Raman link protection control method and apparatus, and communication system
Patent Information
- Application Number
- PCT/CN2025/122200
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-24
- Filing Date
- 2025-09-18
- Publication Date
- 2026-10-01
Smart Images
Figure CN2025122200_01102026_PF_FP_ABST
Abstract
Description
A Raman line protection control method, device and communication system
[0001] Cross-reference of related applications
[0002] This application claims priority to the following patent application:
[0003] (1) A Chinese patent application filed on March 24, 2025, with application number 202510350237.0 and titled “A Raman line protection control method, device and communication system”. Technical Field
[0004] This invention relates to the field of communication technology, and in particular to a Raman line protection control method, device and communication system. Background Technology
[0005] Raman fiber amplifiers are widely used in dense wavelength division multiplexing (DWDM) optical communication systems. Compared to erbium-doped fiber amplifiers (EDBFA), Raman amplifiers utilize the transmission fiber itself as the amplification medium, offering advantages such as full-band amplification, distributed amplification, and a high optical-to-noise ratio, making them particularly suitable for ultra-long-distance and submarine transmission systems. Currently, Raman fiber amplifier control methods are mainly divided into two types: analog and digital schemes. Digital schemes employ microcontrollers, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), and digital-to-analog converters (DACs) to convert analog signals into digital signals that the FPGA can process. The FPGA then performs feedforward control and multi-level feedback control to achieve high gain and slope accuracy. However, current digital schemes still have a drawback: when the transmission fiber is used as the gain medium, and the bending radius of the fiber is significantly reduced, the pump energy of the Raman circuit (RAMAN) quickly reaches its maximum. Prolonged operation at maximum power accelerates pump aging. Furthermore, when the bending radius of the transmission fiber is restored to normal, the gain of the RAMAN cannot automatically return to normal, which leads to a shorter transmission distance and a significant increase in the transmission bit error rate. Finally, after the bending radius of the transmission fiber is restored to normal, the gain flatness performance of the RAMAN cannot be guaranteed properly, which also leads to an increase in the bit error rate of signal transmission.
[0006] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field.
[0007] Application content
[0008] The technical problem to be solved by the present invention is to provide a Raman line protection control method, device and communication system to solve the problem in the prior art that the gain flatness cannot be restored after the optical fiber is bent for a period of time and then restored to normal.
[0009] The present invention adopts the following technical solution:
[0010] In a first aspect, the present invention provides a Raman line protection control method, comprising:
[0011] Monitor the various control parameters of the Raman circuit. When the corresponding control parameter is detected to meet the fiber bend recovery condition, readjust the gain so that the Raman circuit can achieve gain flat recovery after the fiber bend is recovered.
[0012] The optical fiber bend recovery conditions include one or more of the first condition, the second condition, or the third condition.
[0013] Preferably, the first condition is:
[0014] The difference between the actual gain and the target gain of the Raman circuit is greater than the first preset value, and the pump power of each pump on the Raman circuit is within the first preset range, and the total power of the Raman circuit is less than the second preset value, and the gain compensation of each pump on the Raman circuit is within the second preset range.
[0015] Preferably, the second condition is that the gain compensation of at least one pump on the Raman circuit exceeds a third preset range.
[0016] Preferably, the third condition is:
[0017] The difference between the actual gain and the target gain of the Raman circuit is less than the third preset value, and the difference between the actual gain flat slope and the target gain flat slope of the Raman circuit is greater than the fifth preset value, and the gain compensation of each pump on the Raman circuit is within the fourth preset range.
[0018] Preferably, the gain readjustment specifically includes:
[0019] Update the gain compensation of each pump to the default gain compensation value, update the gain flatness compensation to the default flatness compensation value, refresh the maximum gain value to the default maximum gain, and refresh the minimum gain value to the default minimum gain to trigger the floating gain adjustment of each pump.
[0020] Preferably, the floating gain adjustment of each pump specifically includes:
[0021] During the i-th floating gain adjustment process, the floating gain value is increased or decreased by a preset step size to obtain the i-th floating gain value. Using the i-th floating gain value and the target slope, the expected out-of-band ASE power of each pump during the i-th floating gain adjustment process is calculated.
[0022] Determine whether the actual ASE power of each pump is locked with the expected out-of-band ASE power of each pump during the i-th floating gain adjustment. If at least one pump is not locked, then perform the (i+1)-th floating gain adjustment until the actual ASE power of each pump is locked with the expected out-of-band ASE power of each pump.
[0023] The last floating gain value is used as the new target gain. The target power of each pump is calculated based on the new target gain and target slope. The target power is used to control the power of each pump. In the first floating gain adjustment process, the target gain is used as the i-th floating gain value.
[0024] Preferably, before using Raman circuitry for optical amplification, the method further includes:
[0025] Enter power mode, turn on each pump, set the target power for each pump, and adjust the proportional parameter, derivative parameter, and adjustment period in the first-stage feedback control to lock the pump power of each pump to the target power so that the first-stage feedback control takes effect.
[0026] Under the current gain flat slope, determine the leakage factor of each pump and the out-of-band ASE power at different gains. Use the gain flat slope, gain and out-of-band ASE power to perform curve fitting to complete the calibration of the ASE power formula.
