An adaptive digital domain compensation system and compensation method for optical signal transmission damage

Abstract

The present invention proposes an adaptive digital domain compensation system and compensation method for optical signal transmission damage. By adding the bit error rate monitoring and calculation comparison function before error correction in the DSP, comparing the bit error rate values ​​before and after the error correction and the set bit error rate threshold before error correction, the function of quickly adjusting the degree of compensation of DSP dispersion and nonlinear algorithm is realized, so that the coherent optical module / board of the same specification can match the actual link's demand for DSP algorithm compensation capability as much as possible, releasing DSP computing power resources and reducing operating power consumption. At the same time, compared with the traditional adaptive compensation algorithm, the present invention only increases or decreases the DSP dispersion and nonlinear algorithm compensation amount in a single direction, greatly reducing the calculation complexity and convergence time. It can not only be applied to business start-up, but also supports performance adjustment in business online operation and has performance threshold warning function.

Description

Technical Field

[0001] The present invention provides an adaptive digital domain compensation system and compensation method for optical signal transmission damage, and relates to the research field of dispersion and nonlinear compensation of optical fiber communication technology. Background Art

[0002] In optical communication systems, optical signals transmitted in optical fibers are affected by loss, dispersion, nonlinearity and other effects, causing signal distortion and resulting in reduced transmission performance. Optical amplifiers can compensate for the decrease in signal light power caused by fiber loss, while dispersion and nonlinear damage become the main limiting factors for optical signal transmission. The industry has conducted a lot of research on compensation schemes for optical signal transmission damage, mainly including two categories: optical domain signal processing and electrical domain signal processing.

[0003] Optical domain signal processing methods are mainly based on analog signal processing to directly compensate for dispersion and nonlinear damage of optical signals in the optical domain, such as using dispersion-compensating optical fiber, gratings, etc. to compensate for dispersion, and using semiconductor optical amplifiers (SOA) and high nonlinear optical fibers (HNLF) to construct optical signal processing solutions to compensate for nonlinear damage. Optical domain signal processing methods process directly in the optical domain, which is helpful for all-optical networking, and there is no need for optoelectronic conversion, and the processing delay is low. However, there are disadvantages such as limited compensation capability, relatively fixed, and inflexible. In addition, the technology is at the forefront of exploration and still requires theoretical and technological breakthroughs.

[0004] With the emergence of coherent optical communication systems and their widespread deployment around the world, electrical domain signal processing solutions have become the mainstream in the industry. Digital signal processing technology (DSP) is used in coherent receivers to compensate for transmission impairments in the digital domain. At the receiving end, the optical signal is first converted into an electrical signal, then converted into a digital signal through a digital-to-analog converter and sent to the DSP chip, where the digital signal is compensated and restored through the DSP algorithm. For different impairment compensations, it is only necessary to write the corresponding algorithm into the DSP chip. The cost can be quickly reduced through large-scale application, and it has the advantages of high technical flexibility and low cost. In the current single-carrier coherent optical communication systems of 100Gbit / s and above, DSP technology is used to compensate for optical fiber transmission impairments. See Figure 1 shown.

[0005] In actual coherent optical communication system applications, for the same rate and the same encoding method, manufacturers usually only produce one or a few optical module / board models to cover the needs of all transmission distance scenarios. For various transmission distance scenarios faced in large-scale deployment, the same fixed algorithm capability or several configurable algorithm capabilities are used to compensate for link transmission damage. Compared with the actual transmission distance, there is often a certain or greater DSP algorithm capability redundancy, which will lead to a waste of DSP computing resources and an increase in power consumption. Another solution is to use a traditional adaptive compensation algorithm to estimate the fluctuation of prior information. For example Figure 2 As shown in the figure, the adaptive compensation part is controlled by a feedback signal. This feedback signal is an adjustment signal of the prior information of the fluctuation obtained by calculating a certain cost function after the carrier recovery of the received signal. After N iterations, the optimal value is finally obtained. However, this solution requires multiple calculations of the cost function for iteration. The high computational complexity will bring great challenges to the performance of the DSP chip, and also increase the power consumption and cost of the chip. In addition, due to the long convergence time, it is mainly used in service activation scenarios. Summary of the invention

[0006] In order to solve the problem that the actual transmission distances of coherent optical modules or boards of the same specification in network deployment vary greatly, the present invention proposes an adaptive digital domain compensation system and compensation method for optical signal transmission damage. By adding the pre-error correction bit error rate monitoring and calculation comparison function in the DSP, comparing the two pre-error correction bit error rate values ​​and the set pre-error correction bit error rate threshold, the function of quickly adjusting the DSP dispersion and nonlinear algorithm compensation degree is realized, so that the coherent optical modules / boards of the same specification can match the actual link's requirements for DSP algorithm compensation capabilities as much as possible, releasing DSP computing resources and reducing operating power consumption. Figure 3 shown.

