Phase noise and dispersion joint compensation method and system based on dual-pilot-frequency auxiliary digital subcarrier multiplexing signal

Abstract

The invention provides a phase noise and dispersion joint compensation method based on a dual-pilot-frequency auxiliary digital subcarrier multiplexing signal, and relates to the technical field of optical fiber communication. The method comprises the following steps: firstly, setting a guard interval on a digital subcarrier multiplexing signal sent by a transmitting end, and inserting two pilot signals with set amplitudes and phases into the guard interval; then, the amplitude of the pilot signal is extracted, and the dispersion amount of the digital subcarrier multiplexing signal in optical fiber communication system transmission is estimated; and according to the phases of the two pilot signals, obtaining a combination of phase noise of the transmitting end and the receiving end at the receiving end, performing signal processing on the phase noise, and separating the phase noise of the transmitting end and the phase noise of the receiving end. Secondly, reconstructing the phase noise of the transmitting end to obtain the reconstructed phase noise of the transmitting end; and reconstructing the phase noise of the receiving end to obtain the reconstructed phase noise of the receiving end. And finally, compensating the phase noise and dispersion of the receiving end and the phase noise of the transmitting end according to the reconstructed phase noise of the transmitting end and the reconstructed phase noise and dispersion amount of the receiving end. The phase noise and dispersion generated in the transmission process of the digital subcarrier multiplexing signal are estimated by using the phase and amplitude of the pilot signal, the transmission performance of the digital subcarrier multiplexing signal is improved, and the performance of an optical fiber communication system is optimized.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber communication, and more specifically relates to a phase noise and dispersion joint compensation method and system based on dual-pilot assisted digital subcarrier multiplexing signals. Background Art

[0002] As the core hub of global information exchange, data centers carry the functions of storing, processing and distributing massive amounts of data. With the rapid development of cloud computing and big data technologies, data centers have an increasing demand for high-speed, large-capacity optical interconnection technologies. As the main means of connection within and between data centers, the development of fiber-optic communication systems is closely related to the evolution of data centers. Fiber nonlinearity, as a decisive factor limiting the transmission capacity of fiber-optic communication systems, remains a challenge. In order to suppress fiber nonlinearity in optical communication systems, digital subcarrier multiplexing technology is widely used. Compared with traditional single-carrier systems, digital subcarrier multiplexing technology provides higher tolerance to nonlinearity, which enables optical communication systems to achieve higher data transmission rates while maintaining signal integrity.

[0003] However, during the optical fiber transmission process, the signal will be affected by dispersion, and the receiving end needs to adopt dispersion compensation technology to eliminate the damage introduced by dispersion. During the dispersion compensation process, the interaction between laser phase noise and dispersion will produce balanced enhanced phase noise. This damage will cause the signal-to-noise ratio to decrease, thereby affecting the overall performance of the transmission system. The existing technology uses two pilots to eliminate the balanced enhanced phase noise, but only uses two pilot phases, the pilot utilization rate is low, and it is impossible to accurately estimate the phase noise and dispersion generated during the transmission of digital subcarrier multiplexing signals, resulting in reduced performance of digital subcarrier multiplexing signal transmission and affecting the performance of the optical fiber communication system. Summary of the invention

[0004] In order to solve the problem that currently only two pilot phases are used, the pilot utilization rate is low, and the phase noise and dispersion generated in the digital subcarrier multiplexed signal transmission process cannot be accurately estimated, resulting in reduced performance of the digital subcarrier multiplexed signal transmission, the present invention provides a phase noise and dispersion joint compensation method based on dual pilot assisted digital subcarrier multiplexed signals to improve the performance of digital subcarrier multiplexed signal transmission.

