CN114039831B - Method and device for converting QPSK signal into PAM signal format - Google Patents

Method and device for converting QPSK signal into PAM signal format Download PDF

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CN114039831B
CN114039831B CN202111274764.6A CN202111274764A CN114039831B CN 114039831 B CN114039831 B CN 114039831B CN 202111274764 A CN202111274764 A CN 202111274764A CN 114039831 B CN114039831 B CN 114039831B
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qpsk
pam
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vector
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CN114039831A (en
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崔嘉斌
纪越峰
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Beijing University of Posts and Telecommunications
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Beijing University of Posts and Telecommunications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/3405—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
    • H04L27/3444—Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power by applying a certain rotation to regular constellations

Abstract

The invention provides a method and a device for converting a QPSK signal into a PAM signal format, and belongs to the technical field of signal processing. The method comprises the following steps: acquiring a quadrature phase shift keying QPSK signal; adding phase shift to four constellation points of the QPSK signal, so that after the four constellation points are rotated by a preset angle to realize constellation rotation, the QPSK signal with the constellation rotation is obtained and serves as a first signal; and carrying out vector shifting on the four constellation points of the first signal based on the non-degenerate Phase Sensitive Amplification (PSA), so as to obtain a Pulse Amplitude Modulation (PAM) signal format, wherein the real values of the vectors of the four constellation points are positive or negative, or the imaginary values of the vectors are positive or negative, and the Pulse Amplitude Modulation (PAM) signal format corresponds to the preset angle. The embodiment of the invention realizes flexible conversion between QPSK signals and various PAM signal formats.

Description

Method and device for converting QPSK signal into PAM signal format
Technical Field
The invention relates to the technical field of signal processing, in particular to a method and a device for converting a QPSK signal into a PAM signal format.
Background
In recent years, optical communication networks have become an important backbone of modern communication industry, and are widely applied to fields from ethernet to telecommunication backbone networks and other communication fields, and become an important infrastructure for high-speed data transmission. Different types of optical transmission networks are suitable for different types of modulation format signals, and are mainly classified into short-distance transmission networks and medium-long-distance transmission networks according to transmission distance.
The All-optical Signal Processing (ASP) technology avoids the use of a photoelectric conversion method, directly processes optical signals in a network in an optical domain, can greatly improve the Processing speed of data signals, and gets rid of the limitation of 'electronic speed'. Among them, many ASP techniques and applications based on optical nonlinear effect are proposed, such as Phase-sensitive Amplification (PSA) technique. PSA technology is gradually becoming a research hotspot in ASP due to its low noise and high gain characteristics, and PSA technology based on all-optical has been widely paid attention and researched in the direction of signal format conversion. Most of the proposed format conversion schemes focus On the conversion between the basic modulation format signals, such as On-Off Keying (OOK), Binary Phase Shift Keying (BPSK), and Quadrature Phase Shift Keying (QPSK). The conversion research between QPSK and PAM signals which are applied in the actual optical transmission network is lacked, so that the conversion between the QPSK signal and various PAM signal formats is realized, and the method has great application value and practical significance for the optical transmission network.
Disclosure of Invention
The embodiment of the invention provides a method and a device for converting a QPSK signal into a PAM signal format, which are used for solving the problem that the current practical optical transmission network is lack of flexible conversion between the QPSK signal and various PAM signal formats.
In a first aspect, a method for converting a QPSK signal into a PAM signal format according to an embodiment of the present invention includes:
acquiring a quadrature phase shift keying QPSK signal;
adding phase shift to four constellation points of the QPSK signal, so that after the four constellation points are rotated by a preset angle to realize constellation rotation, the QPSK signal after constellation rotation is obtained and used as a first signal;
and carrying out vector shifting on the four constellation points of the first signal based on the non-degenerate Phase Sensitive Amplification (PSA), so as to obtain a Pulse Amplitude Modulation (PAM) signal format, wherein the real values of the vectors of the four constellation points are positive or negative, or the imaginary values of the vectors are positive or negative, and the Pulse Amplitude Modulation (PAM) signal format corresponds to the preset angle.
Preferably, phase shifts are added to the four constellation points of the QPSK signal, which is formulated as follows:
Figure BDA0003329771890000021
wherein the content of the first and second substances,
Figure BDA0003329771890000022
for vector expression of the acquired QPSK signal, A q Is that it isThe amplitude of the QPSK signal is then used,
Figure BDA0003329771890000023
for the phase of the QPSK signal,
Figure BDA0003329771890000024
vector expression, A, of a first signal obtained after adding a phase shift to a QPSK signal s Is the amplitude of the first signal and is,
Figure BDA0003329771890000025
delta is a phase of the first signal, is a preset angle of controllable rotation of the QPSK signal, and is a constant.
