CN115276810A

CN115276810A - Signal sending device, signal receiving device and communication system

Info

Publication number: CN115276810A
Application number: CN202110484816.6A
Authority: CN
Inventors: 甘霖; 郭强; 刘博�; 任建新; 毛雅亚
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2022-11-01

Abstract

The present application provides a signal transmitting device, a signal receiving device and a communication system, which can be applied to the spatial division multiplexing optical transmission scenarios represented by parallel single-mode optical fibers, multi-core optical fibers, few-mode optical fibers, and multi-core few-mode optical fibers. , the first transmitter in the signal sending device is used to modulate the optical carrier into an auxiliary optical signal, which can be used for channel estimation. The second transmitter in the signal sending device is used to modulate the optical carrier into a service optical signal. The signal sending device multiplexes one or more service optical signals and auxiliary optical signals and sends them to the signal receiving device. One data processing module in the signal receiving device estimates the channel according to the auxiliary optical signal, and the other data processing modules restore the received service signal according to the result of the channel estimation. The device used for channel estimation is simple in structure, low in cost, and easy to implement technology promotion.

Description

Signal sending device, signal receiving device and communication system

Technical Field

The present application relates to the field of communications, and in particular, to a signal transmitting apparatus, a signal receiving apparatus, and a communication system.

Background

With the explosive increase of information transmission demand, the transmission capacity of the traditional single mode fiber approaches the limit, space division multiplexing technologies represented by few-mode fibers, multi-core fibers and multi-core few-mode fibers are widely concerned in recent years, the system capacity can be greatly improved, and the bandwidth crisis of the future single mode fibers is solved.

In the application process of the spatial multiplexing technology, a plurality of service signals in different modes output by a transmitting end are transmitted to a receiving end through a plurality of channels. When a service signal output by a transmitting end is transmitted in a channel, the service signal is affected by various linear effects and nonlinear effects of an optical fiber and changes, so that the transmission channel needs to be monitored. The receiving end can perform joint estimation on the channels of each mode, and simultaneously process the service signals received by each channel through a specific digital signal processing algorithm so as to recover the original service signals output by the transmitting end.

However, the device structure used for jointly estimating the channel of each mode is complex, high in cost and not beneficial to technical popularization. How to reasonably monitor a transmission channel and recover a service signal received by a receiving end is a difficult problem to be solved urgently.

Disclosure of Invention

The application provides a signal sending device, a signal receiving device and a communication system, and the adopted devices are simple in structure, low in cost and easy to realize technical popularization.

A first aspect of the present application provides a signal transmission apparatus, including: the system comprises a laser device, a first transmitter, a second transmitter and a multiplexer; the output end of the laser device is connected with the input end of the first transmitter and the input end of the second transmitter; the output end of the first transmitter is connected with the first input end of the multiplexer; the output end of the second transmitter is connected with the second input end of the multiplexer; the laser equipment is used for outputting optical carriers with different wavelengths; the first transmitter is configured to modulate the optical carrier into an auxiliary optical signal, where the auxiliary optical signal is used for channel estimation, and the center wavelengths of the auxiliary optical signal and the service signal are the same; the second transmitter is configured to modulate the optical carrier into the service optical signal; the multiplexer is configured to multiplex the auxiliary optical signal and the service optical signal.

In this application, a first transmitter in a signal transmission device is used to modulate an optical carrier into an auxiliary optical signal, which can be used for channel estimation. A second transmitter in the signal transmission device is configured to modulate the optical carrier into a service optical signal. And the signal sending equipment multiplexes one or more paths of service optical signals and the auxiliary optical signals and then sends the multiplexed signals to the signal receiving equipment. One data processing module in the signal receiving equipment carries out channel estimation according to the auxiliary optical signal, and other data processing modules recover the received service signal according to the result of the channel estimation. The device used for channel estimation has simple structure, low cost and easy technical popularization.

In one possible implementation form of the first aspect, the auxiliary optical signal comprises a frequency comb signal.

In this possible implementation manner, when the frequency comb signal is used for performing the channel estimation function, after the frequency comb signal is downloaded, the first data processing module in the signal receiving device receives an auxiliary electrical signal, where the auxiliary electrical signal is an electrical signal converted from the frequency comb signal. And a second data processing module in the signal receiving equipment receives the service optical signal. The first data processing module can extract parameters such as clock signals, dispersion magnitude, frequency offset and phase noise by using the auxiliary electric signals. The second data processing module can perform clock estimation, dispersion compensation, polarization compensation and frequency offset phase noise compensation on the service electric signal according to the parameters obtained by the first data processing module. I.e. the service electrical signal is recovered by analyzing the parameters derived from the auxiliary electrical signal. The signal receiving equipment can realize various channel estimation functions through the frequency comb signal, and can carry out channel estimation more comprehensively, so that the signal receiving equipment can recover the service signal more accurately.

In a possible implementation manner of the first aspect, the comb teeth of the frequency comb signal are equally spaced.

The possible implementation mode provides a possible implementation form of the frequency comb signal, and the realizability of the scheme is improved.

In one possible implementation form of the first aspect, the comb tooth interval of the frequency comb signal ranges from 500MHz to 5GHz.

In a possible implementation manner of the first aspect, the frequency comb signal includes a first frequency comb and a second frequency comb, polarization states of the first frequency comb and the second frequency comb are orthogonal, and a center frequency of the first frequency comb and a center frequency of the second frequency comb have a deviation. Typically between 1GHz and 10 GHz.

In this possible implementation manner, when the auxiliary optical signal is a multi-polarization frequency comb signal, the comb tooth pitch described above refers to the pitch of comb teeth of the frequency comb signal in the same polarization state. Illustratively, assuming that the frequency comb signal included in the auxiliary optical signal has a first frequency comb signal in a first polarization state and a second frequency comb signal in a second polarization state, the comb tooth pitch of the first frequency comb signal ranges from 500MHz to 5GHz, and the comb tooth pitch of the second frequency comb signal ranges from 500MHz to 5GHz. The possible implementation mode provides a possible included range of comb tooth intervals in the frequency comb signal, and the realizability of the scheme is improved.

In a possible implementation manner of the first aspect, the signal sending device further includes a first coupler and a second coupler, the first transmitter includes a first modulator and a second modulator, and the second transmitter includes a third modulator and a fourth modulator; the input end of the first coupler is connected with the output end of the laser device, and the output end of the first coupler is connected with the input end of the first modulator and the input end of the third modulator; the input end of the second coupler is connected with the output end of the laser device, and the output end of the second coupler is connected with the input end of the second modulator and the input end of the fourth modulator; the multiplexer is connected with the output ends of the four modulators; the laser device outputs a first optical carrier and a second optical carrier to the first coupler and the second coupler respectively, wherein the wavelengths of the first optical carrier and the second optical carrier are different; the first coupler is used for dividing the received first optical carrier into two paths of optical carriers; the second coupler is used for dividing the received second optical carrier into two optical carriers; the first modulator and the second modulator are configured to modulate a received optical carrier into the auxiliary optical signal; the third modulator and the fourth modulator are configured to modulate the received optical carrier into the service optical signal.

In this possible implementation, it is assumed that the first coupler receives the optical carrier a, and the first coupler divides the optical carrier a into two paths A1 and A2, and then inputs A1 and A2 to the first modulator and the third modulator, respectively. And the second coupler receives the optical carrier B, divides the optical carrier B into two paths B1 and B2, and then respectively inputs B1 into the second modulator and B2 into the fourth modulator. The first modulator and the second modulator modulate A1, B1 into an auxiliary optical signal a11 and an auxiliary optical signal B11, respectively, and input the auxiliary optical signals a11 and B11 to the multiplexer. The third modulator and the fourth modulator modulate A2 and B2 into a service optical signal a21 and a service optical signal B21, respectively, and input the service optical signal a21 and the service optical signal B21 to the multiplexer. The possible implementation mode provides a specific possible implementation mode of the first transmitter and the second transmitter, and the realizability of the scheme is improved.

In a possible implementation form of the first aspect, the multiplexer includes a first wavelength multiplexer, a second wavelength multiplexer, and a first mode multiplexer; the input end of the first wavelength multiplexer is connected with the output end of the first modulator and the output end of the second modulator, and the output end of the first wavelength multiplexer is connected with the first input end of the first mode multiplexer; the input end of the second wavelength multiplexer is connected with the output end of the third modulator and the output end of the fourth modulator, and the output end of the second wavelength multiplexer is connected with the second input end of the first mode multiplexer; the first wavelength multiplexer is used for multiplexing the received auxiliary optical signals with different wavelengths into an auxiliary optical signal in a first mode; the second wavelength multiplexer is used for multiplexing the received service optical signals with different wavelengths into service optical signals in a second mode; the first mode multiplexer is configured to multiplex the auxiliary optical signal in the first mode and the traffic optical signal in the second mode.

In this possible implementation, it is assumed that the wavelengths of the auxiliary optical signals a11 and B11 received by the first wavelength multiplexer are different. The first wavelength multiplexer multiplexes a11 and B11 into an auxiliary optical signal C11 in the first mode, and inputs the auxiliary optical signal C11 to the first mode multiplexer. The second wavelength multiplexer receives the auxiliary optical signals a21 and B21 at different wavelengths. The second wavelength multiplexer multiplexes a21 and B21 into an auxiliary optical signal C21 in the second mode, and inputs the auxiliary optical signal C21 to the first mode multiplexer. The first mode multiplexer multiplexes C11 and C21 with different modes and outputs the multiplexed result. The possible implementation mode provides a concrete possible implementation mode of the multiplexer, and the realizability of the scheme is improved.

In a possible implementation manner of the first aspect, the signal sending device further includes a first coupler and a second coupler, the first transmitter includes a first modulator and a second modulator, and the second transmitter includes a third modulator and a fourth modulator; the input end of the first coupler is connected with the output end of the laser device, and the output end of the first coupler is connected with the input end of the first modulator and the input end of the second modulator; the input end of the second coupler is connected with the output end of the laser device, and the output end of the second coupler is connected with the input end of the third modulator and the input end of the fourth modulator; the multiplexer is connected with the output ends of the four modulators; the laser device outputs a first optical carrier and a second optical carrier to the first coupler and the second coupler respectively, wherein the wavelengths of the first optical carrier and the second optical carrier are different; the first coupler is used for dividing the received first optical carrier into two paths of optical carriers; the second coupler is used for dividing the received second optical carrier into two paths of optical carriers; the first modulator and the second modulator are used for modulating the received optical carrier into the auxiliary optical signal; the third modulator and the fourth modulator are configured to modulate a received optical carrier into the service optical signal.

