Histogram based optimization for optical modulation
View Patent ↗The present invention is directed to communication systems and methods. In a specific embodiment, the present invention provides an optical receiver that receives a data stream from an optical transmitter. The optical receiver determines a histogram contour parameter using the data stream and inserts the histogram contour parameter into a back-channel data segment, which is then transmitted to the optical transmitter. The optical transmitter changes its data transmission setting based on the histogram contour parameter. There are other embodiments as well.
1. An optical transceiver apparatus comprising:
an optical receiver for converting incoming optical signals to incoming electrical signals;
a histogram generation module configured to analyze the incoming electrical signals and to generate a histogram characterizing the incoming electrical signals;
a control module configured to process the incoming electrical signal and to generate a signal quality value based on the histogram, the signal quality value being calculated using a quadratic fit of the histogram, the signal quality value being associated with a first order coefficient of the quadratic fit;
a back-channel insertion module configured to insert the signal quality value to an outgoing data stream; and
an optical transmitter for generating output optical signals based on the outgoing data stream.
2. The apparatus of claim 1 wherein further comprising an FEC module configured to encapsulate the back-channel data and a portion of the outgoing data stream into an FEC frame.
3. The apparatus of claim 1 wherein the optical transmitter comprises a laser device.
4. The apparatus of claim 3 wherein the control module is configured to change one or more settings for the laser device based on received back-channel data embedded in the incoming electrical signals.
5. The apparatus of claim 4 wherein the one or more settings include a laser wavelength.
6. The apparatus of claim 1 wherein the optical transmitter comprises a modulator.
7. The apparatus of claim 6 wherein the control module is configured to change one or more settings for the modulator based on received back-channel data embedded in the incoming electrical signals.
8. The apparatus of claim 7 wherein the control module is configured to change base phase offset for the modulator, heating power being associated with a bias phase offset.
9. The apparatus of claim 1 wherein the control module is configured to adjust one or more settings of the optical transceiver until the first order coefficient reaches zero.
10. The apparatus of claim 1 wherein the histogram is based on signal levels and hit counts of the incoming electrical signals.
11. The apparatus of claim 1 wherein the signal quality value comprises a histogram contour parameter.
12. A method for optimizing optical communication, the method comprising:
receiving a first data stream from a first optical transceiver by a second optical transceiver;
detecting a first back-channel data segment at the first data stream by the second optical transceiver;
determining a histogram contour parameter associated with the first data stream by the second optical transceiver, the histogram contour parameter being based on a first order coefficient of a quadratic fit;
generating a second back-channel data by the second optical transceiver, the second back-channel data comprising the first order coefficient;
inserting the second back-channel data to a second data stream by the second optical transceiver;
transmitting the second data stream from the second optical transceiver to the first optical transceiver; and
adjusting one or more operating parameters by the first optical transceiver based on the second back-channel data.
13. The method of claim 12 wherein a first set of adjustments comprises a DAC controlled heating power.
14. The method of claim 12 wherein the first data stream is in PAM4 format.
15. The method of claim 14 wherein the histogram contour parameter is based on a PAM4 histogram of the first data stream.
16. The method of claim 12 wherein further comprising adjust the one or more operating parameters by the first optical transceiver until the first order coefficient is zero.