Preferably, the vector shifting is performed on four constellation points of the first signal based on the non-degenerate phase sensitive amplification PSA, so as to obtain a pulse amplitude modulation PAM signal format in which real vector values of the four constellation points are positive or negative, or virtual vector values are positive or negative, and which corresponds to the preset angle, the pulse amplitude modulation PAM signal format including:
when the first signal and the two pump light signals P0 and P1 are injected into a nonlinear optical medium to carry out mixing processing based on a four-wave mixing FWM effect, by controlling the power ratio of the two pump light signals P0 and P1 to the first signal and the relative phases of the two pump light signals P0 and P1 to the first signal carrier, the real values of vectors of the moved signal vectors serving as four constellation points are positive or negative, or the virtual values of the vectors are positive or negative, and a Pulse Amplitude Modulation (PAM) signal format corresponding to the preset angle is obtained; wherein the optical wave vector expressions of the first signal, the two pump light signals P0 and P1 are respectively
Figure BDA0003329771890000031
Figure BDA0003329771890000032
And
Figure BDA0003329771890000033
and the position relation of the wavelength spectrum between the optical waves is that P1 is located at P0 and the first optical waveThe middle of the signal.
Preferably, the formula of the shifted signal vector is as follows:
Figure BDA0003329771890000034
wherein the content of the first and second substances,
Figure BDA0003329771890000035
representing the shifted signal vector, A out To the magnitude of the output shifted signal vector,
Figure BDA0003329771890000036
amplitude gain, A, of the input first signal for phase-sensitive amplification s Is the amplitude of the incoming first signal,
Figure BDA0003329771890000037
is the carrier phase of the first signal and,
Figure BDA0003329771890000038
is the information phase of the first signal, and n is the idler generated during phase-sensitive amplification
Figure BDA0003329771890000039
And the input first signal
Figure BDA00033297718900000310
The ratio of the amplitudes of (a) to (b),
Figure BDA00033297718900000311
Figure BDA00033297718900000312
δ is a controllable constant that gives a fixed relative phase between the carriers of the two pump optical signals and the first signal.
Preferably, the pulse amplitude modulation PAM signal format corresponding to the preset angle includes:
when controlling the pre-stageSetting an angle delta such that
Figure BDA00033297718900000313
Then, the QPSK signal is converted into an OOK signal;
when the preset angle delta is controlled to be
Figure BDA00033297718900000314
Then, the QPSK signal is converted into a PAM3 signal;
when the preset angle delta is controlled to be
Figure BDA00033297718900000315
When the signal is in the range of (45-90 degrees), the QPSK signal is converted into a PAM4 signal with adjustable eye power ratio;
wherein the content of the first and second substances,
Figure BDA00033297718900000316
the included angle between the constellation point connecting line of the QPSK signal and the horizontal axis of the coordinate is shown.
In a second aspect, an apparatus for implementing QPSK signal conversion into PAM signal format according to an embodiment of the present invention includes:
the QPSK signal acquisition module is used for acquiring a quadrature phase shift keying QPSK signal;
a first signal obtaining module, configured to add phase shifts to four constellation points of the QPSK signal, so that the four constellation points rotate by a preset angle to implement constellation rotation, and obtain a QPSK signal after constellation rotation as a first signal;
and the PAM signal format obtaining module is used for carrying out vector shifting on the four constellation points of the first signal based on the nondegenerate phase sensitive amplification PSA to obtain a pulse amplitude modulation PAM signal format, wherein the real values of the vectors of the four constellation points are positive or negative, or the imaginary values of the vectors are positive or negative, and the pulse amplitude modulation PAM signal format corresponds to the preset angle.
Preferably, the first signal obtaining module is configured to add phase shifts to four constellation points of the QPSK signal, and the formula is as follows:
Figure BDA0003329771890000041
wherein the content of the first and second substances,
Figure BDA0003329771890000042
for vector expression of the acquired QPSK signal, A q For the amplitude of the QPSK signal,
Figure BDA0003329771890000043
for the phase of the QPSK signal,
Figure BDA0003329771890000044
vector expression, A, of a first signal obtained after adding a phase shift to a QPSK signal s Is the amplitude of the first signal and is,
Figure BDA0003329771890000045
delta is a phase of the first signal, is a preset angle of controllable rotation of the QPSK signal, and is a constant.
Preferably, the PAM signal format obtaining module is specifically configured to, when injecting the first signal and the two pump light signals P0 and P1 into a nonlinear optical medium to perform mixing processing based on a four-wave mixing FWM effect, obtain shifted signal vectors as pulse amplitude modulation PAM signal formats that the real values of vectors of the four constellation points are positive or negative or the imaginary values of vectors are positive or negative and are converted correspondingly to the preset angle by controlling the power ratios of the two pump light signals P0 and P1 to the first signal and the relative phases of the two pump light signals P0 and P1 to the first signal carrier; wherein the optical wave vector expressions of the first signal, the two pump light signals P0 and P1 are respectively
Figure BDA0003329771890000046
And
Figure BDA0003329771890000047
and the positional relationship of the wavelength spectrum between the optical waves is that P1 is located in the middle of P0 and the first signal.
In a third aspect, an embodiment of the present invention provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor executes the program to implement the method steps for converting QPSK signals into PAM signal format according to any of the above-mentioned first aspects.
In a fourth aspect, an embodiment of the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the method steps for converting a QPSK signal into a PAM signal format according to any of the above-mentioned first aspects.
