Multicast Synchronization for Audio Device Groups

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Solution Overview

Problem

Existing audio systems that distribute an audio stream across multiple devices lack an efficient method for synchronizing new devices without relying on a master device, leading to potential system instability and limitations in device addition or removal.

Innovation Solution

A method where devices within a synchronized group share their state through multicast messages, with checksums used to verify consistency and trigger voting procedures to establish a common state, allowing new devices to join or leave the group without a master device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a master device is used to control synchronization in the audio system, then new devices can be synchronized with the system, but the system becomes unstable when devices are added or removed and the master device creates a single point of failure

Engineering Contradiction:
Improvesystem stabilityVSAvoidmaster device dependency
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the master device control function from the system architecture. Instead of having a dedicated master device, each device independently maintains its own state and can respond to synchronization requests from other devices. This eliminates the single point of failure associated with master device dependency while maintaining synchronization capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Each device in the system serves itself by maintaining its own state information and being capable of responding to synchronization requests from other devices. When a device needs to synchronize, it sends a request to the group, and any device can respond with its state, allowing the requesting device to update itself without needing a central authority.

Inventive Principle:
Principle #25Self-service

2Adaptability or versatility

If a master device is required for synchronization, then devices can be synchronized, but devices cannot be freely removed from the system without risking system inoperability

Engineering Contradiction:
Improvedevice addition/removal flexibilityVSAvoidsystem operability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent removes the constraint that prevents device removal by extracting the master device dependency. Each device independently maintains state information, so when a device is removed, the remaining devices continue to operate with their own state knowledge. The system remains operational without requiring the master device to be present.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system dynamically adapts its configuration based on device presence. When devices are added or removed, the system parameters (device count, group composition) change automatically. Each device adjusts its behavior based on its own state and the states of other devices, allowing flexible addition and removal without compromising system operability.

Inventive Principle:
Principle #35Parameter changes

3Loss of information

If devices share state information through multicast messages, then synchronization is achieved, but network traffic increases and message collisions may occur

Engineering Contradiction:
Improvestate information consistencyVSAvoidnetwork traffic
Core Design Contradiction:
Loss of informationVSLoss of energy

Solution Approach 1:

Instead of all devices continuously broadcasting their state information (excessive action), devices only send multicast messages when they need to synchronize or when their state changes. This partial action approach reduces network traffic while still ensuring that state information is propagated when necessary, maintaining consistency without constant communication overhead.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4016937B1Method for synchronising and system implementing said method
Publication Date: 2023.01.11 SAGEMCOM BROADBAND SAS
  • EP4016937B1 patent drawingFigure 1
  • EP4016937B1 patent drawingFigure 2A
  • EP4016937B1 patent drawingFigure 2B

AI summary

A method for synchronizing a device with a group of devices controlled by a controller is described. The device to be synchronized sends (S302) a multicast request message for the current state of the group. Each other device in the group receiving (S303) the message randomly selects a duration and waits for that duration. The device whose waiting time expires first, called the first device, sends (S304) a multicast group state message containing a group state known to the first device. Upon receiving the group state message, each other device in the group interrupts its wait, and the device to be synchronized adopts the group state contained in the message. Finally, it sends (S308) a multicast state change message to inform the other devices in the group that it has adopted the group state.