Dynamic FEC Threshold Control for Speech Quality
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Solution Overview
Problem
Digital audio telecommunications over packet-switched networks face challenges in maintaining speech quality due to packet loss, as conventional forward error correction (FEC) methods increase bandwidth and delay, and existing solutions either degrade baseline quality or are ineffective for critical frames.
Innovation Solution
A source- and channel-controlled FEC scheme that dynamically adjusts to transmit redundant copies of critical audio frames based on channel conditions, using a threshold calculation to determine the necessity of retransmission, thereby optimizing speech quality, delay, and data rate without additional delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional forward error correction (FEC) methods are used to protect against packet loss, then speech quality is improved, but bandwidth consumption and transmission delay increase
Solution Approach 1:
The patent applies local quality by providing differential error protection where critical frames receive redundant copies for robust error protection, while non-critical frames use standard protection. This selective approach ensures that bandwidth is consumed only where necessary to maintain speech quality, rather than uniformly protecting all frames.
Solution Approach 2:
The patent implements partial action by transmitting redundant copies only for critical frames identified through analysis of frame importance, rather than protecting all frames equally. This partial protection strategy maintains speech quality for the most important frames while reducing overall bandwidth consumption compared to comprehensive FEC approaches.
2Reliability
If redundant copies of all audio frames are transmitted to ensure error correction, then speech quality is improved, but data rate increases significantly
Solution Approach 1:
The patent implements local quality by applying error correction redundancy selectively only to critical frames rather than all frames. The system identifies critical frames based on their importance to speech quality and provides enhanced protection only where needed, thereby maintaining error correction capability for important frames while controlling overall data rate.
Solution Approach 2:
The patent uses partial action by providing redundant copies only for a subset of critical frames rather than all frames. This selective redundancy approach ensures adequate error correction capability for the most important speech information while significantly reducing the data rate increase compared to universal redundancy transmission.
3Quantity of substance
If critical frames are identified and protected selectively, then bandwidth efficiency is improved, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by performing frame criticality analysis and identifying which frames require protection before transmission occurs. By determining critical frames in advance during the encoding phase, the system can selectively apply redundancy only where needed, improving bandwidth efficiency while managing complexity through upfront analysis rather than complex real-time decisions.
Data Source
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AI summary
Systems, methods, and apparatus as disclosed herein may be implemented to adjust criticality thresholds for speech frames, based on channel conditions. Such a threshold may be used to control retransmission frequency in response to changes in channel state.