High data rate optical transport network using 8-PSK
View Patent ↗Methods, systems, and devices are described for modulating data for optical transmissions and demodulating data from optical transmissions. During modulation, bits are mapped to symbols using an 8-ary modulation scheme. The modulation scheme may be based on 8 Phase Shift Keying (8-PSK), Dual Polarization 8-PSK, or 7-1 PSK for which one of the symbols is located at or near the origin of the constellation. Streams with the symbol-mapped bits are modulated onto a waveform in the digital domain that is converted into a waveform in the analog domain before is output for conversion to an optical signal. The streams may be filtered at baseband with at least one discrete pulse-shaping filter. During demodulation, pulse-shaped data received from an optical signal and comprising symbol-mapped bits based on the 8-ary modulation scheme is sampled. The sampled data is filtered with at least one discrete pulse-shaping filter, and then equalized and demodulated.
1. A method of modulating data for optical transmissions, comprising:
mapping bits to symbols utilizing an 8-ary modulation scheme comprising a 7-1 PSK modulation scheme, the 7-1 PSK modulation scheme being based on a constellation with one symbol offset from an origin of a complex plane;
modulating one or more streams comprising the symbol-mapped bits onto a waveform in the digital domain;
converting the waveform in the digital domain to a waveform in the analog domain; and
outputting the converted waveform in the analog domain for conversion to an optical signal.
2. The method of claim 1 , wherein
the one symbol is offset from the origin of the complex plane along an in-phase axis.
3. The method of claim 1 , wherein outputting the converted waveform in the analog domain comprises:
outputting the converted waveform in the analog domain at a data rate of about 200 Gigabits-per-second for conversion to the optical signal.
4. The method of claim 1 , further comprising:
filtering, at baseband, the one or more streams with at least one discrete pulse-shaping filter.
5. The method of claim 1 , further comprising:
outputting the converted waveform in the analog domain at a data rate of about 200 Gigabits-per-second for conversion to the optical signal, wherein the optical signal is transmitted via a link that supports legacy data rates of 100 Gigabits-per-second or lower.
6. A transmitter device, comprising:
a mapper module configured to map bits to symbols utilizing an 8-ary modulation scheme comprising a 7-1 PSK modulation scheme, the 7-1 PSK modulation scheme being based on a constellation with one symbol offset from an origin of a complex plane;
a modulation module configured to modulate one or more streams comprising the symbol-mapped bits onto a waveform in the digital domain; and
a digital-to-analog converter (DAC) module configured to:
convert the waveform in the digital domain to a waveform in the analog domain, and
output the converted waveform in the analog domain for conversion to a radiated electromagnetic signal.
7. The transmitter device of claim 6 , wherein the one symbol is offset from the origin of the complex plane along an in-phase axis.
8. The transmitter device of claim 6 , wherein the DAC module is configured to output the converted waveform in the analog domain at a rate of about 200 Gigabits-per-second for conversion to the radiated electromagnetic signal.
9. The transmitter device of claim 6 , further comprising:
a filter module configured to filter, at baseband, the one or more streams comprising the symbol-mapped bits.
10. The transmitter device of claim 9 , wherein the filter module comprises at least one discrete pulse-shaping filter.
11. The transmitter device of claim 6 , wherein the DAC module is configured to output the converted waveform in the analog domain at a rate of about 200 Gigabits-per-second for conversion to an optical signal, wherein the optical signal is transmitted via a link that supports legacy data rates of 100 Gigabits-per-second or lower.
12. A system for modulating data for optical transmissions, comprising:
means for mapping bits to symbols utilizing an 8-ary modulation scheme comprising a 7-1 PSK modulation scheme, the 7-1 PSK modulation scheme being based on a constellation with one symbol offset from an origin of a complex plane;
means for modulating one or more streams comprising the symbol-mapped bits onto a waveform in the digital domain;
means for converting the waveform in the digital domain to a waveform in the analog domain; and
means for outputting the converted waveform in the analog domain for conversion to an optical signal.