In this possible implementation manner, the possible implementation manner provides another specific possible connection manner between the first coupler and the second coupler and between the first transmitter and the second transmitter, which improves the realizability of the scheme.

In a possible implementation form of the first aspect, the multiplexer includes a second mode multiplexer, a third mode multiplexer, and a third wavelength multiplexer; the input end of the second mode multiplexer is connected with the output end of the first modulator and the output end of the second modulator, and the output end of the second mode multiplexer is connected with the first input end of the third wavelength multiplexer; the input end of the third mode multiplexer is connected with the output end of the third modulator and the output end of the fourth modulator, and the output end of the third mode multiplexer is connected with the second input end of the third wavelength multiplexer; the second mode multiplexer is used for multiplexing the received auxiliary optical signals in different modes into an auxiliary optical signal under a first wavelength; the third mode multiplexer is used for multiplexing the received service optical signals in different modes into service optical signals under a second wavelength; the third wavelength multiplexer is configured to multiplex the auxiliary optical signal at the first wavelength and the service optical signal at the second wavelength.

In this possible implementation, the auxiliary optical signals a11 and B11 received by the second mode multiplexer are in different modes. The second mode multiplexer multiplexes a11 and B11 into an auxiliary optical signal C11 at the first wavelength, and inputs the auxiliary optical signal C11 to the third wavelength multiplexer. The third mode multiplexer receives the auxiliary optical signals a21 and B21 in different modes. The third mode multiplexer multiplexes a21 and B21 into an auxiliary optical signal C21 at the second wavelength, and inputs the signal to the third wavelength multiplexer. The third wavelength multiplexer multiplexes C11 and C21 having different wavelengths and outputs the multiplexed data. The possible implementation mode provides a multiplexer which firstly carries out space division multiplexing and then carries out wavelength division multiplexing, and the realizability of the scheme is improved.

In a possible implementation manner of the first aspect, the first modulator includes a power splitter, a frequency shifter, a polarization beam splitter, a fifth modulator, a sixth modulator, and a polarization beam combiner; an input end of the power divider is electrically connected to the control module, a first output end of the power divider is connected to the frequency shifter, and a second output end of the power divider is connected to a first input end of the fifth modulator; the output end of the frequency shifter is connected with the first input end of the sixth modulator; the input end of the polarization beam splitter is connected with the output end of the first coupler, the first output end of the polarization beam splitter is connected with the second input end of the fifth modulator, and the second output end of the polarization beam splitter is connected with the second input end of the sixth modulator; a first input end of the polarization beam combiner is connected with an output end of the fifth modulator, a second input end of the polarization beam combiner is connected with an output end of the sixth modulator, and an output end of the polarization beam combiner is connected with an input end of the multiplexer; the power divider is used for dividing the electric signal input by the control module into two paths of electric signals; the frequency shifter is used for modulating the frequency of the received electric signal; the polarization beam splitter is used for splitting an input optical signal into two paths of optical signals with orthogonal polarization states; the fifth modulator is configured to modulate the optical signal output by the polarization beam splitter into a first auxiliary optical signal according to the electrical signal input by the beam splitter; the sixth modulator is configured to modulate the optical signal output by the polarization beam splitter into a second auxiliary optical signal according to the electrical signal input by the frequency shifter, where the polarization states of the first auxiliary optical signal and the second auxiliary optical signal are orthogonal; the polarization beam combiner is configured to combine the first auxiliary optical signal and the second auxiliary optical signal.

In this possible implementation manner, the power divider divides the electrical signal a input by the control module into A1 and A2, inputs A1 into the first modulator, inputs A2 into the frequency shifter, and inputs the frequency shifted signal into the second modulator. The polarization beam splitter divides the optical carrier B into two optical carriers B1 and B2 with different polarization states, and respectively inputs the optical carriers B1 and B2 into the fifth modulator and the sixth modulator. The fifth modulator modulates an optical carrier B1 according to the electrical signal A1 and the sixth modulator modulates an optical carrier B2 according to the electrical signal A2. And the polarization beam combiner combines the auxiliary optical signals modulated by the fifth modulator and the sixth modulator and outputs the combined signals. In this possible implementation manner, the first modulator may modulate a dual-polarization frequency comb signal, and then the receiving device may obtain a relevant parameter related to the frequency offset according to the dual-polarization frequency comb signal, so as to recover the service signal more accurately.

A second aspect of the present application provides a signal receiving apparatus comprising: the system comprises a demultiplexer, a first receiver, a second receiver, a first data processing module and a second data processing module; a first output end of the demultiplexer is connected with an input end of the first receiver, and a second output end of the demultiplexer is connected with an input end of the second receiver; the output end of the first receiver is connected with the input end of the first data processing module; the output end of the first data processing module is connected with the first input end of the second data processing module; the output end of the second receiver is connected with the second input end of the second data processing module; the demultiplexer is configured to demultiplex an optical signal into a service optical signal and an auxiliary optical signal, where the auxiliary optical signal is used to perform channel estimation; the first receiver is configured to convert the auxiliary optical signal into an auxiliary electrical signal; the second receiver is used for converting the service optical signal into a service electrical signal; the first data processing module is used for carrying out channel estimation according to the auxiliary electric signal; and the second data processing module is used for recovering the service optical signal according to the result output by the first data processing module.

In the present application, in terms of channel estimation, one or more spatial channels in a spatial division multiplexing system may be selected, and signals transmitted in the selected channels are specially modulated to modulate them into auxiliary optical signals instead of traffic signals. The auxiliary optical signal is transmitted to the receiving end together with the service optical signal (i.e., data). Therefore, the auxiliary optical signal is analyzed to obtain information such as frequency offset, phase noise, dispersion and the like generated after the auxiliary optical signal is transmitted through the channel, and the data processing module can process the auxiliary optical signal to realize channel estimation. Furthermore, the data processing module can compensate the damage generated after the service signal is transmitted through the channel according to the result obtained by analyzing the auxiliary signal. In the aspect of channel monitoring, in the communication system provided by the present application, one or more spatial channels may transmit a simple frequency comb signal or a PAM signal, and by receiving the conditions of monitoring the frequency spectrum change and the like of the frequency comb signal or the PAM signal, real-time monitoring of various parameters such as power, optical signal-to-noise ratio, chromatic dispersion and the like may be achieved for the entire channel. In addition, compared with the channel estimation by analyzing the traffic signals transmitted by all channels, the implementation of analyzing the auxiliary signals transmitted by one or more spatial channels and then performing the channel estimation can not only reduce the technical cost and simplify the device complexity, but also analyze more parameters from a more primitive perspective.

In one possible implementation form of the second aspect, the auxiliary optical signal comprises a frequency comb signal.

In this possible implementation manner, when the frequency comb signal is used for performing the channel estimation function, after the frequency comb signal is downloaded, the first data processing module in the signal receiving device receives an auxiliary electrical signal, where the auxiliary electrical signal is an electrical signal converted from the frequency comb signal. And a second data processing module in the signal receiving equipment receives the service optical signal. The first data processing module can extract parameters such as clock signals, dispersion magnitude, frequency deviation and phase noise by using the auxiliary electric signals. The second data processing module can perform clock estimation, dispersion compensation, polarization compensation and frequency offset phase noise compensation on the service electric signal according to the parameters obtained by the first data processing module. I.e. the service electrical signal is recovered by analyzing the parameters derived from the auxiliary electrical signal. The signal receiving equipment can realize various channel estimation functions through the frequency comb signal, and can perform channel estimation more comprehensively, so that the signal receiving equipment can recover the service signal more accurately.

In one possible implementation form of the second aspect, the comb teeth of the frequency comb signal are equally spaced.

In one possible implementation form of the second aspect, the comb tooth spacing of the frequency comb signal ranges from 500MHz to 5GHz.

In a possible implementation manner of the second aspect, the frequency comb signal includes a first frequency comb and a second frequency comb, polarization states of the first frequency comb and the second frequency comb are orthogonal, and a center frequency of the first frequency comb and a center frequency of the second frequency comb have a deviation. Typically between 1GHz and 10 GHz.

In one possible implementation of the second aspect, the demultiplexer comprises a first mode demultiplexer, a first wavelength demultiplexer and a second wavelength demultiplexer; the output end of the first mode demultiplexer is connected with the input end of the first wavelength demultiplexer and the input end of the second wavelength demultiplexer; the output end of the first wavelength demultiplexer is connected with the input end of the first receiver; the output end of the second wavelength demultiplexer is connected with the input end of the second receiver; the first mode demultiplexer is configured to demultiplex the optical signal into an auxiliary optical signal in a first mode and a service optical signal in a second mode; the first wavelength demultiplexer demultiplexes the auxiliary optical signal in the first mode into a first auxiliary optical signal and a second auxiliary optical signal, the first auxiliary optical signal having a first mode and a first wavelength, and the second auxiliary optical signal having a first mode and a second wavelength; the second wavelength demultiplexer demultiplexes the service optical signal in the second mode into a first service optical signal and a second service optical signal, where the first service optical signal has the second mode and the first wavelength, and the second service optical signal has the second mode and the second wavelength.

In this possible implementation, the first mode demultiplexer demultiplexes the optical signal into an optical signal A1 and an optical signal B1, and outputs the signal A1 to the first wavelength demultiplexer and the signal B1 to the second wavelength demultiplexer, respectively. Where A1 is the auxiliary optical signal, B1 is the traffic optical signal, and the A1 and B1 modes are different. The first wavelength demultiplexer demultiplexes A1 into an auxiliary optical signal a11 and an auxiliary optical signal a12, and outputs a11 and a12 to the first receiver, where a11 and a12 modes are the same wavelength and different. The second wavelength demultiplexer demultiplexes B1 into an auxiliary optical signal B11 and an auxiliary optical signal B12, and outputs B11 and B12 to the second receiver, where B11 and B12 modes are the same wavelength and different. In the possible implementation modes, a demultiplexer which firstly performs space division demultiplexing and then performs wavelength division demultiplexing is provided, a specific implementation mode of the multiplexer is provided, and the realizability of the scheme is improved.