[0027] Enter gain mode, set the target gain and target gain flat slope for each pump, and adjust the proportional parameter, derivative parameter and adjustment period in the second-stage feedback control until the difference between the out-of-band ASE power and the desired out-of-band ASE power of each pump is less than the preset ASE difference.
[0028] So that in the subsequent optical amplification process, the proportional parameters, derivative parameters, and adjustment period in the adjusted first-stage feedback control, as well as the proportional parameters, derivative parameters, and adjustment period in the adjusted second-stage feedback control, can be used to adjust the gain of the Raman circuit.
[0029] Preferably, the method further includes;
[0030] Before using the Raman circuit for optical amplification, keep all pumps off and measure the total power of the Raman circuit; turn on the first pump, set the power of the first pump to the preset power, measure the out-of-band ASE power, and calculate the insertion loss of the fiber optic connector based on the out-of-band ASE power.
[0031] In a second aspect, the present invention also provides a Raman line protection control device for implementing the Raman line protection control method described in the first aspect, the device comprising:
[0032] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor for performing the Raman line protection control method described in the first aspect.
[0033] Thirdly, the present invention also provides a non-volatile computer storage medium storing computer-executable instructions that are executed by one or more processors to perform the method described in the first aspect.
[0034] Fourthly, a chip is provided, comprising: a processor and an interface for calling and running a computer program stored in memory, performing the method as described in the first aspect.
[0035] Fifthly, a computer program product containing instructions is provided that, when executed on a computer or processor, causes the computer or processor to perform the method as described in the first aspect.
[0036] In a sixth aspect, a communication system is provided, including a Raman line, and the Raman line protection and control device described in the second aspect is used to protect and control the Raman line.
[0037] This invention analyzes various situations in actual use to summarize the change patterns of each control parameter after fiber bending recovery. By analyzing the changes in control parameters, it can inversely predict whether the fiber can work normally after bending recovery. If it cannot work normally, gain adjustment is performed to restore the Raman fiber to a flat and stable gain state. Attached Figure Description
[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.
[0039] Figure 1 is a flowchart illustrating a Raman line protection control method provided in an embodiment of the present invention;
[0040] Figure 2 is a flowchart illustrating a Raman line protection control method provided in an embodiment of the present invention;
[0041] Figure 3 is a flowchart illustrating a Raman line protection control method provided in an embodiment of the present invention;
[0042] Figure 4 is a schematic diagram of the gain after optical fiber bending recovery in a prior art according to an embodiment of the present invention;
[0043] Figure 5 is a schematic diagram of the gain after optical fiber bending recovery in a Raman line protection control method provided in an embodiment of the present invention.
[0044] Figure 6 is a schematic diagram of the gain after optical fiber bending recovery in a prior art according to an embodiment of the present invention;
[0045] Figure 7 is a schematic diagram of the gain after optical fiber bending recovery in a Raman line protection control method provided in an embodiment of the present invention.
[0046] Figure 8 is a schematic diagram of the gain after optical fiber bending recovery in a prior art according to an embodiment of the present invention;
[0047] Figure 9 is a schematic diagram of the gain after optical fiber bending recovery in a Raman line protection control method provided in an embodiment of the present invention.
[0048] Figure 10 is a schematic diagram of the architecture of a Raman line protection control device provided in an embodiment of the present invention. Detailed Implementation
[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0050] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.
[0051] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the corresponding features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.
[0052] In the description of this invention, the expression “A and / or B” (where A and B are used to formally represent specific features) will be used. The corresponding expression includes the following three combinations: only A, only B, and a combination of A and B.
[0053] As used in this invention, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from a particular value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).
[0054] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0055] Example 1:
[0056] Embodiment 1 of the present invention provides a Raman line protection control method, as shown in Figure 1, including:
[0057] In step 201, various control parameters of the Raman circuit are monitored. These control parameters include parameters measured from the Raman circuit (such as power measured using a photodetector) and other parameters calculated based on the measured parameters (such as compensation values used in the Raman circuit amplification control).
[0058] In step 202, when the corresponding control parameters are detected to meet the fiber optic bend recovery condition, the gain is readjusted to ensure that the Raman circuit can achieve gain flattening recovery after the fiber optic bend is recovered. The fiber optic bend recovery condition includes one or more of the first, second, or third conditions. The execution subject of the method described in this embodiment can be an FPGA.
[0059] The first condition is as follows: the difference between the actual gain and the target gain of the Raman circuit is greater than a first preset value, the pump power of each pump on the Raman circuit is within a first preset range, the total power of the Raman circuit is less than a second preset value, and the gain compensation of each pump on the Raman circuit is within a second preset range.
[0060] The second condition is: the gain compensation of at least one pump on the Raman circuit exceeds the third preset range.
[0061] The gain flatness compensation value is calculated at regular intervals. The latest calculated gain flatness compensation value is the real-time gain flatness compensation value. However, the reporting period for the gain flatness compensation value is often longer than the calculation period. The gain flatness compensation value is only actually used in the Raman circuit after it is reported. Therefore, there may be a gap between the gain flatness compensation value used and the calculated real-time gain flatness compensation value.
[0062] The third condition is: the difference between the actual gain and the target gain of the Raman circuit is less than the third preset value, and the difference between the actual gain flat slope and the target gain flat slope of the Raman circuit is greater than the fifth preset value, and the gain compensation of each pump on the Raman circuit is within the fourth preset range.
