Integrated Access and Backhaul Reversed Scheduling for Timing Alignment

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Solution Overview

Problem

Existing IAB networks face challenges with misaligned transmit/receive timing, inefficient scheduling, and power imbalance due to strict hierarchical scheduling strategies, particularly in high-frequency TDD systems, leading to inefficiencies and limitations in data transmission.

Innovation Solution

Implementing a symmetric, reversed scheduling approach where each IAB link adheres to downlink slots in a TDD system, allowing co-scheduling of upstream data with downlink data and reducing the need for strict hierarchical scheduling, thereby aligning timing and reducing transmission delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If strict hierarchical scheduling is implemented in IAB networks, then scheduling control is simplified, but transmit/receive timing alignment deteriorates and transmission efficiency decreases

Engineering Contradiction:
Improvescheduling control complexityVSAvoidtransmission delay
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The patent inverts the traditional hierarchical scheduling approach by allowing child IAB nodes to autonomously schedule upstream backhaul transmissions instead of being strictly controlled by parent nodes. This inversion enables each IAB node to independently manage its transmit/receive timing, achieving timing alignment without complex hierarchical coordination, thereby reducing transmission delays while maintaining scheduling simplicity.

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If parent nodes schedule all upstream backhaul data, then centralized control is maintained, but scheduling efficiency and resource utilization deteriorate

Engineering Contradiction:
Improvecontrol consistencyVSAvoidscheduling efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent enables child IAB nodes to autonomously schedule their own upstream backhaul transmissions based on local buffer status and channel conditions. This self-service approach eliminates the need for parent nodes to centrally schedule all upstream traffic, significantly improving scheduling efficiency and resource utilization while maintaining control consistency through standardized protocols and timing alignment mechanisms.

Inventive Principle:
Principle #25Self-service

3Stability of the object's composition

If TDD patterns are strictly followed for uplink scheduling, then channel structure is maintained, but timing alignment between parent and child nodes deteriorates

Engineering Contradiction:
Improvechannel structure stabilityVSAvoidtiming alignment precision
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent introduces dynamic timing adjustment mechanisms that allow child IAB nodes to flexibly adapt their transmit timing while maintaining TDD channel structure. By dynamically adjusting timing based on propagation delay and synchronization requirements, the system maintains both TDD pattern stability and precise timing alignment between parent and child nodes, resolving the contradiction between structural integrity and synchronization precision.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3915319B1Integrated access and backhaul with reversed scheduling
Publication Date: 2025.07.23 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3915319B1 patent drawingFigure 1
  • EP3915319B1 patent drawingFigure 2
  • EP3915319B1 patent drawingFigure 3

AI summary

There is provided mechanisms for performing IAB in a cellular telecommunications network that comprises a first IAB node and a second IAB node. A method is performed by the first IAB node. The method comprises scheduling, in a first phase, downstream backhaul data from the first IAB node to the second IAB node. The method comprises receiving, in a third phase, from the second IAB node, upstream backhaul data as scheduled by the second IAB node.