In one possible implementation of the second aspect, the demultiplexer comprises a third wavelength demultiplexer, a second mode demultiplexer and a third mode demultiplexer; the output end of the third wavelength demultiplexer is connected with the input end of the second mode demultiplexer and the input end of the third mode demultiplexer; the output end of the second mode demultiplexer is connected with the input end of the first receiver; the output end of the third mode demultiplexer is connected with the input end of the second receiver; the third wavelength demultiplexer is configured to demultiplex the optical signal into the auxiliary optical signal and the service optical signal, where the auxiliary optical signal has a first wavelength and the service optical signal has a second wavelength; the second mode demultiplexer demultiplexes the auxiliary optical signal into a first auxiliary optical signal and a second auxiliary optical signal, the first auxiliary optical signal having a first wavelength and a first mode, the second auxiliary optical signal having a first wavelength and a second mode; the third mode demultiplexer demultiplexes the service optical signal into a first service optical signal and a second service optical signal, where the first service optical signal has a second wavelength and a first mode, and the second service optical signal has a second wavelength and a second mode.

In this possible implementation, the third wavelength demultiplexer demultiplexes the optical signal into an optical signal A1 and an optical signal B1, and outputs the signal A1 to the second mode demultiplexer and the signal B1 to the third mode demultiplexer, respectively. Where A1 is the auxiliary optical signal, B1 is the service optical signal, and A1 and B1 are different in wavelength. The second mode demultiplexer demultiplexes A1 into an auxiliary optical signal a11 and an auxiliary optical signal a12, and outputs a11 and a12 to the first receiver, where a11 and a12 are different in the same mode of wavelength. The third mode demultiplexer demultiplexes B1 into an auxiliary optical signal B11 and an auxiliary optical signal B12, and outputs B11 and B12 to the second receiver, where B11 and B12 have the same wavelength and different modes. The possible implementation mode provides a demultiplexer which firstly carries out wavelength division demultiplexing and then carries out space division demultiplexing, provides a specific implementation mode of the multiplexer, and improves the realizability of the scheme.

In a possible implementation manner of the second aspect, the signal receiving device further includes a local oscillation optical module, the first receiver includes a first coherent receiver and a second coherent receiver, and the second receiver includes a third coherent receiver and a fourth coherent receiver; a first input end of the first coherent receiver and a first input end of the second coherent receiver are connected with an output end of the multiplexer, a second input end of the first coherent receiver and a second input end of the second coherent receiver are connected with an output end of the local oscillation optical module, and an output end of the first coherent receiver and an output end of the second coherent receiver are connected with the first data processing module; a first input end of the third coherent receiver and a first input end of the fourth coherent receiver are connected with an output end of the multiplexer, a second input end of the third coherent receiver and a second input end of the fourth coherent receiver are connected with an output end of the local oscillation optical module, and an output end of the third coherent receiver and an output end of the fourth coherent receiver are connected with the second data processing module; the first coherent receiver is used for converting the first auxiliary optical signal into a first auxiliary electrical signal according to the local oscillator optical signal; the second coherent receiver is configured to convert the second auxiliary optical signal into a second auxiliary electrical signal according to the local oscillator optical signal; the third phase dry receiver is used for converting the first service optical signal into a first service electrical signal according to the local oscillator optical signal; and the fourth coherent receiver is configured to convert the second service optical signal into a second service electrical signal according to the local oscillator optical signal.

In this possible implementation, it is assumed that the first receiver receives the auxiliary optical signal A1, wherein the first coherent receiver receives the auxiliary optical signal a11 and the second coherent receiver receives the auxiliary optical signal a12. The first coherent receiver may convert the auxiliary optical signal a11 into an auxiliary electrical signal a21 according to the local oscillator light output by the local oscillator light module, and input a21 into the first data processing module. Similarly, the second coherent receiver may convert the auxiliary optical signal a12 into an auxiliary electrical signal a22 according to the local oscillator light output by the local oscillator light module, and input a22 into the first data processing module. Similarly, assume that a second receiver receives service optical signal B1, wherein a third coherent receiver receives service optical signal B11 and a fourth coherent receiver receives service optical signal B12. The third phase dry receiver may convert the service optical signal B11 into a service electrical signal B21 according to the local oscillation light output by the local oscillation optical module, and input B21 into the second data processing module. Similarly, the second coherent receiver may convert the service optical signal B12 into the service electrical signal B22 according to the local oscillation light output by the local oscillation light module, and input the service electrical signal B22 into the second data processing module. The possible implementation mode provides a specific implementation mode of the receiver, and the realizability of the scheme is improved.

In one possible implementation manner of the second aspect, the first coherent receiver includes a first polarization beam splitter, a second polarization beam splitter, a first detector, and a second detector; the input end of the first polarization beam splitter is connected with the output end of the local oscillation optical module, and the output end of the first polarization beam splitter is connected with the first input end of the first detector and the first input end of the second detector; the input end of the second polarization beam splitter is connected with the output end of the demultiplexer, and the output end of the second polarization beam splitter is connected with the second input end of the first detector and the second input end of the second detector; the output end of the first detector and the output end of the second detector are connected with the input end of the first data processing module; the first polarization beam splitter is used for splitting the local oscillator optical signals into two paths of local oscillator optical signals with orthogonal polarization states; the second polarization beam splitter is used for splitting the input first auxiliary optical signal into two paths of auxiliary optical signals with orthogonal polarization states; the first detector is used for converting the auxiliary optical signal into a third auxiliary electrical signal according to the local oscillator optical signal; the second detector is used for converting the auxiliary optical signal into a fourth auxiliary electrical signal according to the local oscillator optical signal.

In this possible implementation manner, it is assumed that the first polarization beam splitter splits the local oscillation optical signal C into two local oscillation optical signals C1 and C2 with orthogonal polarization states. The second polarization beam splitter splits the auxiliary optical signal a11 into two auxiliary optical signals D1 and D2 with orthogonal polarization states. The first detector converts the auxiliary optical signal D1 into an electrical signal D11 according to the local oscillator optical signal C1, and the second detector converts the auxiliary optical signal D2 into an electrical signal D21 according to the local oscillator optical signal C2. The first and second detectors input D11 and D21 to the first data processing module. The first data processing module performs channel estimation according to the obtained auxiliary electrical signal. The first coherent receiver can demodulate the dual-polarization frequency comb signal, and the receiving device can obtain the related parameters related to the frequency offset according to the dual-polarization frequency comb signal, so that the service signal can be recovered more accurately.

A third aspect of the present application provides a communication system, where the communication system includes a signal sending device and a signal receiving device, where the signal sending device is the signal sending device described in the first aspect or any one of the possible implementation manners of the first aspect, and the signal receiving device is the signal receiving device described in the second aspect or any one of the possible implementation manners of the second aspect.

Drawings

Fig. 1 is a schematic structural diagram of a communication system provided in the present application;

fig. 2 is a schematic structural diagram of a signal transmission device provided in the present application;

fig. 3a is another schematic structural diagram of a signal transmitting apparatus provided in the present application;

fig. 3b is another schematic structural diagram of a signal transmitting device provided in the present application;

fig. 4 is another schematic structural diagram of a signal transmitting apparatus provided in the present application;

fig. 5 is another schematic structural diagram of a signal transmitting device provided in the present application;

fig. 6 is a schematic diagram of a first modulator according to the present application;

FIG. 7 is a schematic diagram of a dual-offset comb signal provided herein;

fig. 8 is a schematic structural diagram of a signal receiving apparatus provided in the present application;

fig. 9 is a schematic processing flow diagram of a frequency comb signal provided in the present application;

fig. 10 is a schematic diagram of a frequency comb signal provided in the present application;

fig. 11 is a schematic diagram of channel monitoring provided in the present application;

fig. 12 is a schematic diagram of an application of a PAM signal provided herein;

fig. 13 is a schematic structural diagram of another signal receiving apparatus provided in the present application;

fig. 14 is a schematic structural diagram of a signal receiving apparatus provided in the present application;

fig. 15a is a schematic structural diagram of a signal receiving apparatus provided in the present application;

fig. 15b is a schematic structural diagram of a signal receiving apparatus provided in the present application;

fig. 16 is a schematic diagram of a first coherent receiver according to the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application are described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present application, but not all embodiments. As can be known to those skilled in the art, with the advent of new application scenarios, the technical solution provided in the embodiments of the present application is also applicable to similar technical problems.

The terms "first," "second," and the like in the description and claims of this application and in the foregoing drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be implemented in other sequences than those illustrated or described herein. Moreover, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or modules is not necessarily limited to those steps or modules explicitly listed, but may include other steps or modules not expressly listed or inherent to such process, method, article, or apparatus. The naming or numbering of the steps appearing in the present application does not mean that the steps in the method flow have to be executed in the chronological/logical order indicated by the naming or numbering, and the named or numbered process steps may be executed in a modified order depending on the technical purpose to be achieved, as long as the same or similar technical effects are achieved.

However, the device structure adopted for performing the joint estimation on the channel of each mode is complex, high in cost and not beneficial to the technical popularization. How to reasonably monitor a transmission channel and recover a service signal received by a receiving end is a difficult problem to be solved urgently.

In order to solve the problems in the above solutions, the present application provides a signal transmitting apparatus, a signal receiving apparatus, and a communication system, where the signal transmitting apparatus multiplexes one or more service optical signals and an auxiliary optical signal and then transmits the multiplexed signal to the signal receiving apparatus. And one data processing module in the signal receiving equipment estimates the channel according to the auxiliary optical signal, and other data processing modules in the signal receiving equipment recover the received service signal according to the result of channel estimation. The device used for channel estimation has simple structure, low cost and easy technical popularization. The following describes a signal transmitting apparatus, a signal receiving apparatus, and a communication system provided by the present application, respectively.

First, a communication system provided in the present application is introduced, and fig. 1 is a schematic structural diagram of the communication system provided in the present application.

Referring to fig. 1, the communication system provided in the present application includes a signal transmitting apparatus 10 and a signal receiving apparatus 20. Wherein the signal transmitting apparatus 10 transmits a signal to the signal receiving apparatus 20 through a spatial division channel.

Optionally, in the communication system provided in this application, the space division channel between the signal sending device 10 and the signal receiving device 20 may be one or a group of few-mode channels, the space division channel may also be one or a group of multi-core channels, the space division channel may also be a group of single-mode channels, and the space division channel may also be another type of channel, which is not limited herein.

