Method and apparatus for frequency domain equalization with low complexity and loop delay
AssigneeHuawei Technologies Co., Ltd.
InventorsChuandong Li, Jianhong Ke
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Abstract
Methods and devices are described for frequency domain equalization with low complexity and loop delay. A transmitter inserts pilot symbols into a data signal at intervals of every n data bits. These pilot symbols are used by a receiver-side frequency-domain equalizer to calculate error levels and equalize the received data signal to effect impairment compensation such as SOP tracking. QPSK or BPSK symbols may be used for the pilot symbols, simplifying error calculation into an addition operation instead of the conventional multiplication operation required by conventional FDEQs. Equalizers are described that may operate in a pilot-assisted mode, a conventional decision-directed mode, or both.
Claims19
A device comprising:
- a coherent receiver for receiving an optical signal and generating an electrical signal based on the optical signal, the optical signal comprising a plurality of pilot symbols and a plurality of data symbols;
- and
- a frequency-domain adaptive equalizer (FDEQ) configured to receive a digital signal based on the electrical signal, comprising:
- an equalization path comprising one or more equalizer taps for equalizing the digital signal in the frequency domain using one or more tape values based on a pilot error signal, thereby generating an equalized digital signal;
- and
- a pilot error tap update path for:
- generating the pilot error signal by calculating a phase angle based on the angle between one or more predetermined pilot symbols and one or more received pilot symbols of the equalized digital signal;
- and
- updating the equalizer taps based on the pilot error signal according to a pilot error update interval.
A method comprising:
- receiving a digital signal comprising a plurality of pilot symbols and a plurality of data symbols;
- using one or more equalizer taps to equalize the digital signal in the frequency domain using one or more tap values based on a pilot error signal, thereby generating an equalized digital signal;
- generating the pilot error signal by calculating a phase angle based on the angle between one or more predetermined pilot symbols and one or more received pilot symbols of the equalized digital signal;
- and
- updating the equalizer taps based on the pilot error signal according to a pilot error update interval.
Dependencies are inferred from the claim text.