13. The system of claim 12 , wherein
the one symbol is offset from the origin of the complex plane along an in-phase axis.
14. A method of demodulating data from optical transmissions, comprising:
sampling pulse-shaped data received from an optical signal, the pulse-shaped data comprising symbol-mapped bits based on an 8-ary modulation scheme, and the optical signal being an optical conversion of a waveform in the analog domain modulated with the pulse-shaped data, wherein the 8-ary modulation scheme comprises a 7-1 PSK modulation scheme, the 7-1 PSK modulation scheme being based on a constellation with one symbol offset from an origin of a complex plane;
filtering the sampled pulse-shaped data with at least one discrete pulse-shaping filter;
equalizing the filtered data; and
demodulating one or more streams comprising the equalized data.
15. The method of claim 14 , wherein sampling the pulse-shaped data comprises:
sampling the pulse-shaped data at a first sampling rate that is twice a symbol rate of the optical signal; and
down-sampling the sampled pulse-shaped data at a second sampling rate that is between 1.0 and 1.3 the symbol rate of the optical signal.
16. An optical modem apparatus, comprising:
a transmitter configured to:
map bits to symbols utilizing an 8-ary modulation scheme comprising a 7-1 PSK modulation scheme, the 7-1 PSK modulation scheme being based on a constellation with one symbol offset from an origin of a complex plane
modulate one or more streams comprising the symbol-mapped bits onto a waveform in the digital domain, and
convert the waveform in the digital domain to a waveform in the analog domain for conversion to a first optical signal; and
a receiver configured to:
sample pulse-shaped data received from a second optical signal, the pulse-shaped data comprising symbol-mapped bits based on the 8-ary modulation scheme, wherein the 8-ary modulation scheme comprises the 7-1 PSK modulation scheme, and
demodulate bits from symbols recovered from the sampled pulse-shaped data.
17. The method of claim 1 , wherein the one symbol is offset from the origin of the complex plane along a quadrature axis.
18. The method of claim 1 , wherein the one symbol is offset from both an in-phase axis and a quadrature axis of the complex plane.
19. The transmitter device of claim 6 , wherein the one symbol is offset from the origin of the complex plane along a quadrature axis.
20. The transmitter device of claim 6 , wherein the one symbol is offset from both an in-phase axis and a quadrature axis of the complex plane.
21. The system of claim 12 , wherein the one symbol is offset from the origin of the complex plane along a quadrature axis.
22. The system of claim 12 , wherein the one symbol is offset from both an in-phase axis and a quadrature axis of the complex plane.
23. The method of claim 14 , wherein the one symbol is offset from the origin of the complex plane along an in-phase axis.
24. The method of claim 14 , wherein the one symbol is offset from the origin of the complex plane along a quadrature axis.
25. The method of claim 14 , wherein the one symbol is offset from both an in-phase axis and a quadrature axis of the complex plane.
26. A receiver device, comprising:
an analog to digital converter module configured to sample pulse-shaped data received from an optical signal, the pulse-shaped data comprising symbol-mapped bits based on an 8-ary modulation scheme, and the optical signal being an optical conversion of a waveform in the analog domain modulated with the pulse-shaped data, wherein the 8-ary modulation scheme comprises a 7-1 PSK modulation scheme based on a constellation with one symbol offset from an origin of a complex plane;
a matched filter module configured to filter the sampled pulse-shaped data with at least one discrete pulse-shaping filter;
an adaptive equalizer module configured to equalize the filtered data; and
a demodulator module configured to demodulate one or more streams comprising the equalized data.
27. The receiver device of claim 26 , wherein the one symbol is offset from the origin of the complex plane along an in-phase axis.
28. The receiver device of claim 26 , wherein the one symbol is offset from the origin of the complex plane along a quadrature axis.
29. The receiver device of claim 26 , wherein the one symbol is offset from both an in-phase axis and a quadrature axis of the complex plane.