance is improved, but communication link management complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the communication links into distinct source cell and target cell connections, each with its own RRC configuration and data radio bearers. This segmentation allows independent management of each link while maintaining both simultaneously active. The dualStackHandoverConfiguration parameter creates separate configuration contexts for source and target cells, making the complex management task more tractable through structured organization.
Solution Approach 2:
The patent implements feedback mechanisms through measurement reports that the UE sends to the network about signal quality from both source and target cells. This feedback enables the network to make informed decisions about when to trigger handover and how to manage the dual active connections. The continuous monitoring and reporting of link quality allows dynamic adjustment of the dual stack configuration to optimize performance while managing complexity.
Data Source
AI summary
A method and apparatus for a source cell release indication for dual stack mobility in a wireless communication system is provided. A wireless device, which initiates a mobility from a source node to a target node, keeps communicating with the source node, and receives, from the target node, an indication. Upon receiving the indication, the wireless device stops communicating with the source node.