In this application, the communication system may be optionally applied to a space division multiplexing optical transmission scenario represented by a parallel single-mode optical fiber, a multi-core optical fiber, a few-mode light, and a multi-core few-mode optical fiber, and may also be applied to other scenarios, which is not limited here specifically.

In the present application, when the signal transmitting apparatus 10 uses the space division multiplexing technique to transmit data, one or more spatial channels may be selected to transmit the auxiliary optical signal. I.e. the first transmitter in the signal transmitting device 10 is used to modulate the optical carrier into the auxiliary optical signal. The auxiliary optical signal can be matched with a special digital signal processing flow to realize various functions in an optical communication network. A second transmitter in the signal transmitting apparatus 10 is used to modulate the optical carrier into a traffic optical signal. The signal transmission apparatus 10 multiplexes one or more traffic optical signals and the auxiliary optical signal and transmits the multiplexed signals to the signal reception apparatus 20 through the space division channel. One data processing module in the signal receiving device 20 estimates a channel according to the auxiliary optical signal, and the other data processing modules recover the received service signal according to the result of channel estimation. The device used for channel estimation has simple structure, low cost and easy technical popularization.

Based on the communication system shown in fig. 1, a signal transmission apparatus provided by the present application is described below.

Fig. 2 is a schematic structural diagram of a signal transmitting apparatus provided in the present application.

Referring to fig. 2, in the present application, the signal transmitting apparatus 10 at least includes: a laser device 101, a first transmitter 102, a second transmitter 103 and a multiplexer 104.

Wherein the output of the laser device 101 is connected to the input of the first transmitter 102 and the input of the second transmitter 103, and the output of the first transmitter 102 is connected to the first input of the multiplexer 104. An output of the second transmitter 103 is connected to a second input of the multiplexer 104.

In this application, the laser device 101 is configured to output optical carriers with different wavelengths, the first transmitter 102 is configured to modulate the optical carriers into auxiliary optical signals, the auxiliary optical signals are used for channel estimation, and the center wavelengths of the auxiliary optical signals and the service signals are the same. The second transmitter 103 is used to modulate the optical carrier into a traffic optical signal. The multiplexer 104 is used to multiplex the auxiliary optical signal and the service optical signal.

In this application, optionally, the laser device 101 may be one or more laser arrays, and the laser device 101 may also be a plurality of individual lasers, which is not limited herein.

In this application, optionally, the auxiliary signal may not be used to transmit data, and the auxiliary signal may also be used to transmit data, which is not limited herein.

In this application, the auxiliary optical signal may be a frequency comb signal, the auxiliary optical signal may be a PAM signal, and the auxiliary optical signal may also be a QPSK signal, which is not limited herein. If the auxiliary optical signal is a frequency comb signal, the pitches of the comb teeth in the frequency comb signal are the same, and due to manufacturing errors, the pitches between the comb teeth are not strictly equal, and the deviation range is within 100 kHz. The spacing may range between 500 megahertz (MHz) and 5 gigahertz (GHz). Illustratively, the spacing between the comb teeth may be 500MHz, the spacing between the comb teeth may be 1GHz, the spacing between the comb teeth may be 5GHz, or other spacings, which is not limited herein.

In the present application, when the auxiliary optical signal is a multi-polarization frequency comb signal, the inter-comb tooth distance described above refers to an inter-comb tooth distance of the frequency comb signal in the same polarization state. Illustratively, assuming that the frequency comb signal included in the auxiliary optical signal has a first frequency comb signal in a first polarization state and a second frequency comb signal in a second polarization state, the comb tooth pitch of the first frequency comb signal ranges from 500MHz to 5GHz, and the comb tooth pitch of the second frequency comb signal ranges from 500MHz to 5GHz.

In this application, optionally, the frequency comb signal may be a flat frequency comb containing more than 2 frequencies, and the frequency comb signal may be a chirped frequency comb containing more than 2 frequencies, which is not limited herein.

In this application, the frequency comb signal may be an intensity frequency comb signal or an amplitude frequency comb signal, where the intensity frequency comb signal may modulate an optical carrier in an intensity modulation manner to obtain the intensity frequency comb signal. Similarly, the amplitude-frequency comb signal may modulate the optical carrier in an amplitude modulation manner to obtain the amplitude-frequency comb signal.

In this application, if the frequency comb signal has two orthogonal polarization states, the frequency comb having the first polarization state is referred to as a first frequency comb, the frequency comb having the second polarization state is referred to as a second frequency comb, the polarization states of the first frequency comb and the second frequency comb are orthogonal, and the center frequency of the first frequency comb and the center frequency of the second frequency comb are deviated. The range of this deviation is typically between 1GHz and 10 GHz.

Optionally, the signal sending device provided by the present application may be applied to a C-band transmission system, and the corresponding wavelength range is 1530-1565nm, that is, the frequency is 191.5 to 196.1THz. The frequency ranges can be specified as wavelength channels, typically at intervals of 100GHz, such as 191.1 + -0.05THz, 191.2 + -0.05THz, 191.3 + -0.05 THz, and so on. For a certain wavelength signal, such as 191.3 +/-0.05 THz, the central wavelength of the frequency comb signal is 191.3THz, and the range of the frequency comb does not exceed +/-0.05 THz, namely +/-50 GHz. The range of traffic signals is also 191.3 ± 0.05 THz.

In this application, optionally, compared to the signal sending device in the example shown in fig. 2, the signal sending device may further include more laser devices, more transmitters, more multiplexers, and other devices, which is not limited herein.

In the application, the signal sending device sends the one or more service optical signals and the auxiliary optical signal to the signal receiving device after multiplexing. One data processing module in the signal receiving equipment estimates the channel according to the auxiliary optical signal, and other data processing modules recover the received service signal according to the result of channel estimation. The device used for channel estimation has simple structure, low cost and easy technical popularization.

In the present application, in addition to the above-mentioned components, the signal transmission device may further include other components. In addition, the first transmitter and the second transmitter included in the signal transmission device may have various specific implementations, which will be described in detail below.

Fig. 3a is a schematic structural diagram of another signal transmitting apparatus provided in the present application.

Referring to fig. 3a, in the present application, the signal transmitting apparatus 10 further includes a first coupler 105 and a second coupler 106, the first transmitter 102 includes a first modulator 107 and a second modulator 108, and the second transmitter 103 includes a third modulator 109 and a fourth modulator 110.

Wherein an input of the first coupler 105 is connected to an output of the laser device and an output of the first coupler 105 is connected to an input of the first modulator 107 and an input of the third modulator 109. An input of the second coupler 106 is connected to an output of the laser device 101 and an output of the second coupler 106 is connected to an input of the second modulator 108 and to an input of the fourth modulator 110. A first input of the multiplexer 104 is connected to an output of the first modulator 107 and to an output of the second modulator 108. A second input of the multiplexer 104 is connected to an output of a third modulator 109 and to an output of a fourth modulator 110.

The laser device outputs a first optical carrier and a second optical carrier to a first coupler and a second coupler respectively, and the wavelengths of the first optical carrier and the second optical carrier are different.

The first coupler 105 is configured to split the received first optical carrier into two optical carriers. The second coupler 106 is configured to split the received second optical carrier into two optical carriers. The first modulator 107 and the second modulator 108 are used to modulate the received optical carrier into an auxiliary optical signal. The third modulator 109 and the fourth modulator 110 are used to modulate the received optical carrier into a traffic optical signal.

For example, suppose that the first coupler receives an optical carrier a, the first coupler divides the optical carrier a into two paths A1 and A2, and then inputs A1 and A2 to the first modulator and the third modulator, respectively. And the second coupler receives the optical carrier B, divides the optical carrier B into two paths B1 and B2, and then respectively inputs B1 into the second modulator and B2 into the fourth modulator. The first modulator and the second modulator modulate A1, B1 into an auxiliary optical signal a11 and an auxiliary optical signal B11, respectively, and input the auxiliary optical signals a11 and B11 to the multiplexer. The third modulator and the fourth modulator modulate A2 and B2 into a service optical signal a21 and a service optical signal B21, respectively, and input the service optical signal a21 and the service optical signal B21 to the multiplexer.

Fig. 3b is another schematic structural diagram of a signal transmitting apparatus provided in the present application.

Referring to fig. 3b, in the present application, the signal transmitting apparatus 10 further includes a first coupler 105 and a second coupler 106, the first transmitter 102 includes a first modulator 107 and a second modulator 108, and the second transmitter 103 includes a third modulator 109 and a fourth modulator 110.

Wherein an input of the first coupler 105 is connected to an output of the laser device 101 and an output of the first coupler 105 is connected to an input of the first modulator 107 and an input of the second modulator 108. An input of the second coupler 106 is connected to an output of the laser device 101 and an output of the second coupler 106 is connected to an input of a third modulator 109 and to an input of a fourth modulator 110. A first input of the multiplexer 104 is connected to an output of the first modulator 107 and to an output of the second modulator 108. A second input of the multiplexer 104 is connected to an output of the third modulator 109 and to an output of the fourth modulator 110.

In this application, the above example illustrates one implementation manner of the first transmitter and the second transmitter, and the multiplexer included in the signal transmission device may also have a variety of specific implementation forms. Optionally, the multiplexer may perform wavelength division multiplexing on the optical signal before performing space division multiplexing, the multiplexer may also perform space division multiplexing on the optical signal before performing wavelength division multiplexing, and the multiplexer may also process the optical signal according to other manners, which is not limited herein. As will be described in detail below.

The method I comprises the following steps: the multiplexer wavelength division multiplexes and space division multiplexes the optical signals.

Fig. 4 is a schematic structural diagram of a signal transmitting device provided in the present application.

Referring to fig. 4, optionally, the multiplexer 104 may include a first wavelength multiplexer 111, a second wavelength multiplexer 112, and a first mode multiplexer 113;

the input end of the first wavelength multiplexer 111 is connected with the output end of the first modulator 107 and the output end of the second modulator 108, and the output end of the first wavelength multiplexer 111 is connected with the first input end of the first mode multiplexer 113; an input of the second wavelength multiplexer 112 is connected to an output of the third modulator 109 and an output of the fourth modulator 110, and an output of the second wavelength multiplexer 112 is connected to a second input of the first mode multiplexer 113.

In the present application, the first wavelength multiplexer 111 is configured to multiplex the received auxiliary optical signals with different wavelengths into the auxiliary optical signal in the first mode. The second wavelength multiplexer 112 is configured to multiplex the received service optical signals with different wavelengths into a service optical signal in the second mode. The first mode multiplexer 113 is configured to multiplex the auxiliary optical signal in the first mode and the service optical signal in the second mode.

