Modified Timestamps for VoIP Jitter Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing communication systems face end-to-end jitter issues in VoIP applications due to delay variations, leading to unsatisfactory user experiences, especially when long distance calls are prioritized over local ones, and synchronization challenges between source and destination timing logic.
Innovation Solution
A timing system that generates modified timestamps based on average relative delays experienced by packets, allowing for efficient scheduling that reduces end-to-end jitter and prevents long distance traffic from being prioritized over local traffic, thereby enabling smaller de-jitter buffers and improved user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time timestamps are used for packet scheduling, then end-to-end jitter is reduced, but long distance calls are prioritized over local calls causing unsatisfactory user experience
Solution Approach 1:
The patent applies local quality by making the timestamp modification destination-specific. The forward link scheduler computes different modified timestamps for packets destined to different destinations based on their individual average delays. This allows local calls to receive appropriate scheduling priority while long distance calls are handled differently, ensuring fair user experience for all destinations without compromising overall jitter reduction.
Solution Approach 2:
The patent changes the timestamp parameter from absolute real-time values to modified relative values. By subtracting the average delay specific to each destination from the real-time timestamp, the system transforms the scheduling parameter to reflect relative delay compensation rather than absolute timing, thereby preventing systematic bias toward long distance calls.
2Reliability
If absolute real-time timestamps are used for scheduling, then packets experiencing long delays are prioritized, but timing synchronization between source and scheduler becomes complex requiring GPS or global timing standards
Solution Approach 1:
The forward link scheduler acts as an intermediary that receives packets with real-time timestamps from the core network and transforms them into modified timestamps before forwarding to the de-jitter buffer. This intermediary function eliminates the need for synchronization between source and destination timing logic by performing the delay compensation locally at the scheduler based on pre-computed average delays for each destination.
Solution Approach 2:
The patent extracts the delay compensation function from the global timing synchronization system. Instead of requiring synchronized clocks throughout the network, the system extracts and applies destination-specific average delay values at the forward link scheduler, separating the compensation mechanism from the timing synchronization requirement.
3Reliability
If de-jitter buffers are sized to handle maximum delay variations, then all packets are buffered adequately, but end-to-end delay increases reducing real-time communication quality
Solution Approach 1:
The system performs preliminary action by pre-computing average delays for each destination before packet arrival. The forward link scheduler uses these pre-computed values to modify timestamps in advance, enabling the de-jitter buffer to use smaller, optimized sizes without risking packet loss, thereby reducing end-to-end delay while maintaining reliability.
Data Source
AI summary
Methods and apparatus for providing modified timestamps in a communication system. In an aspect, a method includes receiving one or more packets associated with a selected destination, computing an average relative delay associated with each packet, determining a modified timestamp associated with each packet based on the average relative delay associated with each packet, and outputting the one or more packets and their associated modified timestamps. In an aspect, an apparatus is provided for generating modified timestamps. The apparatus includes a packet receiver configured to receive one or more packets associated with a selected destination and processing logic configured to compute an average relative delay associated with each packet, determine a modified timestamp associated with each packet based on the average relative delay associated with each packet, and output the one or more packets and their associated modified timestamps.