[0007] The present invention provides a schematic diagram of an adaptive digital domain compensation system architecture for optical signal transmission impairments, such as Figure 4 As shown, specifically:

[0008] The system consists of a first optical module, a second optical module and a digital signal processing module. It should be pointed out that this section only describes the logical relationship between the different components of the system. In actual physical implementation, the digital signal processing module can be integrated in the second optical module or on a board outside the optical module. Among them:

[0009] First optical module: the optical sending unit in the first optical module is used to send an optical signal to the second optical module;

[0010] Second optical module: The light receiving unit in the second optical module converts the received optical signal sent by the first optical module into an electrical signal through the photoelectric detector of the light receiving unit, and the electrical signal is processed by the digital signal processing module.

[0011] Digital signal processing module: mainly composed of a pre-error correction bit error rate monitoring unit, a storage unit, a calculation unit, a control unit, a dispersion compensation unit and a nonlinear compensation unit, etc.; wherein the pre-error correction bit error rate monitoring unit is used to monitor the real-time or fixed interval pre-error correction bit error rate value of the signal, and send the monitored pre-error correction bit error rate value to the storage unit; the storage unit is used to store the pre-error correction bit error rate value corresponding to the current dispersion / nonlinear compensation algorithm capability and the previous dispersion / nonlinear compensation algorithm capability and the set pre-error correction bit error rate threshold, and send them to the calculation unit; the calculation unit is used to compare the size relationship between the pre-error correction bit error rate values ​​corresponding to the two previous and subsequent settings of the dispersion / nonlinear compensation algorithm capability, and the size relationship between the pre-error correction bit error rate value after setting the current dispersion / nonlinear compensation algorithm capability and the set pre-error correction bit error rate threshold, and send the calculation result to the control unit; the control unit is used to receive the result of the calculation unit, generate control information for setting the dispersion and nonlinear compensation strength according to the result of the calculation unit, and send the control information to the dispersion compensation unit and the nonlinear compensation unit. The dispersion compensation unit and the nonlinear compensation unit configure the strength of the dispersion and nonlinear compensation algorithms respectively according to the control information received from the control unit. The strength of the dispersion and nonlinear compensation algorithms is controlled by the compensation strength factor. The compensation strength factor is used as a control variable of the dispersion compensation algorithm and / or the nonlinear compensation algorithm, and may include the transmission distance compensated by the algorithm, the step size setting of the algorithm compensation, and the adjustment weights of other parameters related to the transmission distance in the dispersion / nonlinear compensation algorithm, and the value range is: [0,1].

[0012] The advantages and beneficial effects of the present invention are:

[0013] The present invention faces the scenario where the transmission distance of the same specification coherent optical module or board in the actual application of network deployment is quite different. By adding the bit error rate monitoring and calculation comparison function before error correction in DSP, the bit error rate values ​​before and after error correction and the set bit error rate threshold before error correction are compared, and the function of quickly adjusting the compensation degree of DSP dispersion and nonlinear algorithm is realized, so that the same specification coherent optical module / board matches the actual link's demand for DSP algorithm compensation capability as much as possible, releasing DSP computing power resources and reducing operating power consumption. At the same time, compared with the traditional adaptive compensation algorithm, the present invention only increases or decreases the compensation amount of DSP dispersion and nonlinear algorithm in a single direction, greatly reducing the calculation complexity and convergence time. It can not only be applied to business start-up, but also supports performance adjustment in business online operation and has performance threshold warning function. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a framework diagram of the digital domain compensation solution for coherent optical communication systems.

[0015] Figure 2This is the schematic diagram of the traditional adaptive compensation algorithm.

[0016] Figure 3 It is the algorithm principle diagram of the innovative adaptive digital domain compensation method for optical signal transmission impairment.

