IAB Uplink Scheduling via Anticipatory Resource Grants
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Solution Overview
Problem
In integrated access backhaul (IAB) networks, conventional Buffer Status Report (BSR) mechanisms face challenges in multi-hop scenarios, leading to increased end-to-end latency and buffer buildup, which can result in packet drops and inadequate support for delay-sensitive services.
Innovation Solution
The proposed solution involves enhancing BSR mechanisms by allowing intermediate IAB nodes to send resource grants before receiving upstream grants, and incorporating hop count or time values to schedule UL transmissions, enabling more accurate buffer status reporting and reducing latency by anticipating data arrival times across multiple hops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional BSR mechanisms are used in multi-hop IAB networks, then network architecture is simple and easy to implement, but end-to-end latency increases and buffer buildup occurs leading to packet drops
Solution Approach 1:
The patent applies preliminary action by allowing intermediate IAB nodes to send resource grants to downstream nodes before receiving upstream grants from upstream nodes. This anticipatory scheduling based on hop count values prevents buffer buildup and reduces latency by proactively allocating resources before data arrives at intermediate nodes.
Solution Approach 2:
The patent segments the BSR mechanism by introducing hop count values that track the number of hops from the data source. This segmentation allows each intermediate node to independently make scheduling decisions based on its position in the multi-hop chain, reducing overall system latency while maintaining manageable complexity at each node.
2Productivity
If intermediate nodes wait for upstream grants before sending downstream grants, then resource allocation is conservative and buffer overflow is avoided, but scheduling delay increases and productivity decreases
Solution Approach 1:
The patent implements feedback mechanisms where intermediate nodes report buffer status and hop count information upstream, and use received grant information to make informed downstream scheduling decisions. This feedback loop enables efficient resource allocation while maintaining buffer management reliability through continuous monitoring and adjustment.
Solution Approach 2:
The patent changes the scheduling parameter from waiting for upstream grant confirmation to using hop count-based anticipatory scheduling. By modifying the scheduling decision parameter to include hop count values and expected data arrival times, the system achieves higher productivity while maintaining reliability through parameter-driven resource allocation.
3Loss of time
If resource grants are sent sequentially from upstream to downstream, then scheduling control is simple, but end-to-end latency increases due to waiting delays
Solution Approach 1:
The patent applies preliminary action by enabling intermediate IAB nodes to send resource grants downstream before receiving upstream grants. This reverses the traditional sequential scheduling flow and reduces scheduling delay by allowing parallel grant transmission based on hop count information and expected data arrival times.
Solution Approach 2:
The patent inverts the traditional upstream-to-downstream sequential scheduling approach by allowing intermediate nodes to send downstream grants before receiving upstream grants. This inversion of the scheduling control flow reduces end-to-end latency while managing complexity through hop count-based decision making.
Data Source
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AI summary
Embodiments include methods, performed by first node in an integrated access backhaul (IAB) network, for scheduling uplink (UL) transmissions in the IAB network. Such methods include receiving, from a first downstream node in the IAB network, a first buffer status report (BSR) indicating a first amount of UL data, with the first amount including UL data buffered at the first downstream node, and/or UL data expected to be received by the first downstream node. Such methods also include sending, to the first downstream node, a first UL resource grant indicating a time schedule of resources available for the first downstream node to transmit at least a portion of the first amount of UL data. In some embodiments, the first UL resource grant is sent after receiving the first BSR and without receiving a second UL resource grant from an upstream node in response to a second BSR.