IAB Uplink Flow Control Using Buffer Occupancy Feedback
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Solution Overview
Problem
Existing flow control mechanisms in integrated access and backhaul networks are inadequate in addressing uplink congestion, leading to buffer overflows and packet drops, particularly due to delayed reaction times and inefficient resource allocation.
Innovation Solution
Implementing a mechanism where buffer occupancy information is explicitly shared among IAB nodes to enable faster congestion awareness and proactive resource allocation, using projected buffer occupancy and buffer status reports to adjust uplink resources dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If implicit backpressure mechanism is used for uplink flow control, then buffer overflow risk is reduced locally, but congestion propagates slowly and buffer overflows occur at multiple nodes
Solution Approach 1:
The patent implements explicit feedback by having IAB nodes send buffer occupancy status messages to their parent nodes. This feedback mechanism allows parent nodes to be informed of buffer occupancy levels at child nodes and adjust uplink resource allocation accordingly, enabling faster congestion response compared to implicit backpressure.
Solution Approach 2:
The patent applies preliminary action by having nodes proactively report buffer occupancy status before actual buffer overflow occurs. The buffer occupancy status message is transmitted when the buffer reaches a predetermined occupancy level, allowing the system to take preventive measures and adjust resource allocation in advance.
2Reliability
If buffer occupancy status is shared explicitly among IAB nodes, then congestion awareness is improved, but device complexity increases
Solution Approach 1:
The patent segments the flow control functionality by introducing a dedicated BAP layer for handling buffer occupancy status messages separately from the main data transmission protocol. This segmentation allows the flow control mechanism to be implemented as a distinct module with specific responsibilities, making the overall system more manageable.
Solution Approach 2:
The patent uses buffer occupancy status messages as intermediary elements that carry congestion information between IAB nodes. These messages act as mediators that enable nodes to share buffer occupancy information without requiring complex direct coordination mechanisms, simplifying the overall system architecture.
3Productivity
If uplink resources are allocated without considering projected buffer occupancy, then resource allocation is simpler, but packet drops increase due to buffer overflows
Solution Approach 1:
The patent implements dynamic resource allocation by continuously adjusting uplink resource grants based on reported buffer occupancy status. The network dynamically modifies resource allocation decisions in response to changing buffer conditions, transitioning from static to dynamic resource management to prevent buffer overflows and improve packet delivery success.
Data Source
AI summary
Systems and methods provide flow control for uplink traffic in an integrated access and backhaul network. A first relay node determines that its uplink buffer has reached an occupancy level higher than a pre-determined level. In response, the first relay node transmits, to a second relay node associated with the first relay node, a message indicating a buffer occupancy status of the uplink buffer of the first relay node.