Illustratively, the first wavelength multiplexer receives the auxiliary optical signals a11 and B11 at different wavelengths. The first wavelength multiplexer multiplexes a11 and B11 into an auxiliary optical signal C11 in the first mode, and inputs the auxiliary optical signal C11 to the first mode multiplexer. The second wavelength multiplexer receives the auxiliary optical signals a21 and B21 at different wavelengths. The second wavelength multiplexer multiplexes a21 and B21 into an auxiliary optical signal C21 in the second mode, and inputs the auxiliary optical signal C21 to the first mode multiplexer. The first mode multiplexer multiplexes C11 and C21 with different modes and outputs the multiplexed result.

The second method comprises the following steps: the multiplexer performs space division multiplexing and then wavelength division multiplexing on the optical signals.

Fig. 5 is a schematic structural diagram of a signal transmitting apparatus provided in the present application.

Referring to fig. 5, optionally, multiplexer 104 may include a second mode multiplexer 114, a third mode multiplexer 115, and a third wavelength multiplexer 116;

in this application, the input terminal of the second mode multiplexer 114 is connected to the output terminal of the first modulator 107 and the output terminal of the second modulator 108, and the output terminal of the second mode multiplexer 114 is connected to the first input terminal of the third wavelength multiplexer 116; the input of the third mode multiplexer 115 is connected to the output of the third modulator 109 and the output of the fourth modulator 110, and the output of the third mode multiplexer 115 is connected to a second input of the third wavelength multiplexer 115; the second mode multiplexer 114 is configured to multiplex the received auxiliary optical signals in different modes into an auxiliary optical signal at the first wavelength; the third mode multiplexer 115 is configured to multiplex the received service optical signals in different modes into a service optical signal at the second wavelength; the third wavelength multiplexer 116 is configured to multiplex the auxiliary optical signal at the first wavelength and the service optical signal at the second wavelength.

Illustratively, the second mode multiplexer receives the auxiliary optical signals a11 and B11 in different modes. The second mode multiplexer multiplexes a11 and B11 into an auxiliary optical signal C11 at the first wavelength, and inputs the auxiliary optical signal C11 to the third wavelength multiplexer. The third mode multiplexer receives the auxiliary optical signals a21 and B21 in different modes. The third mode multiplexer multiplexes a21 and B21 into an auxiliary optical signal C21 at the second wavelength, and inputs the signal to the third wavelength multiplexer. The third wavelength multiplexer multiplexes C11 and C21 having different wavelengths and outputs the multiplexed data.

In this application, the above examples corresponding to fig. 4 and 5 illustrate two possible implementation structures of the multiplexer 104. Optionally, the first transmitter may perform dual-polarization modulation on the auxiliary optical signal, and modulate the signal output by the control module to different polarization states of the dual-polarization beam through the power splitter and the polarization beam splitter, and send the dual-polarization beam after polarization combination. A specific implementation of the first transmitter that can implement double-bias modulation will be described in detail below.

In this application, the foregoing example takes two couplers and four optical paths as an example to illustrate the signal sending device, and optionally, the signal sending device may include more couplers and more optical paths, which is not limited herein.

Fig. 6 is a schematic structural diagram of a first modulator provided in the present application.

Referring to fig. 6, in the present application, optionally, the first modulator 107 includes a power splitter 117, a frequency shifter 118, a polarization beam splitter 119, a fifth modulator 120, a sixth modulator 121, and a polarization beam combiner 122.

An input end of the power divider 117 is electrically connected to the control module, a first output end of the power divider 117 is connected to the frequency shifter, and a second output end of the power divider 117 is connected to a first input end of the fifth modulator 120; the output of the frequency shifter 118 is connected to a first input of a sixth modulator 121; the input end of the polarization beam splitter 119 is connected to the output end of the first coupler 105, the first output end of the polarization beam splitter 119 is connected to the second input end of the fifth modulator 120, and the second output end of the polarization beam splitter 119 is connected to the second input end of the sixth modulator 121; a first input end of the polarization beam combiner 122 is connected to an output end of the fifth modulator 120, a second input end of the polarization beam combiner 122 is connected to an output end of the sixth modulator 121, and an output end of the polarization beam combiner 122 is connected to an input end of the multiplexer 104.

In this application, the power divider 117 is configured to divide the electrical signal input by the control module into two electrical signals. The frequency shifter 118 is configured to shift the frequency of the received electrical signal, for example, shift the frequency of the electrical signal a with the frequency f1 by delta _ f, so that the frequency of the shifted electrical signal a is f1+ delta _ f. The polarization beam splitter 119 is used to split an input optical signal into two optical signals with orthogonal polarization states. The fifth modulator 120 is configured to modulate the optical signal output from the polarization beam splitter into the first auxiliary optical signal according to the electrical signal input from the beam splitter. The sixth modulator 121 is configured to modulate the optical signal output by the polarization beam splitter 119 into a second auxiliary optical signal according to the electrical signal input by the frequency shifter, where the polarization state of the first auxiliary optical signal is orthogonal to that of the second auxiliary optical signal. The polarization beam combiner 122 is configured to combine the first auxiliary optical signal and the second auxiliary optical signal.

Illustratively, the power divider divides the electrical signal a input by the control module into A1 and A2, inputs A1 to the first modulator, inputs A2 to the frequency shifter, and inputs the frequency shifted signal to the second modulator. The polarization beam splitter divides the optical carrier B into two optical carriers B1 and B2 with different polarization states, and respectively inputs the optical carriers B1 and B2 into the fifth modulator and the sixth modulator. The fifth modulator modulates an optical carrier B1 according to the electrical signal A1 and the sixth modulator modulates an optical carrier B2 according to the electrical signal A2. And the polarization beam combiner combines the auxiliary optical signals modulated by the fifth modulator and the sixth modulator and outputs the combined signals.

In this application, optionally, if the fifth modulator and the sixth modulator included in the first modulator are both intensity modulators, the auxiliary optical signal is an intensity frequency comb signal. If the fifth modulator and the sixth modulator comprised in the first modulator are both amplitude modulators, the auxiliary optical signal is an amplitude comb signal.

Fig. 7 is a schematic diagram of a dual-offset comb signal according to the present application.

In the present application, for example, the frequency spectrums of the dual polarization combs obtained by different modulation schemes may be as shown before transmission in fig. 7, where the solid line represents X polarization, the dotted line represents Y polarization, and the frequency combs of the two polarizations have equal amplitudes. After transmission through the channel, the amplitude of the spectrum of the dual offset comb signal changes to different degrees due to the influence of factors such as dispersion in the channel, as shown after transmission in fig. 7. After the signal receiving equipment receives the double offset frequency comb signals, the data processing module analyzes the change of the double offset frequency comb signals, and therefore the function of channel estimation can be achieved.

In the present application, the first transmitter in the signal transmission device 10 is used to modulate the optical carrier into an auxiliary optical signal, which can be used for channel estimation. The second transmitter in the signal transmitting device is used for modulating the optical carrier into a service optical signal. And the signal sending equipment multiplexes one or more paths of service optical signals and the auxiliary optical signals and then sends the multiplexed signals to the signal receiving equipment. One data processing module in the signal receiving equipment estimates the channel according to the auxiliary optical signal, and other data processing modules recover the received service signal according to the result of channel estimation. The device used for channel estimation has simple structure, low cost and easy technical popularization.

Based on the communication system shown in fig. 1, a signal receiving apparatus provided by the present application is described below.

Fig. 8 is a schematic structural diagram of a signal receiving apparatus provided in the present application.

Referring to fig. 8, in the present application, a signal receiving apparatus 20 includes: a demultiplexer 201, a first receiver 202, a second receiver 203, a first data processing module 204 and a second data processing module 205.

Wherein, a first output terminal of the demultiplexer 201 is connected with an input terminal of the first receiver 202, and a second output terminal of the demultiplexer 201 is connected with an input terminal of the second receiver 203; the output end of the first receiver 202 is connected with the input end of the first data processing module 204; the output end of the first data processing module 204 is connected with the first input end of the second data processing module 205; an output of the second receiver 203 is connected to a second input of the second data processing module 205; the demultiplexer 201 is configured to demultiplex the optical signal into a service optical signal and an auxiliary optical signal, where the auxiliary optical signal is used for channel estimation.

In this application, the first receiver 202 is used to convert the auxiliary optical signal into an auxiliary electrical signal. The second receiver 203 is used to convert the service optical signal into a service electrical signal. The first data processing module 204 is configured to perform channel estimation through the auxiliary signal. The second data processing module 205 is configured to recover the service optical signal according to the result output by the first data processing module.

In this application, the auxiliary optical signal received by the signal receiving device is similar to the auxiliary optical signal sent by the signal sending device in the above example, and details are not described here.

In the present application, in terms of channel estimation, one or more spatial channels in the spatial division multiplexing system may be selected, and signals transmitted in the selected channels are specially modulated and modulated into auxiliary optical signals to replace service signals. The auxiliary optical signal is transmitted to the receiving end together with the service optical signal (i.e., data). Therefore, the auxiliary optical signal is analyzed to obtain information such as frequency offset, phase noise, chromatic dispersion and the like generated after the auxiliary optical signal is transmitted through the channel, and the data processing module processes the auxiliary optical signal to realize channel estimation. Furthermore, the data processing module can compensate the damage generated after the service signal is transmitted through the channel according to the result obtained by analyzing the auxiliary signal. In the aspect of channel monitoring, in the communication system provided by the application, one or more spatial channels can transmit a simple frequency comb signal or PAM signal, and by receiving the conditions of monitoring the frequency spectrum change and the like of the frequency comb signal or PAM signal, the real-time monitoring of various parameters such as power, optical signal to noise ratio and dispersion can be realized for the whole channel. In addition, compared with the method of analyzing the traffic signals transmitted by all channels to perform channel estimation, the method of analyzing the auxiliary signals transmitted by one or more spatial channels to perform channel estimation not only can reduce the technical cost and simplify the device complexity, but also can analyze more parameters from a more-element perspective. Optionally, the auxiliary optical signal may implement multiple functions such as channel estimation, channel monitoring, optical label switching, and the like, and the auxiliary optical signal may also implement other functions, which is not limited herein.

