Method and system for determining decision threshold of multi-channel asynchronous wavelength label signal

Abstract

The present application relates to a method and system for determining a decision threshold for a multi-channel asynchronous wavelength label signal, and relates to the field of optical communication technology. The method comprises the following steps: when receiving a target wavelength label signal obtained after positive and negative alternating coding, demodulating the target wavelength label signal to obtain a signal power value corresponding to each bit in the target wavelength label signal; iteratively calculating based on the signal power value to obtain an average signal power value and noise power value corresponding to each bit; and calculating based on the average signal power value and noise power value to obtain a decision threshold corresponding to each bit. The present application stabilizes the probability of transmitting bit 0 and bit 1 per unit time at a level of 50% through positive and negative alternating coding, thereby reducing the influence of non-random signals on the decision threshold, so that the obtained decision threshold is suitable for judging dynamic random signals and static non-random signals; and achieves high-precision adaptive adjustment of the decision threshold through an iterative method, thereby reducing the influence of noise on the decision threshold.

Description

Technical Field

[0001] The present application relates to the field of optical communication technology, and in particular to a method and system for determining a decision threshold of a multi-channel asynchronous wavelength label signal. Background Art

[0002] In recent years, with the development of wavelength division multiplexing (WDM) technology, the capacity of optical communication networks has increased dramatically. Therefore, to ensure the normal operation and maintenance of such high-capacity optical networks, signal quality monitoring is essential. Traditional monitoring technologies primarily rely on electrical layer overhead. However, as transmission distances increase, the number of relay nodes and transmission paths become increasingly complex, monitoring signal quality at the protocol layer becomes increasingly difficult. At the same time, with the gradual development of all-optical networks, current WDM networks can implement optical signal addition and subtraction, as well as cross-connection, without optoelectronic conversion. Therefore, in this context, direct signal quality monitoring at the optical layer using wavelength labeling technology has become an essential component of modern optical network management.

[0003] Among them, wavelength label technology refers to the monitoring of a single channel by loading low-frequency modulation (MHz) on a high-speed (above GHz) optical wavelength channel; while in the WDM system, frequency division technology is used to load different pilot signals on different wavelengths to achieve multi-channel monitoring. However, since each wavelength label signal comes from a transmitter at a different network node, its modulation depth, transmission power and transmission path are different, resulting in significant differences in the power of each asynchronous wavelength label signal when detected and received at a certain node, making the traditional fixed threshold judgment method unsuitable. Therefore, in the existing technology, the judgment threshold of multiple asynchronous wavelength label signals is often established in the following two ways: (1) the demodulation of each wavelength label signal requires an independent calibration sequence to establish the judgment threshold; (2) the judgment threshold is adjusted in real time according to the signal characteristics.

[0004] However, the method of establishing the decision threshold through calibration sequence has the problem of low transmission efficiency; and the decision threshold obtained based on signal characteristics can only be used to judge dynamic random signals. However, the bit information sent by the wavelength label signal is fixed and unchanged, which is a typical static non-random signal. Therefore, how to effectively determine the decision threshold of multi-channel asynchronous wavelength label signals is an urgent problem that needs to be solved. Summary of the Invention

[0005] The present application provides a method and system for determining a decision threshold for multi-channel asynchronous wavelength label signals, so as to solve the problem in the related art that the decision threshold for multi-channel asynchronous wavelength label signals cannot be effectively determined.

[0006] In a first aspect, a method for determining a decision threshold for a multi-channel asynchronous wavelength label signal is provided, comprising the following steps:

[0007] When receiving the target wavelength label signal obtained after the forward and reverse alternating encoding, demodulating the target wavelength label signal to obtain a signal power value corresponding to each bit in the target wavelength label signal;

[0008] Performing iterative calculation based on the signal power value to obtain an average signal power value and a noise power value corresponding to each bit;

[0009] A decision threshold corresponding to each bit is calculated based on the average signal power value and the noise power value.

[0010] In some embodiments, after the step of calculating the decision threshold corresponding to each bit based on the average signal power value and the noise power value, the method further includes:

[0011] A level decision is performed on each bit according to the magnitude relationship between the decision threshold and the signal power value to obtain a bit sequence after the decision.