[0005] In order to achieve the above technical effects, the technical solution of the present invention is as follows:

[0006] In the first aspect, the present application proposes a method for joint compensation of phase noise and dispersion based on a dual-pilot assisted digital subcarrier multiplexed signal, the method being applied to an optical fiber communication system, the optical fiber communication system comprising a transmitting end and a receiving end, and using the digital subcarrier multiplexed signal as an optical fiber transmission signal of the optical fiber communication system; comprising the following steps:

[0007] S1: Set a guard interval on the digital subcarrier multiplexed signal sent by the transmitter, and insert two pilot signals with set amplitude and phase into the guard interval;

[0008] S2: extract the amplitude of the pilot signal and estimate the dispersion of the digital subcarrier multiplexed signal during transmission in the optical fiber communication system;

[0009] S3: acquiring a combination of the phase noise of the transmitting end and the receiving end at the receiving end according to the phases of the two pilot signals, performing signal processing on the phase noise, and separating the phase noise of the transmitting end and the phase noise of the receiving end;

[0010] S4: reconstructing the phase noise of the transmitting end to obtain the reconstructed phase noise of the transmitting end; reconstructing the phase noise of the receiving end to obtain the reconstructed phase noise of the receiving end;

[0011] S5: Compensating for the phase noise and dispersion at the receiving end and the phase noise at the transmitting end according to the reconstructed phase noise at the transmitting end, the reconstructed phase noise and dispersion at the receiving end.

[0012] Furthermore, the specific steps of step S1 are:

[0013] Symmetrical guard intervals are set on the X polarization and Y polarization of the digital subcarrier multiplexed signal, and a pilot signal with a set amplitude and phase is inserted at the center of each guard interval; the amplitude of the pilot signal carries information of the modulation code type; and the size of the guard interval is a set value.

[0014] Furthermore, the method further comprises: the receiving end identifying the modulation code type of the digital subcarrier multiplexing signal sent by the transmitting end according to the amplitude of the pilot signal;

[0015] The process of identifying the modulation code type of the digital subcarrier multiplexing signal sent by the transmitter according to the amplitude of the pilot signal is as follows:

[0016] First, extract the amplitude of the pilot signal, the expression is:

[0017] A=abs(S tone )

[0018] Where A represents the amplitude of the pilot signal, S tone represents the pilot signal extracted by digital signal processing at the receiving end;

[0019] Then, the amplitude of the pilot signal is determined and demodulated to identify the modulation code type of the digital subcarrier multiplexed signal sent by the transmitter.

[0020] According to the above technical means, different modulation patterns represent different digital subcarrier multiplexed signal encoding and transmission methods, and identifying the modulation pattern helps ensure accurate reception and demodulation of the digital subcarrier multiplexed signal. By identifying the modulation pattern, the receiving end processes the received digital subcarrier multiplexed signal according to the modulation pattern, thereby improving the efficiency and accuracy of digital subcarrier multiplexed signal processing.

[0021] Furthermore, the dispersion estimation process satisfies:

[0022] First, a cross-correlation operation is performed on the amplitude of the extracted pilot signal, and the relative delay caused by dispersion after the pilot signal is transmitted through the optical fiber is calculated based on the result of the cross-correlation operation; the process satisfies:

[0023] R(m)=E[|A left (k,z)| 2 ·|A right (km,z)| 2 ]

[0024] Δτ=m max T s

[0025] In the formula, A left , A right represents the amplitude of the inserted pilot signal, R(m) represents the cross-correlation value, k represents the kth sampling point, z represents the signal transmission distance, T s represents the sampling period, Δτ represents the relative delay of the pilot signal caused by dispersion after the pilot signal is transmitted through the optical fiber, and m represents an integer 0, 1, 2, ...;

[0026] Next, the dispersion amount is estimated based on the relative time delay caused by dispersion after the pilot signal is transmitted through the optical fiber. The expression is:

[0027]

[0028] In the formula, CD represents the dispersion, F c represents the optical carrier frequency, f p represents the frequency of the pilot signal, and c represents the speed of light in a vacuum.

[0029] Furthermore, the expressions of the phase noise of the transmitting end and the phase noise of the receiving end are respectively:

[0030]

[0031] In the formula, represents the combination of the transmitting and receiving phase noises obtained by the receiving end of the first pilot signal, φ TX represents the phase noise caused by the laser line width at the transmitting end, φ RXrepresents the phase noise caused by the laser line width at the receiving end, P represents the insertion position of the pilot signal, L represents the fiber length, β2 represents the fiber dispersion parameter, Δω subcarrier represents the subcarrier bandwidth, Δω interval represents the guard interval bandwidth, Represents the combination of the transmitting and receiving phase noises obtained by the receiving end of the second pilot signal.

