Latency Margin Detection for Ethernet Frame Timing
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Solution Overview
Problem
In data communication networks, particularly non-arbitrary Ethernet networks, there is a challenge in minimizing latency for high-priority data transmission while ensuring timely delivery of frames to prevent late arrival, which is crucial for maintaining low latency and ensuring media clock rates for audio and video data.
Innovation Solution
A system comprising a receiving module, memory, medium access control (MAC) module, and host module that stores data samples with timestamps, builds frames based on predetermined latency periods, and includes a latency detector module to adjust and update latency margins, ensuring frames are transferred according to expected reception times by the MAC module, thereby minimizing latency within the talker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined latency period is used to build frames, then frame delivery timing is ensured, but latency margin is increased
Solution Approach 1:
The system dynamically adjusts the predetermined latency period based on measured margins of latency. The latency detector module continuously monitors the actual latency experienced by frames and updates the predetermined latency period to optimize the balance between reliable delivery timing and minimizing latency margin, transforming a static parameter into a dynamic one that adapts to actual network conditions.
Solution Approach 2:
The latency detector module provides feedback about the actual latency experienced by frames to the frame building process. This feedback loop allows the system to measure the margin of latency and use this information to adjust future frame building timing, ensuring that the predetermined latency period is optimized based on real-world performance data.
2Loss of time
If latency margin is minimized, then overall latency is reduced, but risk of late frame arrival increases
Solution Approach 1:
The system performs preliminary measurements of latency margin through the latency detector module before finalizing the predetermined latency period. By proactively measuring and analyzing latency characteristics in advance, the system can set an optimized latency period that minimizes overall latency while incorporating sufficient margin to prevent late frame arrival, rather than reacting to timing issues after they occur.
Solution Approach 2:
The feedback mechanism continuously monitors frame arrival timing and adjusts the predetermined latency period accordingly. When frames arrive on time with consistent margins, the system can reduce the latency period to minimize overall latency. When timing variability increases, the feedback loop increases the margin to prevent late arrivals, dynamically balancing these competing requirements.
Data Source
AI summary
A system including a receiving module in a device and receiving samples of data transferred from a data source. A memory stores the samples and timestamps when the data was sampled. A host module builds a frame including the samples based on a first timestamp and a predetermined latency period between the first timestamp and a second timestamp in a descriptor of the frame. The second timestamp indicates a time when the frame is expected to be received by a MAC module. A transfer module transfers the frame to the MAC module according to the second timestamp. A detector module determines a margin of latency based on a difference between a time subsequent to when the frame is finished being built and a time when the frame is received at the MAC module. The detector module updates the first predetermined latency period based on the determined margin of latency.