IAB Handover IP Context Updates for Low-Latency F1 Communication
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Solution Overview
Problem
F1 interface reestablishment in IAB networks causes significant service latency and signaling overheads during topology updates, affecting terminal performance.
Innovation Solution
The IAB node obtains an IP address and updates control plane context information based on this address to maintain communication with the CU of the IAB donor, thereby avoiding the need for F1 interface reestablishment and reducing service latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If F1 interface reestablishment is performed during IAB topology update, then connection reliability is improved, but service latency increases significantly and signaling overheads become enormous
Solution Approach 1:
The patent applies preliminary action by pre-establishing the F1 interface context and control plane context before the handover occurs. The target DU is pre-configured with the necessary context information, so that when handover happens, the F1 interface can be immediately activated without requiring full reestablishment, thus reducing service latency while maintaining connection reliability
Solution Approach 2:
The patent implements dynamics by making the F1 interface context establishment process adaptive to handover scenarios. Instead of a static reestablishment procedure, the system dynamically determines whether full reestablishment is needed or if context transfer suffices, allowing the protocol to flex between these modes based on whether the IAB donor CU remains the same, thereby optimizing the balance between reliability and latency
2Reliability
If F1 interface reestablishment is performed during IAB topology update, then connection reliability is improved, but signaling overheads increase enormously
Solution Approach 1:
The patent extracts the essential context information (control plane context, F1 interface parameters) from the source DU and transfers it directly to the target DU, separating the necessary context transfer from the full F1 interface reestablishment procedure. This extraction approach eliminates redundant signaling messages while ensuring all critical information is preserved, thus reducing signaling overheads while maintaining connection reliability
Solution Approach 2:
The patent applies discarding and recovering by selectively discarding the F1 interface reestablishment procedure when context transfer is sufficient, while recovering and reusing the existing control plane context information. This avoids generating new signaling overheads for information that can be directly transferred and reused, thereby reducing signaling load while maintaining reliability
3Loss of time
If F1 interface reestablishment is avoided during IAB topology update, then service latency is reduced, but connection reliability may be compromised
Solution Approach 1:
The patent applies preliminary action by pre-establishing the F1 interface context and control plane context before the handover occurs. The target DU is pre-configured with the necessary context information, so that when handover happens, the F1 interface can be immediately activated without requiring full reestablishment, thus reducing service latency while maintaining connection reliability
Solution Approach 2:
The patent implements feedback mechanisms where the source DU provides the target DU with the F1 interface context and control plane context information during the handover preparation phase. This feedback ensures that the target DU receives accurate and complete information, maintaining connection reliability while avoiding the need for full reestablishment and reducing service latency
Data Source
AI summary
A communication method includes a first IAB node receives a first message from a CU of an IAB donor, where the first message indicates the first IAB node to be handed over from a first parent node to a second parent node, and the first message includes a first IP address of the first IAB node. The first IAB node determines first transport network layer association information between the first IAB node and the CU of the IAB donor based on the first IP address. The first IAB node updates control plane context information of an F1 interface by using the first transport network layer association information, where the F1 interface is an interface between the first IAB node and CU of the IAB donor. An IAB node communicates with a CU of an IAB donor by using a first IP address as soon as possible after handover is completed.