[0017] Figure 4 It is a schematic diagram of the system architecture of an adaptive digital domain compensation method for optical signal transmission impairment. DETAILED DESCRIPTION

[0018] The present invention further proposes a compensation method for an adaptive digital domain compensation system for optical signal transmission damage. The method can be applied to service start-up, supports performance adjustment during service online operation, and has a performance threshold warning function. The specific steps are as follows:

[0019] Applicable to service deployment:

[0020] Step 1: The optical sending unit of the first optical module transmits an optical signal with a central wavelength of 1550nm and a rate of 56Gbit / s, which is transmitted to the second optical module via an optical fiber channel. The single-segment optical fiber transmission link is a standard single-mode optical fiber of 80km.

[0021] Step 2: The light receiving unit of the second optical module converts the received optical signal into an electrical signal through the photoelectric detection unit, and then sends the electrical signal to the digital signal processing module for digital domain compensation;

[0022] Step 3: The pre-error correction bit error rate monitoring unit of the digital signal processing module monitors the real-time pre-error correction bit error rate value or the pre-error correction bit error rate value at a fixed interval, and sends the monitored pre-error correction bit error rate value to the storage unit;

[0023] Step 4: The storage unit stores the corresponding pre-error correction bit error rate value Pre-FEC BER when setting the current dispersion / nonlinear compensation algorithm capability now , stores the corresponding pre-correction bit error rate value Pre-FEC BER when setting the previous dispersion / nonlinear compensation algorithm capability last , and store the set pre-correction bit error rate threshold Pre-FEC BER threshold , and sent to the computing unit. Considering the capacity of the storage unit and the occupied resources, the stored value can be cleared after all resources are occupied, or the stored value can be cleared regularly / according to the resource occupation ratio, or the original storage resources can be replaced in each iteration.

[0024] Step 5: The calculation unit compares the magnitude relationship between the corresponding pre-error correction bit error rate values ​​after the dispersion / nonlinear compensation algorithm capability is set twice before and after, and the magnitude relationship between the pre-error correction bit error rate value after the current dispersion / nonlinear compensation algorithm capability is set and the set pre-error correction bit error rate threshold, and sends the calculation result to the control unit. A subtractor can be used to calculate the magnitude relationship.

[0025] Step 6: The control unit is used to receive the result of the calculation unit, generate control information for setting the dispersion and nonlinear compensation strength according to the result of the calculation unit, that is, the dispersion compensation strength factor A and the nonlinear compensation strength factor B, the initial values ​​of A and B are both 1, and send the control information to the dispersion compensation unit and the nonlinear compensation unit. If the monitored pre-error correction bit error rate value is less than the set pre-error correction bit error rate threshold, such as the monitored pre-error correction bit error rate value is Pre-FEC BER now =5e-5 (5e-5 is 5×10-5, scientific notation), the pre-error correction bit error rate threshold is set as Pre-FEC BER threshold =2.4e-2, the next pre-correction bit error rate value Pre-FEC BER corresponding to the adjusted dispersion / nonlinear algorithm compensation capability next =4e-2, then reduce the dispersion and nonlinear compensation strength, generate corresponding control information, that is, reduce the compensation strength factors A and B, and send them to the dispersion compensation unit and the nonlinear compensation unit for adjustment; if the monitored adjusted pre-error correction bit error rate value is less than the set pre-error correction bit error rate threshold and greater than the pre-error correction bit error rate value before adjustment, such as the monitored pre-error correction bit error rate value before adjustment is Pre-FEC BER now =5e-5, the error rate threshold before error correction is set to Ptr-FRC BRT threshold =2.4e-2, the next pre-correction bit error rate value Pre-FEC BER corresponding to the adjusted dispersion / nonlinear algorithm compensation capability next =5e-4, then continue to reduce the dispersion and nonlinear compensation strength, that is, continue to reduce the compensation strength factors A and B; if the monitored adjusted pre-error correction bit error rate value is less than the set pre-error correction bit error rate threshold and less than the pre-error correction bit error rate value before adjustment, such as the monitored pre-error correction bit error rate value before adjustment is Pre-FEC BER now =5e-5, the pre-error correction bit error rate threshold is set as Pre-FEC BER threshold =2.4e-2, the next pre-correction bit error rate value Pre-FEC BER corresponding to the adjusted dispersion / nonlinear algorithm compensation capability next=5e-6, indicating that the adjustment parameters are opposite to the expected results, the parameters are configured in the opposite direction, that is, the compensation strength factors A and B are increased; if the monitored adjusted pre-error correction bit error rate value is greater than the set pre-error correction bit error rate threshold, such as the monitored adjusted pre-error correction bit error rate value Pre-FEC BER now =3e-2, the pre-error correction bit error rate threshold is set as Pre-FEC BER threshold =2.4e-2, the next pre-correction bit error rate value Pre-FEC BER corresponding to the adjusted dispersion / nonlinear algorithm compensation capability next =4e-2, then the dispersion and nonlinear compensation strength before adjustment is restored, and a certain margin is retained, that is, the compensation strength factor is restored to be slightly larger than A and B before adjustment; or the dispersion and nonlinear compensation strength after adjustment is maintained, and the dispersion and nonlinear compensation strength is no longer reduced, that is, the compensation strength factors A and B remain unchanged. According to the set rules, when the bit error rate before error correction reaches a certain value, an alarm information can be reported to the management and control system.

