Polarization switching for optical fiber communications
View Patent ↗A method implemented in a transmission apparatus used in an optical fiber communications system for a polarization switched differential quaternary phase-shift keying (DQPSK) signal is disclosed. The method comprises splitting data into two or more data streams, inputting said two or more data streams to 1-bit DQPSK precoders to perform 1-bit DQPSK precoding, and multiplexing inphase outputs of the 1-bit DQPSK precoders to generate a first output; and multiplexing quadrature outputs of the 1-bit DQPSK precoders to generate a second output. Other methods, apparatuses, and systems also are disclosed.
1. A method implemented in a transmission apparatus used in an optical fiber communications system for a polarization switched differential quaternary phase-shift keying (DQPSK) signal, the method comprising:
splitting data into two or more data streams; inputting said two or more data streams to 1-bit DQPSK precoders to perform 1-bit DQPSK precoding;
multiplexing inphase outputs of the 1-bit DQPSK precoders to generate a first output; and
multiplexing quadrature outputs of the 1-bit DQPSK precoders to generate a second output,
wherein an operation speed of the 1-bit DQPSK precoders is set to half of a total data rate to perform differential encoding of the two of more data streams,
wherein the first and second outputs 1 and 2 have the following signals:
output 1 : x 1 y 1 x 3 y 3 x 5 y 5 . . .
output 2 :x 0 y 0 x 2 y 2 x 4 y 4 . . .
where xn and yn represent nth data from odd and even channels, and each output has at least part of two independent data streams x and y and when performing 2-bit differential detection (x 3 -x 1 , y 3 -yl, x 5 -x 3 , y 5 -y 3 , . . . ) on a receiver side, precoded data in each data can be correctly decoded.
2. The method as in claim 1 ,
wherein the two or more data streams comprise even and odd channels.
3. The method as in claim 1 ,
wherein the 1-bit DQPSK precoding is preformed independently by each of the 1-bit DQPSK precoders.
4. The method as in claim 1 ,
wherein the DQPSK precoders are driven by a clock at a half symbol rate.
5. The method as in claim 1 , further comprising:
time-aligning the inphase outputs and the quadrature outputs ofthe 1-bit DQPSK precoders with one or more time delay units.
6. The method as in claim 5 ,
wherein the inphase outputs of the 1-bit DQPSK precoders are time-aligned so that the inphase outputs are in the original time order of the data.
7. The method as in claim 5 ,
wherein the quadrature outputs of the 1-bit DQPSK precoders are time-aligned so that the quadrature outputs are in the original time order of the data.
8. A transmission apparatus used in an optical fiber communications system for a polarization switched differential quaternary phase-shift keying (DQPSK) signal, the transmission apparatus comprising:
a splitting unit to split data into two or more data streams;
1-bit DQPSK precoders to perform 1-bit DQPSK precoding for said two or more data streams;
a first multiplexer to multiplex inphase outputs of the 1-bit DQPSK precoders to generate a first output; and
a second multiplexer to multiplex quadrature outputs of the 1-bit DQPSK precoders to generate a second output,
wherein an operation speed of the 1-bit DQPSK precoders is set to half of a total data rate to perform differential encoding of the two of more data streams, and
the first and second outputs 1 and 2 have the following signals:
output 1 : x 1 y 1 x 3 y 3 x 5 y 5 . . .
output 2 :x 0 y 0 x 2 y 2 x 4 y 4 . . .
where xn and yn represent nth data from odd and even channels, and each output has at least part of two independent data streams x and y and when performing 2-bit differential detection (x 3 -x 1 , y 3 -yl, x 5 -x 3 , y 5 -y 3 , . . . ) on a receiver side, precoded data in each data can be correctly decoded.
9. The transmission apparatus as in claim 8 ,
wherein the two or more data streams comprise even and odd channels.
10. The transmission apparatus as in claim 8 ,
wherein the 1-bit DQPSK precoding is preformed independently by each of the 1-bit DQPSK precoders.
11. The transmission apparatus as in claim 8 ,
wherein the DQPSK precoders are driven by a clock at a half symbol rate.
12. The transmission apparatus as in claim 8 , further comprising:
a time delay unit to time-align the inphase outputs and the quadrature outputs of the 1-bit DQPSK precoders.
13. The transmission apparatus as in claim 12 ,
wherein the inphase outputs of the 1-bit DQPSK precoders are time-aligned so that the inphase outputs are in the original time order of the data.
14. The transmission apparatus as in claim 12 ,
wherein the quadrature outputs of the 1-bit DQPSK precoders are time-aligned so that the quadrature outputs are in the original time order of the data.
15. A method implemented in an optical fiber communications system for a polarization switched differential quaternary phase-shift keying (DQPSK) signal, the method comprising:
splitting data into two or more data streams;
inputting said two or more data streams to 1-bit DQPSK precoders to perform 1-bit DQPSK precoding;
multiplexing inphase outputs of the 1-bit DQPSK precoders to generate a first output; and
multiplexing quadrature outputs of the 1-bit DQPSK precoders to generate a second output,
wherein an operation speed of the 1-bit DQPSK precoders is set to half of a total data rate to perform differential encoding of the two of more data streams,
wherein the first and second outputs 1 and 2 have the following signals:
output 1 : x 1 y 1 x 3 y 3 x 5 v 5 . . .
output 2 :x 0 v 0 x 2 y 2 x 4 y 4 . . .
where xn and yn represent nth data from odd and even channels, and each output has at least part of two independent data streams x and y and when performing 2-bit differential detection (x 3 -x 1 , y 3 -yl, x 5 -x 3 , y 5 -y 3 , . . . ) on a receiver side, precoded data in each data can be correctly decoded.
16. The method as in claim 15 ,
wherein the two or more data streams comprise even and odd channels.
17. The method as in claim 15 ,
wherein the 1-bit DQPSK precoding is preformed independently by each ofthe 1-bit DQPSK precoders.
18. The method as in claim 15 ,
wherein the DQPSK precoders are driven by a clock at a half symbol rate.
19. The method as in claim 15 , further comprising:
time-aligning the inphase outputs and the quadrature outputs of the 1-bit DQPSK precoders with one or more time delay units.
20. The method as in claim 19 ,
wherein the inphase outputs of the 1-bit DQPSK precoders are time-aligned so that the inphase outputs are in the original time order of the data or the quadrature outputs of the 1-bit DQPSK precoders are time-aligned so that the quadrature outputs are in the original time order ofthe data.