Performance enhancement through optical variants
First Claim
1. An apparatus comprising an optical receiver that comprises:
- a front-end circuit configured to convert an optical input signal into a corresponding plurality of digital electrical signals; and
a processor configured to;
process the plurality of digital electrical signals to generate a first set of complex values, each corresponding to a first bit-word, said first set of complex values including at least three complex values;
sum the at least three complex values of the first set to generate a summed complex value; and
map the summed complex value onto a constellation to determine the first bit-word; and
wherein, in response to the optical input signal having at least a first optical variant, a second optical variant, and one or more additional optical variants, with each of said first, second, and one or more additional optical variants carrying the first bit-word, the processor is configured to include into the at least three complex values;
at least one complex value that corresponds to the first optical variant;
at least one complex value that corresponds to the second optical variant; and
at least one complex value that corresponds to an additional optical variant.
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Abstract
An optical transport system configured to transmit a set of two or more optical variants per bit-word, with the optical variants in the set being different from one another in one or more of the time of transmission, spatial localization, polarization of light, carrier wavelength, and subcarrier frequency. Differences between the optical variants may also be due to different respective constellation mapping. The optical variants of each set are detected and processed at the receiver in a manner that enables coherent summation of the corresponding electrical signals prior to constellation de-mapping. The coherent summation tends to average out the deleterious effects of linear and nonlinear noise/distortions imparted on the individual optical variants in the optical transport link because said noise/distortions are incoherent in nature. A BER reduction enabled by the use of optical variants may be implemented in addition to or instead of that provided by FEC coding.
31 Citations
20 Claims
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1. An apparatus comprising an optical receiver that comprises:
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a front-end circuit configured to convert an optical input signal into a corresponding plurality of digital electrical signals; and a processor configured to; process the plurality of digital electrical signals to generate a first set of complex values, each corresponding to a first bit-word, said first set of complex values including at least three complex values; sum the at least three complex values of the first set to generate a summed complex value; and map the summed complex value onto a constellation to determine the first bit-word; and wherein, in response to the optical input signal having at least a first optical variant, a second optical variant, and one or more additional optical variants, with each of said first, second, and one or more additional optical variants carrying the first bit-word, the processor is configured to include into the at least three complex values; at least one complex value that corresponds to the first optical variant; at least one complex value that corresponds to the second optical variant; and at least one complex value that corresponds to an additional optical variant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification