VoIP Packet Prioritization for Jitter Protection
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Solution Overview
Problem
Existing VoIP systems face challenges in protecting voice packets from network jitter, particularly at the beginning and end of talk spurts, where packet loss can occur due to insufficient jitter protection, leading to voice quality degradation.
Innovation Solution
A method and apparatus that prioritize voice packets based on their location within a sequence, increasing priority for critical packets at the start and end of talk spurts and during handoffs to ensure timely arrival and reduce jitter-related losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed jitter buffer is used to compensate for network jitter, then voice quality is maintained for packets within the buffer delay, but packets arriving later than the fixed delay are lost and voice quality degrades
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed jitter buffer to a variable jitter buffer that dynamically adjusts its size based on real-time network conditions. The buffer expands when network jitter increases and contracts when jitter decreases, allowing the system to adapt to changing network conditions while maintaining optimal playback latency and preventing packet loss.
2Reliability
If time expansion is applied to increase jitter buffer latency, then more jitter delay can be handled, but the first several packets of a talk spurt remain vulnerable to network jitter
Solution Approach 1:
The patent applies preliminary action by proactively identifying packets that are likely to be vulnerable to jitter (such as the first several packets of a talk spurt) and preemptively applying time expansion to them. This ensures that these critical packets receive enhanced jitter protection before they can be lost, while maintaining overall playback latency within acceptable ranges.
3Reliability
If conventional packet loss concealment techniques are used, then some voice quality degradation can be limited, but excessive packet loss results in significant voice quality degradation
Solution Approach 1:
The patent applies beforehand cushioning by implementing a variable jitter buffer that proactively protects against packet loss before it occurs. By dynamically adjusting the buffer size based on network conditions and applying time expansion to vulnerable packets, the system prevents packet loss rather than relying on post-loss concealment techniques, thereby maintaining voice quality even under excessive jitter conditions.
Data Source
AI summary
A method and apparatus for routing voice packets through a communications network wherein the routing priority of the packets is based on a location of a packet within a sequence of transmitted voice packets, relative to one or more identified voice packets in the transmitted sequence. In one embodiment of the invention, the routing priority of a voice packet is based on the location of the packet in a sequence of packets relative to voice activity, such as the beginning, middle or end of a talk spurt. For example, the routing priority of the first several voice packets of a talk spurt is increased to compensate for the fact that there is less network jitter protection available at the receiver for these packets. In another embodiment, the routing priority of a voice packet may depend upon its location relative to a cellular handoff from one transmitter to another.