The embodiment of the invention provides a method and a device for converting a QPSK signal into a PAM signal format, wherein the method comprises the steps of obtaining a Quadrature Phase Shift Keying (QPSK) signal, adding phase shifts to four constellation points of the QPSK signal, enabling the four constellation points to rotate by a preset angle to realize constellation rotation, obtaining the QPSK signal after constellation rotation as a first signal, carrying out vector shifting on the four constellation points of the first signal based on nondegenerate Phase Sensitive Amplification (PSA), and obtaining the PAM signal format of pulse amplitude modulation, wherein the real values of the vectors of the four constellation points are positive or negative or the virtual values of the vectors are positive or negative, and the PAM signal format corresponds to the preset angle. The invention realizes flexible conversion between QPSK signal and various PAM signal formats.
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In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
Fig. 1 is a conceptual diagram of the whole scheme for converting QPSK signal into PAM signal format according to the present invention;
fig. 2 is a schematic flowchart of a method for converting a QPSK signal into a PAM signal format according to the present invention;
fig. 3 is a functional schematic diagram of an all-optical conversion scheme provided by the present invention for converting QPSK signals into PAM signal format;
FIG. 4(a) is a schematic block diagram of the non-degenerate PSA based vector movement provided by the present invention;
fig. 4(b) is a wavelength spectrum relationship diagram between signal light after constellation rotation and optical waves of two pump lights provided by the present invention;
fig. 5 is an overall block diagram for implementing QPSK signal conversion into PAM signal format according to the present invention;
fig. 6 is a schematic structural diagram of an apparatus for implementing conversion of QPSK signal into PAM signal format according to the present invention;
fig. 7 is a schematic structural diagram of an electronic device provided by the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a scheme for converting a QPSK signal into a PAM signal format based on a primary phase-sensitive amplification process, wherein the signal processing process is divided into two parts and comprises a signal constellation rotation process and a vector shifting process based on PSA. The overall concept of the scheme is as shown in fig. 1, QPSK signals applicable to a long-distance transmission network can be converted into PAM signals applicable to a short-distance transmission network after being processed by the format conversion scheme, and the QPSK signals can be selectively converted into OOK, PAM3 or PAM4 signals with different power ratios, so that flexible format conversion from one path of QPSK signals to PAM signals is realized, and a flexible all-optical path is built between the long-distance transmission network and short-distance transmission networks such as optical interconnection of a data center and various convergence accesses.
Several key protection points of the technical scheme of the invention are as follows:
1) the conversion of constellation rotation and vector movement adopts the conversion process of firstly constellation rotation and then vector movement, can convert signals such as QPSK and the like, and has good expandability. The input signal is processed in a single path from beginning to end, and the problem of coherence influenced by environmental factors caused by the split processing does not exist.
2) By adjusting the relative phase between the pump light and the signal carrier in the constellation rotation step, different types of PAM signals can be finally output.
3) The whole conversion function can be realized only by one section of nonlinear optical medium, namely, one-time phase sensitive amplification process, and the process is simple and easy to realize.
A method and an apparatus for converting QPSK signals into PAM signal format according to the present invention are described below with reference to fig. 2 to fig. 7.
The embodiment of the invention provides a method for converting a QPSK signal into a PAM signal format. Fig. 2 is a flowchart illustrating a method for converting a QPSK signal into a PAM signal format according to an embodiment of the present invention, as shown in fig. 2, the method includes:
step 210, obtaining quadrature phase shift keying QPSK signals;
step 220, adding phase shift to four constellation points of the QPSK signal, so that after the four constellation points are all rotated by a preset angle to realize constellation rotation, a constellation-rotated QPSK signal is obtained as a first signal;
and step 230, carrying out vector shifting on the four constellation points of the first signal based on the non-degenerate Phase Sensitive Amplification (PSA), so as to obtain a Pulse Amplitude Modulation (PAM) signal format corresponding to the preset angle, wherein real vector values of the four constellation points are positive or negative, and imaginary vector values of the four constellation points are positive or negative.
Compared with the prior art, the method provided by the embodiment of the invention can realize format conversion of higher-order signals through two simple operations of constellation rotation and vector movement, has stronger expansibility, and keeps the wavelength of input signals and the wavelength of output signals consistent in the conversion.
In particular toThe specific implementation process of the all-optical conversion scheme of the present invention is shown in fig. 3, and is firstly a constellation rotation process, wherein a phase shift is added to a QPSK signal through a programmable filter (Waveshaper), and constellation points of the QPSK signal are rotated by a certain angle, as shown in fig. 3
Figure BDA0003329771890000081
Is the included angle between the straight line of the constellation point and the horizontal axis of the coordinate. The term "adding a phase shift to the input QPSK signal" is used to distinguish its four constellation points in terms of power after subsequent vector shifting. The constellation rotated QPSK signal is delivered to a PSA-based vector shifting section, which functions to add a constant vector to the input vector to achieve overall shifting. After the QPSK signal is shifted, the real values of all the constellation point vectors are the same sign, i.e., all the constellation point vectors are positive or all the constellation point vectors are negative. The process can also make the imaginary values of the constellation point vectors of the rotated QPSK signals all be the same sign through the vector shifting process. Therefore, the four constellation points of the QPSK signal can be distinguished in power, and the all-optical conversion from the QPSK signal to the PAM signal is realized.
