PCIe Precoding Mechanism for DFE Error Mitigation
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Solution Overview
Problem
In high-speed serial communications, data patterns like alternating 1s and 0s are prone to error propagation due to decision feedback equalizer (DFE) settings, leading to potential data corruption from single bit flips, which manifest as contiguous error bursts.
Innovation Solution
Implementing a precoding mechanism where scrambled data bits are pre-coded before transmission and decoded after reception, specifically using an XOR function to mitigate DFE-induced errors, while preserving existing encoding and link training flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If decision feedback equalizer (DFE) settings with larger values are used in receivers, then equalization performance is improved, but error propagation occurs on alternating data patterns (1s and 0s) leading to contiguous error bursts
Solution Approach 1:
The patent applies precoding to data bits before transmission, specifically transforming alternating patterns (101010...) into non-alternating patterns. This preliminary action prevents the DFE from propagating errors on these vulnerable patterns, thereby maintaining both equalization performance and data reliability simultaneously
2Reliability
If precoding is applied to all data bits, then error bursts are reduced, but device complexity and processing overhead increase
Solution Approach 1:
The patent implements selective precoding where only specific data bits requiring protection (those in vulnerable alternating patterns) are precoded, while other bits are transmitted without precoding. This local application of precoding reduces error bursts while minimizing processing complexity and overhead
3Reliability
If new precoding mechanism is implemented, then DFE-induced errors are mitigated, but compatibility with existing encoding and link training flows may be affected
Solution Approach 1:
The patent introduces precoding as an intermediary step between existing encoding and transmission processes. The precoding operation is designed to be transparent to existing link training and encoding flows, allowing error mitigation without disrupting compatibility with established protocols and procedures
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces error bursts by minimizing DFE-induced errors, ensuring reliable data transmission across serial communication links like PCIe, with precoding only applied to scrambled bits to maintain compatibility and efficiency.
Implementation Method 1
specifically using an XOR function to mitigate DFE-induced errors
Data Source
AI summary
In embodiments, an apparatus for serial communication includes a transceiver, to receive a precoding request from a downlink receiver across a serial communication link, and to transmit data bits to the downlink receiver over the serial communication link. In embodiments, the apparatus further includes a precoder, coupled to the transceiver, to: receive scrambled data bits of a subset of the data bits to be transmitted, from a coupled scrambler, and, in response to the request from the downlink receiver, precode the scrambled data bits, and output the precoded scrambled data bits to the transceiver, for transmission to the downlink receiver across the serial communication link together with other unscrambled data bits.