In the present application, when the auxiliary optical signal is different in type, the data processing module can perform different processing on the auxiliary optical signal, which will be described in detail below.

(1) The auxiliary optical signal is a frequency comb signal.

Fig. 9 is a schematic processing flow diagram of a frequency comb signal provided in the present application.

As shown in fig. 9, in the present application, the processing flow of the frequency comb signal is executed on the signal receiving apparatus. When the frequency comb signal is used for the channel estimation function, the specific working flow is shown in fig. 9. After the frequency comb signal is downloaded, the signal receiving device receives an auxiliary electrical signal, which is an electrical signal converted from the frequency comb signal. The signal receiving device receives a service electrical signal. The signal receiving device may extract parameters such as a clock signal, a dispersion magnitude, a frequency offset, and a phase noise by using the auxiliary electrical signal. The signal receiving device can perform clock estimation, dispersion compensation, polarization compensation and frequency offset phase noise compensation on the service electrical signal according to the parameters obtained by processing the auxiliary electrical signal. I.e. the service electrical signal is recovered by analyzing the parameters derived from the auxiliary electrical signal.

In the application, the shared clock information can be obtained by processing the auxiliary electrical signal through the first data processing module. The other data processing modules do not need to additionally perform clock recovery. Because optical signals of different modes have a fixed dispersion relation when dispersion occurs, the dispersion can be roughly estimated through the phase spectrum of the frequency comb signal, so that the dispersion estimation modules of other spatial channels can be simplified, and even the dispersion estimation module can be eliminated. Meanwhile, the frequency offset and phase noise information assumes that each spatial channel has a fixed and small time delay difference, and time delay can be introduced in a digital domain for compensation, so that frequency offset estimation and phase noise recovery modules of other spatial channel modules are removed.

In the above example, it is mentioned that when the signal receiving apparatus performs channel estimation through the auxiliary optical signal, functions such as clock estimation, dispersion estimation (giving the estimated value to other channels, and other channels have additional algorithms for dispersion compensation), polarization compensation, and frequency offset phase noise compensation can be achieved. Assuming that the auxiliary optical signal is a frequency comb signal, when the dispersion compensation function is realized by the frequency comb signal, firstly, the dispersion estimation is performed on the frequency comb signal. The process of estimating the dispersion by frequency combing the signal is described below.

Fig. 10 is a schematic diagram of a frequency comb signal provided in the present application.

As shown in fig. 10, in the present application, dispersion may affect a signal by changing the phase of each spectral component in an optical signal, for example. Assuming that the frequency comb signal a has 4 wavelengths, a schematic diagram of the frequency comb signal a before transmission is shown in the left diagram of fig. 10. The comb pitch of the frequency comb signal A is 1GHz, and the frequency spectrum after transmission through 100km optical fiber changes as shown in the right drawing of FIG. 10.

In the present application, due to the dispersion characteristic, the side components of the frequency comb signal can be transmitted at different speeds, resulting in different phase differences. At the transmitting end, the sidebands of the frequency comb signal have the same phase, and after transmission through the link, the change of the phase will generate a difference, thereby generating a phase difference. When the phase difference is an odd multiple of pi, the amplitudes of the two signals are opposite, so that the power of the radio frequency signal obtained by the detector is the lowest. Thus, the signal receiving apparatus can estimate the dispersion of the optical fiber link by extracting the power characteristics. Through the frequency comb signals, a plurality of groups of radio frequency signals can be obtained, so that a plurality of groups of dispersion estimation is realized, and the estimation accuracy is improved.

In the above example, it is mentioned that the signal receiving apparatus can perform functions such as clock estimation, dispersion compensation, polarization compensation, and frequency offset phase noise compensation when performing channel estimation by the auxiliary optical signal. Optionally, the signal receiving device may further implement a channel monitoring function through the frequency comb signal, and a process of implementing channel monitoring through the frequency comb signal by the signal receiving device is described below.

Fig. 11 is a schematic view of channel monitoring provided in the present application.

In the application, the filtering center deviation and the filtering sideband damage can be estimated through the amplitude spectrum of the frequency comb. For example, the frequency comb signal with single bias strength shown in fig. 11, the frequency comb signal generated by the signal transmitting apparatus is a flat frequency comb signal. The channel monitoring function can be realized by comparing and observing the change of the frequency spectrum intermediate frequency comb of the frequency comb signal received by the signal receiving equipment. Optionally, the first data processing module may monitor the center deviation of the filtering reception through center frequency comb displacement. The first data processing module can further monitor the damage condition of the filtering sideband according to the amplitude change of the edge frequency comb. In addition, the signal transmission device may further modulate the auxiliary optical signal into a double-bias strength frequency comb signal, the double-bias strength frequency comb signal including a flat frequency comb having more than 4 frequencies, the frequency comb range being smaller than the system channel interval. The first data processing module compares the received frequency comb spectrum with the original spectrum, so that the channel monitoring in other aspects such as polarization-dependent loss, polarization rotation and the like is realized. The first data processing module included in the signal receiving device may further implement other channel monitoring functions according to the frequency comb signal, which is not limited herein.

(2) The auxiliary optical signal is a PAM signal or a QPSK signal.

In the present application, the auxiliary optical signal may also be a PAM signal or a QPSK signal. The signal receiving apparatus can implement a channel monitoring function by the PAM signal and the QPSK signal. When the first modulator in the signal transmission device modulates the auxiliary optical signal by using the PAM modulation scheme or the QPSK modulation scheme, it indicates that the first modulator only performs simple PAM modulation or QPSK modulation on the light source corresponding to the selected spatial channel. The first coherent receiver simply demodulates the received PAM signal or QPSK signal and then sends the demodulated PAM signal or QPSK signal to the first data processing module to realize the channel monitoring function.

The following describes a procedure in which the first data module implements a channel monitoring function, taking a PAM signal as an example. The first modulator performs simple PAM modulation on the local oscillator optical signal to obtain a PAM signal (auxiliary optical signal). The signal receiving equipment can realize multiple functions through the change of the PAM signal frequency spectrum of the receiving end.

Fig. 12 is a schematic diagram of an application of a PAM signal provided by the present application.

Referring to fig. 12, the upper drawing of fig. 12 is a schematic diagram of a PAM signal transmitted by a signal transmitting device, and the lower drawing of fig. 12 is a schematic diagram of a PAM signal received by a signal receiving device. The signal receiving equipment can realize the channel monitoring function according to the difference between the PAM signal transmitted by the signal transmitting equipment and the PAM signal which is already received. Optionally, the signal receiving device may implement the power monitoring function through the PAM signal, scan a spectrum of the PAM signal received by the signal receiving device to obtain an optical power value at the central wavelength, and then implement the power monitoring function through the optical power value at the central wavelength. Optionally, the signal receiving device may implement an osnr monitoring function through the PAM signal, and the signal receiving device may obtain the power at the center frequency of the single wavelength channel and the power at two frequency points on the same side, so as to perform osnr estimation. Optionally, the signal receiving device may implement a dispersion monitoring function through the PAM signal, and the signal receiving device may obtain narrowband spectrum components of upper and lower sidebands of a signal spectrum to be monitored at the same time, and obtain a delay amount through cross-correlation of two power waveform signals having a delay therebetween, so as to perform dispersion monitoring.

The above examples describe the types of the auxiliary optical signals and the processes of performing channel estimation by the auxiliary optical signals, and the following embodiments will specifically describe specific implementations of various devices in the signal receiving apparatus provided in this application. In the present application, there are various implementations of the demultiplexer included in the signal receiving apparatus set forth in the above-described examples. Optionally, the mode demultiplexer may perform mode demultiplexing on the optical signal first and then perform wavelength demultiplexing, the mode demultiplexer may perform mode demultiplexing on the optical signal first and then perform mode demultiplexing, and may also demultiplex the received optical signal in other manners, which is not limited herein. Specific implementations are described in detail in the following examples.

The first method is as follows: firstly carrying out mode demultiplexing and then carrying out wavelength demultiplexing.

Fig. 13 is a schematic structural diagram of another signal receiving apparatus provided in the present application.

Referring to fig. 13, in the present application, optionally, the demultiplexer 201 may include a first mode demultiplexer 206, a first wavelength demultiplexer 207, and a second wavelength demultiplexer 208;

wherein the output of the first mode demultiplexer 206 is connected to the input of the first de-wavelength multiplexer 207 and to the input of the second wavelength demultiplexer 208. An output of the first wavelength demultiplexer 206 is connected to an input of the first receiver 202. An output of the second wavelength demultiplexer 208 is connected to an input of the second receiver 203.

In this application, the first mode demultiplexer 206 is configured to demultiplex an optical signal into an auxiliary optical signal in the first mode and a service optical signal in the second mode. The first wavelength demultiplexer 207 demultiplexes the auxiliary optical signal in the first mode into a first auxiliary optical signal having the first mode and the first wavelength and a second auxiliary optical signal having the first mode and the second wavelength. The second wavelength demultiplexer 208 demultiplexes the service optical signal in the second mode into a first service optical signal and a second service optical signal, where the first service optical signal has the second mode and the first wavelength, and the second service optical signal has the second mode and the second wavelength.

Illustratively, the first mode demultiplexer demultiplexes the optical signal into an optical signal A1 and an optical signal B1, and outputs the signal A1 to the first wavelength demultiplexer and the signal B1 to the second wavelength demultiplexer, respectively. Where A1 is the auxiliary optical signal, B1 is the traffic optical signal, and the A1 and B1 modes are different. The first wavelength demultiplexer demultiplexes A1 into an auxiliary optical signal a11 and an auxiliary optical signal a12, and outputs a11 and a12 to the first receiver, where a11 and a12 modes are the same wavelength and different. The second wavelength demultiplexer demultiplexes B1 into an auxiliary optical signal B11 and an auxiliary optical signal B12, and outputs B11 and B12 to the second receiver, where B11 and B12 modes are the same wavelength and different.

The second method comprises the following steps: and carrying out wavelength demultiplexing firstly and then carrying out mode demultiplexing.

Fig. 14 is a schematic structural diagram of a signal receiving apparatus provided in the present application.

Referring to fig. 14, in the present application, the demultiplexer 201 may optionally include a third wavelength demultiplexer 209, a second mode demultiplexer 210, and a third mode demultiplexer 211.

Wherein the output of the third wavelength demultiplexer 209 is connected to the input of the second mode multiplexer 210 and to the input of the third mode multiplexer 211. An output of the second mode multiplexer 210 is coupled to an input of the first receiver 202. The output of the third mode multiplexer 211 is connected to the input of the second receiver 203.