[0026] Step 7: The dispersion compensation unit and the nonlinear compensation unit configure the capabilities and strengths of the dispersion and nonlinear compensation algorithms respectively according to the control information received from the control unit, namely the compensation strength factor. The dispersion and nonlinear compensation strengths may be changed at the same time, or only the dispersion compensation strength may be changed, or only the nonlinear compensation strength may be changed.

[0027] Step 8: If a transmission link or device fails and the optical module / board needs to be powered off and restarted, the dispersion compensation unit and nonlinear compensation unit in the digital signal processing module, the storage unit and other dynamic adjustment units involved in this solution are restored to their initial states, and the dispersion compensation algorithm strength factor and the nonlinear compensation algorithm strength factor are reset to 1. Then, the above steps are repeated to adjust the dispersion and nonlinear compensation strength according to the new operating state after the subsequent power-on.

[0028] Applied to business online operation:

[0029] Step 1: The optical sending unit of the first optical module transmits an optical signal with a central wavelength of 1550nm and a rate of 56Gbit / s, which is transmitted to the second optical module via an optical fiber channel. The single-segment optical fiber transmission link is a standard single-mode optical fiber of 80km.

[0030] Step 2: The light receiving unit of the second optical module converts the received optical signal into an electrical signal through the photoelectric detection unit, and then sends the electrical signal to the digital signal processing module for digital domain compensation;

[0031] Step 3: The pre-error correction bit error rate monitoring unit of the digital signal processing module monitors the real-time pre-error correction bit error rate value or the pre-error correction bit error rate value at a fixed interval, and sends the monitored pre-error correction bit error rate value to the storage unit;

[0032] Step 4: The storage unit stores the corresponding pre-error correction bit error rate value Pre-FEC BER when setting the current dispersion / nonlinear compensation algorithm capability now , stores the corresponding pre-correction bit error rate value Pre-FEC BER when setting the previous dispersion / nonlinear compensation algorithm capability last , and store the set pre-correction bit error rate threshold Pre-FEC BER threshold , and sent to the computing unit. Considering the capacity of the storage unit and the occupied resources, the stored value can be cleared after all resources are occupied, or the stored value can be cleared regularly / according to the resource occupation ratio, or the original storage resources can be replaced in each iteration.

[0033] Step 5: The calculation unit compares the magnitude relationship between the corresponding pre-error correction bit error rate values ​​after the dispersion / nonlinear compensation algorithm capability is set twice before and after, and the magnitude relationship between the pre-error correction bit error rate value after the current dispersion / nonlinear compensation algorithm capability is set and the set pre-error correction bit error rate threshold, and sends the calculation result to the control unit. A subtractor can be used to calculate the magnitude relationship.

