Fast least-mean-square (lms) equalization
AssigneeInfinera Corporation
InventorsAhmed AWADALLA, Han Henry SUN, Kuang-Tsan WU
Life of this patent
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Abstract
Apparatus and methods may provide improved equalizer performance, e.g., for optical-fiber-based communication systems. A least-mean-square (LMS) equalizer may include a decision feedback path containing feedback carrier recovery (FBCR), which may have low latency, and which may thus enable high-speed tap updating in the equalizer. Feed-forward carrier recovery (FFCR) may be applied, in parallel with the FBCR, to provide equalizer output by compensating, e.g., for phase noise, with improved carrier recovery/compensation, versus using FBCR to generate the output.
Claims22
An adaptive equalizer system, including:
- a filter configured to receive input signal samples and provide a filter output, the filter having a plurality of taps having respective tap-weights;
- a tap-weight updating circuit configured to receive the input signal samples and to update one or more of the tap-weights of the filter;
- a feedback carrier recovery (FBCR) circuit configured to receive the filter output and to output first phase-error compensated output;
- a decision circuit configured to receive the first phase-compensated output and to provide decision-based output to the tap-weight updater;
- and
- a feed-forward carrier recovery (FFCR) circuit configured to receive and phase-compensate the filter output to obtain second phase-error compensated output, such that the filter is coupled to the FBCR circuit and the FFCR circuit.
A method of adaptive equalization, including:
- filtering input signal samples to generate filter output;
- updating filter tap-weights of the filtering based at least in part on the input signal samples;
- performing feedback carrier recovery (FBCR) on the filter output to output first phase-compensated output;
- providing decision-based output based on the first phase-compensated output, and using the decision-based output in the updating filter tap-weights;
- and
- performing feed-forward carrier recovery (FFCR) on the filter output, in parallel with the performing FBCR, to generate equalizer output.
A non-transitory machine-readable medium containing executable instructions configured to cause one or more processing devices to implement operations including:
- filtering input signal samples to generate filter output;
- updating filter tap-weights of the filtering based at least in part on the input signal samples;
- performing feedback carrier recovery (FBCR) on the filter output to output phase-compensated output;
- providing decision-based output based on the phase-compensated output, and using the decision-based output in the updating tap weights;
- and
- performing feed-forward carrier recovery (FFCR) on the filter output, in parallel with the performing FBCR, to generate equalizer output.
Dependencies are inferred from the claim text.