ACK Delay Control for Fair Network Congestion Allocation

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Solution Overview

Problem

Traditional loss-based and delay-based congestion control protocols suffer from RTT unfairness and buffer-bloat, leading to inefficient bandwidth allocation and exploitation by receivers artificially delaying acknowledgements.

Innovation Solution

Implementing a controlled delay mechanism on acknowledgement messages to adjust the round-trip time based on a propagation delay goal, thwarting unfair bandwidth gains by detecting and mitigating large artificial delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If delay-based congestion control protocols are used, then bandwidth utilization is improved, but RTT unfairness occurs where longer RTT flows receive more bandwidth

Engineering Contradiction:

Improvebandwidth utilizationVSAvoidbandwidth allocation fairness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the parameter used for congestion control from total RTT to one-way propagation delay. By measuring only the forward path delay (not including acknowledgment processing and return trip), the system eliminates the RTT unfairness where longer RTT flows received more bandwidth, while maintaining high bandwidth utilization through delay-based control.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If receivers artificially delay acknowledgements, then their bandwidth share increases, but this exploits the delay-based mechanism unfairly

Engineering Contradiction:

Improvebandwidth shareVSAvoidmechanism integrity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent extracts the acknowledgment message from the congestion control measurement process. By measuring propagation delay only on forward-path packets (not on acknowledgments), the system removes the ability of receivers to manipulate their bandwidth share through acknowledgment delay, as the return trip time is no longer included in the measurement.

Inventive Principle:

Principle #2Taking out (Extraction)

3Device complexity

If traditional loss-based congestion control is used, then implementation is simple, but RTT unfairness and buffer-bloat occur

Engineering Contradiction:

Improveprotocol complexityVSAvoidbandwidth allocation fairness

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent substitutes loss-based congestion control signals with delay-based measurements. Instead of using packet loss events (which are coarse and cause buffer-bloat), the system uses precise one-way propagation delay measurements to control congestion, achieving both fairness and efficiency while maintaining relatively simple implementation through standard timestamping mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20250373562A1Systems, methods, and media for implementing network congestion control

Publication Date: 2025.12.04 THE TRUSTEES OF COLUMBIA UNIV IN THE CITY OF NEW YORK

AI summary

Mechanisms, including systems, methods, and media, for implementing network congestion control are provided, the methods including: imposing a delay on traffic on a connection between a sender and a receiver; determining a minimum round-trip time for traffic on the connection with the delay imposed; and adjusting the delay imposed on the traffic to an adjusted delay based on a minimum propagation delay goal and the round-trip time. In some of these embodiments, the methods further comprise setting an initial value of the delay to the propagation delay goal. In some of these embodiments, the delay is imposed on an acknowledgment message that is part of the traffic. In some of these embodiments, the adjusted delay is equal to the propagation delay goal minus the minimum round-trip time minus the delay.