TCP Congestion Window Adjustment for Bandwidth Utilization

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Solution Overview

Problem

Current TCP congestion control algorithms, such as Reno and CUBIC, face challenges in effectively utilizing network bandwidth and adjusting to actual network conditions, leading to suboptimal throughput and prolonged recovery times during congestion.

Innovation Solution

A method and apparatus that dynamically adjust the congestion window based on expected throughput and current network conditions, using a first congestion window determined by target throughput and round-trip time to control TCP data packet sending, allowing for more efficient bandwidth utilization and improved throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the congestion window size is increased to improve throughput, then the data sending rate increases, but the possibility of network congestion increases

Engineering Contradiction:
ImprovethroughputVSAvoidnetwork congestion probability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent implements dynamic adjustment of the congestion window size based on real-time network conditions. The sending device continuously monitors network state parameters (such as RTT variations, packet loss rates, and throughput changes) and adapts the congestion window size accordingly, transitioning between different growth phases (linear, exponential, quadratic) to optimize throughput while preventing congestion.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs feedback mechanisms where the sending device receives acknowledgments from the receiving device and uses this information to adjust the congestion window. The system monitors network response metrics and feeds this information back into the congestion control algorithm, enabling continuous optimization of the window size based on actual network performance and congestion indicators.

Inventive Principle:
Principle #23Feedback

2Reliability

If the congestion window size is decreased to prevent network congestion, then the data sending rate decreases, but the throughput is reduced

Engineering Contradiction:
Improvenetwork congestion preventionVSAvoidthroughput
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts the congestion window size based on real-time network conditions rather than using a fixed conservative value. By monitoring network state parameters and adapting the window size accordingly, the system can prevent congestion when necessary while maximizing throughput when network conditions permit, thus resolving the trade-off between safety and performance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the growth rate and phase of the congestion window based on network conditions. The system transitions between different mathematical growth models (linear, exponential, quadratic) and adjusts key parameters such as the growth rate coefficient based on monitored network metrics, allowing optimal throughput while maintaining congestion prevention.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If traditional congestion control algorithms (Reno, CUBIC) are used to adjust the congestion window, then the network can maintain stability, but the throughput cannot meet high-throughput application requirements

Engineering Contradiction:
Improvenetwork stabilityVSAvoidthroughput
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent combines multiple congestion control strategies and mathematical growth models into a composite algorithm. It integrates elements of traditional algorithms with novel phased growth approaches (linear, exponential, quadratic phases) and adapts the combination based on network conditions, achieving both stability and high throughput performance required by modern applications.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The system dynamically selects and transitions between different congestion window growth phases and mathematical models based on real-time network conditions. This dynamic adaptation allows the system to maintain stability through controlled growth while achieving high throughput when network capacity permits, surpassing the performance of static traditional algorithms.

Inventive Principle:
Principle #15Dynamics

4Reliability

If the congestion window recovers slowly after packet loss to ensure stability, then network stability is maintained, but the recovery time is prolonged

Engineering Contradiction:
Improvenetwork stabilityVSAvoidrecovery time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements periodic monitoring of network conditions and phased recovery strategies. After packet loss, the system enters a recovery phase where it periodically assesses network state and progressively increases the congestion window through defined phases, balancing stability requirements with the need for rapid recovery to minimize time loss.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the recovery rate based on current network conditions. Rather than using a fixed slow recovery rate, the system monitors network responsiveness and adapts the window increase rate during recovery, enabling faster recovery when network conditions permit while maintaining stability when conditions are marginal, thus reducing overall recovery time.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3255847B1Transmission control protocol data packet transmission method, transmission device and system
Publication Date: 2020.08.05 HUAWEI TECH CO LTD
  • EP3255847B1 patent drawingFigure 1A~1C
  • EP3255847B1 patent drawingFigure 2
  • EP3255847B1 patent drawingFigure 3~4

AI summary

Embodiments of the present invention disclose a method and an apparatus for sending a Transmission Control Protocol TCP data packet and a system. The sending method includes: obtaining a first round-trip time of sending a TCP data packet in a network, and determining a second round-trip time; if the first round-trip time is longer than the second round-trip time, using a congestion window determined according to a first algorithm as a first congestion window; or if the first round-trip time is shorter than or equal to the second round-trip time, using a congestion window determined according to a second algorithm as the first congestion window; and sending the TCP data packet by using the first congestion window. In the technical solution disclosed in the present invention, a current congestion window that exists when a first round-trip time is obtained grows to a first congestion window at one go, so that a requirement of a service for a throughput can be better met, and a network bandwidth can be utilized more effectively.