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US 9,806,823 B2Granted
Cycle slip compensation in a coherent receiver
AssigneeInphi Corporation
InventorsMario Alejandro Castrillon, Damian Alfonso Morero, Mario Rafael Hueda
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Abstract
A receiver architecture and method recovers data received over an optical fiber channel in the presence of cycle slips. In a first cycle slip recovery architecture, a receiver detects and corrects cycle slips based on pilot symbols inserted in the transmitted data. In a second cycle slip recovery architecture, a coarse cycle slip detection is performed based on pilot symbols and a cycle slip position estimation is then performed based on carrier phase noise. The receiver compensates for cycle slips based on the position estimation.
Claims20
A method for compensating for cycle slips in a receiver, the method comprising:
- converting, by an optical front end circuit, an optical signal to an analog electrical signal;
- sampling, by an analog front end circuit, the analog electrical signal based on a sampling clock to generate an input digital signal, the input digital signal comprising a sequence of frames;
- processing the sequence of frames to correct for phase noise smaller than a rotational distance between constellation points to generate a phase-corrected sequence of frames;
- estimating a first phase rotation of a target frame in the phase-corrected sequence of frames based on pilot symbols in the target frame and an expected sequence of pilot symbols;
- estimating a second phase rotation of a subsequent frame in the phase-corrected sequence of frames based on pilot symbols in the subsequent frame and the expected sequence of pilot symbols, the subsequent frame following the target frame in the phase-corrected sequence of frames;
- responsive to the first phase rotation not matching the second phase rotation, detecting a location of a cycle slip in the target frame;
- adjusting, based on the first and second phase rotations, a phase of data symbol blocks in the phase-corrected sequence of frames to generate a corrected target frame;
- demodulating a corrected sequence of frames including the corrected target frame by a demodulator;
- and
- decoding the corrected sequence of frames by a decoder to generate a digital output signal.
7 more elements
A receiver system comprising:
- an optical front end circuit configured to convert an optical signal to an analog electrical signal;
- an analog front end circuit configured to sample the analog electrical signal based on a sampling clock to generate an input digital signal, the input digital signal comprising a sequence of frames;
- a digital signal processor;
- and
- a non-transitory computer-readable storage medium storing instructions that when executed by the digital signal processor perform steps including:
- processing the sequence of frames to correct for phase noise smaller than a rotational distance between constellation points to generate a phase-corrected sequence of frames;
- estimating a first phase rotation of a target frame in the phase-corrected sequence of frames based on pilot symbols in the target frame and an expected sequence of pilot symbols;
- estimating a second phase rotation of a subsequent frame in the phase-corrected sequence of frames based on pilot symbols in the subsequent frame and the expected sequence of pilot symbols, the subsequent frame following the target frame in the phase-corrected sequence of frames;
- responsive to the first phase rotation not matching the second phase rotation, detecting a location of a cycle slip in the target frame;
- adjusting, based on the first and second phase rotations, a phase of data symbol blocks in the phase-corrected sequence of frames to generate a corrected target frame;
- demodulating a corrected sequence of frames including the corrected target frame by a demodulator;
- and
- decoding the corrected sequence of frames by a decoder to generate a digital output signal.
10 more elements
A non-transitory computer-readable storage medium storing instructions that when executed by a processor cause the processor to perform steps including:
- receiving an input digital signal comprising a sequence of frames;
- processing the sequence of frames to correct for phase noise smaller than a rotational distance between constellation points to generate a phase-corrected sequence of frames;
- estimating a first phase rotation of a target frame in the phase-corrected sequence of frames based on pilot symbols in the target frame and an expected sequence of pilot symbols;
- estimating a second phase rotation of a subsequent frame in the phase-corrected sequence of frames based on pilot symbols in the subsequent frame and the expected sequence of pilot symbols, the subsequent frame following the target frame in the phase-corrected sequence of frames;
- responsive to the first phase rotation not matching the second phase rotation, detecting a location of a cycle slip in the target frame;
- adjusting, based on the first and second phase rotations, a phase of data symbol blocks in the phase-corrected sequence of frames to generate a corrected target frame;
- and
- outputting a corrected sequence of frames including the corrected target frame.
5 more elements
Dependencies are inferred from the claim text.