[0034] Step 6: The control unit is used to receive the result of the calculation unit, generate control information for setting the dispersion and nonlinear compensation strength according to the result of the calculation unit, that is, the dispersion compensation strength factor A and the nonlinear compensation strength factor B, the initial values ​​of A and B are both 1, and send the control information to the dispersion compensation unit and the nonlinear compensation unit. For services that are already running online, the link status may fluctuate or continue to deteriorate with the running time (such as fiber aging, connector contamination, etc.). If the monitored adjusted pre-error correction bit error rate value is less than the set pre-error correction bit error rate threshold and greater than the pre-error correction bit error rate value before adjustment, such as the monitored pre-error correction bit error rate value before adjustment is Pre-FEC BER now =5e-5, the pre-error correction bit error rate threshold is set as Pre-FEC BER threshold =2.4e-2, the next pre-correction bit error rate value Pre-FEC BER corresponding to the adjusted dispersion / nonlinear algorithm compensation capability next =5e-4, then continue to reduce the dispersion and nonlinear compensation strength, that is, reduce the compensation strength factors A and B; if the monitored adjusted pre-error correction bit error rate value is less than the set pre-error correction bit error rate threshold and less than the pre-error correction bit error rate value before adjustment, such as the monitored pre-error correction bit error rate value before adjustment is Pre-FECBER now =5e-5, the pre-error correction bit error rate threshold is set as Pre-FEC BER threshold =2.4e-2, the next pre-correction bit error rate value Pre-FEC BER corresponding to the adjusted dispersion / nonlinear algorithm compensation capabilitynext =5e-6, indicating that the adjustment parameters are opposite to the expected results, and the parameters are configured in the opposite direction, that is, the compensation strength factors A and B are increased; if the monitored adjusted pre-error correction bit error rate value is greater than the set pre-error correction bit error rate threshold, such as the monitored adjusted pre-error correction bit error rate value Pre-FEC BER now =3e-2, the pre-error correction bit error rate threshold is set as Pre-FEC BER threshold =2.4e-2, the next pre-correction bit error rate value Pre-FEC BER corresponding to the adjusted dispersion / nonlinear algorithm compensation capability next =4e-2, then restore the configuration to the dispersion and nonlinear compensation strength before adjustment, retain a certain margin, that is, the compensation strength factor is restored to be slightly larger than A and B before adjustment; or maintain the adjusted dispersion and nonlinear compensation strength, and no longer reduce the dispersion and nonlinear compensation strength, that is, the compensation strength factors A and B remain unchanged. According to the set rules, when the bit error rate before error correction reaches a certain value, the alarm information can be reported to the management and control system.

[0035] Step 7: The dispersion compensation unit and the nonlinear compensation unit configure the capabilities and strengths of the dispersion and nonlinear compensation algorithms respectively according to the control information received from the control unit, namely the compensation strength factor. The dispersion and nonlinear compensation strengths may be changed at the same time, or only the dispersion compensation strength may be changed, or only the nonlinear compensation strength may be changed.

[0036] Step 8: If a transmission link or device fails and the optical module / board needs to be powered off and restarted, the dispersion compensation unit and nonlinear compensation unit in the digital signal processing module, the storage unit and other dynamic adjustment units involved in this solution are restored to their initial states, and the dispersion compensation algorithm strength factor and the nonlinear compensation algorithm strength factor are reset to 1. Then, the above steps are repeated to adjust the dispersion and nonlinear compensation strength according to the new operating state after the subsequent power-on.

Claims

1. An adaptive digital domain compensation system for optical signal transmission impairment, characterized in that: Specifically, the system is composed of a first optical module, a second optical module and a digital signal processing module; wherein the optical sending unit in the first optical module is used to send an optical signal to the second optical module; the optical receiving unit in the second optical module converts the optical signal sent by the first optical module into an electrical signal through the photoelectric detector of the optical receiving unit, and the electrical signal is processed by the digital signal processing module; the pre-error correction bit error rate monitoring unit of the digital signal processing module monitors the real-time pre-error correction bit error rate value or the pre-error correction bit error rate value at a fixed interval, and sends the monitored pre-error correction bit error rate value to the storage unit; Among them, the digital signal processing module is composed of a pre-error correction bit error rate monitoring unit, a storage unit, a calculation unit, a control unit, a dispersion compensation unit and a nonlinear compensation unit; wherein the pre-error correction bit error rate monitoring unit is used to monitor the real-time or fixed interval pre-error correction bit error rate value of the signal, and send the monitored pre-error correction bit error rate value to the storage unit; the storage unit is used to store the pre-error correction bit error rate value corresponding to the current dispersion / nonlinear compensation algorithm capability and the previous dispersion / nonlinear compensation algorithm capability and the set pre-error correction bit error rate threshold, and send them to the calculation unit; the calculation unit is used to compare the size relationship between the pre-error correction bit error rate values ​​corresponding to the two settings of the dispersion / nonlinear compensation algorithm capability, and the pre-error correction bit error rate after setting the current dispersion / nonlinear compensation algorithm capability. The control unit is used to receive the result of the calculation unit, generate control information for setting the dispersion and nonlinear compensation strength according to the result of the calculation unit, and send the control information to the dispersion compensation unit and the nonlinear compensation unit; the dispersion compensation unit and the nonlinear compensation unit respectively configure the strength of the dispersion and nonlinear compensation algorithm according to the control information received from the control unit; the strength of the dispersion and nonlinear compensation algorithm is controlled by the compensation strength factor, and the compensation strength factor is used as a control variable of the dispersion compensation algorithm and / or the nonlinear compensation algorithm, including the transmission distance compensated by the algorithm, the step size setting of the algorithm compensation, and the adjustment weights of other parameters related to the transmission distance in the dispersion / nonlinear compensation algorithm.