Based on any of the above embodiments, phase shifts are added to the four constellation points of the QPSK signal, and the formula is as follows:
Figure BDA0003329771890000082
wherein the content of the first and second substances,
Figure BDA0003329771890000083
for vector expression of the acquired QPSK signal, A q For the amplitude of the QPSK signal,
Figure BDA0003329771890000084
in order to be the phase of the QPSK signal,
Figure BDA0003329771890000085
vector expression, A, of a first signal obtained after adding a phase shift to a QPSK signal s Is the amplitude of the first signal and is,
Figure BDA0003329771890000086
delta is a phase of the first signal, is a preset angle of controllable rotation of the QPSK signal, and is a constant.
In particular, the constellation rotation part adopted by the invention is realized by adding phase shift to the signal, and the actual operation process can be realized by a programmable filter (waveshape). The waveshape is a mature optical signal processing device, can finely control the amplitude and phase characteristics of signals in a C waveband, an L waveband or a C + L waveband, and can introduce any additional phase into an input QPSK signal through program control to realize constellation rotation. Adding a phase shift process to the input QPSK signal via waveshape can be simply expressed as:
Figure BDA0003329771890000087
wherein the content of the first and second substances,
Figure BDA0003329771890000088
and
Figure BDA0003329771890000089
and respectively representing the input QPSK signal and the vector expression of the QPSK signal added with the phase shift by the Waveshape, wherein delta is the phase shift added by the Waveshape for the input QPSK signal, so that the function of constellation rotation is realized.
Based on any of the above embodiments, vector shifting is performed on four constellation points of the first signal based on a non-degenerate phase sensitive amplification PSA, and a pulse amplitude modulation PAM signal format is obtained in which real vector values of the four constellation points are positive or negative, or imaginary vector values are positive or negative, and the format corresponds to the preset angle, and the method includes:
when the first signal and the two pump optical signals P0 and P1 are injected into a nonlinear optical medium for frequency mixing processing based on four-wave mixing FWM effect, the power ratio of the two pump optical signals P0 and P1 to the first signal is controlled to obtain a first signalAnd relative phases of the two pump light signals P0 and P1 and the first signal carrier wave, obtaining a Pulse Amplitude Modulation (PAM) signal format, wherein real values of the moved signal vectors serving as four constellation points are positive or negative, or virtual values of the vectors are positive or negative, and the Pulse Amplitude Modulation (PAM) signal format corresponds to the preset angle; wherein the optical wave vector expressions of the first signal and the two pump light signals P0 and P1 are respectively
Figure BDA0003329771890000091
Figure BDA0003329771890000092
And
Figure BDA0003329771890000093
and the positional relationship of the wavelength spectrum between the optical waves is that P1 is located in the middle of P0 and the first signal.
Specifically, the constellation-rotated signal is input into a vector shifting portion based on a non-degenerate PSA, which is configured as shown in fig. 4(a), two pump lights P0 and P1 and a constellation-rotated first signal light S are injected into a segment of a nonlinear optical medium for FWM effect, the wavelength spectrum relationship between the three light waves is shown in fig. 4(b), and P1 is located at a position intermediate between P0 and S. The vectors of the three input light waves are
Figure BDA0003329771890000094
Figure BDA0003329771890000095
And signal light
Figure BDA0003329771890000096
According to the principle of the non-degenerate PSA, the output signal of the optical wave having the above-mentioned spectrum relationship after passing through the FWM effect is:
Figure BDA0003329771890000097
wherein the content of the first and second substances,
Figure BDA0003329771890000098
representing the shifted signal vector, i.e. the converted output signal,
Figure BDA0003329771890000099
refers to the amplitude gain of the input signal by the phase sensitive amplification process,
Figure BDA00033297718900000910
the phase of the idler light generated in the phase-sensitive amplification process satisfies the condition
Figure BDA00033297718900000911
Based on any of the above embodiments, the formula of the shifted signal vector is as follows:
Figure BDA00033297718900000912
wherein the content of the first and second substances,
Figure BDA00033297718900000913
representing the shifted signal vector, A out To the magnitude of the output shifted signal vector,
Figure BDA0003329771890000101
amplitude gain, A, of the input first signal for phase-sensitive amplification s Is the amplitude of the incoming first signal,
Figure BDA0003329771890000102
is the carrier phase of the first signal and,
Figure BDA0003329771890000103
is the information phase of the first signal, and n is the idler generated during phase-sensitive amplification
Figure BDA0003329771890000104
And the input first signal
Figure BDA0003329771890000105
The ratio of the amplitudes of (a) to (b),
Figure BDA0003329771890000106
Figure BDA0003329771890000107
δ is a controllable constant that gives a fixed relative phase between the carriers of the two pump optical signals and the first signal.
In particular, the input first signal phase may be expressed as the sum of the carrier phase and the information phase, i.e.