[0032] Furthermore, the calculation process of the reconstructed transmitting end phase noise satisfies:

[0033] First, based on the phase noise of the two pilot signals, the change in the phase noise at the transmitter after the delay is calculated, and its expression is:

[0034]

[0035] Next, according to the number of samples within the delay range, the variation between the phase noise samples at the transmitter is calculated, and the expression is:

[0036]

[0037] In the formula, α represents the number of samples within the delay range, and Ts is the sampling period;

[0038] Finally, the phase noise of the transmitter is reconstructed by integrating and accumulating, and the process satisfies:

[0039]

[0040] In the formula, represents an initial fixed phase value, represents the reconstructed transmitter phase noise.

[0041] Furthermore, the calculation process of the reconstructed receiving end phase noise is:

[0042] The reconstructed transmitter phase noise is processed with two different time delays, and then the corresponding pilot signal phase noise is subtracted from the delayed transmitter phase noise, and the average value is calculated to obtain the reconstructed receiver phase noise. The calculation expression of this process is:

[0043]

[0044] In the formula, represents the reconstructed receiving end phase noise.

[0045] According to the above technical means, by separating the phase noise of the transmitter and the receiver, the impact of the two parts of the transmitter and the receiver on the transmission of the optical fiber communication system can be accurately analyzed; then the phase noise of the transmitter and the receiver is reconstructed to obtain the detailed characteristics of the phase noise of the transmitter and the receiver, which helps to achieve more accurate phase noise compensation.

[0046] Furthermore, the specific process of step S5 is:

[0047] Before dispersion compensation, the reconstructed receiving end phase noise is used to compensate the receiving end phase noise; then, the estimated dispersion amount is used to compensate the dispersion; the reconstructed transmitting end phase noise is used to compensate the transmitting end phase noise, and the process satisfies:

[0048]

[0049] In the formula, S rx (t) represents the signal received by the receiving end, h CDC (t) represents the dispersion compensation function, represents the convolution symbol, CD represents the estimated dispersion amount, and S(t) represents the compensated signal.

[0050] The present invention also provides a phase noise and dispersion joint compensation system based on dual pilot assisted digital subcarrier multiplexing signal, comprising:

[0051] A pilot signal insertion module is used to set a guard interval on the digital subcarrier multiplexed signal sent by the transmitting end, and insert two pilot signals with set amplitude and phase in the guard interval;

[0052] A dispersion estimation module is used to extract the amplitude of the pilot signal and estimate the dispersion of the digital subcarrier multiplexed signal during transmission in the optical fiber communication system;

[0053] The receiving-end phase noise acquisition module is used to acquire the combination of the transmitting-end and receiving-end phase noises at the receiving end according to the phases of the two pilot signals, perform signal processing on the phase noises, and separate the transmitting-end phase noise and the receiving-end phase noise;

[0054] The phase noise reconstruction module of the transmitting and receiving end is used to reconstruct the phase noise of the transmitting end to obtain the reconstructed phase noise of the transmitting end; and reconstruct the phase noise of the receiving end to obtain the reconstructed phase noise of the receiving end;

[0055] The compensation module compensates for the phase noise and dispersion of the receiving end and the phase noise of the transmitting end according to the reconstructed phase noise of the transmitting end, the reconstructed phase noise of the receiving end and the dispersion amount.

[0056] The present invention also provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the steps of the phase noise and dispersion joint compensation method based on dual-pilot assisted digital subcarrier multiplexing signal through the computer program.

