Base Station Handover Sequencing for NTN Cell Overlap

Solution Overview

Problem

Conventional technologies face increased signaling overhead and communication delays during simultaneous handovers of UEs from source to target NTN cells due to the movement of NTN coverage areas, leading to inefficient use of frequency and time resources.

Innovation Solution

A base station and terminal system that prioritizes handover commands and back-off instructions based on the distance of UEs from a reference position in the target cell, controlling handovers to occur in an ordered manner to minimize signaling overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If handover commands are transmitted to all terminals simultaneously, then all terminals can perform handover at the same time, but signaling overhead increases and frequency and time resources are wasted

Engineering Contradiction:

Improvehandover processing speedVSAvoidsignaling overhead

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent segments the terminal devices into multiple groups based on their distance from the target cell's reference position. Terminals are divided into first terminal devices (closer to target cell) and second terminal devices (farther from target cell), allowing handover commands to be transmitted in staged batches rather than simultaneously to all terminals, thereby reducing signaling overhead while maintaining efficient handover processing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different handover command transmission strategies to different groups of terminals based on their local characteristics (distance from reference position). Terminals closer to the target cell receive handover commands first, while terminals farther away receive commands later, creating a spatially differentiated handover process that reduces overall signaling overhead

Inventive Principle:

Principle #3Local quality

2Productivity

If handover commands are transmitted to all terminals simultaneously, then all terminals can perform handover at the same time, but communication delay increases

Engineering Contradiction:

Improvehandover processing speedVSAvoidcommunication delay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent segments the terminal devices into multiple groups based on their distance from the target cell's reference position. Terminals are divided into first terminal devices (closer to target cell) and second terminal devices (farther from target cell), allowing handover commands to be transmitted in staged batches rather than simultaneously to all terminals, thereby reducing signaling overhead while maintaining efficient handover processing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action by first identifying and classifying terminals based on their distance from the target cell reference position before transmitting handover commands. This pre-sorting of terminals into groups enables the system to send handover commands in an optimized sequence, reducing overall communication delay while maintaining efficient handover processing

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If handover commands are transmitted preferentially to terminals closer to the target cell, then signaling overhead is reduced, but terminals farther from the target cell may experience extended wait time

Engineering Contradiction:

Improvesignaling overheadVSAvoidhandover wait time

Core Design Contradiction:

Quantity of substanceVSDuration of action of moving object

Solution Approach 1:

The patent segments the terminal devices into multiple groups based on their distance from the target cell's reference position. Terminals are divided into first terminal devices (closer to target cell) and second terminal devices (farther from target cell), allowing handover commands to be transmitted in staged batches rather than simultaneously to all terminals, thereby reducing signaling overhead while maintaining efficient handover processing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic action by transmitting handover commands to different terminal groups at different time periods. First terminal devices receive handover commands in an initial transmission, while second terminal devices receive handover commands in a subsequent transmission after a predetermined time interval, creating a periodic handover command transmission pattern that balances signaling overhead reduction with fair wait time management

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS20260019911A1Base station and terminal

Publication Date: 2026.01.15 NTT DOCOMO INC

AI summary

A base station includes: a control unit that controls handovers of terminals, which are located in a first cell formed by a network located above a ground, to a second cell adjacent to the first cell; and a transmitting unit that transmits a handover command to the terminals, the handover command being transmitted preferentially to a terminal whose distance from a reference position in the second cell to the terminal is shorter than a threshold value.