PHY Slicer Link Loss Detection Without Timer Delay
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Solution Overview
Problem
Current link loss detection in PHY devices delays the indication of link failure to higher-level applications, leading to potential errors due to the wait timer expiring before the link is brought down, even if the PHY receiver is in a failed state.
Innovation Solution
A link loss detection module that analyzes input/output samples of a PHY device slicer to generate a signal indicating link loss independently of a timer, using conditions such as near zero, invalid level, and stuck detection events, allowing immediate indication of link failure when the PHY receiver is in a failed state, unless retrain is enabled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PHY device waits and observes communication loss for some time to determine persistence before indicating link failure, then the reliability of link status indication is improved, but the speed of link loss indication deteriorates
Solution Approach 1:
The patent implements preliminary action by detecting link loss conditions at the slicer level before the traditional link failure indication point. The slicer continuously monitors signal quality and detects degradation early, triggering a link loss indication before the maximum wait timer expires. This preliminary detection at an earlier stage in the signal processing chain resolves the contradiction by providing both early speed and reliable confirmation through multiple detection criteria.
2Measurement precision
If the PHY device uses a maximum wait timer to confirm persistent link loss before indication, then the accuracy of link failure detection is improved, but the time delay in indicating link loss increases
Solution Approach 1:
The slicer performs preliminary detection of link loss conditions by monitoring signal quality parameters (such as eye diagram quality, signal amplitude, or bit error rate) continuously during normal operation. When degradation exceeds thresholds, the slicer generates a link loss indication immediately without waiting for the maximum wait timer. This preliminary action maintains accuracy through multiple detection criteria while eliminating the time delay.
Solution Approach 2:
The slicer acts as an intermediary component between the physical signal and the link status indication. It mediates between the raw physical layer signal and the higher-layer link status by providing early detection capabilities. The slicer translates physical signal quality into link loss indications, serving as an intermediate detection layer that operates independently of the traditional timer-based mechanism, thus reducing delay while maintaining precision.
Data Source
AI summary
This disclosure describes techniques for detecting link loss in a physical layer receiver of a communication system. The system includes a slicer coupled to receive, at a slicer input, a signal from a channel equalizer and map the signal to a physical coding sublayer (PCS) level at a slicer output and processor coupled to at least one of the slicer input or the slicer output. The processor is configured to analyze a window of consecutive samples at the at least one of the slicer input or the slicer output over a time window; increment a counter as a function of the window of consecutive samples at the at least one of the slicer input or the slicer output; compare the counter to a threshold; and generate a signal indicating link loss in response to determining that the counter corresponds to the threshold independently of a timer.