Ingress Policing for Scheduled Frames in Ethernet In-Vehicle Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In Ethernet-based in-vehicle networks, existing time aware shaper (TAS) technologies face challenges in maintaining ultra-low latency and jitter due to potential dysfunction in nodes, leading to unpredictable delays and increased errors, especially when time synchronization software malfunctions, which is critical for deterministic scheduling in time-sensitive applications.
Innovation Solution
Implementing an ingress policing mechanism with defined arrival and dropping windows in bridges and switches to detect scheduling dysfunctions, ensuring that only scheduled frames arriving within a specified arrival window are forwarded, while frames outside this window are dropped to prevent delays and maintain deterministic latency and jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time aware shaper (TAS) is implemented for deterministic scheduling, then latency and jitter are guaranteed, but the system becomes vulnerable to dysfunction propagation when nodes fail
Solution Approach 1:
The patent applies preliminary anti-action by implementing ingress policing that proactively detects and drops late-arriving scheduled frames before they can propagate errors through the network. The policing mechanism anticipates potential dysfunction by monitoring frame arrival times against expected schedules and preemptively removing problematic frames, thereby preventing the harmful effect of error propagation that would otherwise occur in TAS-based networks
2Manufacturing precision
If scheduled frames are transmitted according to strict time slots, then deterministic delay is achieved, but any late arrival causes subsequent frames to also arrive late
Solution Approach 1:
The patent applies the taking out principle by extracting problematic late-arriving frames from the network stream through ingress policing. When a scheduled frame arrives outside its expected time window, the policing mechanism identifies and removes this frame before it can interfere with the timing of subsequent frames. This extraction prevents the cumulative delay effect where one late frame would otherwise push all subsequent frames beyond their scheduled delivery times
3Reliability
If guard bands are used to protect scheduled traffic from non-scheduled traffic, then transmission protection is improved, but additional latency is introduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the timing parameters of scheduled frames based on actual network conditions and measured latencies. Rather than using fixed, conservative guard band intervals that always introduce delay, the system monitors frame transmission times and adapts scheduling parameters accordingly. This allows the network to maintain protection for scheduled traffic while minimizing unnecessary guard band delays that would otherwise be required to account for worst-case scenarios
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
For switching incoming scheduled frames in an Ethernet-based in vehicle network (20), wherein the network (20) comprises at least one bridge (2, 3, 4, 5) configured for transmitting TAS-based frames (F1, F2, F3), it this suggested that at least one bridge (2, 3, 4, 5) checks, whether an incoming scheduled frame (F1, F2, F3) arrives within the predefined time interval (45) of a dropping window and to drop the frame (F1, F2, F3) if it has arrived within the dropping window.