[0057] Compared with the prior art, the beneficial effects of this method are:

[0058] The present invention provides a phase noise and dispersion joint compensation method based on dual pilot-assisted digital subcarrier multiplexing signals. First, two pilot signals with set amplitude and phase are inserted to help the receiving end of the optical fiber communication system to accurately synchronize and calibrate the signal of the transmitting end. Then, the phase noise of the transmitting end, the phase noise of the receiving end and the dispersion are calculated by amplitude and phase to achieve more accurate phase noise and dispersion compensation. The present invention uses the phase and amplitude of the pilot signal to estimate the phase noise and dispersion generated during the transmission of the digital subcarrier multiplexing signal, improve the performance of the digital subcarrier multiplexing signal transmission, and optimize the performance of the optical fiber communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A flow chart showing a method for joint compensation of phase noise and dispersion based on a dual pilot assisted digital subcarrier multiplexed signal in an embodiment of the present invention;

[0060] Figure 2 A structural diagram showing a phase noise and dispersion joint compensation system based on a dual pilot assisted digital subcarrier multiplexing signal proposed in an embodiment of the present invention;

[0061] Figure 3 A schematic diagram showing an electronic device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0063] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the actual size;

[0064] It is understandable to those skilled in the art that descriptions of certain well-known contents in the drawings may be omitted.

[0065] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0066] The positional relationships described in the drawings are only for illustrative purposes and should not be construed as limiting the present patent;

[0067] Example 1

[0068] This embodiment proposes a phase noise and dispersion joint compensation method based on dual pilot assisted digital subcarrier multiplexing signal, such as Figure 1 The flowchart of the method shown in the figure is applied to an optical fiber communication system, wherein the optical fiber communication system includes a transmitting end and a receiving end, and the digital subcarrier multiplexing signal is used as an optical fiber transmission signal of the optical fiber communication system; the method proposed in this embodiment includes the following steps as a whole:

[0069] S1: Set a guard interval on the digital subcarrier multiplexed signal sent by the transmitter, and insert two pilot signals with set amplitude and phase into the guard interval;

[0070] S2: extract the amplitude of the pilot signal and estimate the dispersion of the digital subcarrier multiplexed signal during transmission in the optical fiber communication system;

[0071] S3: acquiring a combination of the phase noise of the transmitting end and the receiving end at the receiving end according to the phases of the two pilot signals, performing signal processing on the phase noise, and separating the phase noise of the transmitting end and the phase noise of the receiving end;

[0072] S4: reconstructing the phase noise of the transmitting end to obtain the reconstructed phase noise of the transmitting end; reconstructing the phase noise of the receiving end to obtain the reconstructed phase noise of the receiving end;

[0073] S5: Compensating for the phase noise and dispersion at the receiving end and the phase noise at the transmitting end according to the reconstructed phase noise at the transmitting end, the reconstructed phase noise and dispersion at the receiving end.

[0074] In this embodiment, the specific steps of step S1 are: mutually symmetrical guard intervals are set on the X polarization and Y polarization of the digital subcarrier multiplexed signal, and a pilot signal with a set amplitude and phase is inserted at the center of each guard interval; the amplitude of the pilot signal carries information of the modulation code type; and the size of the guard interval is a set value.

[0075] In this embodiment, the pilot signal is subjected to two-level amplitude modulation, the low level amplitude is 1, and the high level amplitude is greater than 1. Each frame carries 4 bits of modulation code type information. The 4 bits of modulation code type information can identify 16 modulation code types.

[0076] In this embodiment, the process of extracting the amplitude of the pilot signal and estimating the dispersion amount of the digital subcarrier multiplexed signal in the transmission of the optical fiber communication system includes:

[0077] First, a cross-correlation operation is performed on the amplitude of the extracted pilot signal, and the relative delay caused by dispersion after the pilot signal is transmitted through the optical fiber is calculated based on the result of the cross-correlation operation; the process satisfies:

[0078] R(m)=E[|Aleft (k,z)| 2 ·|A right (km,z)| 2 ]

[0079] Δτ=m max T s

[0080] In the formula, A left , A right represents the amplitude of the inserted pilot signal, R(m) represents the cross-correlation value, k represents the kth sampling point, z represents the signal transmission distance, T s represents the sampling period, Δτ represents the relative delay of the pilot signal caused by dispersion after the pilot signal is transmitted through the optical fiber, and m represents an integer 0, 1, 2, ...;

[0081] Next, the dispersion amount is estimated based on the relative time delay caused by dispersion after the pilot signal is transmitted through the optical fiber. The expression is:

[0082]

[0083] In the formula, CD represents the dispersion, F c represents the optical carrier frequency, f p represents the frequency of the pilot signal, and c represents the speed of light in a vacuum.