[0063] In practical use, if any one of the first, second, or third conditions is met, it is considered that the fiber bending recovery condition has been met. It can be assumed that the fiber has been bent for a long time, making it difficult to restore the gain flatness performance after the fiber bending is recovered.
[0064] The first preset value, the second preset value, the third preset value, the fourth preset value, the fifth preset value, the first preset range, the second preset range, the third preset range, and the fourth preset range are all obtained by those skilled in the art based on experience and the usage requirements of Raman circuits.
[0065] This embodiment analyzes various situations in actual use to summarize the change law of each control parameter after fiber bending recovery. By reverse-engineering the change of control parameters, it can predict whether the fiber can work normally after bending recovery (i.e., gain flattening recovery). If it cannot work normally, gain adjustment is performed to restore the Raman fiber to a stable gain flattening state.
[0066] In a specific application scenario, the gain readjustment, as shown in Figure 2, specifically includes:
[0067] In step 301, the gain compensation of each pump is updated to the default gain compensation value, and the gain flatness compensation is updated to the default flatness compensation value. The default gain compensation value and the default flatness compensation value are obtained and stored in advance by those skilled in the art based on experience. In actual use, the default gain compensation value and the default flatness compensation value can be 0.
[0068] In step 302, the maximum gain value is refreshed to the default maximum gain, and the minimum gain value is refreshed to the default minimum gain to trigger the floating gain adjustment of each pump. The default minimum gain and default maximum gain are both preset and stored by those skilled in the art. The pump floating gain adjustment process can be understood as adjusting the pump gain and power to achieve gain locking and power locking. The maximum gain value and minimum gain value are used to limit the target gain of the pump.
[0069] It was observed that after the Raman fiber bends and recovers, its maximum gain, minimum gain, gain compensation, and gain flatness compensation often become abnormal, making it difficult to trigger gain adjustment. Therefore, this embodiment refreshes these parameters to trigger gain adjustment, thereby correcting the gain flatness of the Raman fiber.
[0070] In a practical application scenario, the re-adjustment of gain further includes: updating the actual gain flattening slope of the Raman circuit (i.e., the stored value of the actual gain flattening slope in the program) to 0; and when the actual gain flattening slope is detected to be 0, pulling the gain adjustment signal from low to high; when the gain adjustment signal is detected to be high, starting a timer; and after the timer reaches a preset time, executing steps 301-302 above; and after the floating gain adjustment is completed, pulling the gain adjustment signal low (i.e., changing it to a low level). The timer is used for delay. Since the parameters required for calculating the gain flattening compensation value may need to be resent from the host computer, a timer is set to ensure that the required parameters are received after the delay, thus enabling the calculation of the compensation value. The preset time is obtained by those skilled in the art based on experience.
[0071] In a preferred embodiment, the floating gain adjustment of each pump, as shown in Figure 3, specifically includes:
[0072] In step 401, during the i-th floating gain adjustment, the (i-1)-th floating gain value is increased or decreased by a preset step size to obtain the i-th floating gain value. Using the i-th floating gain value and the target slope, the expected out-of-band ASE power of each pump during the i-th floating gain adjustment is calculated. The preset step size can be 0.1 dB, where the increase or decrease of the step size is determined by the magnitude of the actual ASE power relative to the expected out-of-band ASE power. The current target gain is taken as the 0th floating gain value.
[0073] In step 402, it is determined whether the actual ASE power of each pump is locked with the expected out-of-band ASE power of each pump during the i-th floating gain adjustment. If at least one pump is not locked, the (i+1)-th floating gain adjustment is performed until the actual ASE power of each pump is locked with the expected out-of-band ASE power of each pump.
[0074] In step 403, the last floating gain value is used as the new target gain, and the target power of each pump is calculated based on the new target gain and target slope. The target power is used to control the power of each pump. In the first floating gain adjustment process, the target gain is used as the i-th floating gain value.
[0075] The calculation of the target power of each pump based on the new target gain and target slope is expressed in mathematical formula as follows:
[0076] pump_exp_pwr=f(raman_gain_fluct, raman_gain_offset, raman_gain_comp, raman_tilt, raman_tilt_comp, point_loss)
[0077] Wherein, f() is a preset function, obtained by those skilled in the art based on experience, and the relevant parameters in the preset function are all pre-calibrated by those skilled in the art. raman_gain_fluct is the floating gain value, raman_gain_offset is the gain calibration value corresponding to the floating gain value, which is pre-calibrated and stored by those skilled in the art, raman_gain_comp is the gain compensation amount, which is 0 when floating gain adjustment is started, raman_tilt is the target slope, raman_tilt_comp is the gain flattening compensation amount, which is 0 when floating gain adjustment is started. As the floating gain adjustment process proceeds, the gain compensation amount and the gain flattening compensation amount are also calculated by the second-level feedback control to obtain non-zero values, and point_loss is the insertion loss of the access fiber (i.e., connector loss).
[0078] After adjusting the floating gain to determine the target gain, the laser's conventional gain adjustment is then performed. In a practical application scenario, the conventional gain adjustment of the Raman circuit can be achieved using both first-stage and second-stage feedback control. Specifically:
[0079] The control objective of the first-stage feedback control is pump power. The feedback algorithm ensures that the actual output power (i.e., pump power) of each pump equals the target power, thus achieving rapid pump power locking. The feedback algorithm typically employs a PID feedback algorithm, specifically a PID controller (Proportional-Derivative-Integral controller). This embodiment uses only proportional and derivative parameters, with one PID controller for each pump. The first-stage feedback control process is as follows: Using the PID controller, reasonable proportional and derivative parameters are set according to the actual situation. While maintaining stable pump output, the pump output DAC is adjusted to regulate the pump drive current, thereby rapidly locking the actual pump output power to the corresponding target power.
