External Jitter Buffer for Packet Voice Continuity
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Solution Overview
Problem
Packet network systems experience irregularities in packet arrival times, leading to discontinuities and losses in speech communication due to inadequate bandwidth and congestion, which existing internal jitter buffers struggle to address effectively, especially in terms of cost and capacity.
Innovation Solution
A packet voice communication system with an external jitter buffer that holds voice packets and provides them synchronously to a voice processor, including an indicator of holding time, allowing the processor to adjust retrieval rates based on buffer conditions, and notifying the buffer of queue status to maintain continuous speech playback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an internal jitter buffer is incorporated into the voice processor, then speech discontinuity and loss are reduced, but manufacturing cost increases
Solution Approach 1:
The jitter buffer function is extracted from the voice processor and implemented as a separate external device. This allows the voice processor to remain simple and inexpensive while the jitter buffer handles the complex buffering and synchronization tasks, resolving the contradiction between reliability and manufacturing cost.
Solution Approach 2:
The system is segmented into two independent components: a simple voice processor and a separate jitter buffer device. This segmentation allows each component to be optimized independently - the voice processor for low cost and the jitter buffer for high reliability, thereby resolving the contradiction.
2Reliability
If a larger jitter buffer is used to accommodate more jitter, then speech continuity is improved, but device complexity and cost increase
Solution Approach 1:
By extracting the jitter buffer as a separate external device, the system can provide large buffering capacity without increasing the complexity of the voice processor itself. The buffer size can be scaled independently in the external device.
Solution Approach 2:
The jitter buffer implements dynamic retrieval rates that adjust based on packet arrival patterns. This dynamic adaptation allows the buffer to handle variable jitter conditions efficiently without requiring excessively large fixed buffer sizes, reducing overall system complexity.
3Reliability
If packets are buffered to handle arrival irregularities, then speech loss is reduced, but playback delay increases
Solution Approach 1:
The jitter buffer dynamically adjusts its retrieval rate based on actual packet arrival patterns. When packets arrive regularly, the buffer releases them quickly minimizing delay. When jitter occurs, the buffer temporarily holds packets to maintain continuity. This dynamic behavior reduces average playback delay while maintaining reliability.
Solution Approach 2:
The system changes the retrieval parameter (retrieval rate) based on buffer conditions and packet arrival patterns. This parameter adjustment allows the buffer to optimize between delay and reliability in real-time, reducing playback delay while preventing speech loss.
Data Source
AI summary
A packet voice communication system having a jitter buffer external to a voice processor. The jitter buffer stores voice packets received from a packet network. The voice processor processes the voice packets from the jitter buffer. A jitter buffer processor may place an indicator in each voice packet it holds. The indicator can indicate a length of time the voice packet was held. The rate at which packets come from the jitter buffer may be based upon the indicator, a higher rate if holding times are high and a slower rate if low. The voice processor can store the voice packets in a packet queue prior to processing the voice packets. The rate voice packets come to the voice processor may be based upon how full the packet queue is, a higher rate if the packet queue is relatively empty and a slower rate if relatively full.