[0084] In this embodiment, according to the phase of the two pilot signals, a combination of the phase noise of the transmitting end and the receiving end is obtained at the receiving end, and the phase noise is signal processed to separate the phase noise of the transmitting end and the phase noise of the receiving end. The expressions of the phase noise of the transmitting end and the phase noise of the receiving end are respectively:

[0085]

[0086] In the formula, represents the combination of the transmitting and receiving phase noises obtained by the receiving end of the first pilot signal, φ TX represents the phase noise caused by the laser line width at the transmitter, φ RX represents the phase noise caused by the laser line width at the receiving end, P represents the insertion position of the pilot signal, L represents the fiber length, β2 represents the fiber dispersion parameter, Δω subcarrier represents the subcarrier bandwidth, Δω interval represents the guard interval bandwidth, Represents the combination of the phase noise of the transmitter and receiver obtained by the second pilot signal receiving end. P∈[-N SC / 2,N SC / 2] indicates the insertion position of the pilot signal. SC Indicates the total number of subcarriers.

[0087] In this embodiment, dispersion may cause walk-off between pilot signals after optical fiber transmission, resulting in a time delay between subcarriers for the phase noise at the transmitting end associated with the pilot signal, while the phase noise at the receiving end associated with the pilot signal is the same.

[0088] In this embodiment, the optical fiber communication system further includes: a transmitting end laser and a receiving end laser. The signal light of the transmitting end and the local oscillator light of the receiving end come from different laser light sources, and both have randomly changing laser phase noise. The phase noise of the transmitting end is caused by the line width of the transmitting end laser, and the phase noise of the receiving end is caused by the line width of the receiving end laser.

[0089] In this embodiment, the phase noise of the transmitting end is reconstructed to obtain the reconstructed phase noise of the transmitting end; the calculation process of the reconstructed phase noise of the transmitting end satisfies:

[0090] First, based on the phase noise of the two pilot signals, the change in the phase noise at the transmitter after the delay is calculated, and its expression is:

[0091]

[0092] Next, according to the number of samples within the delay range, the variation between the phase noise samples at the transmitter is calculated, and the expression is:

[0093]

[0094] In the formula, α represents the number of samples within the delay range, and Ts is the sampling period;

[0095] Finally, since the laser phase noise is a Wiener process, the transmitter phase noise is reconstructed by integration and accumulation, and the process satisfies:

[0096]

[0097] In the formula, represents an initial fixed phase value, represents the reconstructed transmitter phase noise.

[0098] In this embodiment, the phase noise of the receiving end is reconstructed to obtain the reconstructed phase noise of the receiving end. The calculation process of the reconstructed phase noise of the receiving end is:

[0099] The reconstructed transmitter phase noise is processed with two different time delays, and then the corresponding pilot signal phase noise is subtracted from the delayed transmitter phase noise, and the average value is calculated to obtain the reconstructed receiver phase noise. The calculation expression of this process is:

[0100]

[0101] In the formula, represents the reconstructed receiving end phase noise.

[0102] The specific process of step S5 is: according to the reconstructed phase noise of the transmitting end, the reconstructed phase noise of the receiving end and the dispersion amount, the phase noise of the receiving end, the dispersion and the phase noise of the transmitting end are compensated. Before the dispersion compensation, the reconstructed phase noise of the receiving end is used to compensate the phase noise of the receiving end; then, the estimated dispersion amount is used to compensate the dispersion; the reconstructed phase noise of the transmitting end is used to compensate the phase noise of the transmitting end, and the process satisfies:

[0103]

[0104] In the formula, S rx (t) represents the signal received by the receiving end, h CDC (t) represents the dispersion compensation function, represents the convolution symbol, CD represents the estimated dispersion amount, and S(t) represents the compensated signal.