[0080] The second-stage feedback control includes: calculating the expected out-of-band ASE power of each pump using the ASE formula based on the set target gain and target slope, and detecting the actual out-of-band ASE power of each pump using a photodetector (PD). Since the input of the Raman fiber amplifier is also its output, it is impossible to calculate whether the target gain has been reached based solely on the input and output power. Therefore, out-of-band ASE is used to control the gain. The gain and slope are locked by determining whether the out-of-band ASE has reached the expected value. Therefore, the expected and actual out-of-band ASE power of each pump must first be determined. For each pump, the actual out-of-band ASE power is calculated by PD detection of the out-of-band ASE output from the pump, followed by photoelectric conversion and analog-to-digital conversion, and then combining the PD detection power and leakage factor. If the out-of-band ASE of the pump is not locked, it is considered that the gain and flatness of the Raman circuit are not locked. In this case, the second-stage feedback control determines the pump's gain compensation and gain flatness compensation, and feeds the compensation back to the aforementioned preset function and ASE formula for recalculation. In this case, the target gain can be used as a floating gain value substituted into the preset function for calculation.
[0081] The control objective of the second-stage feedback control is the out-of-band ASE power. It determines whether the gain and slope are locked to the target gain and slope by judging whether the actual out-of-band ASE power reaches the expected out-of-band ASE power. If not locked, the currently set gain and slope need to be adjusted. Specifically, this is done by setting reasonable proportional and derivative parameters through a PID controller for dynamic adjustment. The PID controller outputs a gain compensation amount Δgain and a slope compensation amount Δtilt, which are then used to compensate for the gain and slope, changing the feedforward calculation results. That is, the target power of each pump is recalculated according to the aforementioned preset function. To ensure the accuracy of the gain and slope, compensation is applied not only to the feedforward algorithm control but also to the control of the expected out-of-band ASE. The gain compensation amount Δgain and slope compensation amount Δtilt from the second-stage feedback are simultaneously substituted into the ASE formula for corresponding compensation. That is, the expected out-of-band ASE power of each pump is recalculated according to expect_ase = G(gain + Δgain, tilt + Δtilt), thereby improving the locking accuracy and achieving more precise control. expect_ase is the expected out-of-band ASE power, Δgain is the gain compensation amount, Δtilt is the gain flattening compensation amount, gain is the target gain, and tilt is the target slope. G() is a preset function, which is obtained by those skilled in the art based on experience. The relevant parameters in the preset function are all pre-calibrated by those skilled in the art.
[0082] The first-stage feedback control and the second-stage feedback control are repeated for each pump until the actual out-of-band ASE power of the pump is locked to the corresponding desired out-of-band ASE power, thereby achieving gain and slope locking.
[0083] Before implementing first-stage and second-stage feedback control, it is necessary to calibrate the parameters used. This includes the following steps before using Raman circuitry for optical amplification:
[0084] Enter power mode, turn on each pump, set the target power for each pump, and adjust the proportional parameters, derivative parameters, and adjustment period in the first-stage feedback control to lock the pump power of each pump to the target power, so that the first-stage feedback control takes effect.
[0085] Under the current gain flat slope, the leakage factor of each pump and the out-of-band ASE power at different gains are determined. Curve fitting is performed using the gain flat slope, gain and out-of-band ASE power to complete the calibration of the ASE power formula.
[0086] Enter gain mode, set the target gain and target gain flat slope for each pump, and adjust the proportional parameter, derivative parameter and adjustment period in the second-stage feedback control until the difference between the out-of-band ASE power and the desired out-of-band ASE power of each pump is less than the preset ASE difference.
[0087] This allows for gain adjustment of the Raman circuit during subsequent optical amplification using the adjusted proportional, derivative, and adjustment periods from the first-stage feedback control, as well as the adjusted proportional, derivative, and adjustment periods from the second-stage feedback control. The calibrated parameters are used in the aforementioned floating adjustment process, the first-stage feedback control, and the second-stage feedback control.
[0088] The method also includes: before using the Raman circuit for optical amplification, keeping all pumps in the off state and detecting the total power of the Raman circuit; turning on the first pump, setting the power of the first pump to a preset power, measuring the out-of-band ASE power, and calculating the insertion loss of the fiber optic connector based on the out-of-band ASE power.
[0089] In practical applications, the method further includes: in gain mode, setting multiple fixed gain points, calculating the difference between the input optical power when the pump is on (not amplified) and the input optical power when the pump is off, and recording the differences corresponding to these fixed gain points. The differences are then fitted to a curve with the target gain to calculate the corresponding gain compensation amount for different target gains.
[0090] After completing the above calibration and initialization, execute the method described in steps 201-202 above.
[0091] Example 2:
[0092] Based on the method described in Embodiment 1, this invention combines specific application scenarios and uses technical descriptions in relevant scenarios to illustrate the implementation process of the features of this invention in those scenarios.
