USING MULTI-LEVEL PULSE AMPLITUDE MODULATION WITH PROBABILISTIC SHAPING
First Claim
1. An optical receiver apparatus, comprising:
- a photo detector that detects amplitude modified optical signals transmitted through an optical transmission channel and mapped to constellation points and converts the optical signal into electrical signals;
a sampling circuit that samples the electrical signals and generates digital signals; and
a signal processing circuit that has a two-step equalization algorithm converging actual constellation points into desired constellation points, the two-step equalization algorithm comprising;
a first equalization algorithm that uses multiple modulus in performing an error signal calculation; and
a second equalization algorithm that includes a filtering procedure that compares actual constellation points in an intermediate signal resulting from the first equalization algorithm with desired constellation points and an adjustment procedure that iteratively adjusts parameters of the filtering procedure in accordance with the comparison result,wherein the first equalization algorithm includes a cascaded multi-modulus algorithm that utilizes at least two reference circles in a cascaded way, and wherein the at least two reference circles include reference circles that have reference radiuses corresponding to the highest and lowest amplitudes of the amplitude modified optical signal.
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Accused Products
Abstract
An optical receiver apparatus includes a photo detector that detects amplitude modified optical signals transmitted through an optical transmission channel and mapped to constellation points and converts the optical signal into electrical signals, a sampling circuit that samples the electrical signals and generates digital signals, and a signal processing circuit that has a two-step equalization algorithm converging actual constellation points into desired constellation points. The two-step equalization algorithm includes a first equalization algorithm that uses multiple modulus in performing an error signal calculation, and a second equalization algorithm that includes a filtering procedure that compares actual constellation points with desired constellation points and an adjustment procedure that iteratively adjusts parameters of the filtering procedure in accordance with the comparison result.
5 Citations
20 Claims
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1. An optical receiver apparatus, comprising:
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a photo detector that detects amplitude modified optical signals transmitted through an optical transmission channel and mapped to constellation points and converts the optical signal into electrical signals; a sampling circuit that samples the electrical signals and generates digital signals; and a signal processing circuit that has a two-step equalization algorithm converging actual constellation points into desired constellation points, the two-step equalization algorithm comprising; a first equalization algorithm that uses multiple modulus in performing an error signal calculation; and a second equalization algorithm that includes a filtering procedure that compares actual constellation points in an intermediate signal resulting from the first equalization algorithm with desired constellation points and an adjustment procedure that iteratively adjusts parameters of the filtering procedure in accordance with the comparison result, wherein the first equalization algorithm includes a cascaded multi-modulus algorithm that utilizes at least two reference circles in a cascaded way, and wherein the at least two reference circles include reference circles that have reference radiuses corresponding to the highest and lowest amplitudes of the amplitude modified optical signal. - View Dependent Claims (2, 3, 5)
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4. (canceled)
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6. An optical communication system, comprising:
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a light source that generates a light wave as an optical carrier wave, at a transmitter side; a modulation signal generator that processes information bits to be transferred in a form of an optical multi-level pulse amplitude modulation signal using a probabilistic shaping scheme, at the transmitter side; an optical signal receiving circuit that detects the optical multi-level pulse amplitude modulation signal mapped to constellation points and converts the optical signal into electrical signals, at a receiver side; and a signal processing circuit that has a two-step equalization algorithm converging actual constellation points into desired constellation points, at the receiver side, the two-step equalization algorithm comprising; a first equalization algorithm that uses multiple modulus in performing an error signal calculation; and a second equalization algorithm that includes a filtering procedure that compares actual constellation points in an intermediate signal resulting from the first equalization algorithm with desired constellation points and an adjustment procedure that iteratively adjusts parameters of the filtering procedure in accordance with the comparison result, wherein the first equalization algorithm includes a cascaded multi-modulus algorithm that utilizes at least two reference circles in a cascaded way, and wherein the at least two reference circles include reference circles that have reference radiuses corresponding to the highest and lowest amplitudes of the amplitude modified optical signal. - View Dependent Claims (7, 8, 9, 10, 11, 12, 14)
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13. (canceled)
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15. A method of recovering information bits from a probabilistically shaped (PS), multi-level pulse amplitude modulation (PAM) optical signals, comprising:
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receiving the PS multi-level PAM optical signal mapped to constellation points; converting the optical signal into an electrical signal; and processing the converted electrical signal using a two-step equalization algorithm converging actual constellation points into desired constellation points, at the receiver side, the two-step equalization algorithm comprising; a first equalization algorithm that uses multiple modulus in performing an error signal calculation; and a second equalization algorithm that includes a filtering procedure that compares actual constellation points in an intermediate signal resulting from the first equalization algorithm with desired constellation points and an adjustment procedure that iteratively adjusts parameters of the filtering procedure in accordance with the comparison result, wherein the first equalization algorithm includes a cascaded multi-modulus algorithm that utilizes at least two reference circles in a cascaded way, and wherein the at least two reference circles include reference circles that have reference radiuses corresponding to the highest and lowest amplitudes of the amplitude modified optical signal. - View Dependent Claims (17, 18, 19, 20)
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16. (canceled)
Specification