Adaptive De-Jitter Buffer for VoIP Packet Switching
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Solution Overview
Problem
In packet-switched communication systems, especially VoIP, fixed de-jitter buffers often lead to inefficient processing as they apply a large delay to all packets, including those with smaller delays, resulting in sub-optimal user experience due to excessive end-to-end delays and underflows, which degrade voice quality.
Innovation Solution
An adaptive de-jitter buffer that adjusts its target length based on packet arrival statistics and uses time warping to compress or expand packets, ensuring that voice data is played back at optimal intervals, minimizing underflows and maintaining low end-to-end delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed de-jitter buffer with large delay is used, then packet underflows are reduced, but end-to-end delay increases excessively
Solution Approach 1:
The patent implements a dynamic de-jitter buffer that adapts its delay characteristics based on real-time packet arrival statistics. The buffer transitions from a fixed delay mechanism to a variable delay mechanism that adjusts according to observed jitter patterns, allowing it to reduce delay when packets arrive on time while maintaining sufficient delay when jitter occurs
Solution Approach 2:
The patent changes the delay parameter of the de-jitter buffer dynamically based on packet arrival statistics. By monitoring actual packet arrival times and adjusting the buffer delay parameter accordingly, the system optimizes the balance between preventing underflows and minimizing end-to-end delay
2Ease of operation
If a fixed de-jitter buffer is used, then simple processing is achieved, but voice quality degrades due to excessive delay and underflows
Solution Approach 1:
The patent introduces a feedback mechanism where packet arrival statistics are continuously monitored and used to adjust de-jitter buffer behavior. This closed-loop control enables the system to automatically optimize voice quality by adapting to changing network conditions without complex manual configuration
Solution Approach 2:
The de-jitter buffer performs self-optimization by automatically adjusting its parameters based on observed packet arrival patterns. The system uses its own performance data to improve its operation, reducing the need for external control while maintaining high voice quality
3Productivity
If time warping is applied to compress or expand packets, then optimal playback intervals are achieved, but processing complexity increases
Solution Approach 1:
The patent applies time warping operations in advance during the packet processing stage, before playback. By pre-compressing or expanding packets based on predicted playback requirements, the system ensures optimal playback intervals without adding complexity to the real-time playback path
Data Source
AI summary
Adaptive De-Jitter Buffer for Voice over IP (VoIP) for packet switch communications. The de-jitter buffer methods and apparatus presented avoid playback of underflows while balancing end-to-end delay. In one example, the de-jitter buffer is recalculated at the beginning of each talkspurt. In another example, talkspurt packets are compressed upon receipt of all remaining packets.