2. A compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 1, characterized in that: Applicable to service deployment: Step 1: The optical sending unit of the first optical module transmits an optical signal, which is transmitted to the second optical module via an optical fiber channel, and the single-segment optical fiber transmission link is a standard single-mode optical fiber; Step 2: The light receiving unit of the second optical module converts the received optical signal into an electrical signal through the photoelectric detection unit, and then sends the electrical signal to the digital signal processing module for digital domain compensation; Step 3: The pre-error correction bit error rate monitoring unit of the digital signal processing module monitors the real-time pre-error correction bit error rate value or the pre-error correction bit error rate value at a fixed interval, and sends the monitored pre-error correction bit error rate value to the storage unit; Step 4: The storage unit stores the corresponding pre-error correction bit error rate value Pre-FEC BER when setting the current dispersion / nonlinear compensation algorithm capability now , stores the corresponding pre-correction bit error rate value Pre-FEC BER when setting the previous dispersion / nonlinear compensation algorithm capability last , and store the set pre-correction bit error rate threshold Pre-FEC BER threshold , and sent to the computing unit; Step 5: The calculation unit compares the magnitude relationship between the bit error rate values ​​before error correction corresponding to the two settings of the dispersion / nonlinear compensation algorithm capabilities, and the magnitude relationship between the bit error rate value before error correction after setting the current dispersion / nonlinear compensation algorithm capabilities and the set bit error rate threshold before error correction, and sends the calculation result to the control unit; Step 6: The control unit is used to receive the result of the calculation unit, generate control information for setting the dispersion and nonlinear compensation strengths according to the result of the calculation unit, that is, the dispersion compensation strength factor A and the nonlinear compensation strength factor B, where the initial values ​​of A and B are both 1, and send the control information to the dispersion compensation unit and the nonlinear compensation unit; Step 7: The dispersion compensation unit and the nonlinear compensation unit configure the capabilities and strengths of the dispersion and nonlinear compensation algorithms respectively according to the control information, i.e., the compensation strength factor, received from the control unit; and change the dispersion and nonlinear compensation strengths at the same time, or only change the dispersion compensation strength, or only change the nonlinear compensation strength. Step 8: If a transmission link or device fails and the optical module / board needs to be powered off and restarted, the dispersion compensation unit, nonlinear compensation unit, and storage unit in the digital signal processing module are restored to their initial states, and the dispersion compensation intensity factor and the nonlinear compensation intensity factor are reset to 1. The above steps are repeated to adjust the dispersion and nonlinear compensation intensity according to the new operating state after the subsequent power-on.

3. The compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 2, characterized in that: In step 6, if the monitored pre-error correction bit error rate value is less than the set pre-error correction bit error rate threshold, the dispersion and nonlinear compensation strengths are reduced, and corresponding control information is generated, that is, the compensation strength factors A and B are reduced, and sent to the dispersion compensation unit and the nonlinear compensation unit for adjustment.

4. The compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 2, characterized in that: In step 6, if the monitored adjusted bit error rate value before error correction is less than the set bit error rate threshold before error correction and greater than the bit error rate value before error correction before adjustment; then continue to reduce the dispersion and nonlinear compensation intensity, that is, continue to reduce the compensation intensity factors A and B.

5. The compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 2, characterized in that: In step 6, if the monitored adjusted pre-error correction bit error rate value is less than the set pre-error correction bit error rate threshold and less than the pre-error correction bit error rate value before adjustment, it means that the adjustment parameters are opposite to the expected results, and the parameters are configured in the opposite direction, that is, the compensation intensity factors A and B are increased.