[0093] In the pump-off state, the input power when the pump is off is obtained by inputting the detection power of the PD, and is denoted as pump_off_pin.
[0094] During pump startup, the output power of pump 1 (the first pump) is set to 100mW, and a 100ms delay is allowed for the pump output power to stabilize. The out-of-band ASE power is obtained by detecting the PD (Power Distribution Device) of the out-of-band ASE power. The insertion loss of the access fiber is calculated using the formula Point_Loss = f(Outband_ase_pwr).
[0095] Enter APC mode, i.e., power mode, set the desired power for each pump, and adjust the proportional, derivative, and adjustment periods of the first-stage feedback to ensure that the output power of each pump is stable and locked to the target power without fluctuations. The first-stage feedback control then takes effect. Under the currently set gain flattening slope Tilt_set, determine the power of each pump at different gains under the current Tilt_set. Then, fit the curve to determine the corresponding gain parameter K1, gain flattening slope parameter K2, and offset value B in the formula mW = f(Gain_set, Tilt_set).
[0096] Out-of-band ASE locking calibration determines the leakage factor and corresponding out-of-band ASE power at different gains based on the currently set gain flattening slope Tilt_set. Then, a curve is fitted to determine the corresponding parameters in expect_ase = g(Gain_set, Tilt_set).
[0097] Enter AGC mode, i.e. gain mode, set the target gain Gain_set and the target gain flat slope Tilt_set, and adjust the proportional parameter, derivative parameter and adjustment period of the second-stage feedback so that the real-time out-of-band ASE value can be stably adjusted to approach the target out-of-band ASE value through feedback.
[0098] In AGC mode, several fixed gain points are set, and the difference between the input optical power when the pump is on (not amplified) and the input optical power when the pump is off is calculated. The differences corresponding to these fixed gain points are recorded. The difference is fitted to the target gain curve to calculate the corresponding gain compensation amount under different target gains.
[0099] Gain calibration of small gain G1 and large gain G2 is performed during the pump start-up process. The gain calibration values of small gain G1 and large gain G2 are constrained, and the constraint range is denoted as [Gainoffset1, Gainoffset2].
[0100] After completing the initialization process described above, monitor the control parameters on the Raman circuit, specifically including:
[0101] (1) Monitor in real time the error between the reported gain Gain_add_offset of the current RAMAN feedback control and the set target gain. This error is recorded as Gain_error. Determine whether the error Gain_error exceeds the set error threshold, which is recorded as Gain_error_thr.
[0102] (2) Monitor the power of each pump in the RAMAN in real time. The power of each pump in the RAMAN is denoted as Pump_pwr1, Pump_pwr2, and Pump_pwr_n, where n represents the total number of pumps, and this value is less than or equal to 7. Determine whether the power of each pump, Pump_pwr1, is less than the maximum power, Pump_pwr1_max; whether Pump_pwr2 is less than the maximum power, Pump_pwr2_max; and whether Pump_pwr_n is less than the maximum power, Pump_pwrn_max. Simultaneously, determine whether the power of each pump, Pump_pwr1, is greater than the minimum power, Pump_pwr1_min; whether Pump_pwr2 is greater than the minimum power, Pump_pwr2_min; and whether Pump_pwr_n is greater than the minimum power, Pump_pwrn_min.
[0103] (3) Monitor the total pump power of RAMAN in real time, which is denoted as Pump_pwr_total. Determine whether the total pump power is less than the total power threshold, which is denoted as Pump_pwr_total_thr.
[0104] (4) Monitor the feedback compensation value of RAMAN in real time. This feedback compensation value is denoted as Gain_offset. Determine whether the feedback compensation value Gain_offset exceeds the compensation range. The range of this feedback compensation value is denoted as [Gainoffset_min1, Gainoffset_max1].
[0105] When the above conditions (1) are met, the error between the reported gain of RAMAN feedback control and the set target gain is greater than the error threshold Gain_error_thr; condition (2) the power of each pump of RAMAN is less than its corresponding maximum power and the power of each pump is greater than its corresponding minimum power; condition (3) the total power of RAMAN, Pump_pwr_total, is less than Pump_pwr_total_thr; condition (4) the feedback compensation value is within the range of [Gainoffset_min, Gainoffset_max].
[0106] When conditions (1), (2), (3), and (4) are all satisfied simultaneously, the RAMAN control logic will refresh the maximum and minimum gain values, triggering an internal gain floating adjustment process. This causes the current pump power to exit saturation and redistributes the target power of each pump. Through first-stage and second-stage feedback control, the power of the target out-of-band ASE is locked to the actual out-of-band ASE power, thus locking the target gain. In other words, when the internal gain floating adjustment process is executed, the target power of the pump is refreshed. After the target power of the pump is refreshed, the target power of the feedback control is also updated synchronously, adjusting the redistribution of the actual pump power.
[0107] Another implementation method exists as follows:
[0108] (5) Monitor in real time the error between the reported gain of the current RAMAN feedback control and the set target gain. Check whether the gain error Gain_error is less than the gain error threshold. The gain error threshold is recorded as Gain_error_min.
[0109] (6) Monitor in real time the error between the currently reported gain flatness compensation value Tilt_offset and the real-time calculated value Tilt_calc controlled by RAMAN. This error is recorded as Tilt_error.
