Frame Preemption Timing for Deterministic TSN Services
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Solution Overview
Problem
The IEEE 802.3br standard's frame preemption mechanism results in uncertain preemption delays and associated jitter due to varying transmission states of preemptable MAC frames, which is problematic for Time Sensitive Networking (TSN) services requiring deterministic performance.
Innovation Solution
Implement a method where an express MAC packet is sent when timing reaches a predetermined preemption delay target value, setting each hop's frame preemption delay to a fixed value to eliminate jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the existing frame preemption mechanism is used, then the eMAC can preempt the pMAC frame, but the preemption delay becomes uncertain and causes end-to-end jitter
Solution Approach 1:
The patent changes the parameter of preemption delay from a variable value (dependent on transmission state) to a fixed target value. By setting a predetermined preemption delay target value and using timing mechanisms to ensure packets are sent exactly when this timing is reached, the patent eliminates the uncertainty and jitter in preemption delay while maintaining the preemption functionality.
2Productivity
If the eMAC preempts the pMAC frame based on transmission state, then preemption can occur, but the preemption delay varies on each hop
Solution Approach 1:
The patent applies preliminary action by pre-calculating and setting a fixed preemption delay target value before the actual preemption occurs. The timing mechanism is prepared in advance to ensure that the eMAC packet is sent exactly when the predetermined timing is reached, rather than waiting for variable transmission state conditions. This preliminary timing setup ensures consistent preemption delay across all hops.
3Adaptability or versatility
If the frame preemption mechanism allows variable transmission states, then flexibility is maintained, but end-to-end jitter is introduced
Solution Approach 1:
The patent transforms the static, variable transmission state-based preemption into a dynamic timing-controlled mechanism. By using a predetermined preemption delay target value and continuous timing monitoring, the system dynamically adjusts to ensure packets are sent at the exact correct moment, eliminating jitter while maintaining the ability to handle different transmission scenarios through the flexible timing mechanism.
Data Source
AI summary
A frame preemption method and apparatus, a device, and a storage medium are provided. The method includes: determining that an express Media Access Control (eMAC) packet needs to be sent; and sending the eMAC packet when timing reaches a preemption delay target value.