Figure BDA0003329771890000108
As defined herein
Figure BDA0003329771890000109
This is introduced into the formula (4) to obtain the following formula (5):
Figure BDA00033297718900001010
wherein n is an idler frequency light
Figure BDA00033297718900001011
And an input signal
Figure BDA00033297718900001012
The amplitude ratio n can be controlled by controlling the power ratio of P0, P1 and S, and δ can be made a controllable constant by making the relative phase between the two pump lights and the signal carrier fixed.
It can be seen from the formula (5) that when δ is a controllable constant, the FWM process can be regarded as a process of adding a fixed vector to an input vector, the shifting force can be realized by controlling an n variable, and δ can be adjusted by controlling the relative phase between the pump light and the signal carrier. In the method process of the present invention, no matter how many degrees the input QPSK signal is rotated by the constellation, the vector shifting process must change the real values of all constellation point vectors into the same sign, i.e. both positive or both negative, or the imaginary values of the QPSK constellation point vectors after vector shifting are all the same sign, thus realizing the vector shifting process based on the PSA technology required in the method of the present invention.
It should be noted that, after constellation rotation and vector shift processing, the originally input QPSK signal can be converted into a PAM signal and received by detection, and the overall block diagram of the present invention is shown in fig. 5. The continuous wave is modulated by the phase modulator to generate an optical frequency comb, i.e. coherent pump light and signal carrier required in the method of the present invention. The signal carrier is IQ modulated and coupled into Spontaneous Emission (ASE) noise to obtain an arbitrary QPSK signal carrying noise. The constellation rotation required in the method can be realized by adding phase shift on a signal carrier through a programmable filter, namely Waveshape in figure 5, then the rotated QPSK signal carrying noise and coherent pump are injected into a conversion system, the all-optical conversion to the PAM signal is realized through a vector moving process, and finally, the detection, the receiving and the analysis are directly carried out through a photoelectric detector.
Based on any of the above embodiments, the pulse amplitude modulation PAM signal format corresponding to the preset angle includes:
when the preset angle delta is controlled to be
Figure BDA0003329771890000111
Then, the QPSK signal is converted into an OOK signal;
when the preset angle delta is controlled to be
Figure BDA0003329771890000112
Then, the QPSK signal is converted into a PAM3 signal;
when the preset angle delta is controlled to be
Figure BDA0003329771890000113
When the signal is in the range of (45-90 degrees), the QPSK signal is converted into a PAM4 signal with adjustable eye power ratio;
wherein，
Figure BDA0003329771890000114
The included angle between the constellation point connecting line of the QPSK signal and the horizontal axis of the coordinate is shown.
Specifically, the originally input QPSK signal is converted into a PAM signal after constellation rotation and vector shift. By controlling the angle delta of constellation rotation, the specific format of the converted PAM signal can be controlled. As shown in the figure 3 of the drawings,
Figure BDA0003329771890000115
is the included angle between the straight line of the constellation point and the horizontal axis of the coordinate. When the temperature is higher than the set temperature
Figure BDA0003329771890000116
Is/are as follows
Figure BDA0003329771890000117
The QPSK signal is converted into an OOK signal. When in use
Figure BDA0003329771890000118
Is/are as follows
Figure BDA0003329771890000119
The QPSK signal is converted into a PAM3 signal. When in use
Figure BDA00033297718900001110
Is
Figure BDA00033297718900001111
In the range of (45-90 deg.), the QPSK signal is converted into a PAM4 signal with adjustable eye power ratio.
The following describes an apparatus for implementing QPSK signal conversion into PAM signal format according to an embodiment of the present invention, and the following description and the above-described method for implementing QPSK signal conversion into PAM signal format may be referred to in correspondence.
Fig. 6 is a schematic structural diagram of a device for converting a QPSK signal into a PAM signal format according to an embodiment of the present invention, as shown in fig. 6, the device includes a QPSK signal obtaining module 610, a first signal obtaining module 620, and a PAM signal format obtaining module 630;
the QPSK signal obtaining module 610 is configured to obtain a quadrature phase shift keying QPSK signal;
the first signal obtaining module 620 is configured to add phase shifts to four constellation points of the QPSK signal, so that the four constellation points rotate by a preset angle to realize constellation rotation, and then obtain a constellation-rotated QPSK signal as a first signal;
the PAM signal format obtaining module 630 is configured to perform vector shifting on the four constellation points of the first signal based on the non-degenerate phase sensitive amplification PSA, to obtain a pulse amplitude modulation PAM signal format in which real values of vectors of the four constellation points are positive or negative, or virtual values of vectors are positive or negative, and the pulse amplitude modulation PAM signal format corresponds to the preset angle.
Compared with the prior art, the device provided by the embodiment of the invention can realize format conversion of higher-order signals through two simple operations of constellation rotation and vector movement, has stronger expansibility, and keeps the wavelength of input signals and the wavelength of output signals consistent in the conversion.
