Optimistic TCP Acknowledgment for Delay Reduction

Solution Overview

Problem

The TCP slow start algorithm is inefficient as it takes approximately log2N round trip times to reach the optimal congestion window, leading to delayed transmission and low network utilization, especially for small data transfers, and existing solutions require changes to TCP senders or routers, making them impractical for deployment.

Innovation Solution

A TCP receiver sends optimistic acknowledgment segments before receiving all data segments, assuming their successful receipt, and detects lost segments to request retransmissions, thereby increasing the transmission rate and reducing delay without modifying the sender or intermediate routers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the TCP slow start algorithm is used to determine transmission rate, then the transmission rate starts conservatively small and doubles every RTT, but this results in delayed transmission and low network utilization especially for small data transfers

Engineering Contradiction:

Improvetransmission reliabilityVSAvoiddelay time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The receiver sends optimistic ACK segments before actually receiving the data segments, assuming they will be successfully received. This preliminary acknowledgment allows the sender to increase its congestion window faster than the traditional slow start algorithm, reducing delay time while maintaining transmission reliability through subsequent loss detection and retransmission mechanisms

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback mechanism where the receiver monitors for lost data segments and requests retransmissions when losses are detected. This feedback loop maintains protocol reliability by correcting transmission errors while allowing the optimistic ACK mechanism to accelerate initial transmission rate determination

Inventive Principle:

Principle #23Feedback

2Reliability

If the TCP slow start algorithm is used to determine transmission rate, then the congestion window starts at less than 4KB and doubles every RTT, but this requires approximately log2N RTTs to reach the proper cwnd

Engineering Contradiction:

Improveprotocol reliabilityVSAvoidnetwork utilization rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The receiver sends optimistic ACK segments before actually receiving the data segments, assuming they will be successfully received. This preliminary acknowledgment allows the sender to increase its congestion window faster than the traditional slow start algorithm, reducing delay time while maintaining transmission reliability through subsequent loss detection and retransmission mechanisms

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback mechanism where the receiver monitors for lost data segments and requests retransmissions when losses are detected. This feedback loop maintains protocol reliability by correcting transmission errors while allowing the optimistic ACK mechanism to accelerate initial transmission rate determination

Inventive Principle:

Principle #23Feedback

3Productivity

If existing techniques are used to improve TCP slow start performance, then transmission efficiency may be improved, but these techniques require changes to TCP transmitter or intermediate router which makes deployment difficult

Engineering Contradiction:

Improvetransmission efficiencyVSAvoiddeployment ease

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

Instead of modifying the TCP sender or intermediate routers as in existing techniques, this invention inverts the approach by implementing the improvement at the TCP receiver side. The receiver sends optimistic acknowledgments and performs loss detection, achieving performance improvement without requiring changes to senders or network infrastructure, thus enabling easy deployment

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP3417585B1Terminal and communication method thereof

Publication Date: 2021.06.30 SAMSUNG ELECTRONICS CO LTD

Figure 1
Figure 2A~2B
Figure 2C

AI summary

The present disclosure relates to a terminal using and a communication method thereof. In the communication method, the terminal receives at least one data segment from a sender and transmits at least one acknowledgment (ACK) segment corresponding to the at least one data segment to the sender. In addition, the terminal transmits a predetermined number of optimistic ACK segments corresponding to data segments to be received to the sender. Other embodiments are also possible.