Packet-Switched Call Initiation Delay During Network Handover

Solution Overview

Problem

During a network handover process in packet-switched networks, initiating a call simultaneously can result in the UE transmitting a call initiation message over the previous network, leading to call failures due to incomplete handover and mismatched network connections.

Innovation Solution

Implementing a delay in sending the call initiation message when a handover is detected, using a predetermined timer to ensure the handover process is complete or expired, allowing the message to be transmitted over the new network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the UE transmits the call initiation message immediately upon user input, then the call establishment speed is improved, but the call may fail due to incomplete handover and network mismatch

Engineering Contradiction:

Improvecall establishment speedVSAvoidcall establishment reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary detection of handover status before transmitting the call initiation message. The UE checks whether a handover process is ongoing or completed before proceeding with call setup, ensuring that the message is sent only when the network connection is stable and appropriate. This preliminary check prevents call failures caused by sending messages during incomplete handovers while minimizing delay by only waiting when necessary.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the UE delays the call initiation message to ensure handover completion, then the call establishment reliability is improved, but the call establishment time increases

Engineering Contradiction:

Improvecall establishment reliabilityVSAvoidcall establishment time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary detection of handover status before transmitting the call initiation message. The UE checks whether a handover process is ongoing or completed before proceeding with call setup, ensuring that the message is sent only when the network connection is stable and appropriate. This preliminary check prevents call failures caused by sending messages during incomplete handovers while minimizing delay by only waiting when necessary.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the timing of call initiation based on the actual handover status. Rather than using a fixed delay, the UE continuously monitors handover indicators and adapts its transmission timing accordingly. When handover is complete or not occurring, the message is sent immediately; when handover is in progress, the transmission is delayed until appropriate. This dynamic approach optimizes both reliability and timing.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12452748B2Call initiation delay to facilitate network handover

Publication Date: 2025.10.21 GOOGLE LLC

AI summary

A user equipment (UE) is configured to implement selective call initiation delay responsive to detection of a contemporaneous handover process. When a user provides input indicating initiation of a packet-switched call, the UE determines whether there is a handover process ongoing. If not, a call initiation message (e.g., a SIP INVITE message) is transmitted without further delay. However, if a handover process is ongoing at the time of the user input, the UE refrains from promptly transmitting the call initiation message and starts a timer of a predetermined duration to provide additional time for the handover process to complete. Responsive to the timer expiring or to the handover process completing before the timer expires, the UE then promptly transmits the call initiation message to initiate establishment of the packet-switched call over whatever network to which the UE is currently attached.