IAB Node End-to-End Flow Control via Donor Signaling
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Solution Overview
Problem
In integrated access and backhaul (IAB) systems, congestion and overload issues arise due to multi-hop backhauling and multi-connectivity, making it difficult to implement effective end-to-end flow control, especially in scenarios where intermediate IAB nodes lack information about congestion associated with specific data radio bearers or parent nodes.
Innovation Solution
The implementation of enhanced DDDS and gNB-DU status indication messages that allow IAB nodes to report congestion through F1 signaling, using identifiers for RLC channels, logical channels, parent nodes, and child nodes, enabling the donor node to take corrective actions such as reducing data rates to alleviate congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multi-hop backhauling and multi-connectivity are implemented in IAB systems, then coverage area and network flexibility are improved, but congestion and overload issues arise that make flow control difficult
Solution Approach 1:
The patent segments the flow control function by introducing separate congestion indication messages for different congestion types (RLC channel congestion and parent node congestion). This allows the system to handle congestion at different levels independently, reducing the overall complexity of flow control in multi-hop backhauling networks while maintaining extended coverage capability
2Reliability
If intermediate IAB nodes report congestion to parent nodes, then local congestion can be addressed, but end-to-end flow control cannot be implemented effectively
Solution Approach 1:
The patent implements feedback mechanisms where intermediate IAB nodes send congestion indication messages directly to the donor node, providing end-to-end congestion information. The donor node receives these feedback messages and can make informed flow control decisions, preventing information loss that would occur if congestion reports were only forwarded through intermediate parent nodes
Solution Approach 2:
The patent introduces the donor node as an intermediary that receives congestion information from intermediate IAB nodes and coordinates the overall flow control. This intermediary role allows the donor node to aggregate congestion information from multiple sources and implement end-to-end flow control without requiring intermediate nodes to maintain complex state information
3Adaptability or versatility
If IAB nodes have multiple parent nodes or child nodes, then network versatility is improved, but difficulty in detecting and measuring congestion increases
Solution Approach 1:
The patent applies local quality by creating specific congestion indication messages tailored to different congestion scenarios (RLC channel congestion vs. parent node congestion). Each message type contains targeted information about the specific congestion location and cause, making it easier to detect and measure congestion in multi-parent and multi-child node configurations without overwhelming complexity
Data Source
AI summary
Embodiments of the present disclosure relate to methods and apparatuses for end-to-end flow control. According to an embodiment of the present disclosure, a method includes: determining whether congestion happens at an IAB node; and transmitting a message to a donor node in response to determining that the congestion happens at the IAB node, wherein the message comprises at least one of: (1) a first message indicating the congestion associated with a radio link control channel; or (2) a second message indicating the congestion associated with a parent node of the IAB node.