[0012] In some embodiments, before the step of receiving the wavelength label signal obtained after the forward and reverse alternating encoding, the method further includes:

[0013] Combining a wavelength label signal to be sent and a modulation depth corresponding to the wavelength label signal to be sent into a frame;

[0014] The framed data is encoded alternately in forward and reverse order frame by frame to obtain the target wavelength label signal.

[0015] In some embodiments, after the step of determining each bit based on the magnitude relationship between the determination threshold and the signal power value to obtain a determined bit sequence, the method further includes:

[0016] Performing a bitwise exclusive OR operation on the preset frame header and the determined bit sequence to obtain a bitwise exclusive OR operation result;

[0017] Extracting the modulation depth according to the bitwise XOR operation result;

[0018] The optical power is calculated based on the modulation depth and the decision threshold.

[0019] In some embodiments, extracting the modulation depth according to the bitwise XOR operation result includes:

[0020] If the bitwise XOR operation results are all 0, the modulation depth is extracted from the positive frame data;

[0021] If the bitwise XOR operation results are all 1, the inverted frame data is inverted to obtain inverted data, and the modulation depth is extracted from the inverted data.

[0022] In some embodiments, performing iterative calculation based on the signal power value to obtain an average signal power value and a noise power value corresponding to each bit includes:

[0023] Substituting the signal power value into the first iterative calculation formula to obtain an average signal power value;

[0024] Substituting the signal power value into the second iterative calculation formula to obtain the noise power value;

[0025] The first iterative calculation formula is:

[0026] P m [k] = (1-α m )P m [k-1]+α m P[k]

[0027] The second iteration calculation formula is:

[0028] P n [k] = (1-α n )P n [k-1]+α n P[k]

[0029] Where, P m [k] represents the average signal power value of the kth bit, P m [k-1] represents the average signal power value of the k-1th bit, P[k] represents the signal power value of the kth bit, P n [k] represents the noise power value of the kth bit, P n [k-1] represents the noise power value of the k-1th bit, α m and α n Both represent iteration coefficients.

[0030] In some embodiments, the iteration coefficient α m and the iteration coefficient α n The value range is (1 / 4 times the frame length to 1 / 16 times the frame length).

[0031] In some embodiments, when calculating the noise power value of the kth bit, it is determined whether the signal power value of the kth bit is less than a decision threshold of the k-1th bit;

[0032] If yes, updating the noise power value based on the signal power value of the k-th bit and the second iterative calculation formula to obtain the noise power value of the k-th bit;

[0033] If not, the noise power value of the k-1th bit is used as the noise power value of the kth bit.

[0034] In some embodiments, demodulating the target wavelength label signal to obtain a signal power value corresponding to each bit in the target wavelength label signal includes:

[0035] Demodulating the target wavelength label signal to obtain a label baseband signal corresponding to each bit;

[0036] The tag baseband signal corresponding to each bit is squared to obtain the signal power value corresponding to each bit.

[0037] In a second aspect, a system for determining a decision threshold for a multi-channel asynchronous wavelength label signal is provided, comprising:

[0038] A signal demodulation module is used to demodulate the target wavelength label signal obtained after positive and negative alternating encoding when receiving the target wavelength label signal, and obtain the signal power value corresponding to each bit in the target wavelength label signal;

[0039] A threshold updating module is used to perform iterative calculation based on the signal power value to obtain the average signal power value and noise power value corresponding to each bit; and to calculate the decision threshold corresponding to each bit based on the average signal power value and the noise power value.

[0040] The present application provides a method and system for determining a decision threshold for a multi-channel asynchronous wavelength label signal. The method comprises: upon receiving a target wavelength label signal obtained after alternating positive and negative encoding, demodulating the target wavelength label signal to obtain a signal power value corresponding to each bit in the target wavelength label signal; iteratively calculating an average signal power value and a noise power value corresponding to each bit based on the signal power value; and calculating a decision threshold corresponding to each bit based on the average signal power value and the noise power value. The present application adjusts the proportion of transmitted bits 0 and 1 by alternating positive and negative encoding of each wavelength label signal, so that the probability of transmitting bits 0 and 1 per unit time is stabilized at 50%, thereby reducing the impact of non-random signals on the decision threshold. The calculated decision threshold is then applicable to the judgment of both dynamic random signals and static non-random signals. The method also implements high-precision adaptive adjustment of the decision threshold through an iterative method, reducing the impact of noise on the decision threshold. Thus, the present application can effectively determine the decision threshold for multi-channel asynchronous wavelength label signals without the need for a calibration sequence, and the decision threshold is applicable to the judgment of any state signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0042] Figure 1 A flowchart of a method for determining a decision threshold for a multi-channel asynchronous wavelength label signal provided in an embodiment of the present application;