In this application, the third wavelength demultiplexer 209 is configured to demultiplex the optical signal into an auxiliary optical signal and a service optical signal, where the auxiliary optical signal has the first wavelength and the service optical signal has the second wavelength. The second mode demultiplexer 210 demultiplexes the auxiliary optical signal into a first auxiliary optical signal having a first wavelength and a first mode and a second auxiliary optical signal having the first wavelength and a second mode. The third mode demultiplexer 211 demultiplexes the service optical signal into a first service optical signal and a second service optical signal, where the first service optical signal has the second wavelength and the first mode, and the second service optical signal has the second wavelength and the second mode.

Illustratively, the third wavelength demultiplexer demultiplexes the optical signal into an optical signal A1 and an optical signal B1, and outputs the signal A1 to the second mode demultiplexer and the signal B1 to the third mode demultiplexer, respectively. Where A1 is an auxiliary optical signal, B1 is a traffic optical signal, and A1 and B1 have different wavelengths. The second mode demultiplexer demultiplexes A1 into an auxiliary optical signal a11 and an auxiliary optical signal a12, and outputs a11 and a12 to the first receiver, where a11 and a12 are different in the same mode of wavelength. The third mode demultiplexer demultiplexes B1 into an auxiliary optical signal B11 and an auxiliary optical signal B12, and outputs B11 and B12 to the second receiver, where B11 and B12 are different in the same mode of wavelength.

In the present application, various implementations of the demultiplexer are set forth in the above examples. In this application, the signal transmitting device may further include a local oscillation optical module in addition to the device described in the above example. In addition, the first receiver and the second receiver may also have specific implementation forms, and the specific implementation forms will be described in detail by the following examples.

Fig. 15a is a schematic structural diagram of a signal receiving device provided in the present application.

Referring to fig. 15a, in the present application, optionally, the signal receiving device 20 further includes a local oscillation optical module 212, the first receiver 202 includes a first coherent receiver 213 and a second coherent receiver 214, and the second receiver includes a third coherent receiver 215 and a fourth coherent receiver 216.

A first input end of the first coherent receiver 213 and a first input end of the second coherent receiver 214 are connected to an output end of the demultiplexer 201, a second input end of the first coherent receiver 213 and a second input end of the second coherent receiver 214 are connected to an output end of the local oscillation optical module 212, and an output end of the first coherent receiver 213 and an output end of the second coherent receiver 214 are connected to the first data processing module. A first input terminal of the third coherent receiver 215 is connected to a first input terminal of the fourth coherent receiver 216 and an output terminal of the demultiplexer, a second input terminal of the third coherent receiver 215 is connected to a second input terminal of the fourth coherent receiver 216 and an output terminal of the local oscillation module 212, and an output terminal of the third coherent receiver 215 and an output terminal of the fourth coherent receiver 216 are connected to the second data processing module 205.

In this application, the first coherent receiver 213 is configured to convert the first auxiliary optical signal into a first auxiliary electrical signal according to the local oscillator optical signal. The second coherent receiver 214 is configured to convert the second auxiliary optical signal into a second auxiliary electrical signal according to the local oscillator optical signal. The third phase coherent receiver 215 is configured to convert the first service optical signal into a first service electrical signal according to the local oscillator optical signal. The fourth coherent receiver 216 is configured to convert the second service optical signal into a second service electrical signal according to the local oscillator optical signal.

Illustratively, assume that a first receiver receives the auxiliary optical signal A1, wherein the first coherent receiver receives the auxiliary optical signal a11 and the second coherent receiver receives the auxiliary optical signal a12. The first coherent receiver may convert the auxiliary optical signal a11 into an auxiliary electrical signal a21 according to the local oscillator light output by the local oscillator light module, and input a21 into the first data processing module. Similarly, the second coherent receiver may convert the auxiliary optical signal a12 into an auxiliary electrical signal a22 according to the local oscillator light output by the local oscillator light module, and input a22 into the first data processing module. Similarly, assume that a second receiver receives service optical signal B1, wherein a third coherent receiver receives service optical signal B11 and a fourth coherent receiver receives service optical signal B12. The third phase dry receiver may convert the service optical signal B11 into a service electrical signal B21 according to the local oscillation light output by the local oscillation optical module, and input B21 into the second data processing module. Similarly, the second coherent receiver may convert the service optical signal B12 into the service electrical signal B22 according to the local oscillation light output by the local oscillation light module, and input the service electrical signal B22 into the second data processing module.

In the present application, specific implementation forms of the first receiver and the second receiver are set forth in the above examples. In the above example, optionally, the demultiplexer may also perform mode demultiplexing before wavelength demultiplexing, as shown in fig. 15b, which is not limited herein. In this application, the first coherent receiver and the second coherent receiver have specific implementations, and the following example takes the first coherent receiver as an example to illustrate one possible implementation of the first coherent receiver or the second coherent receiver.

In this application, the receiver may be an optical-to-electrical converter, and the receiver may also be other devices, which is not limited herein.

In this application, the foregoing example illustrates the signal receiving apparatus by taking two receivers and a four-path optical path as an example, and optionally, the signal receiving apparatus may include more receivers and more optical paths, which is not limited herein.

Referring to fig. 16, in the present application, optionally, the first coherent receiver includes a first polarization beam splitter, a second polarization beam splitter, a first detector and a second detector.

An input end of the first polarization beam splitter 217 is connected to an output end of the local oscillation optical module, and an output end of the first polarization beam splitter 217 is connected to a first input end of the first detector 219 and a first input end of the second detector 220. An input of the second polarization beam splitter 218 is connected to an output of the demultiplexer, and an output of the second polarization beam splitter 218 is connected to a second input of the first detector 219 and a second input of the second detector 220. The output of the first detector 219 and the output of the second detector 220 are connected to the input of a first data processing module.

In this application, the first polarization beam splitter 217 is configured to split the local oscillation optical signal into two local oscillation optical signals with orthogonal polarization states. The second polarization beam splitter 218 is used for splitting the input first auxiliary optical signal into two auxiliary optical signals with orthogonal polarization states. The first detector 219 is configured to convert the auxiliary optical signal into a third auxiliary electrical signal according to the local oscillator optical signal. The second detector 220 is configured to convert the auxiliary optical signal into a fourth auxiliary electrical signal according to the local oscillator optical signal.

Illustratively, the first polarization beam splitter splits the local oscillation optical signal C into two local oscillation optical signals C1 and C2 with orthogonal polarization states. The second polarization beam splitter splits the auxiliary optical signal a11 into two auxiliary optical signals D1 and D2 with orthogonal polarization states. The first detector converts the auxiliary optical signal D1 into an electrical signal D11 according to the local oscillator optical signal C1, and the second detector converts the auxiliary optical signal D2 into an electrical signal D21 according to the local oscillator optical signal C2. The first and second detectors input D11 and D21 to the first data processing module. And the first data processing module carries out channel estimation according to the obtained auxiliary electric signal.

In this application, a first transmitter in a signal transmission device is used to modulate an optical carrier into an auxiliary optical signal, which can be used for channel estimation. The second transmitter in the signal transmitting device is used for modulating the optical carrier into a service optical signal. The signal sending equipment multiplexes one or more service optical signals and the auxiliary optical signal and sends the multiplexed signal to the signal receiving equipment. One data processing module in the signal receiving equipment estimates the channel according to the auxiliary optical signal, and other data processing modules recover the received service signal according to the result of channel estimation. The device used for channel estimation has simple structure, low cost and easy technical popularization.

The foregoing detailed description has been made on the signal transmitting device, the signal receiving device and the communication system provided in the embodiments of the present application, and specific examples are applied herein to explain the principles and embodiments of the present application. Meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.

Claims

1. A signal transmission device characterized by comprising: the system comprises a laser device, a first transmitter, a second transmitter and a multiplexer;

the output end of the laser device is connected with the input end of the first transmitter and the input end of the second transmitter;

the output end of the first transmitter is connected with the first input end of the multiplexer;

the output end of the second transmitter is connected with the second input end of the multiplexer;

the laser equipment is used for outputting optical carriers;

the first transmitter is configured to modulate the optical carrier into an auxiliary optical signal, where the auxiliary optical signal is used to perform channel estimation, and the center wavelengths of the auxiliary optical signal and a service signal are the same;

the second transmitter is used for modulating the optical carrier into the service optical signal;

the multiplexer is configured to multiplex the auxiliary optical signal and the service optical signal.

2. The signal transmission apparatus of claim 1, wherein the auxiliary optical signal comprises a frequency comb signal.

3. The signal transmission apparatus according to claim 1 or 2, wherein pitches between comb teeth of the frequency comb signal are equal.

4. The signal transmission apparatus according to claims 1 to 3, wherein the comb teeth interval of the frequency comb signal ranges from 500MHz to 5GHz.

5. The apparatus according to claims 2 to 4, wherein the frequency comb signal comprises a first frequency comb and a second frequency comb, polarization states of the first frequency comb and the second frequency comb are orthogonal, and a center frequency of the first frequency comb and a center frequency of the second frequency comb are deviated.

6. The signal transmission apparatus according to any one of claims 1 to 5, characterized in that the signal transmission apparatus further comprises a first coupler and a second coupler, the first transmitter comprises a first modulator and a second modulator, the second transmitter comprises a third modulator and a fourth modulator;

the input end of the first coupler is connected with the output end of the laser device, and the output end of the first coupler is connected with the input end of the first modulator and the input end of the third modulator;

the input end of the second coupler is connected with the output end of the laser device, and the output end of the second coupler is connected with the input end of the second modulator and the input end of the fourth modulator;

the multiplexer is connected with the output ends of the four modulators;

the laser device outputs a first optical carrier and a second optical carrier to the first coupler and the second coupler respectively, wherein the wavelengths of the first optical carrier and the second optical carrier are different;

the first coupler is used for dividing the received first optical carrier into two paths of optical carriers;

the second coupler is used for dividing the received second optical carrier into two optical carriers;

the first modulator and the second modulator are configured to modulate a received optical carrier into the auxiliary optical signal;

the third modulator and the fourth modulator are configured to modulate the received optical carrier into the service optical signal.

