PON Time Synchronization for Low-Jitter TSN Scheduling
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Solution Overview
Problem
Existing PON systems face issues with unstable forwarding delays and large jitters, failing to meet the time-sensitive network (TSN) service requirements due to traditional packet scheduling methods influenced by Serial Number (SN) request windows, ranging windows, and Dynamically Bandwidth Assignment (DBA) scheduling cycles.
Innovation Solution
Implement time synchronization through broadcasting a time synchronization future superframe and timestamp, determine TSN packet entrance and exit, control scheduling based on delay information, reduce window duration, and increase DBA frequency to enhance TSN packet transmission in PON systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional priority scheduling and weight scheduling are used in PON systems, then bandwidth allocation is simplified, but transmission delays and jitters increase, failing to meet TSN service requirements
Solution Approach 1:
The patent segments the scheduling process into distinct phases: time synchronization phase, packet classification phase, and scheduled transmission phase. By dividing the scheduling cycle into smaller time slots with specific functions, the system achieves both simplified implementation and reduced transmission delays for TSN packets.
Solution Approach 2:
The patent performs time synchronization and packet classification before the actual transmission scheduling. The OLT broadcasts time synchronization information in advance, and packets are classified into TSN and non-TSN categories before the scheduling decision, enabling deterministic low-latency transmission for time-sensitive packets.
2Ease of operation
If traditional DBA scheduling cycle is used, then system operation is simplified, but forwarding delay stability deteriorates
Solution Approach 1:
The patent implements dynamic scheduling where the DBA cycle is adjusted based on service type. For TSN packets, a shorter and fixed DBA cycle is used to ensure stable and predictable forwarding delays, while non-TSN packets can use longer cycles. This dynamic adaptation maintains ease of operation while improving delay stability for time-sensitive traffic.
Solution Approach 2:
The patent changes the scheduling parameter (DBA cycle duration) based on the packet type. TSN packets are assigned a fixed, shorter DBA cycle parameter, while other packets use the traditional variable cycle. This parameter differentiation resolves the contradiction by providing stability for TSN without overly complicating the overall system operation.
3Adaptability or versatility
If larger SN request window and ranging window are used, then bandwidth allocation flexibility is improved, but transmission jitter increases
Solution Approach 1:
The patent segments the window allocation by packet type. TSN packets are assigned dedicated, smaller request and ranging windows with fixed timing, while non-TSN packets share the remaining bandwidth with larger, more flexible windows. This segmentation provides both the flexibility needed for bandwidth allocation and the determinism required to reduce jitter for time-sensitive traffic.
Data Source
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AI summary
Provided are a method for implementing a time-sensitive network for a passive optical network system, a device, and a medium. The method includes: performing time synchronization by broadcasting a time synchronization future superframe and a timestamp; determining a TSN packet entrance, a TSN packet exit, and delay information; controlling the TSN packet entrance and the TSN packet exit to schedule a TSN packet according to the delay information; and reducing the window duration of the TSN packet and increasing the DBA frequency of the TSN packet. In this manner, the TSN is implemented through the PON system, the transmission delays of TSN packets are reduced, data transmission jitters are reduced, and the performance requirements of service scenarios for the TSN are satisfied.