IAB RRC Connection Update for Inter-Donor Backhaul Handover
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Solution Overview
Problem
Existing wireless communication systems face challenges with radio link failures and unfavorable conditions on wireless backhaul links, particularly in integrated access and backhaul (IAB) networks, which affect data rates and link reliability.
Innovation Solution
The implementation of an IAB node with processor and transmitter circuitry to manage RRC connections, including re-establishment indications and context transfers, to handle radio link failures and facilitate seamless transitions to new donor nodes, ensuring robust communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an IAB node performs RRC connection update to a new donor node, then network connectivity is improved, but radio link failure risk increases during the transition
Solution Approach 1:
The source donor node transfers the RRC context to the target donor node before the IAB node actually switches connections. This preliminary context transfer ensures that the target donor is fully prepared with all necessary information (security parameters, bearer configurations, etc.) before the handover executes, minimizing the risk of radio link failure during the transition.
Solution Approach 2:
The source donor node acts as an intermediary that coordinates the entire handover process. It initiates the context transfer, selects the target donor, and manages the timing of the connection switch. This intermediary role ensures a controlled and supervised transition rather than a direct IAB-to-target-donor connection, reducing failure risk.
2Reliability
If the IAB node switches to a new donor node, then link quality is improved, but service interruption occurs during re-establishment
Solution Approach 1:
The RRC context is transferred in advance from the source donor to the target donor before the IAB node actually switches connections. This preliminary preparation includes all security parameters, bearer configurations, and node identifiers, so that when the handover executes, the IAB node can immediately establish connectivity without time-consuming setup procedures at the target donor.
Solution Approach 2:
The handover process is designed to maintain continuous useful action by ensuring the target donor is fully prepared before the switch. The context transfer completes beforehand, and the IAB node seamlessly switches to the new donor with all parameters already in place, minimizing the interruption window and maintaining near-continuous service.
3Area of stationary object
If the IAB node performs inter-donor handover, then coverage area is expanded, but signaling overhead increases
Solution Approach 1:
The handover signaling is merged into the existing RRC connection management framework. The context transfer uses standardized RRC messages that the IAB node and donor nodes already exchange for other purposes, rather than introducing entirely new signaling protocols. This consolidation reduces the total signaling overhead while enabling inter-donor handover functionality.
Solution Approach 2:
The RRC context structure is designed to be universal and multi-functional, containing all necessary information (security parameters, bearer configurations, node identifiers) that can serve multiple purposes: initial connection setup, handover execution, and connection re-establishment. This universality means the same signaling framework handles multiple scenarios, reducing overall signaling overhead.
4Reliability
If the IAB node maintains RRC connection with multiple donor nodes, then network robustness is improved, but device complexity increases
Solution Approach 1:
The IAB node's donor connection is made dynamic rather than static. The node can actively switch between donor nodes based on radio conditions, and the system supports seamless transitions. This dynamic capability provides robustness (if one donor fails, another can take over) while the standardized handover procedures keep the management complexity manageable through automation rather than requiring complex multi-connection protocols.
Data Source
AI summary
An IAB node communicates over at least two radio interfaces including a first interface and a second interface, the first interface being configured to establish a radio resource control (RRC) connection with a donor node, the second interface being configured to serve one or more cells to communicate with one or more child nodes. In an example embodiment and mode the IAB node comprises processor circuitry and transmitter circuitry. The processor circuitry is configured to establish an RRC connection with a first donor node, and perform an update of the RRC connection to be used for a second donor node. The transmitter circuitry is configured to transmit, using the second interface, a re-establishment indication, upon performing the update of the RRC connection. The re-establishment indication is used to request that each of the one or more child nodes initiate an RRC re-establishment procedure. During the RRC re-establishment procedure, the one or more cells are considered as candidate cells.