Adaptive Equalizer Settings Reuse for Fast Data-Rate Switching
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Solution Overview
Problem
Conventional adaptive equalizers face challenges in rapidly adapting to changes in signal parameters, such as data rate, within limited time frames, leading to increased error rates and delayed link establishment in communication standards like Fibre Channel, where training periods are not allowed.
Innovation Solution
An adaptive equalizer that stores derived settings for different signal parameters and uses these stored settings as initial settings when changes occur, allowing for faster convergence and accurate adaptation without requiring very fast hardware, and resets settings if no changes are detected for a predetermined period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional adaptive equalizers adapt to signal parameter changes in real-time, then accuracy is maintained, but adaptation time increases and link establishment is delayed
Solution Approach 1:
The equalizer stores previously derived settings for different signal parameters in advance. When a signal parameter change is detected, the equalizer retrieves the pre-stored settings corresponding to the new parameter value, eliminating the need for time-consuming real-time adaptation. This preliminary preparation of settings for various parameter scenarios directly resolves the contradiction by enabling instant adaptation without accuracy loss.
2Speed
If the equalizer uses very fast hardware to reduce adaptation time, then link establishment is faster, but device complexity increases
Solution Approach 1:
Instead of relying on fast hardware for real-time calculation, the system performs the computationally intensive equalizer derivation in advance and stores the results. The retrieval operation during parameter changes is simple memory access, not complex calculation. This approach achieves fast adaptation through smart architecture rather than brute-force hardware speed, avoiding increased device complexity.
Solution Approach 2:
The invention creates copies of equalizer settings for different signal parameter values and stores them in memory. When a parameter change occurs, the system copies the appropriate pre-derived settings into the active equalizer registers. This copying mechanism enables instant adaptation without requiring fast computational hardware, as the heavy lifting was already done during the initial derivation phase.
3Measurement precision
If the equalizer stores settings for multiple signal parameters, then adaptation accuracy improves, but memory requirements increase
Solution Approach 1:
The equalizer stores settings specifically for discrete signal parameter values that are actually used in the communication system (e.g., specific data rates). Rather than storing continuous or exhaustive parameter combinations, the system stores only the locally relevant settings needed for practical operation. This selective storage approach provides high adaptation accuracy for actual use cases while minimizing unnecessary memory consumption.
Data Source
AI summary
Methods and apparatus adapting equalizers for compensating for signal distortion of a received digital signal are disclosed. The method comprises deriving equalizer settings for a received signal, determining at least one signal parameter of said received signal; and storing the derived equalizer settings together with an indication of the signal parameter. The signal parameter could, for instance, comprise the data rate of the signal. If the signal parameter changes the equalizer is configured to use any stored settings which are appropriate for the new signal parameter. Thus, rather than start an entirely new equalizer adaptation routine every time the signal parameter changes the equalizer will use any stored settings which are appropriate for the changed parameter.