[0110] (7) Monitor the feedback compensation value Gain_offset of RAMAN in real time. Determine whether the feedback compensation value Gain_offset exceeds the compensation range. The range of the feedback compensation value is recorded as [Gainoffset_min2, Gainoffset_max2].
[0111] If condition (5) determines that the error between the current reported gain of the RAMAN feedback control and the set target gain is less than Gain_error_min; condition (6) determines that the error between the currently reported gain flatness compensation value Tilt_offset and the real-time calculated value Tilt_offset_calc of the RAMAN control, Tilt_error, is less than the gain flatness threshold Tilt_error_thr; and condition (7) determines that the feedback compensation value is outside the range of [Gainoffset_min2, Gainoffset_max2], then the RAMAN control logic will also re-perform the internal gain floating adjustment process. When the internal gain floating adjustment process is executed, the target power of the pump will be refreshed. After the target power of the pump is refreshed, the target power of the feedback control will also be updated synchronously, and the actual power of the pump will be redistributed.
[0112] In practical applications, there is another implementation method:
[0113] (8) Determine whether the error between the reported gain and the target gain of RAMAN is less than Gain_error_min.
[0114] (9) When the bending radius of the transmission fiber returns to normal, determine whether the error between the target gain flat slope Tilt_set and the actual calculated gain flat slope Tilt_calc of RAMAN is greater than Tilt_error_thr.
[0115] (10) When the bending radius of the transmission fiber returns to normal, determine whether the gain compensation amount Gain_offset_comp of RAMAN is within the range of [Gainoffset_min2, Gainoffset_max2].
[0116] When all three conditions (8), (9), and (10) are met, the maximum and minimum values of the internal control gain are forcibly refreshed, the gain floating adjustment process is started, the current pump power exits the saturation state, and the target power of each pump is redistributed. Through the first-level feedback control and the second-level feedback control, the power of the target out-of-band ASE is locked with the power of the actual out-of-band ASE, thereby achieving the locking of the target gain.
[0117] There is also a fourth implementation method:
[0118] When the gain compensation of at least one pump on the Raman circuit exceeds the third preset range, the maximum and minimum values of the internal control gain are forcibly refreshed, the gain floating adjustment process is started, the current pump power exits the saturation state, and the target power of each pump is redistributed. Through the first-stage feedback control and the second-stage feedback control, the power of the target out-of-band ASE is locked with the power of the actual out-of-band ASE, thereby achieving the locking of the target gain.
[0119] Specifically, refreshing the maximum and minimum values of the internal control gain and initiating the gain floating adjustment process includes generating a high-level flag signal, which is temporarily defined as gain_add_offset_alarm_flag.
[0120] When gain_add_offset_alarm_flag is high, the current tilt compensation value (tilt_comp) will be cleared to 0. Here, tilt_comp = tilt_comp_k * gain_comp, where tilt_comp_k is the parameter value set by the module at the factory.
[0121] When gain_add_offset_alarm_flag is high, a delay timer for tilt_comp calculation is initiated. This tilt_comp calculation delay timer primarily addresses the issue of tilt_comp crossing regions. A tilt_comp crossing region refers to the software dividing the tilt range into multiple regions as set by the customer. For example, if the customer can set the tilt range to [-2:2], the software will divide [-2:2] into [-2:-1); [-1:0); [0:1); [1:2]. When a previously used tilt_comp crosses regions with the latest tilt_comp, the tilt_comp calculation will continue based on the parameters of the new region. The parameters of the new region need to be resent from the host computer to the FPGA, and this resentment takes time. Therefore, a delay timer is used to match the time requirements for parameter transmission.
[0122] When the delay timer for tilt_comp expires, the current tilt_comp value will be refreshed, that is, refreshed from the cleared state to tilt_comp = tilt_comp_k * gain_comp. At this time, the value of tilt_comp will change once, that is, from 0 to tilt_comp_k * gain_comp.
[0123] When the FPGA software detects a change in tilt_comp, it will perform the following operations:
[0124] The values of Gain_max and Gain_min are forcibly changed from the values at the time of the fault to the factory default parameters; when a fault occurs after the fiber bend is repaired, Gain_max and Gain_min are no longer the factory default parameter values.
[0125] The gain used internally to calculate the target pump power is adjusted from the gain_set_fluct (internal floating gain value) when a fault occurs. This adjustment is based on the delay time and adjustment step size configured at the module's factory settings.
[0126] When the internal floating gain value changes, the target power of each pump changes, and the feedback regulation adjusts according to the new target pump power.
[0127] When the fiber optic bend fault disappears, the target power of the pump changes, causing the feedback to readjust. The logic of the feedback control will then restore the pump power lock state that occurred when the fault occurred to normal, and thus the gain control and tilt control will return to normal as the normal adjustment is restored.
[0128] The floating gain adjustment process specifically includes:
[0129] (1) When the actual gain flattening slope is forcibly changed from non-zero to 0, the FPGA logic, upon detecting this change, will pull the signal triggering gain floating adjustment from low to high to initiate gain floating adjustment. The specific execution is as follows:
[0130] (1.1) After the FPGA logic detects that the signal that triggers gain adjustment changes from low level to high level, it refreshes the current maximum gain value from the actual gain when the fiber is bent to the factory default maximum gain value (when the fiber is bent abnormally, the maximum gain value = the actual gain). At the same time, it refreshes the current minimum gain value from the actual gain value when the fiber is bent to the factory default minimum gain value.
