NR IAB-Node Migration With DAPS for Mobility Robustness
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Solution Overview
Problem
Current wireless communication systems face challenges in enhancing mobility robustness during the migration of integrated access and backhaul nodes in 5G new radio (NR) networks, particularly in maintaining seamless transmission during inter-donor and intra-donor migrations.
Innovation Solution
Implementing a dual active protocol stack (DAPS) to maintain simultaneous connections with both the source and target IAB-nodes during migration, ensuring continuous data transmission by sending handover request messages and F1AP messages with DAPS configuration information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional single active protocol stack is used during IAB-node migration, then device complexity is reduced, but mobility robustness and transmission continuity deteriorate
Solution Approach 1:
The protocol stack transitions from a static single-active state to a dynamic dual-active state during migration. The system dynamically activates both source and target protocol stacks simultaneously, allowing the IAB-node to maintain connections with both source and target parent nodes during handover, thereby ensuring transmission continuity while managing complexity through controlled dynamic behavior
Solution Approach 2:
The target protocol stack is activated and configured in advance before the actual handover occurs. The IAB-node establishes preliminary connections with the target parent node while maintaining the source connection, preparing the dual-active state beforehand to ensure seamless transition and avoid service interruption during migration
2Reliability
If dual active protocol stack is implemented during migration, then transmission continuity is improved, but signaling overhead and processing complexity increase
Solution Approach 1:
The handover request and configuration messages are merged into a unified signaling flow. The source gNB-DU and target gNB-DU coordinate through the IAB-donor-CU to combine the handover preparation, execution, and completion signaling into an integrated process, reducing redundant signaling messages while supporting dual-active protocol stack operation
Solution Approach 2:
The IAB-donor-CU acts as an intermediary that coordinates the dual-active protocol stack activation between the source and target gNB-DUs. It manages the F1AP messaging and resource allocation, shielding the IAB-node from complex signaling interactions and reducing overall signaling overhead through centralized control
3Reliability
If simultaneous connection with source and target IAB-nodes is maintained, then mobility robustness is enhanced, but resource allocation complexity increases
Solution Approach 1:
The resource allocation is segmented into source-side resources and target-side resources, managed separately during the dual-active period. The IAB-node maintains distinct protocol instances for source and target connections, allowing independent resource management and reducing allocation complexity through modular, segmented resource handling
Solution Approach 2:
The protocol stack design enables universal resource management mechanisms that can handle both source and target connections through common procedures. The same resource allocation algorithms and management protocols are applied universally to both active connections, simplifying complexity through standardized multi-functional handling rather than separate specialized mechanisms
Data Source
AI summary
The present disclosure describes methods, systems, and devices for enhancing mobility robustness to integrated access and backhaul (IAB) for new radio (NR). One method includes enhancing mobility robustness of a migrating integrated access and backhaul-node (IAB-node) for NR during migration from a source IAB-donor-central unit (CU) to a target IAB-donor-CU by sending, by the source IAB-donor-CU, a handover request message to the target IAB-donor-CU, the handover request message comprising a dual active protocol stack (DAPS) request information. Another method includes enhancing mobility robustness of a migrating IAB-node for NR during migration from a source parent IAB-node to a target parent IAB-node by sending, by an IAB-donor-CU, a F1AP message to the migrating IAB-node, the F1AP message comprising a radio resource control re-configuration (RRCReconfiguration) message comprising a DAPS configuration information.