Based on any of the above embodiments, with reference to fig. 6, the first signal obtaining module 620 is configured to add phase shifts to four constellation points of the QPSK signal, and the formula is as follows:
Figure BDA0003329771890000121
wherein the content of the first and second substances,
Figure BDA0003329771890000122
for vector expression of the acquired QPSK signal, A q For the amplitude of the QPSK signal,
Figure BDA0003329771890000123
for the phase of the QPSK signal,
Figure BDA0003329771890000124
obtained by adding a phase shift to a QPSK signalVector expression of the first signal, A s Is the amplitude of the first signal and is,
Figure BDA0003329771890000125
delta is a phase of the first signal, is a preset angle of controllable rotation of the QPSK signal, and is a constant.
Based on any of the above embodiments, with reference to fig. 6, the PAM signal format obtaining module 630 is specifically configured to, when injecting the first signal and the two pump light signals P0 and P1 into a nonlinear optical medium to perform mixing processing based on a four-wave mixing FWM effect, obtain, by controlling the power ratio between the two pump light signals P0 and P1 and the first signal and the relative phases between the two pump light signals P0 and P1 and the first signal carrier, that the real vector values of the shifted signal vectors as four constellation points are positive or negative, or the imaginary vector values are positive or negative, and modulate a pulse amplitude modulation PAM signal format corresponding to the preset angle; wherein the optical wave vector expressions of the first signal, the two pump light signals P0 and P1 are respectively
Figure BDA0003329771890000131
And
Figure BDA0003329771890000132
and the positional relationship of the wavelength spectrum between the optical waves is that P1 is located in the middle of P0 and the first signal.
Based on any of the above embodiments, the formula of the shifted signal vector is as follows:
Figure BDA0003329771890000133
wherein the content of the first and second substances,
Figure BDA0003329771890000134
representing the shifted signal vector, A out To the magnitude of the output shifted signal vector,
Figure BDA0003329771890000135
amplitude gain, A, of the input first signal for phase-sensitive amplification s Is the amplitude of the incoming first signal,
Figure BDA0003329771890000136
is the carrier phase of the first signal and,
Figure BDA0003329771890000137
is the information phase of the first signal, and n is the idler generated during phase-sensitive amplification
Figure BDA0003329771890000138
And the input first signal
Figure BDA0003329771890000139
The ratio of the amplitudes of (a) to (b),
Figure BDA00033297718900001310
Figure BDA00033297718900001311
δ is a controllable constant that gives a fixed relative phase between the carriers of the two pump optical signals and the first signal.
Based on any of the above embodiments, the pulse amplitude modulation PAM signal format corresponding to the preset angle includes:
when the preset angle delta is controlled to be
Figure BDA00033297718900001312
Then, the QPSK signal is converted into an OOK signal;
when the preset angle delta is controlled to be
Figure BDA00033297718900001313
Then, the QPSK signal is converted into a PAM3 signal;
when the preset angle delta is controlled to be
Figure BDA00033297718900001314
In (45 ° -cWhen the phase shift keying (QPSK) signal is in a 90 DEG range, the QPSK signal is converted into a PAM4 signal with adjustable eye power ratio;
wherein the content of the first and second substances,
Figure BDA00033297718900001315
the included angle between the constellation point connecting line of the QPSK signal and the horizontal axis of the coordinate is shown.
Fig. 7 is a schematic structural diagram of an electronic device according to an embodiment of the present invention, and as shown in fig. 7, the electronic device may include: a processor (processor)710, a communication Interface (Communications Interface)720, a memory (memory)730, and a communication bus 740, wherein the processor 710, the communication Interface 720, and the memory 730 communicate with each other via the communication bus 740. Processor 710 may invoke logic instructions in memory 730 to perform a method of implementing the conversion of QPSK signals to PAM signal format, the method comprising: acquiring a quadrature phase shift keying QPSK signal; adding phase shift to four constellation points of the QPSK signal, so that after the four constellation points are rotated by a preset angle to realize constellation rotation, the QPSK signal after constellation rotation is obtained and serves as a first signal; and carrying out vector shifting on the four constellation points of the first signal based on the non-degenerate Phase Sensitive Amplification (PSA), so as to obtain a Pulse Amplitude Modulation (PAM) signal format, wherein the real values of the vectors of the four constellation points are positive or negative, or the imaginary values of the vectors are positive or negative, and the Pulse Amplitude Modulation (PAM) signal format corresponds to the preset angle.
In addition, the logic instructions in the memory 730 can be implemented in the form of software functional units and stored in a computer readable storage medium when the software functional units are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In another aspect, an embodiment of the present invention further provides a computer program product, where the computer program product includes a computer program stored on a non-transitory computer-readable storage medium, the computer program includes program instructions, and when the program instructions are executed by a computer, the computer can execute a method for implementing conversion of a QPSK signal into a PAM signal format, where the method includes: acquiring a quadrature phase shift keying QPSK signal; adding phase shift to four constellation points of the QPSK signal, so that after the four constellation points are rotated by a preset angle to realize constellation rotation, the QPSK signal after constellation rotation is obtained and serves as a first signal; and carrying out vector shifting on the four constellation points of the first signal based on the non-degenerate Phase Sensitive Amplification (PSA), so as to obtain a Pulse Amplitude Modulation (PAM) signal format, wherein the real values of the vectors of the four constellation points are positive or negative, or the imaginary values of the vectors are positive or negative, and the Pulse Amplitude Modulation (PAM) signal format corresponds to the preset angle.