[0105] Example 2

[0106] This embodiment provides a method for joint compensation of phase noise and dispersion based on dual-pilot assisted digital subcarrier multiplexing signals, and also includes: the receiving end identifies the modulation code type of the digital subcarrier multiplexing signal sent by the transmitting end according to the amplitude of the pilot signal. Different modulation code types represent different digital subcarrier multiplexing signal encoding and transmission methods. Identifying the modulation code type helps to ensure accurate reception and demodulation of the digital subcarrier multiplexing signal. By identifying the modulation code type, the receiving end processes the received digital subcarrier multiplexing signal according to the modulation code type, thereby improving the efficiency and accuracy of digital subcarrier multiplexing signal processing.

[0107] The process of identifying the modulation code type of the digital subcarrier multiplexing signal sent by the transmitter according to the amplitude of the pilot signal is as follows:

[0108] First, extract the amplitude of the pilot signal, the expression is:

[0109] A=abs(S tone )

[0110] Where A represents the amplitude of the pilot signal, S tone represents the pilot signal extracted by digital signal processing at the receiving end;

[0111] Then, the amplitude of the pilot signal is determined and demodulated to identify the modulation code type of the digital subcarrier multiplexed signal sent by the transmitter.

[0112] In this embodiment, the modulation code type of the digital subcarrier multiplexed signal sent by the transmitting end is identified according to the modulation code type coding table.

[0113] In this embodiment, the modulation code encoding table is: 0000 represents binary phase shift keying BPSK, 0001 represents orthogonal phase shift keying QPSK, 0010 represents 8QAM, 0011 represents 6QAM, 0100~0111 represents high-order QAM modulation, 1000~1011 represents time domain hybrid QAM modulation, and 1100~1111 represents multi-dimensional format.

[0114] Specifically, during the decision demodulation process, the phase and frequency of the signal are calibrated and synchronized according to the information provided by the pilot signal. Then, the demodulation algorithm is used to decode the signal. Finally, the information after decision demodulation is compared with the modulation code type encoding table, and the receiving end can determine the modulation code type that the received signal conforms to.

[0115] Example 3

[0116] In this embodiment, a phase noise and dispersion joint compensation system based on dual pilot assisted digital subcarrier multiplexing signal is also provided. The structure diagram of the system is shown in FIG. Figure 2 As shown, the system includes:

[0117] A pilot signal insertion module is used to set a guard interval on the digital subcarrier multiplexed signal sent by the transmitting end, and insert two pilot signals with set amplitude and phase in the guard interval;

[0118] A dispersion estimation module is used to extract the amplitude of the pilot signal and estimate the dispersion of the digital subcarrier multiplexed signal during transmission in the optical fiber communication system;

[0119] The receiving-end phase noise acquisition module is used to acquire the combination of the transmitting-end and receiving-end phase noises at the receiving end according to the phases of the two pilot signals, perform signal processing on the phase noises, and separate the transmitting-end phase noise and the receiving-end phase noise;

[0120] The phase noise reconstruction module of the transmitting and receiving end is used to reconstruct the phase noise of the transmitting end to obtain the reconstructed phase noise of the transmitting end; and reconstruct the phase noise of the receiving end to obtain the reconstructed phase noise of the receiving end;

[0121] The compensation module compensates for the phase noise and dispersion of the receiving end and the phase noise of the transmitting end according to the reconstructed phase noise of the transmitting end, the reconstructed phase noise of the receiving end and the dispersion amount.

[0122] Example 4

[0123] like Figure 3As shown, an embodiment of the present invention further proposes an electronic device, comprising a memory 101, a processor 102, and a computer program stored in the memory 101 and running on the processor 102, wherein when the processor 102 executes the computer program, the steps of the phase noise and dispersion joint compensation method based on dual-pilot assisted digital subcarrier multiplexing signal proposed in this embodiment are implemented.

