MCPTT Floor Transfer Arbitration in Off-Network Terminals

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Solution Overview

Problem

In Mission Critical Push to Talk (MCPTT) services, transferring a floor in an off-network environment is inefficient due to the lack of a central control server, leading to ineffective operations and potential failures in floor transfers.

Innovation Solution

A method is introduced where terminals in an MCPTT group call manage and update floor arbitrator information with delayed updates and transmit floor taken messages, allowing stable floor transfers even if the next floor arbitrator does not respond, by storing the next floor arbitrator's SSRC and updating it when valid media packets or control messages are received.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If floor transfer is performed in off-network MCPTT group call without central control server, then autonomy and independence are improved, but floor transfer reliability and stability deteriorate due to lack of arbitration

Engineering Contradiction:

ImproveautonomyVSAvoidfloor transfer reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system enables terminals to autonomously perform floor arbitration and management without relying on a central control server. Each terminal independently executes floor transfer protocols, selects next floor arbitrators, and manages floor grants locally within the MCPTT group, achieving self-service operation in off-network environments.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system pre-selects and stores candidate next floor arbitrators before actual floor transfer occurs. Terminals maintain a list of potential arbitrators and their SSRC information in advance, enabling rapid and reliable floor transfer when needed without requiring real-time server intervention.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If floor transfer is performed quickly in off-network, then communication efficiency is improved, but floor transfer stability deteriorates due to potential failures

Engineering Contradiction:

Improvecommunication efficiencyVSAvoidfloor transfer stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Terminals pre-identify and store SSRC information of next floor arbitrators before floor transfer is needed. This preliminary preparation enables rapid floor transfer while maintaining stability, as the system already has candidate arbitrator information ready without requiring time-consuming selection during the transfer process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where terminals monitor floor transfer status and arbitrator responsiveness. When a floor transfer is initiated, the system tracks whether the next floor arbitrator responds appropriately, and can trigger re-selection or error handling procedures if feedback indicates failure, ensuring stable operation.

Inventive Principle:

Principle #23Feedback

3Speed

If next floor arbitrator is selected immediately, then floor transfer speed is improved, but system robustness deteriorates when arbitrator does not respond

Engineering Contradiction:

Improvefloor transfer speedVSAvoidsystem robustness

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary selection of next floor arbitrators and stores their SSRC information in advance, but does not immediately execute the transfer. This allows the system to have candidates ready for rapid transfer while maintaining the flexibility to abort or re-select if the chosen arbitrator proves unresponsive, balancing speed with robustness.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system maintains backup candidate arbitrators and alternative selection mechanisms ready in advance. If the selected next floor arbitrator fails to respond, the system has pre-prepared alternatives to fall back on, cushioning against the failure and maintaining system robustness without compromising the ability to perform fast transfers when successful.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11343656B2Method of operating terminal mission critical push to talk group participating in mission critical push to talk group call in off network

Publication Date: 2022.05.24 SAMSUNG ELECTRONICS CO LTD

AI summary

A method of operating a first terminal participating in a Mission Critical Push To Talk (MCPTT) group call in an off-network includes: receiving a first floor grant message configured to indicate a floor transfer from a second terminal to a third terminal; storing a Synchronization Source (SSRC) of the third terminal included in the first floor grant message as an SSRC of a next floor arbitrator; receiving a media packet or a floor control message; and, if a transmitter of the media packet or the floor control message is the next floor arbitrator, updating an SSRC of a current floor arbitrator as the SSRC of the next floor arbitrator.