Group Mobility Mobile Station for Train Wireless Offloading

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Solution Overview

Problem

In conventional radio communication systems, the performance degrades due to control signals and inter-terminal interference when multiple terminals within a moving object, such as a train or bus, communicate individually with radio base stations, especially when the object crosses cell boundaries.

Innovation Solution

A radio communication system with a dedicated GM mobile station and GM base station that uses MIMO and beam forming to relay communications between user terminals and macro/small base stations, offloading communications to reduce load and improve system performance without modifying user terminals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If each terminal communicates individually with radio base stations, then terminal autonomy and communication flexibility are maintained, but system performance degrades due to control signal overhead and inter-terminal interference

Engineering Contradiction:
Improveterminal autonomyVSAvoidsystem performance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent merges multiple terminals into a single group mobility terminal that communicates with the base station on behalf of the entire group. This consolidation reduces control signal overhead and eliminates inter-terminal interference while maintaining communication flexibility through the group terminal's autonomous operation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The group mobility terminal acts as an intermediary between the base station and multiple user terminals. It receives and processes control signals from the base station, then distributes appropriate signals to individual terminals, thereby reducing the overall control overhead on the network while maintaining terminal autonomy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Area of stationary object

If terminals communicate individually through base stations, then communication coverage is extended, but performance degrades remarkably when the moving object passes through cell boundaries

Engineering Contradiction:
Improvecommunication coverageVSAvoidsystem performance during handover
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

By consolidating multiple terminals into a single group mobility terminal, the patent reduces the number of simultaneous handover operations when passing through cell boundaries. This merging approach minimizes handover-related performance degradation while maintaining extended coverage through the group terminal's mobile station functionality.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a dedicated GM mobile station and GM base station are introduced to improve system performance, then control overhead and interference are reduced, but device complexity increases

Engineering Contradiction:
Improvesystem performanceVSAvoidsystem architecture
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The group mobility terminal is designed with multi-functionality, serving both as a regular user terminal and as a base station for other terminals within the moving object. This universal design reduces the need for separate dedicated GM equipment, thereby limiting the increase in device complexity while maintaining improved system performance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enhances communication stability and throughput by reducing overhead and interference, maintaining system performance even during handovers and fast channel variations, thereby stabilizing the network.

Implementation Method 1

uses MIMO and beam forming to relay communications

Methodology Applied
Scientific EffectMIMO (Multiple Input Multiple Output):

Implementation Method 2

uses MIMO and beam forming to relay communications

Methodology Applied
Scientific EffectBeam forming:

Data Source

PatentEP3057378B1Wireless communications system, wireless mobile station, and wireless base station
Publication Date: 2020.03.11 NTT DOCOMO INC
  • EP3057378B1 patent drawingFigure 1
  • EP3057378B1 patent drawingFigure 2
  • EP3057378B1 patent drawingFigure 3

AI summary

To improve system performance for mobile communications (group mobility) in a plurality of terminals existing inside the same moving object, a radio communication system of the present invention is a radio communication system for mobile communications in a plurality of user terminals existing in a moving object, and has a radio base station for forming a cell on a moving path of the moving object, and a radio mobile station installed in the moving object to relay communications between the plurality of user terminals and the radio base station. By this means, by offloading communications according to user terminals inside the moving object by the dedicated system for group mobility, it is possible to reduce the load on the existing radio communication system, and it is possible to improve system performance of the entire radio communication system.