[0124] Specifically, in the present embodiment, the processor 102 may include a central processing unit (CPU) or a specific integrated circuit, or be configured to implement one or more integrated circuits of the present embodiment, and the memory 101 may include a large-capacity memory for data or instructions. It may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. In appropriate cases, the memory 101 may include a removable or non-removable (or fixed) medium. In appropriate cases, the memory 101 may be inside or outside the integrated gateway disaster recovery device.

[0125] The embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for joint compensation of phase noise and dispersion based on dual pilot assisted digital subcarrier multiplexing signal, the method is applied to an optical fiber communication system, the optical fiber communication system includes a transmitting end and a receiving end, and the digital subcarrier multiplexing signal is used as an optical fiber transmission signal of the optical fiber communication system, characterized in that: The following steps are involved: S1: Set a guard interval on the digital subcarrier multiplexed signal sent by the transmitter, and insert two pilot signals with set amplitude and phase into the guard interval; S2: extract the amplitude of the pilot signal and estimate the dispersion of the digital subcarrier multiplexed signal during transmission in the optical fiber communication system; S3: acquiring a combination of the phase noise of the transmitting end and the receiving end at the receiving end according to the phases of the two pilot signals, performing signal processing on the phase noise, and separating the phase noise of the transmitting end and the phase noise of the receiving end; S4: reconstructing the phase noise of the transmitting end to obtain the reconstructed phase noise of the transmitting end; reconstructing the phase noise of the receiving end to obtain the reconstructed phase noise of the receiving end; S5: Compensating for the phase noise and dispersion at the receiving end and the phase noise at the transmitting end according to the reconstructed phase noise at the transmitting end, the reconstructed phase noise and dispersion at the receiving end.

2. The method for joint compensation of phase noise and dispersion based on dual pilot assisted digital subcarrier multiplexing signal according to claim 1, characterized in that: The specific steps of step S1 are: Symmetrical guard intervals are set on the X polarization and Y polarization of the digital subcarrier multiplexed signal, and a pilot signal with a set amplitude and phase is inserted at the center of each guard interval; the amplitude of the pilot signal carries information of the modulation code type; and the size of the guard interval is a set value.

3. The method for joint compensation of phase noise and dispersion based on dual pilot assisted digital subcarrier multiplexing signal according to claim 1, characterized in that: Also includes: The receiving end identifies the modulation code type of the digital subcarrier multiplexed signal sent by the transmitting end according to the amplitude of the pilot signal; The process of identifying the modulation code type of the digital subcarrier multiplexing signal sent by the transmitter according to the amplitude of the pilot signal is as follows: First, extract the amplitude of the pilot signal, the expression is: A=abs(S tone ) Where A represents the amplitude of the pilot signal, S tone represents the pilot signal extracted by digital signal processing at the receiving end; Then, the amplitude of the pilot signal is determined and demodulated to identify the modulation code type of the digital subcarrier multiplexed signal sent by the transmitter.

4. The method for joint compensation of phase noise and dispersion based on dual pilot assisted digital subcarrier multiplexing signal according to claim 3, characterized in that: The dispersion estimation process satisfies: First, a cross-correlation operation is performed on the amplitude of the extracted pilot signal, and the relative delay caused by dispersion after the pilot signal is transmitted through the optical fiber is calculated based on the result of the cross-correlation operation; the process satisfies: R(m)=E[|A left (k,z)| 2 ·|A right (k-m,z)| 2 ] Δτ=m max T s In the formula, A ｌeft , A right represents the amplitude of the inserted pilot signal, R(m) represents the cross-correlation value, k represents the kth sampling point, z represents the signal transmission distance, T s represents the sampling period, Δτ represents the relative delay of the pilot signal caused by dispersion after the pilot signal is transmitted through the optical fiber, and m represents an integer 0, 1, 2…; Next, the dispersion amount is estimated based on the relative time delay caused by dispersion after the pilot signal is transmitted through the optical fiber. The expression is: In the formula, CD represents the dispersion, f c represents the optical carrier frequency, f p represents the frequency of the pilot signal, and c represents the speed of light in a vacuum.