In another aspect, an embodiment of the present invention further provides a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program is implemented by a processor to execute the above-provided methods for converting a QPSK signal into a PAM signal format, where the method includes: acquiring a quadrature phase shift keying QPSK signal; adding phase shift to four constellation points of the QPSK signal, so that after the four constellation points are rotated by a preset angle to realize constellation rotation, the QPSK signal after constellation rotation is obtained and serves as a first signal; and carrying out vector shifting on the four constellation points of the first signal based on the non-degenerate Phase Sensitive Amplification (PSA), so as to obtain a Pulse Amplitude Modulation (PAM) signal format, wherein the real values of the vectors of the four constellation points are positive or negative, or the imaginary values of the vectors are positive or negative, and the Pulse Amplitude Modulation (PAM) signal format corresponds to the preset angle.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (7)

1. A method for converting a QPSK signal to a PAM signal format, comprising:
acquiring a quadrature phase shift keying QPSK signal;
adding phase shift to four constellation points of the QPSK signal, so that after the four constellation points are rotated by a preset angle to realize constellation rotation, the QPSK signal after constellation rotation is obtained and serves as a first signal;
carrying out vector shifting on four constellation points of the first signal based on a non-degenerate Phase Sensitive Amplification (PSA) to obtain a Pulse Amplitude Modulation (PAM) signal format, wherein real values of vectors of the four constellation points are positive or negative, or virtual values of the vectors are positive or negative, and the Pulse Amplitude Modulation (PAM) signal format corresponds to the preset angle;
the method for carrying out vector shifting on four constellation points of the first signal based on the non-degenerate Phase Sensitive Amplification (PSA) to obtain the Pulse Amplitude Modulation (PAM) signal format corresponding to the preset angle, wherein the Pulse Amplitude Modulation (PAM) signal format comprises the following steps:
when the first signal and the two pump light signals P0 and P1 are injected into a nonlinear optical medium to carry out mixing processing based on a four-wave mixing FWM effect, by controlling the power ratio of the two pump light signals P0 and P1 to the first signal and the relative phases of the two pump light signals P0 and P1 to the first signal carrier, the real values of vectors of the moved signal vectors serving as four constellation points are positive or negative, or the virtual values of the vectors are positive or negative, and a Pulse Amplitude Modulation (PAM) signal format corresponding to the preset angle is obtained; wherein the optical wave vector expressions of the first signal, the two pump light signals P0 and P1 are respectively
Figure 324717DEST_PATH_IMAGE001
、
Figure 77909DEST_PATH_IMAGE002
And
Figure 834644DEST_PATH_IMAGE003
and the positional relationship of the wavelength spectrum between the optical waves is that P1 is located in the middle of P0 and the first signal;
the formula of the shifted signal vector is as follows:
Figure 800326DEST_PATH_IMAGE004
；
wherein the content of the first and second substances,
Figure 309804DEST_PATH_IMAGE005
indicating after movingThe vector of the signals is then converted into a vector of signals,
Figure 109264DEST_PATH_IMAGE006
to the magnitude of the output shifted signal vector,
Figure 477929DEST_PATH_IMAGE007
the amplitude gain on the input first signal for the phase sensitive amplification process,
Figure 637515DEST_PATH_IMAGE008
is the amplitude of the incoming first signal,
Figure 876866DEST_PATH_IMAGE009
is the carrier phase of the first signal and,
Figure 847227DEST_PATH_IMAGE010
is the information phase of the first signal,
Figure 703188DEST_PATH_IMAGE011
for idler light generated during phase-sensitive amplification
Figure 400885DEST_PATH_IMAGE012
And the input first signal
Figure 25902DEST_PATH_IMAGE013
The ratio of the amplitudes of (a) to (b),
Figure 167164DEST_PATH_IMAGE014
，
Figure 244842DEST_PATH_IMAGE015
，
Figure 746230DEST_PATH_IMAGE016
in order to have a controllable constant of fixed relative phase between the carriers of the two pump optical signals and the first signal.
2. The method of claim 1, wherein phase shifts are added to four constellation points of the QPSK signal, and the equation is as follows:
Figure 491332DEST_PATH_IMAGE017
；
wherein the content of the first and second substances,
Figure 537917DEST_PATH_IMAGE018
for the vector expression of the acquired QPSK signal,
Figure 227524DEST_PATH_IMAGE019
in order to be the amplitude of the QPSK signal,
Figure 142390DEST_PATH_IMAGE020
for the phase of the QPSK signal,
Figure 617365DEST_PATH_IMAGE021
a vector expression of the first signal obtained after adding a phase shift to the QPSK signal,
Figure 225064DEST_PATH_IMAGE022
is the amplitude of the first signal and is,
Figure 401968DEST_PATH_IMAGE023
is the phase of the first signal and is,
Figure 854946DEST_PATH_IMAGE024
the QPSK signal is rotated by a controllable preset angle and is constant.