7. The signal transmission apparatus according to claim 6, wherein the multiplexer includes a first wavelength multiplexer, a second wavelength multiplexer, and a first mode multiplexer;

the input end of the first wavelength multiplexer is connected with the output end of the first modulator and the output end of the second modulator, and the output end of the first wavelength multiplexer is connected with the first input end of the first mode multiplexer;

the input end of the second wavelength multiplexer is connected with the output end of the third modulator and the output end of the fourth modulator, and the output end of the second wavelength multiplexer is connected with the second input end of the first mode multiplexer;

the first wavelength multiplexer is used for multiplexing the received auxiliary optical signals with different wavelengths into an auxiliary optical signal in a first mode;

the second wavelength multiplexer is used for multiplexing the received service optical signals with different wavelengths into service optical signals in a second mode;

the first mode multiplexer is configured to multiplex the auxiliary optical signal in the first mode and the traffic optical signal in the second mode.

8. The signal transmission apparatus according to any one of claims 1 to 5, characterized in that the signal transmission apparatus further comprises a first coupler and a second coupler, the first transmitter comprises a first modulator and a second modulator, the second transmitter comprises a third modulator and a fourth modulator;

the input end of the first coupler is connected with the output end of the laser device, and the output end of the first coupler is connected with the input end of the first modulator and the input end of the second modulator;

the input end of the second coupler is connected with the output end of the laser device, and the output end of the second coupler is connected with the input end of the third modulator and the input end of the fourth modulator;

the multiplexer is connected with the output ends of the four modulators;

the first modulator and the second modulator are used for modulating the received optical carrier into the auxiliary optical signal;

9. The signal transmission apparatus according to claim 8, wherein the multiplexer includes a second mode multiplexer, a third mode multiplexer, and a third wavelength multiplexer;

the input end of the second mode multiplexer is connected with the output end of the first modulator and the output end of the second modulator, and the output end of the second mode multiplexer is connected with the first input end of the third wavelength multiplexer;

the input end of the third mode multiplexer is connected with the output end of the third modulator and the output end of the fourth modulator, and the output end of the third mode multiplexer is connected with the second input end of the third wavelength multiplexer;

the second mode multiplexer is used for multiplexing the received auxiliary optical signals of different modes into an auxiliary optical signal under a first wavelength;

the third mode multiplexer is used for multiplexing the received service optical signals in different modes into service optical signals under a second wavelength;

the third wavelength multiplexer is configured to multiplex the auxiliary optical signal at the first wavelength and the service optical signal at the second wavelength.

10. The signal transmission apparatus according to claim 7 or 9, wherein the first modulator comprises a power splitter, a frequency shifter, a polarization beam splitter, a fifth modulator, a sixth modulator, and a polarization beam combiner;

the input end of the power divider is electrically connected with the control module, the first output end of the power divider is connected with the frequency shifter, and the second output end of the power divider is connected with the first input end of the fifth modulator;

the output end of the frequency shifter is connected with the first input end of the sixth modulator;

the input end of the polarization beam splitter is connected with the output end of the first coupler, the first output end of the polarization beam splitter is connected with the second input end of the fifth modulator, and the second output end of the polarization beam splitter is connected with the second input end of the sixth modulator;

a first input end of the polarization beam combiner is connected with an output end of the fifth modulator, a second input end of the polarization beam combiner is connected with an output end of the sixth modulator, and an output end of the polarization beam combiner is connected with an input end of the multiplexer;

the power divider is used for dividing the electric signal input by the control module into two paths of electric signals;

the frequency shifter is used for modulating the frequency of the received electric signal;

the polarization beam splitter is used for splitting an input optical signal into two paths of optical signals with orthogonal polarization states;

the fifth modulator is used for modulating the optical signal output by the polarization beam splitter into a first auxiliary optical signal according to the electric signal input by the beam splitter;

the sixth modulator is configured to modulate the optical signal output by the polarization beam splitter into a second auxiliary optical signal according to the electrical signal input by the frequency shifter, where the polarization states of the first auxiliary optical signal and the second auxiliary optical signal are orthogonal;

the polarization beam combiner is configured to combine the first auxiliary optical signal and the second auxiliary optical signal.

11. A signal receiving apparatus, characterized in that the signal receiving apparatus comprises: the system comprises a demultiplexer, a first receiver, a second receiver, a first data processing module and a second data processing module;

a first output end of the demultiplexer is connected with an input end of the first receiver, and a second output end of the demultiplexer is connected with an input end of the second receiver;

the output end of the first receiver is connected with the input end of the first data processing module;

the output end of the first data processing module is connected with the first input end of the second data processing module;

the output end of the second receiver is connected with the second input end of the second data processing module;

the demultiplexer is configured to demultiplex an optical signal into a service optical signal and an auxiliary optical signal, where the auxiliary optical signal is used to perform channel estimation;

the first receiver is configured to convert the auxiliary optical signal into an auxiliary electrical signal;

the second receiver is used for converting the service optical signal into a service electrical signal;

the first data processing module is used for carrying out channel estimation according to the auxiliary electric signal;

and the second data processing module is used for recovering the service optical signal according to the result output by the first data processing module.

12. The signal receiving device of claim 11, wherein the auxiliary optical signal comprises a frequency comb signal.

13. The signal receiving apparatus according to claim 11 or 12, wherein pitches between comb teeth of the frequency comb signal are equal.

14. The signal receiving apparatus of claims 11 to 13, wherein the comb tooth interval of the frequency comb signal ranges from 500MHz to 5GHz.

15. The signal receiving apparatus as claimed in claims 12 to 14, wherein the frequency comb signal comprises a first frequency comb and a second frequency comb, polarization states of the first frequency comb and the second frequency comb are orthogonal, and a center frequency of the first frequency comb and a center frequency of the second frequency comb are offset.

16. The signal receiving apparatus according to any one of claims 11 to 15, wherein the demultiplexer comprises a first mode demultiplexer, a first wavelength demultiplexer, and a second wavelength demultiplexer;

the output end of the first mode demultiplexer is connected with the input end of the first wavelength demultiplexer and the input end of the second wavelength demultiplexer;

the output end of the first wavelength demultiplexer is connected with the input end of the first receiver;

the output end of the second wavelength demultiplexer is connected with the input end of the second receiver;

the first mode demultiplexer is configured to demultiplex the optical signal into an auxiliary optical signal in a first mode and a service optical signal in a second mode;

the first wavelength demultiplexer demultiplexes the auxiliary optical signal in the first mode into a first auxiliary optical signal and a second auxiliary optical signal, the first auxiliary optical signal having a first mode and a first wavelength, and the second auxiliary optical signal having a first mode and a second wavelength;

the second wavelength demultiplexer demultiplexes the service optical signal in the second mode into a first service optical signal and a second service optical signal, where the first service optical signal has the second mode and the first wavelength, and the second service optical signal has the second mode and the second wavelength.

17. The signal receiving apparatus according to any one of claims 11 to 16, wherein the demultiplexer includes a third wavelength demultiplexer, a second mode demultiplexer, and a third mode demultiplexer;

the output end of the third wavelength demultiplexer is connected with the input end of the second mode demultiplexer and the input end of the third mode demultiplexer;

the output end of the second mode demultiplexer is connected with the input end of the first receiver;

the output end of the third mode demultiplexer is connected with the input end of the second receiver;

the third wavelength demultiplexer is configured to demultiplex the optical signal into the auxiliary optical signal and the service optical signal, where the auxiliary optical signal has a first wavelength and the service optical signal has a second wavelength;

the second mode demultiplexer demultiplexes the auxiliary optical signal into a first auxiliary optical signal and a second auxiliary optical signal, the first auxiliary optical signal having a first wavelength and a first mode, the second auxiliary optical signal having a first wavelength and a second mode;

the third mode demultiplexer demultiplexes the service optical signal into a first service optical signal and a second service optical signal, where the first service optical signal has a second wavelength and a first mode, and the second service optical signal has the second wavelength and a second mode.

18. The signal receiving device according to claim 16 or 17, wherein the signal receiving device further comprises a local oscillation optical module, the first receiver comprises a first coherent receiver and a second coherent receiver, and the second receiver comprises a third coherent receiver and a fourth coherent receiver;

a first input end of the first coherent receiver and a first input end of the second coherent receiver are connected with an output end of the multiplexer, a second input end of the first coherent receiver and a second input end of the second coherent receiver are connected with an output end of the local oscillation optical module, and an output end of the first coherent receiver and an output end of the second coherent receiver are connected with the first data processing module;

a first input end of the third coherent receiver and a first input end of the fourth coherent receiver are connected with an output end of the multiplexer, a second input end of the third coherent receiver and a second input end of the fourth coherent receiver are connected with an output end of the local oscillation optical module, and an output end of the third coherent receiver and an output end of the fourth coherent receiver are connected with the second data processing module;

the first coherent receiver is used for converting the first auxiliary optical signal into a first auxiliary electrical signal according to the local oscillator optical signal;

the second coherent receiver is configured to convert the second auxiliary optical signal into a second auxiliary electrical signal according to the local oscillator optical signal;

the third phase-coherent receiver is used for converting the first service optical signal into a first service electrical signal according to the local oscillator optical signal;

and the fourth coherent receiver is configured to convert the second service optical signal into a second service electrical signal according to the local oscillator optical signal.

19. The signal receiving device of claim 18, wherein the first coherent receiver comprises a first polarizing beam splitter, a second polarizing beam splitter, a first detector, and a second detector;

the input end of the first polarization beam splitter is connected with the output end of the local oscillation optical module, and the output end of the first polarization beam splitter is connected with the first input end of the first detector and the first input end of the second detector;

the input end of the second polarization beam splitter is connected with the output end of the demultiplexer, and the output end of the second polarization beam splitter is connected with the second input end of the first detector and the second input end of the second detector;

the output end of the first detector and the output end of the second detector are connected with the input end of the first data processing module;

the first polarization beam splitter is used for splitting the local oscillator optical signals into two paths of local oscillator optical signals with orthogonal polarization states;

the second polarization beam splitter is configured to split the input first auxiliary optical signal into two auxiliary optical signals with orthogonal polarization states;

the first detector is used for converting the auxiliary optical signal into a third auxiliary electrical signal according to the local oscillator optical signal;

the second detector is configured to convert the auxiliary optical signal into a fourth auxiliary electrical signal according to the local oscillator optical signal.

20. A communication system, characterized in that the communication system comprises a signal transmission apparatus according to any one of claims 1 to 10 and a signal reception apparatus according to any one of claims 11 to 19.