6. The compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 2, characterized in that: In step 6, if the monitored adjusted bit error rate value before error correction is greater than the set bit error rate threshold before error correction, the dispersion and nonlinear compensation strength before adjustment is restored and a certain margin is retained, that is, the compensation intensity factor is restored to be larger than A and B before adjustment; or the adjusted dispersion and nonlinear compensation strength is maintained, and the dispersion and nonlinear compensation strength is no longer reduced, that is, the compensation intensity factors A and B remain unchanged.

7. A compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 1, characterized in that: Applied to business online operation: Step 1: The optical sending unit of the first optical module transmits an optical signal, which is transmitted to the second optical module via an optical fiber channel, and the single-segment optical fiber transmission link is a standard single-mode optical fiber; Step 2: The light receiving unit of the second optical module converts the received optical signal into an electrical signal through the photoelectric detection unit, and then sends the electrical signal to the digital signal processing module for digital domain compensation; Step 3: The pre-error correction bit error rate monitoring unit of the digital signal processing module monitors the real-time pre-error correction bit error rate value or the pre-error correction bit error rate value at a fixed interval, and sends the monitored pre-error correction bit error rate value to the storage unit; Step 4: The storage unit stores the corresponding pre-error correction bit error rate value Pre-FEC BER when setting the current dispersion / nonlinear compensation algorithm capability now , stores the corresponding pre-correction bit error rate value Pre-FEC BER when setting the previous dispersion / nonlinear compensation algorithm capability last , and store the set pre-correction bit error rate threshold Pre-FEC BER threshold , and sent to the computing unit; Step 5: The calculation unit compares the magnitude relationship between the bit error rate values ​​before error correction corresponding to the two settings of the dispersion / nonlinear compensation algorithm capabilities, and the magnitude relationship between the bit error rate value before error correction after setting the current dispersion / nonlinear compensation algorithm capabilities and the set bit error rate threshold before error correction, and sends the calculation result to the control unit; a subtractor is used to calculate the magnitude relationship; Step 6: The control unit is used to receive the result of the calculation unit, generate control information for setting the dispersion and nonlinear compensation strengths according to the result of the calculation unit, that is, the dispersion compensation strength factor A and the nonlinear compensation strength factor B, where the initial values ​​of A and B are both 1, and send the control information to the dispersion compensation unit and the nonlinear compensation unit; Step 7: The dispersion compensation unit and the nonlinear compensation unit configure the capabilities and strengths of the dispersion and nonlinear compensation algorithms respectively according to the control information, i.e., the compensation strength factor, received from the control unit; and change the dispersion and nonlinear compensation strengths at the same time, or only change the dispersion compensation strength, or only change the nonlinear compensation strength. Step 8: If a transmission link or device fails and the optical module / board needs to be powered off and restarted, the dispersion compensation unit, nonlinear compensation unit, and storage unit in the digital signal processing module are restored to their initial states, and the dispersion compensation intensity factor and the nonlinear compensation intensity factor are reset to 1. The above steps are repeated to adjust the dispersion and nonlinear compensation intensity according to the new operating state after the subsequent power-on.

8. The compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 7, characterized in that: In step 6, if the monitored adjusted bit error rate value before error correction is less than the set bit error rate threshold before error correction and greater than the bit error rate value before error correction before adjustment, the dispersion and nonlinear compensation intensity is continued to be reduced, that is, the compensation intensity factors A and B are reduced.

9. The compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 7, characterized in that: In step 6, if the monitored adjusted pre-error correction bit error rate value is less than the set pre-error correction bit error rate threshold and less than the pre-error correction bit error rate value before adjustment, it means that the adjustment parameters are opposite to the expected results, and the parameters are configured in the opposite direction, that is, the compensation intensity factors A and B are increased.

10. The compensation method of the adaptive digital domain compensation system for optical signal transmission impairment according to claim 7, characterized in that: In step 6, if the monitored adjusted bit error rate value before error correction is greater than the set bit error rate threshold before error correction, the dispersion and nonlinear compensation strength before adjustment is restored, and a certain margin is retained, that is, the compensation intensity factor is restored to be larger than A and B before adjustment; or the adjusted dispersion and nonlinear compensation strength is maintained, and the dispersion and nonlinear compensation strength is no longer reduced, that is, the compensation intensity factors A and B remain unchanged.

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