3. The method of claim 2, wherein the Pulse Amplitude Modulation (PAM) signal format corresponding to the preset angle comprises:
when controlling the preset angle
Figure 184427DEST_PATH_IMAGE024
So that
Figure 963027DEST_PATH_IMAGE025
Then, the QPSK signal is converted into an OOK signal;
when controlling the preset angle
Figure 627227DEST_PATH_IMAGE024
So that
Figure 149475DEST_PATH_IMAGE026
Then, the QPSK signal is converted into a PAM3 signal;
when controlling the preset angle
Figure 333463DEST_PATH_IMAGE024
So that
Figure 282964DEST_PATH_IMAGE027
In that
Figure 168881DEST_PATH_IMAGE028
When the signal is within the range, the QPSK signal is converted into a PAM4 signal with adjustable eye power ratio;
wherein the content of the first and second substances,
Figure 494820DEST_PATH_IMAGE027
the included angle between the constellation point connecting line of the QPSK signal and the horizontal axis of the coordinate is shown.
4. An apparatus for converting a QPSK signal to a PAM signal format, comprising:
a QPSK signal acquisition module for acquiring a QPSK signal;
a first signal obtaining module, configured to add phase shifts to four constellation points of the QPSK signal, so that the four constellation points rotate by a preset angle to implement constellation rotation, and obtain a QPSK signal after constellation rotation as a first signal;
a PAM signal format obtaining module, configured to perform vector shifting on four constellation points of the first signal based on a non-degenerate Phase Sensitive Amplification (PSA), to obtain a Pulse Amplitude Modulation (PAM) signal format in which real vector values of the four constellation points are positive or negative or virtual vector values are positive or negative and which corresponds to the preset angle;
the PAM signal format obtaining module is specifically configured to, when the first signal and the two pump light signals P0 and P1 are injected into a nonlinear optical medium to perform mixing processing based on a four-wave mixing FWM effect, obtain shifted signal vectors as pulse amplitude modulation PAM signal formats corresponding to the preset angle, where real values of vectors of the four constellation points are all positive or negative, or virtual values of the vectors are all positive or negative, by controlling power ratios of the two pump light signals P0 and P1 to the first signal and relative phases of the two pump light signals P0 and P1 to the first signal carrier; wherein the optical wave vector expressions of the first signal, the two pump light signals P0 and P1 are respectively
Figure 533314DEST_PATH_IMAGE001
、
Figure 512771DEST_PATH_IMAGE002
And
Figure 26929DEST_PATH_IMAGE003
and the positional relationship of the wavelength spectrum between the optical waves is that P1 is located in the middle of P0 and the first signal;
the formula of the shifted signal vector is as follows:
Figure 766346DEST_PATH_IMAGE004
；
wherein, the first and the second end of the pipe are connected with each other,
Figure 783981DEST_PATH_IMAGE005
representing the shifted signal vector and,
Figure 199919DEST_PATH_IMAGE029
to the magnitude of the output shifted signal vector,
Figure 935793DEST_PATH_IMAGE030
the amplitude gain on the input first signal for the phase sensitive amplification process,
Figure 213322DEST_PATH_IMAGE008
is the amplitude of the incoming first signal,
Figure 351042DEST_PATH_IMAGE009
is the carrier phase of the first signal and,
Figure 203461DEST_PATH_IMAGE010
is the information phase of the first signal,
Figure 161053DEST_PATH_IMAGE011
for idler light generated during phase-sensitive amplification
Figure 242272DEST_PATH_IMAGE012
And the input first signal
Figure 359133DEST_PATH_IMAGE013
The ratio of the amplitudes of (a) to (b),
Figure 992239DEST_PATH_IMAGE014
，
Figure 578073DEST_PATH_IMAGE015
，
Figure 587617DEST_PATH_IMAGE016
for two pump lightsThe signal and the carrier of the first signal have a controllable constant with a fixed relative phase.
5. The apparatus of claim 4, wherein the first signal obtaining module is configured to add phase shifts to four constellation points of the QPSK signal, and the equation is as follows:
Figure 558984DEST_PATH_IMAGE017
；
wherein the content of the first and second substances,
Figure 362992DEST_PATH_IMAGE018
for the vector expression of the acquired QPSK signal,
Figure 170542DEST_PATH_IMAGE019
for the amplitude of the QPSK signal,
Figure 983777DEST_PATH_IMAGE020
for the phase of the QPSK signal,
Figure 75230DEST_PATH_IMAGE021
a vector expression of the first signal obtained after adding a phase shift to the QPSK signal,
Figure 50139DEST_PATH_IMAGE022
is the amplitude of the first signal and is,
Figure 610565DEST_PATH_IMAGE023
is the phase of the first signal and is,
Figure 961912DEST_PATH_IMAGE024
the QPSK signal is rotated by a controllable preset angle and is constant.
6. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method steps of any of claims 1 to 3 for converting QPSK signals to PAM signal format when executing the program.
7. A non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the method steps of carrying out a conversion of a QPSK signal into a PAM signal format according to any one of claims 1 to 3.
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