[0043] Figure 2 A schematic diagram of a specific process of determining a decision threshold for a multi-channel asynchronous wavelength label signal provided in an embodiment of the present application;

[0044] Figure 3 Convergence curves of various parameters when the ratio of bit 0 to bit 1 provided in the embodiment of the present application is 1:9 and positive and negative frames are not alternately encoded frame by frame;

[0045] Figure 4 Convergence curves of various parameters provided in the embodiment of the present application when the ratio of bit 0 to bit 1 is 1:9, using forward and reverse frame alternating encoding and an iterative update coefficient of 1 / 512;

[0046] Figure 5 The spectrum of the signal power value when the ratio of bit 0 to bit 1 is 1:9 provided in the embodiment of the present application;

[0047] Figure 6 When the ratio of bit 0 to bit 1 provided in the embodiment of the present application is 1:9, positive and negative frames are alternately encoded frame by frame and the iterative update coefficient is 1 / 4096, and the convergence curves of various parameters are shown. DETAILED DESCRIPTION

[0048] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0049] The embodiments of the present application provide a method and system for determining a decision threshold for multi-channel asynchronous wavelength label signals, which can solve the problem in related technologies that the decision threshold for multi-channel asynchronous wavelength label signals cannot be effectively determined.

[0050] Figure 1The present invention provides a method for determining a decision threshold of a multi-channel asynchronous wavelength label signal, comprising the following steps:

[0051] Step S10: When receiving the target wavelength label signal obtained after the forward and reverse alternating encoding, demodulate the target wavelength label signal to obtain a signal power value corresponding to each bit in the target wavelength label signal;

[0052] For example, wavelength label signals are characterized by fixed transmission bit information and are not random signals. Multi-channel asynchronous wavelength label signals are characterized by signals originating from transmitters at different nodes, with varying modulation depths, transmission powers, and transmission paths. This can lead to significant differences in the power of each asynchronous wavelength label signal when detected and received at a given node. Consequently, traditional fixed-threshold decision methods are not suitable for determining the decision threshold for multi-channel asynchronous wavelength label signals. Therefore, this embodiment encodes the wavelength label signals using alternating positive and negative coding to adjust the ratio of transmitted bits 0 and 1, ensuring that the probability of transmitting bits 0 and 1 per unit time remains stable at 50%.

[0053] Specifically, the encoding module at the transmitting end of the wavelength label system performs forward and reverse alternating encoding on the wavelength label signal to be transmitted frame by frame to form a target wavelength label signal, so as to achieve a stable 50% probability of transmitting sequence bits 0 and 1 in unit time; then, the modulation module up-converts the encoded information (i.e., the target wavelength label signal) to an electrical pilot frequency of a specific frequency preset by the system, and then loads it onto the service optical signal of the corresponding wavelength through intensity modulation, so that the demodulation module can synchronously detect and receive all asynchronous target wavelength label signals through an optical detector, and perform corresponding demodulation processing to obtain the signal power value corresponding to each bit in the target wavelength label signal.

[0054] Furthermore, before the step of receiving the wavelength label signal obtained after the forward and reverse alternating encoding, the method further includes:

[0055] Combining a wavelength label signal to be sent and a modulation depth corresponding to the wavelength label signal to be sent into a frame;

[0056] The framed data is encoded alternately in forward and reverse order frame by frame to obtain the target wavelength label signal.

[0057] For example, monitoring the optical power of the wavelength channel corresponding to the WDM system based on the wavelength label can greatly simplify the difficulty of troubleshooting the service disconnection caused by insufficient optical power. The current common method of monitoring optical power through wavelength label signals is to use the FFT (Fast Fourier Transform) frequency amplitude corresponding to the wavelength label signal to infer the pilot power, and then further infer the corresponding wavelength channel optical power to realize the monitoring function. However, since the service light modulated with the wavelength label signal is transmitted through the optical fiber, optical noise is superimposed after passing through the optical amplifier method, so that the receiving end will be affected by the noise when calculating the modulation depth, so that the calculated modulation depth deviates from the modulation depth preset by the sending end, which leads to errors in the optical power monitoring results.

