IAB UE Handover with Air Interface Continuity
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Solution Overview
Problem
The challenge of efficiently handling user equipment (UE) handover in integrated access and backhaul (IAB) networks, particularly in high-frequency scenarios with limited coverage and multi-hop connectivity, where maintaining reliable communication during handover is critical.
Innovation Solution
A method and apparatus for UE handover that includes maintaining an air interface between the UE and a wireless network node during the handover process, utilizing a simplified handover procedure that avoids MAC entity resets, RLC entity reestablishment, and random access, facilitated by RRC reconfiguration messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional handover procedure is performed in IAB network, then the UE can be handed over from first BS to second BS, but the communication between UE and wireless network node is interrupted during handover
Solution Approach 1:
The patent segments the handover process into two independent parts: (1) control plane handover between BSs for the wireless network node, and (2) data plane continuity maintenance through preserving the air interface between UE and wireless network node. This segmentation allows the control plane to perform handover while the data plane maintains uninterrupted communication, resolving the contradiction between handover completion and communication reliability.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the air interface resources between UE and wireless network node before the handover is executed. The RRC reconfiguration message is prepared in advance with instructions to maintain the air interface, ensuring that communication continuity is established before the actual handover occurs, thereby minimizing interruption time.
2Productivity
If traditional handover procedure is used, then handover from first BS to second BS is completed, but MAC entity reset and RLC entity reestablishment are required
Solution Approach 1:
The patent extracts and removes the MAC entity reset and RLC entity reestablishment steps from the traditional handover procedure. By taking out these complex reconfiguration actions, the handover process is simplified to only require RRC reconfiguration message exchange, thereby reducing device complexity while maintaining handover speed.
Solution Approach 2:
Instead of following the traditional sequence where handover triggers MAC reset and RLC reestablishment, the patent inverts the approach by maintaining the air interface throughout handover. This inversion eliminates the need for lower layer reconfigurations, simplifying the procedure while achieving fast handover.
3Reliability
If full handover reconfiguration is performed, then handover completeness is ensured, but UE performance is significantly impacted during transition
Solution Approach 1:
The patent applies local quality by selectively maintaining the air interface quality between UE and wireless network node during handover, while allowing the control plane to perform necessary handover functions. This localized preservation of communication quality ensures handover completeness at the control plane level while maintaining high UE performance at the data plane level.
Data Source
AI summary
Embodiments of the present disclosure relate to method and apparatus for handing over a UE in an IAB network. According to some embodiments of the disclosure, a UE may: communicate with a first BS via a wireless network node; receive an RRC reconfiguration message for handing over the UE from the first BS to a second BS together with the wireless network node; and in response to receiving the RRC reconfiguration message, maintain an air interface between the UE and the wireless network node while performing the handover from the first BS to the second BS.