TCP Packet Delay for Handover Outage Adaptation

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Solution Overview

Problem

TCP sessions in cellular networks experience interruptions due to handover outages, leading to timeouts and unsatisfactory performance, as handover outages prevent timely transmission of TCP packets and acknowledgments, resulting in increased round trip times and retransmission timeouts.

Innovation Solution

A network node delays TCP packet transfer before a handover outage to increase the round trip time, allowing the retransmission timeout to be adapted for the handover duration, thereby reducing timeouts and improving throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If TCP packets are transmitted normally during handover, then data transfer continues without deliberate delay, but TCP timeouts occur due to handover outage preventing timely acknowledgment receipt

Engineering Contradiction:

ImproveTCP connection reliabilityVSAvoidhandover outage duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The network node performs preliminary actions by delaying TCP packet transmission before the handover outage occurs. This preliminary delay ensures that the TCP retransmission timeout is extended to accommodate the upcoming handover outage, preventing TCP timeouts and maintaining connection reliability during the handover process.

Inventive Principle:

Principle #10Preliminary action

2Speed

If retransmission timeout is kept short for normal operation, then TCP responsiveness is improved, but TCP timeouts occur during handover outages

Engineering Contradiction:

ImproveTCP responsivenessVSAvoidTCP connection stability during handover

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system dynamically adjusts the retransmission timeout based on the network state. During normal operation, the timeout remains short for fast responsiveness. When a handover outage is detected, the network node delays TCP packet transmission to extend the effective timeout period, adapting to the changing conditions and maintaining connection stability without sacrificing normal responsiveness.

Inventive Principle:

Principle #15Dynamics

3Reliability

If TCP packets are delayed before handover, then round trip time increases allowing timeout adaptation, but immediate data transfer is slowed

Engineering Contradiction:

ImproveTCP timeout adaptationVSAvoiddata transfer rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The network node applies preliminary anti-action by deliberately delaying TCP packet transmission before the handover outage. This counterintuitive delay increases the round trip time, which allows the TCP retransmission timeout to be extended and adapted for the handover duration, preventing TCP timeouts and maintaining overall data transfer productivity despite the temporary delay.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS9788362B2Methods and arrangements for improving transmission control protocol performance in a cellular network

Publication Date: 2017.10.10 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method in a network node for improving transmission control protocol, TCP, performance in a cellular network is provided. The network node handles TCP packet transferral between a user equipment and a server in the cellular network. The user equipment and the server are configured to adapt a retransmission timeout setting based on round trip times for performed TCP packet transferrals. When the network node obtains an indication of a handover outage being upcoming for the user equipment, the network node deliberately delays, in a time period preceding the indicated handover outage, a transferal of a TCP packet between the server and the user equipment to increase the round trip time for the TCP packet.