[0058] In order to avoid a deviation between the modulation depth at the receiving end and the modulation depth at the transmitting end, this embodiment inserts the modulation depth information of the wavelength label signal of the transmitter into the frame information through the encoding module located at the transmitting end of the wavelength label system. That is, the modulation depth information is combined with the wavelength label signal to be transmitted into a frame and a fixed frame header is added. The framed frame data is then alternately encoded in positive and negative directions frame by frame to obtain the target wavelength label signal. In this way, the receiving end can directly obtain the modulation depth that is not affected by optical noise through the target wavelength label signal. That is, the modulation depth at the receiving end is consistent with the modulation depth preset by the transmitting end, thereby avoiding errors in the optical power detection results.

[0059] It can be understood that frame-by-frame positive and negative alternating encoding refers to sending positive frames and negative frames alternately in sequence. Taking 2 frames as an example: if the first frame sends a normal code stream, the second frame sends the complement of the first frame, that is, if the first frame sends 1, then the second frame sends 0. Conversely, if the first frame sends 0, then the second frame sends 1, so that the probability can be stabilized at 50% when extracting information.

[0060] Furthermore, the demodulating the target wavelength label signal to obtain a signal power value corresponding to each bit in the target wavelength label signal includes:

[0061] Demodulating the target wavelength label signal to obtain a label baseband signal corresponding to each bit;

[0062] The tag baseband signal corresponding to each bit is squared to obtain the signal power value corresponding to each bit.

[0063] Exemplarily, in this embodiment, the signal demodulation module synchronously detects and receives all asynchronous target wavelength label signals through an optical detector, and uses a digital signal processor to perform channel separation, baseband signal recovery, labeling and other operations on the label signal after sampling by an analog-to-digital converter, thereby obtaining the label baseband signal corresponding to each bit to support the signal processing of subsequent modules; then, the label baseband signal corresponding to each bit recovered by demodulation is squared to obtain the signal power value corresponding to each bit.

[0064] Step S20: performing iterative calculation based on the signal power value to obtain an average signal power value and a noise power value corresponding to each bit;

[0065] For example, it should be understood that in this embodiment, the average signal power and noise power are calculated in an iterative manner, that is, the average signal power and noise power corresponding to each bit are updated respectively by the corresponding iterative calculation formula, so that the threshold update module can process and obtain a high-precision decision threshold.

[0066] Furthermore, performing iterative calculation based on the signal power value to obtain an average signal power value and a noise power value corresponding to each bit includes:

[0067] Substituting the signal power value into the first iterative calculation formula to obtain an average signal power value;

[0068] Substituting the signal power value into the second iterative calculation formula to obtain the noise power value;

[0069] The first iterative calculation formula is:

[0070] P m [k] = (1-α m )P m [k-1]+α m P[k]

[0071] The second iteration calculation formula is:

[0072] P n [k] = (1-α n )P n [k-1]+α n P[k]

[0073] Where, P m [k] represents the average signal power value of the kth bit, P m [k-1] represents the average signal power value of the k-1th bit, P[k] represents the signal power value of the kth bit, P n [k] represents the noise power value of the kth bit, P n[k-1] represents the noise power value of the k-1th bit, α m and α n Both represent iteration coefficients.

[0074] Specifically, when calculating the noise power value of the k-th bit, it is determined whether the signal power value of the k-th bit is less than the decision threshold of the k-1-th bit;

[0075] If yes, updating the noise power value based on the signal power value of the k-th bit and the second iterative calculation formula to obtain the noise power value of the k-th bit;

[0076] If not, the noise power value of the k-1th bit is used as the noise power value of the kth bit.

