L4S Flow Scheduling via ECN-Based Queue Segmentation

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Solution Overview

Problem

In wireless shared media access scenarios, especially in densely populated environments, efficient scheduling of Low Latency, Low Loss, and Scalable throughput (LAS) traffic is challenging due to stochastic and unpredictable conditions, leading to buffer build-up and suboptimal performance.

Innovation Solution

The implementation of a system and method that includes a flow scheduling logic in devices to identify and schedule LAS data flows based on flow requirements and network Quality of Service (QOS) policies, using Explicit Congestion Notification (ECN) indicators and Stream Classification Service (SCS) requests to classify and enqueue data flows in LAS queues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If conventional scheduling is used in wireless shared media access scenarios, then device complexity is reduced, but latency increases and throughput decreases due to buffer build-up in densely populated environments

Engineering Contradiction:
ImprovelatencyVSAvoidscheduling complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent segments data flows into different priority queues based on ECN indicators and QoS policies. High-priority LAS traffic is separated from best-effort traffic, allowing differentiated handling that reduces latency for time-sensitive packets while managing overall network flow through multiple queues.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary classification of data flows by examining ECN indicators and QoS parameters before enqueueing packets. This advance identification and categorization enables optimal queue assignment from the outset, preventing latency accumulation rather than reacting to it later.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If ECN indicators and QoS policies are used to identify LAS traffic, then throughput and latency performance improves, but device complexity increases due to additional classification requirements

Engineering Contradiction:
ImprovethroughputVSAvoidclassification complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent leverages self-service mechanisms where ECN indicators in packet headers automatically provide congestion information without requiring separate signaling. The classification logic uses these pre-marked indicators along with QoS policies to identify LAS traffic, reducing the need for complex external control mechanisms.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent implements a universal classification mechanism that handles multiple traffic types and QoS requirements through a single ECN-based identification system. This multi-functional approach consolidates various classification needs into one unified process, managing complexity rather than increasing it.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Loss of time

If dual queue architecture is implemented for LAS traffic, then latency is reduced through priority scheduling, but device complexity increases due to additional queue management

Engineering Contradiction:
Improvequeuing latencyVSAvoidqueue management complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent applies local quality by providing different service qualities to different queues. The high-priority LAS queue receives expedited processing with minimal queuing delays, while the best-effort queue handles standard traffic. This localized optimization reduces latency for critical traffic without requiring complex management of the entire queue system.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements dynamic queue management where the scheduler adapts to changing network conditions and traffic patterns. Priority assignments and scheduling parameters can be adjusted based on real-time ECN indicators and QoS policy requirements, allowing the system to remain efficient under varying loads without fixed complex configurations.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS20250202827A1Identifying and Scheduling Low Latency, Low Loss, and Scalable Throughput (L4S) Data Flows
Publication Date: 2025.06.19 CISCO TECHNOLOGY INC
  • US20250202827A1 patent drawing
  • US20250202827A1 patent drawing
  • US20250202827A1 patent drawing

AI summary

Devices, networks, systems, methods, and processes for identifying, classifying, and scheduling Low Latency, Low Loss, and Scalable throughput (LAS) traffic are described herein. A device may receive a data flow comprising one or more data packets. The device may parse the one or more data packets to check for a congestion indicator. Upon detecting the congestion indicator in any data packet, the device can classify or mark the data flow as LAS. The device may schedule the data flow by utilizing an Active Queue Management (AQM) queue for L4S data flows. The device can also mark other uplink or downlink data flows associated with the data flow as L4S. The device can also facilitate LAS capability sharing while associating with one or more wireless devices. The device may utilize a management frame with an extended capabilities field to inform the LAS capability of the device.