VoIP Call Setup Latency via TCP Keep Alive Synchronization

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Solution Overview

Problem

Current wireless communication systems, particularly in 5G NR, face challenges in improving Voice over Internet Protocol (VOIP) call setup success rates and latency due to issues like out-of-sync conditions between user equipment (UE) and the network, leading to repeated silent redials and delayed call setups.

Innovation Solution

Implementing a method where the UE actively sends a TCP keep alive message when transitioning from a circuit switched network to a packet switched network, re-establishes the TCP connection with an initial P-CSCF, tries alternative P-CSCFs, releases and re-establishes the IMS PDN connection to acquire new IP and P-CSCF addresses, thereby synchronizing the TCP connection status.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE attempts a mobile originated packet switched call across a packet switched network, then the call setup process initiates, but call setup latency increases and call setup success rate decreases when out-of-sync conditions occur between UE and the network

Engineering Contradiction:

Improvecall setup success rateVSAvoidcall setup latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The UE sends a TCP keep alive message before attempting the mobile originated packet switched call to proactively verify network connectivity and synchronize TCP connection status. This preliminary action prevents out-of-sync conditions that would otherwise cause call setup failures and repeated silent redials, thereby improving call setup success rate without adding significant latency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The TCP keep alive message mechanism provides feedback about the synchronization status of the TCP connection between UE and the network. By monitoring the response to keep alive messages, the UE can detect out-of-sync conditions and take corrective actions before initiating call setup, preventing failed call attempts and reducing overall call setup latency.

Inventive Principle:

Principle #23Feedback

2Reliability

If the UE performs silent redial via circuit switched network upon packet switched call failure, then call establishment may eventually succeed, but call setup latency increases due to repeated redial attempts

Engineering Contradiction:

Improvecall establishment successVSAvoidcall setup latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

By sending TCP keep alive messages before call setup, the UE proactively ensures TCP connection synchronization, preventing call setup failures that would trigger silent redial. This preliminary synchronization action eliminates the need for repeated redial attempts, reducing call setup latency while maintaining call establishment success.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potential harm of TCP connection desynchronization (which causes call failures and repeated redials) into a benefit by using TCP keep alive messages to detect and prevent desynchronization. This transforms a harmful out-of-sync condition into a detectable state that can be corrected before affecting call setup, thereby reducing latency while ensuring successful establishment.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of operation

If the UE maintains TCP connection without verification, then connection simplicity is maintained, but out-of-sync conditions cause repeated silent redials and delayed call setups

Engineering Contradiction:

Improveconnection simplicityVSAvoidcall setup success rate

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The TCP keep alive message mechanism introduces minimal feedback verification into the TCP connection maintenance process. This simple feedback loop allows the UE to verify connection synchronization status without complex procedures, maintaining ease of operation while preventing out-of-sync conditions that would otherwise reduce call setup success rate.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20240187458A1Improving voice over internet protocol (VOIP) call setup success rate and latency

Publication Date: 2024.06.06 QUALCOMM INC

AI summary

A method and apparatus improve Voice over Internet Protocol (VOIP) call setup success rate and latency. The method provides for attempting a mobile originated packet switched call, by a user equipment (UE), across a packet switched network with a transmission control protocol (TCP) connection of the Internet Protocol multimedia subsystem (IMS) session. A silent redial of the mobile originated packet switched call is performed in response to a failure of the mobile originated packet switched call, via a circuit switched network. A keep alive message is transmitted over the packet switched network after the circuit switched network call, which allows reconnection to the packet switched network.