Cell Handover Timing Windows to Reduce Target-Cell Congestion

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Solution Overview

Problem

In non-terrestrial network (NTN) systems, the terminal device faces challenges in determining the optimal timing to execute a cell handover without causing congestion by simultaneously accessing the target cell, as the handover command is often sent in advance and immediate connection establishment is not always necessary.

Innovation Solution

The terminal device determines a first time window for executing the cell handover based on a handover command, allowing it to establish a connection with the target cell within this window, thereby avoiding centralized access and reducing congestion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the terminal device executes cell handover immediately upon receiving the handover command, then the handover speed is improved, but congestion occurs at the target cell due to centralized access

Engineering Contradiction:

Improvehandover speedVSAvoidcongestion at target cell

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The terminal device receives the handover command in advance but does not execute the handover immediately. Instead, it performs preliminary preparation while continuing to communicate with the source cell, and only executes the handover when the first message is received or the first time window expires. This preliminary action approach avoids centralized access congestion while maintaining handover speed.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If the terminal device delays handover execution, then congestion at the target cell is reduced, but the handover timing becomes less precise

Engineering Contradiction:

Improvecongestion at target cellVSAvoidhandover timing precision

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The handover execution timing is made dynamic rather than fixed. The terminal device determines the handover execution time based on receiving the first message from the target cell or based on the first time window, whichever occurs first. This dynamic approach maintains timing precision while avoiding congestion.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the terminal device continues communicating with the source cell after receiving the handover command, then communication continuity is improved, but the handover execution is delayed

Engineering Contradiction:

Improvecommunication continuityVSAvoidhandover execution delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The terminal device maintains continuous communication with the source cell after receiving the handover command by sending and receiving messages during the preparation phase. This continuity of useful action ensures communication reliability while the handover is being prepared, and the handover executes promptly when conditions are met.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS20250317824A1Cell handover method, terminal device and network device

Publication Date: 2025.10.09 QUECTEL WIRELESS SOLUTIONS CO LTD

AI summary

The present application provides a cell handover method, a terminal device and a network device. One example method comprises: receiving, by a terminal device, a handover command sent by a source network device, wherein the handover command indicates that the terminal device can switch from a source cell corresponding to the source network device to a first time window of a target cell corresponding to a target network device; and performing, by the terminal device, cell handover according to the first time window.