[0077] For example, in this embodiment, see Figure 2 As shown ( Figure 2 in|·| 2 represents the signal power value), and an iterative method is used to update the average signal power corresponding to each bit. Specifically, the signal power value can be substituted into the following iterative update formula:

[0078] P m [k] = (1-α m )P m [k-1]+α m P[k] (1)

[0079] Where, P m [k] represents the average signal power value of the kth bit, P m [k-1] represents the average signal power value of the k-1th bit, P[k] represents the signal power value of the kth bit, α m It represents the iteration coefficient, which can be determined according to the convergence speed required for demodulation and the accuracy of the decision threshold.

[0080] Among them, the average signal power P m The initial value does not affect the final result. In actual use, the initial value can be set to 0; for example, when P is initially m [0]=0, when the signal power value P[1] of the first bit is received, the average signal power corresponding to the first bit is updated to P m [1]:

[0081] P m [1]=(1-α m )P m [0]+α m P[1]=α m P[1] (2)

[0082] When the signal power value P[2] of the second bit is received, the average signal power corresponding to the second bit is updated to P m [2]:

[0083] P m [2]=(1-α m )α m P[1]+α m P[2] (3)

[0084] When the signal power value P[k] of the kth bit is received, the average signal power corresponding to the kth bit is updated to P m [k]:

[0085] P m [k] = (1-α m ) k-1 α m P[1]+(1-α m ) k-2 α m P[2]+...+(1-α m )α m P[k-1]+α m P[k]=(1-α m )P m [k-1]+α m P[k] (4)

[0086] It should be understood that although this embodiment performs weighted averaging on k signals, each weight (i.e., the coefficient in front of P[k]) is different, and the size of the weight is related to the order of reception, that is, the earlier the power signal is received, the smaller the weight it has.

[0087] Similarly, this embodiment also uses an iterative method to update the noise power. Specifically, the signal power value can be substituted into the following iterative update formula:

[0088] P n [k] = (1-α n )P n [k-1]+α n P[k] (5)

[0089] Where, P n [k] represents the noise power value of the kth bit, P n [k-1] represents the noise power value of the k-1th bit, P[k] represents the signal power value of the kth bit, α n It represents the iteration coefficient, which can be determined according to the convergence speed required for demodulation and the accuracy of the decision threshold, and the iteration coefficient α n and the iteration coefficient α mThe values ​​are the same in size. It can be understood that when the signal power value is less than the decision threshold, the bit sent by the transmitter is determined to be "0." For an OOK signal, when the transmitter sends a bit "0," its signal power is 0. Therefore, at the receiving end, the bit "0" corresponds to pure noise, and the received signal power value P[k] is pure noise power. Therefore, when updating the noise power value, the noise power value can be obtained by controlling the iterations by ensuring that the signal power value is less than the decision threshold.

[0090] It is understandable that whether the noise power needs to be updated in each iteration depends on the relationship between the decision threshold and the signal power value, that is, if the signal power value is less than the decision threshold, the noise power needs to be updated, and if the signal power value is greater than or equal to the decision threshold, the noise power does not need to be updated, and the noise power value updated in the previous iteration is used as the noise power value updated in this iteration. Specifically, since the noise power P n If the initial values ​​of the decision threshold and the decision threshold are both 0, then in the first iteration, since the signal power value cannot be less than the decision threshold, there is no need to update the noise power at this time, that is, the result of the first iteration is that the noise power value is equal to 0; in the second iteration, the decision threshold calculated based on the average signal power value and the noise power value obtained in the first iteration is no longer equal to 0. At this time, the relationship between the decision threshold and the signal power value will be used to decide whether to update the noise power.

[0091] Furthermore, the iteration coefficient α m and the iteration coefficient α n The value range is (1 / 4 times the frame length to 1 / 16 times the frame length).

[0092] For example, the iteration coefficient α m and the iteration coefficient α n It can be determined based on the convergence speed required for demodulation and the accuracy of the decision threshold. The smaller the iteration coefficient, the slower the convergence time, but the smaller the fluctuation of the obtained decision threshold. It can be preferably set to 1 / (4 to 16 times the frame length).

[0093] Step S30: Calculate a decision threshold corresponding to each bit based on the average signal power value and the noise power value.

[0094] For example, in this embodiment, after calculating the average signal power value and noise power value corresponding to each bit, the average signal power value and noise power value are substituted into the following calculation formula to obtain the decision threshold corresponding to each bit:

[0095]

[0096] Where, P th[k] represents the decision threshold corresponding to the kth bit, P m [k] represents the average signal power value of the kth bit, P n [k] represents the noise power value of the kth bit.