5. The method for joint compensation of phase noise and dispersion based on dual pilot assisted digital subcarrier multiplexing signal according to claim 1, characterized in that: The expressions of the phase noise at the transmitting end and the phase noise at the receiving end are respectively: In the formula, represents the combination of the transmitting and receiving phase noises obtained by the receiving end of the first pilot signal, φ TX represents the phase noise caused by the laser line width at the transmitting end, φ RX represents the phase noise caused by the laser line width at the receiving end, P represents the insertion position of the pilot signal, L represents the fiber length, β2 represents the fiber dispersion parameter, Δω subcarrier represents the subcarrier bandwidth, Δω interval represents the guard interval bandwidth, Represents the combination of the transmitting and receiving phase noises obtained by the receiving end of the second pilot signal.

6. The method for joint compensation of phase noise and dispersion based on dual pilot assisted digital subcarrier multiplexing signal according to claim 5, characterized in that: The calculation process of the reconstructed transmitter phase noise satisfies: First, based on the phase noise of the two pilot signals, the change in the phase noise at the transmitter after the delay is calculated, and its expression is: Next, according to the number of samples within the delay range, the variation between the phase noise samples at the transmitter is calculated, and the expression is: In the formula, α represents the number of samples within the delay range, and Ts is the sampling period; Finally, the phase noise of the transmitter is reconstructed by integrating and accumulating, and the process satisfies: In the formula, represents an initial fixed phase value, represents the reconstructed transmitter phase noise.

7. The method for joint compensation of phase noise and dispersion based on dual pilot assisted digital subcarrier multiplexing signal according to claim 6, characterized in that: The calculation process of the reconstructed receiving end phase noise is: The reconstructed transmitter phase noise is processed with two different time delays, and then the corresponding pilot signal phase noise is subtracted from the delayed transmitter phase noise, and the average value is calculated to obtain the reconstructed receiver phase noise. The calculation expression of this process is: In the formula, represents the reconstructed receiving end phase noise.

8. The method for joint compensation of phase noise and dispersion based on dual pilot assisted digital subcarrier multiplexing signal according to claim 7, characterized in that: The specific process of step S5 is: Before dispersion compensation, the reconstructed receiving end phase noise is used to compensate the receiving end phase noise; then, the estimated dispersion amount is used to compensate the dispersion; the reconstructed transmitting end phase noise is used to compensate the transmitting end phase noise, and the process satisfies: In the formula, S rx (t) represents the signal received by the receiving end, h CDC (t) represents the dispersion compensation function, represents the convolution symbol, CD represents the estimated dispersion amount, and S(t) represents the compensated signal.

9. A phase noise and dispersion joint compensation system based on dual pilot assisted digital subcarrier multiplexing signal, characterized in that: include: A pilot signal insertion module is used to set a guard interval on the digital subcarrier multiplexed signal sent by the transmitting end, and insert two pilot signals with set amplitude and phase in the guard interval; A dispersion estimation module is used to extract the amplitude of the pilot signal and estimate the dispersion of the digital subcarrier multiplexed signal during transmission in the optical fiber communication system; The receiving-end phase noise acquisition module is used to acquire the combination of the transmitting-end and receiving-end phase noises at the receiving end according to the phases of the two pilot signals, perform signal processing on the phase noises, and separate the transmitting-end phase noise and the receiving-end phase noise; The phase noise reconstruction module of the transmitting and receiving end is used to reconstruct the phase noise of the transmitting end to obtain the reconstructed phase noise of the transmitting end; and reconstruct the phase noise of the receiving end to obtain the reconstructed phase noise of the receiving end; The compensation module compensates for the phase noise and dispersion of the receiving end and the phase noise of the transmitting end according to the reconstructed phase noise of the transmitting end, the reconstructed phase noise of the receiving end and the dispersion amount.

10. An electronic device comprising a memory and a processor, characterized in that: A computer program is stored in the memory, and the processor is configured to execute the steps of the method for joint compensation of phase noise and dispersion based on dual-pilot-assisted digital subcarrier multiplexed signals according to any one of claims 1 to 8 through the computer program.

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