[0131] (1.2) After the FPGA logic detects that the signal triggering gain adjustment changes from low to high, it first checks whether the current floating gain value is within the range of the default factory maximum and minimum gain values. If it is within this range, it will increment or decrement the floating gain value by 0.1dB every cycle (this is the so-called floating adjustment). The result of incrementing or decrementing by 0.1dB still needs to meet the constraint of being within the range of the default factory maximum and minimum gain values. Every cycle refers to a fixed period of timing based on the default factory parameters.
[0132] (1.3) After the FPGA logic detects that the signal that triggers gain adjustment changes from low level to high level, it also clears the current gain compensation amount and gain flattening compensation amount to 0.
[0133] (1.4) The target power of each pump is recalculated using parameters such as the floating gain value after adding or subtracting N*0.1dB (N represents the multiple addition and subtraction of 0.1dB), the gain compensation amount after clearing to 0, and the gain flattening compensation amount after clearing to 0.
[0134] (2) When the target power of each pump changes (the target power of each pump is recalculated in step (d), the feedback regulation will be adjusted according to the new target power of the pump).
[0135] (3) When the fiber bending fault disappears, the target power of the pump changes and the feedback is readjusted. In this way, the feedback control will restore the state of locking the pump power when the fault occurred to normal, and thus the gain control and tilt control will return to normal.
[0136] The following comparison of the method described in this embodiment with the prior art in a real-world application scenario illustrates the effectiveness of this embodiment.
[0137] In the existing technology, with the target gain set to flat (Tilt_set = 0dB) and the target gain (Gain_set = 16dB), after the bending radius of the transmission fiber is severely reduced and then restored to normal, as shown in Figure 4, it can be seen that when the bending radius of the transmission fiber is severely reduced, the real-time reported gain (Gain_add_offset) is only about 11dB, deviating from the target gain of 16dB by 5dB. Furthermore, even after repeatedly reducing and restoring the bending radius of the transmission fiber, the real-time reported gain (Gain_add_offset) cannot return to normal.
[0138] After applying the method described in this embodiment, with the target gain flatness Tilt_set = 0dB and the target gain Gain_set = 16dB, after the bending radius of the transmission fiber was severely reduced and then restored to normal, as shown in Figure 5, it can be seen that when the target gain flatness Tilt_set = 0dB and the bending radius of the transmission fiber was severely reduced, the real-time reported gain Gain_add_offset was locked at the target gain of 16dB. Furthermore, after repeatedly reducing the bending radius of the transmission fiber from severely reduced to normal, the real-time reported gain value Gain_add_offset always returned to normal.
[0139] Taking another application scenario as an example, in existing technology, when the target gain flatness Tilt_set = -1.5dB and the target gain Gain_set = 16, after the bending radius of the transmission fiber is severely reduced and then restored to normal, as shown in Figure 6, it can be seen that when the target gain flatness Tilt_set = -1.5dB and the bending radius of the transmission fiber is severely reduced, the real-time reported gain Gain_add_offset is only about 9.5dB, which deviates from the target gain of 16dB by 6.5dB. Furthermore, even after repeatedly reducing the bending radius of the transmission fiber from severely reduced to normal, the real-time reported gain value Gain_add_offset cannot be restored to normal.
[0140] After applying the method described in this embodiment, with the target gain flatness Tilt_set = -1.5dB and the target gain Gain_set = 16dB, after the bending radius of the transmission fiber was severely reduced and then restored to normal, as shown in Figure 7, it can be seen that when the target gain flatness Tilt_set = -1.5dB and the bending radius of the transmission fiber was severely reduced, the real-time reported gain Gain_add_offset was locked at the target gain of 16dB. Furthermore, after repeatedly reducing the bending radius of the transmission fiber from severely reduced to normal, the real-time reported gain value Gain_add_offset always returned to normal.
[0141] Taking another application scenario as an example, in existing technology, when the target gain flatness Tilt_set = 1.5dB and the target gain Gain_set = 16dB, after the bending radius of the transmission fiber is severely reduced and then restored to normal, as shown in Figure 8, it can be seen that when the target gain flatness Tilt_set = 1.5dB and the bending radius of the transmission fiber is severely reduced, the real-time reported gain Gain_add_offset is only about 9.5dB, which deviates from the target gain of 16dB by 6.5dB. Furthermore, even after repeatedly reducing the bending radius of the transmission fiber from severely reduced to normal, the real-time reported gain value Gain_add_offset cannot be restored to normal.
[0142] After applying the method described in this embodiment, with the target gain flatness Tilt_set = 1.5dB and the target gain Gain_set = 16dB, after the bending radius of the transmission fiber was severely reduced and then restored to normal, as shown in Figure 9, it can be seen that when the target gain flatness Tilt_set = 1.5dB and the bending radius of the transmission fiber was severely reduced, the real-time reported gain Gain_add_offset was locked at the target gain of 16dB. Furthermore, after repeatedly reducing the bending radius of the transmission fiber from severely reduced to normal, the real-time reported gain value Gain_add_offset always returned to normal.
[0143] It should be noted that in Figures 4-9, the horizontal axis of each figure represents time count, and the vertical axis represents the reported gain, i.e., the actual gain of the Raman circuit.
