NR IAB-Node DAPS Handover for Seamless Migration
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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 ensuring seamless transmission during inter-donor and intra-donor migrations.
Innovation Solution
Implementing a dual active protocol stack (DAPS) handover mechanism, where migrating IAB-nodes maintain simultaneous connections with both source and target nodes during the migration process, allowing for continuous data transmission through handover request messages and F1AP messages with DAPS configuration information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover mechanism is used for IAB-node migration, then the migration process is simpler to implement, but transmission continuity is disrupted and mobility robustness is reduced
Solution Approach 1:
The target IAB-donor-CU is pre-configured with routing information and path settings before the handover is executed. The F1AP message includes pre-established N3 tunnel endpoint information and BAP routing entries, allowing the target node to be ready to immediately continue data transmission without interruption when the handover occurs.
Solution Approach 2:
The patent maintains continuous data transmission during handover by establishing the F1-U tunnel and configuring BAP routing in advance. The user plane data flow continues uninterrupted through the pre-configured path from source IAB-node to target IAB-donor-CU, ensuring mobility robustness without transmission gaps.
2Reliability
If dual active protocol stack (DAPS) configuration is implemented, then mobility robustness is enhanced and transmission continuity is maintained, but the signaling overhead and message complexity increase
Solution Approach 1:
The F1AP message is designed to serve multiple functions simultaneously: it conveys handover command information, pre-configures routing paths, establishes N3 tunnel endpoints, and sets up BAP routing entries all in a single signaling exchange. This multi-functionality reduces the need for separate signaling messages for each configuration task.
Solution Approach 2:
The patent combines multiple configuration elements (routing information, N3 tunnel endpoints, BAP routing entries) into a single F1AP message structure. By merging these previously separate configuration steps into one unified signaling message, the overall signaling overhead is reduced while still achieving complete DAPS configuration.
3Reliability
If pre-configured routing information is used, then data transmission continuity is maintained during handover, but the initial setup complexity and memory requirements increase
Solution Approach 1:
The target IAB-donor-CU performs preliminary configuration of routing information, N3 tunnel endpoints, and BAP routing entries before the handover is executed. This advance preparation ensures that when data transmission needs to continue during handover, the path is already established and ready to carry traffic without interruption.
Data Source
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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.