Coordinator Handover in Wireless Ad-Hoc Networks

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Solution Overview

Problem

Existing wireless ad-hoc networks for portable devices, such as game consoles, lack the ability to efficiently manage network joining and exiting, station disappearance detection, and coordinator function changes, especially in real-time applications requiring low latency and high-speed data communication.

Innovation Solution

A communication terminal device and system that includes a transmission unit, reception unit, and control unit capable of transmitting and receiving communication parameters, allowing for network control and responding to different communication parameters, enabling functions like mid-game join, exit, and coordinator function changes through autonomous power saving and collision avoidance modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If ad-hoc network is constructed for portable devices, then wireless communication capability is improved, but network management functionality (joining/exiting, disappearance detection, coordinator changeover) is insufficient

Engineering Contradiction:

Improvenetwork management functionalityVSAvoidcommunication continuity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements preliminary actions by having stations prepare join/request frames and exit frames in advance. When a station wants to join or exit, it prepares the necessary frames beforehand. The coordinator also prepares the list of stations and communication parameters in advance, enabling smooth transitions without interrupting ongoing communications. This is evident in the join procedure where the joining station prepares a join/request frame with its identifier before actually joining the network.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs feedback mechanisms through acknowledgment frames. When the coordinator receives a join/request frame, it sends back an acknowledgment frame to confirm the joining station is added to the list. Similarly, when a station exits, the coordinator sends acknowledgment frames to notify other stations. This feedback system ensures reliable network management and maintains communication continuity during joining and exiting operations.

Inventive Principle:

Principle #23Feedback

2Use of energy by moving object

If power saving mode is implemented, then battery consumption is reduced, but response time for network changes increases

Engineering Contradiction:

Improvebattery consumptionVSAvoidresponse time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent implements periodic action through the beacon signal transmission mechanism. The coordinator transmits beacon signals at regular intervals (beacon interval) to announce network status changes, including joining and exiting of stations. This periodic broadcasting allows sleeping stations to wake up at predetermined times to check for network changes, reducing power consumption while maintaining acceptable response time. The beacon signal serves as a periodic wake-up call that balances energy saving with network responsiveness.

Inventive Principle:

Principle #19Periodic action

3Productivity

If multicast communication is used for real-time game data, then communication efficiency is improved, but existing networks cannot handle dynamic station changes mid-communication

Engineering Contradiction:

Improvecommunication efficiencyVSAvoiddynamic network change capability

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent applies preliminary action by having the coordinator maintain an updated list of all stations in the network before multicast transmission. When a station joins or exits, the coordinator updates this list in advance and notifies other stations through beacon signals. This preliminary preparation ensures that when multicast communication occurs, the coordinator already has the correct station list, enabling efficient communication without interruptions for dynamic changes.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses the beacon signal as an intermediary mechanism to communicate network status changes to all stations. Instead of directly interrupting multicast communication to announce changes, the coordinator uses beacon signals as an intermediary channel to broadcast join and exit information. This intermediary approach allows the multicast communication to continue efficiently while still accommodating dynamic station changes, as the beacon signal carries the updated station list without disrupting ongoing data transmission.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7990903B2Communication terminal device, communication system, communication method, and program

Publication Date: 2011.08.02 SONY GROUP CORP

AI summary

A communication terminal device, a communication system, a communication method, and a program which can realize the functions of joining and exiting from a network in the middle of communication, detecting disappearance of stations (communication terminals), and/or changing over a coordinator function. The communication terminal has the capabilities of: detecting disappearance of a coordinator in the network by lack of reception of beacons and frames from other terminals, and, if its transmission timing at a certain TBTT is the shortest within a network, serving as a new coordinator itself to transmit beacons; and serving as a communication-holding coordinator having entered a predetermined mode, and transmitting a change request frame to a communication terminal to which changeover of a coordinator function is requested, thereby transferring the coordinator function to a communication terminal not functioning as the coordinator.