[0144] Example 3:
[0145] Figure 10 shows a schematic diagram of the architecture of a Raman line protection control device according to an embodiment of the present invention. The Raman line protection control device of this embodiment includes one or more processors 21 and a memory 22. Figure 10 illustrates a single processor 21 as an example.
[0146] The processor 21 and the memory 22 can be connected via a bus or other means. Figure 10 shows an example of a connection via a bus.
[0147] The memory 22, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs and non-volatile computer-executable programs, such as the Raman line protection control method in Embodiment 1. The processor 21 executes the Raman line protection control method by running the non-volatile software program and instructions stored in the memory 22.
[0148] Memory 22 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 22 may optionally include memory remotely located relative to processor 21, which can be connected to processor 21 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.
[0149] The program instructions / modules are stored in the memory 22 and, when executed by one or more processors 21, execute the Raman line protection control method in Embodiment 1 above.
[0150] This embodiment also provides a communication system, including a Raman line, and uses the aforementioned Raman line protection and control device to protect and control the Raman line.
[0151] It is worth noting that the information interaction and execution process between the modules and units in the above-mentioned device and system are based on the same concept as the processing method embodiment of the present invention. For details, please refer to the description in the method embodiment of the present invention, and will not be repeated here.
[0152] Those skilled in the art will understand that all or part of the steps in the various methods of the embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc.
[0153] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A Raman line protection control method, characterized in that, include: Monitor the various control parameters of the Raman circuit. When the corresponding control parameter is detected to meet the fiber bend recovery condition, readjust the gain so that the Raman circuit can achieve gain flat recovery after the fiber bend is recovered. The optical fiber bend recovery conditions include one or more of the first condition, the second condition, or the third condition.
2. The Raman line protection control method according to claim 1, characterized in that, The first condition is: The difference between the actual gain and the target gain of the Raman circuit is greater than a first preset value, and the pump power of each pump on the Raman circuit is within a first preset range, and the total power of the Raman circuit is less than a second preset value, and the gain compensation of each pump on the Raman circuit is within a second preset range.
3. The Raman line protection control method according to claim 1, characterized in that, The second condition is: the gain compensation of at least one pump on the Raman circuit exceeds the third preset range.
4. The Raman line protection control method according to claim 1, characterized in that, The third condition is: The difference between the actual gain and the target gain of the Raman circuit is less than the third preset value, and the difference between the actual gain flat slope and the target gain flat slope of the Raman circuit is greater than the fifth preset value, and the gain compensation of each pump on the Raman circuit is within the fourth preset range.
5. The Raman line protection control method according to claim 1, characterized in that, The aforementioned readjustment of gain specifically includes: Update the gain compensation of each pump to the default gain compensation value, update the gain flatness compensation to the default flatness compensation value, refresh the maximum gain value to the default maximum gain, and refresh the minimum gain value to the default minimum gain to trigger the floating gain adjustment of each pump.
6. The Raman line protection control method according to claim 5, characterized in that, The floating gain adjustment of each pump specifically includes: During the i-th floating gain adjustment process, the floating gain value is increased or decreased by a preset step size to obtain the i-th floating gain value. Using the i-th floating gain value and the target slope, the expected out-of-band ASE power of each pump during the i-th floating gain adjustment process is calculated. Determine whether the actual ASE power of each pump is locked with the expected out-of-band ASE power of each pump during the i-th floating gain adjustment. If at least one pump is not locked, then perform the (i+1)-th floating gain adjustment until the actual ASE power of each pump is locked with the expected out-of-band ASE power of each pump. The last floating gain value is used as the new target gain. The target power of each pump is calculated based on the new target gain and target slope. The target power is used to control the power of each pump. In the first floating gain adjustment process, the target gain is used as the i-th floating gain value.
7. The Raman line protection control method according to claim 1, characterized in that, Before using Raman circuits for optical amplification, the method also includes: Enter power mode, turn on each pump, set the target power for each pump, and adjust the proportional parameter, derivative parameter, and adjustment period in the first-stage feedback control to lock the pump power of each pump to the target power so that the first-stage feedback control takes effect. Under the current gain flat slope, determine the leakage factor of each pump and the out-of-band ASE power at different gains. Use the gain flat slope, gain and out-of-band ASE power to perform curve fitting to complete the calibration of the ASE power formula. Enter gain mode, set the target gain and target gain flat slope for each pump, and adjust the proportional parameter, derivative parameter and adjustment period in the second-stage feedback control until the difference between the out-of-band ASE power and the desired out-of-band ASE power of each pump is less than the preset ASE difference. So that in the subsequent optical amplification process, the proportional parameters, derivative parameters, and adjustment period in the adjusted first-stage feedback control, as well as the proportional parameters, derivative parameters, and adjustment period in the adjusted second-stage feedback control, can be used to adjust the gain of the Raman circuit.
8. The Raman line protection control method according to claim 7, characterized in that, The method also includes: Before using the Raman circuit for optical amplification, keep all pumps off and measure the total power of the Raman circuit; turn on the first pump, set the power of the first pump to the preset power, measure the out-of-band ASE power, and calculate the insertion loss of the fiber optic connector based on the out-of-band ASE power.
9. A Raman circuit protection control device, characterized in that, include: At least one processor; And a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the processor for performing the Raman line protection control method according to any one of claims 1-8.
10. A communication system, characterized in that, It includes a Raman circuit, and uses the Raman circuit protection and control device as described in claim 9 to protect and control the Raman circuit.