ALM Terminal Reproduction Delay Control for Stream Jitter

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Solution Overview

Problem

In stream distribution via an ALM tree, existing methods set fixed reproduction delay times ignoring actual RTT variations, leading to suboptimal transmission quality due to potential under or overestimation of delay times, causing jittery images and audios.

Innovation Solution

A communications terminal determines reproduction delay time based on the longest round-trip delay time among sections between the root terminal and each terminal, ensuring retransmission data is received in time for smooth reproduction, using a reproduction delay time determining unit and a reproduction control unit to adjust delays dynamically.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If fixed reproduction delay time is set ignoring RTT variations, then device complexity is reduced, but transmission quality deteriorates due to jittery images and audios

Engineering Contradiction:

Improvedelay time setting complexityVSAvoidtransmission quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies dynamics by transitioning from fixed reproduction delay time to dynamic adjustment based on actual RTT measurements. The reproduction delay time determining unit continuously measures RTT and adjusts the delay time accordingly, allowing the system to adapt to varying network conditions while maintaining transmission quality without excessive complexity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by measuring actual RTT values and using this information to adjust reproduction delay time. The system continuously monitors network conditions through RTT measurement and feeds this information back to the delay time determination mechanism, enabling automatic optimization of transmission quality based on real-time network state

Inventive Principle:

Principle #23Feedback

2Reliability

If reproduction delay time is set based on longest RTT among all sections, then transmission quality is improved by ensuring retransmission data arrives in time, but loss of time increases due to longer delay

Engineering Contradiction:

Improvetransmission qualityVSAvoidreproduction delay time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local quality by determining reproduction delay time based on the specific RTT characteristics of each terminal's position in the ALM tree. Instead of using a uniform delay for all terminals, the system calculates appropriate delay times tailored to each terminal's network path, ensuring optimal quality without unnecessary delays for terminals with shorter RTT

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by dynamically adjusting reproduction delay time based on measured RTT values. The system changes the delay time parameter according to actual network conditions, allowing optimization of transmission quality while minimizing unnecessary time loss by adapting to varying network states

Inventive Principle:

Principle #35Parameter changes

3Loss of time

If reproduction delay time is set according to local RTT only, then loss of time is reduced, but transmission quality deteriorates due to underestimation of delay for retransmission data

Engineering Contradiction:

Improvereproduction delay timeVSAvoidtransmission quality

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent applies preliminary action by setting reproduction delay time to account for the longest RTT in advance, before retransmission actually occurs. This ensures that when retransmission data needs to traverse multiple sections, it will arrive before the reproduction buffer needs to play it, preventing quality deterioration while minimizing the delay to what is strictly necessary

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9184928B2Communications terminal, communications method, and program and integrated circuit for controlling a reproduction delay time in distributing a stream

Publication Date: 2015.11.10 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A communication terminal (100) is one of communication terminals each having one parent terminal and zero or more child terminals. The communication terminals form an Application Layer Multicast (ALM) tree to sequentially distribute retransmission data of stream data from the parent terminal to the child terminal. The communications terminal (100) includes: a reproduction delay time determining unit (1010) determining a reproduction delay time based on a longest round-trip delay time among round-trip delay times of sections between a root terminal and the communications terminal (100), each of the round-trip delay times being required for transmission and reception of data through one of the sections between two neighboring terminals of the communications terminals on the ALM tree; and a reproduction control unit (1020) reproducing the stream data received from the root terminal, with the stream data delayed by the reproduction delay time determined by the reproduction delay time determining unit (1010).