IAB Node Inter-CU Handover Latency Reduction
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Solution Overview
Problem
Current wireless communication systems face challenges in managing mobility and reducing latency during inter-central unit (CU) handover in integrated access and backhaul (IAB) nodes, leading to unnecessary control signaling and service disruptions.
Innovation Solution
A method is introduced where a first gNodeB-CU transmits handover information to lower nodes, identifies nodes for intra-CU and inter-CU handover, and supports handover to a second gNB-CU, while the second gNB-CU performs radio resource control (RRC) re-establishment, optimizing the handover process to reduce latency and signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional handover procedures are used for IAB nodes during inter-CU handover, then handover can be performed, but latency in providing network services to lower nodes increases and unnecessary control signaling occurs
Solution Approach 1:
The source CU performs preliminary actions by identifying which lower nodes should perform intra-CU handover and which should perform inter-CU handover before the IAB node actually hands over. This advance preparation allows the target CU to immediately activate pre-configured lower nodes, eliminating service interruption latency and reducing the need for post-handover control signaling.
Solution Approach 2:
The handover process is segmented by classifying lower nodes into two distinct groups: those performing intra-CU handover and those performing inter-CU handover. This segmentation allows different handover procedures to be applied to different lower nodes simultaneously, optimizing the overall handover process by handling each group according to its specific requirements.
2Reliability
If all lower nodes perform inter-CU handover when IAB node performs inter-CU handover, then handover consistency is maintained, but control signaling overhead increases unnecessarily
Solution Approach 1:
Different handover approaches are applied to different lower nodes based on their local conditions and relationships with the IAB node. Lower nodes that can maintain connection with the source CU perform intra-CU handover, while others perform inter-CU handover. This localized differentiation maintains overall handover consistency while minimizing unnecessary control signaling for nodes that don't require full inter-CU procedures.
3Device complexity
If handover information is not transmitted to lower nodes in advance, then signaling overhead is reduced, but service latency during handover increases
Solution Approach 1:
Handover information is transmitted to lower nodes in advance of the actual IAB node handover. The source CU provides target CU information and handover parameters to lower nodes beforehand, enabling them to prepare their handover procedures. This preliminary information transmission occurs efficiently without causing significant overhead, as it is done during normal operation periods rather than during critical handover transitions.
Data Source
AI summary
The present disclosure relates to a communication system for supporting a high data transfer rate. An embodiment of the present disclosure provides a method, performed by a first gNodeB (gNB)-central unit (CU), of supporting an integrated access and backhaul (IAB) node in performing handover to a second gNB-CU in a wireless communication system. The method includes transmitting handover information to at least one lower node connected to the IAB node, the handover information being determined based on a measurement report for handover of the IAB node, transmitting a handover request message including the handover information of the IAB node to the second gNB-CU, receiving context information from the at least one lower node, based on the context information, identifying, as a first class, a lower node to perform intra-CU handover, and identifying, as a second class, a lower node to perform inter-CU handover from among the at least one lower node, supporting intra-CU handover of the lower node identified as the first class, and supporting inter-CU handover of the IAB node to the second gNB-CU, based on the handover information of the IAB node and a handover acceptance message of the IAB node which is received from the second gNB-CU.