[0097] The following describes the calculation process of the average signal power value, the noise power value, and the decision threshold update in conjunction with specific embodiments.

[0098] Assume that the bit information sent by the transmitter is 1, 1, 0, 1, 0, ..., and the signal amplitude is 2, and the power of each bit received by the receiver is 4.53, 3.34, 0.02, 4.61, 0.03, ..., in order to facilitate demonstration and speed up the convergence process, the two iteration coefficients α can be m and α n The setting is too large, for example, in this embodiment, α m and α n Both are set to 1 / 100.

[0099] Specifically, first, the average signal power P m , noise power P n and the decision threshold P th Set the initial value: For example, P m [0]=0, P n [0]=0, P th [0]=0;

[0100] The first update, that is, k = 1, the received power value at this time is:

[0101] P[1]=4.53

[0102] Update the average signal power value:

[0103]

[0104] Since P[1]=4.53 and P th [0]=0, that is, P[1]<P th [0] is not true, so the noise power value is not updated, then:

[0105] P n [1]=P n [0]=0

[0106] Update the decision threshold:

[0107]

[0108] The second update, that is, k = 2, the received power value at this time is:

[0109] P[2]=3.34

[0110] Update the average signal power value:

[0111]

[0112] Since P[2]=3.34 and P th [1]=0.0227, that is, P[2]<P th [1] does not hold, so the noise power value is not updated, then:

[0113] P n [2]=P n [1]=0

[0114] Update the decision threshold:

[0115]

[0116] The third update, that is, k=3, the received power value at this time is:

[0117] P[3]=0.02

[0118] Update the average signal power value:

[0119]

[0120] Since P[3]=0.02 and P th [2]=0.0776, that is, P[3]<P th [2] holds true, so the noise power value needs to be updated, then:

[0121]

[0122] Update the decision threshold:

[0123]

[0124] The fourth update, i.e. k=4, the received power value is:

[0125] P[4]=4.61

[0126] Update the average signal power value:

[0127]

[0128] Since P[4]=4.61 and P th [3]=0.0387, that is, P[4]<P th [3] does not hold, so the noise power value is not updated, then:

[0129] P n [4]=P n[3] = 0.0002

[0130] Update the decision threshold:

[0131]

[0132] The fifth update, i.e. k=5, the received power value is:

[0133] P[5]=0.03

[0134] Update the average signal power value:

[0135]

[0136] Since P[5]=0.03 ​​and P th [4]=0.0614, that is, P[5]<P th [4] holds true, so the noise power value needs to be updated, then:

[0137]

[0138] Update the decision threshold:

[0139]

[0140] It should be noted that the above are merely presentations of embodiments to enable those skilled in the art to understand or implement the present application. Various modifications may be made to these embodiments according to actual needs, which are not limited here.

[0141] In order to verify the accuracy of the decision threshold calculated by this embodiment, this embodiment conducted experiments to verify the accuracy of the decision threshold calculated by using both the forward and reverse frame frame-by-frame alternating coding and the forward and reverse frame frame-by-frame alternating coding. The experimental results are shown in Figure 3 and Figure 4 .Depend on Figure 3 It can be seen that when the ratio of bit 0 to bit 1 is 1:9 and the positive and negative frames are not alternately encoded frame by frame, the curves of the average signal power and the decision threshold are very different from the curves of the optimal theoretical decision threshold, that is, the accuracy of the calculated decision threshold is poor. It can be seen that the difference in the ratio of bit 0 to bit 1 will directly cause the decision threshold to deviate from the theoretical optimal value; and Figure 4 It can be seen that when the ratio of bit 0 to bit 1 is 1:9 and the ratio of sending bit 0 and bit 1 is adjusted by using positive and negative frames to alternately encode each frame, the ratio of bit 0 to bit 1 becomes 1:1. At this time, the change curve of the average signal power and the decision threshold is very close to the curve of the optimal theoretical decision threshold, that is, the decision threshold calculated in this embodiment has high accuracy.

[0142] However, see Figure 5As shown in FIG, after the forward and reverse frames are encoded frame by frame, the spectrum of the signal power value P has a strong frequency component at 1 Hz, which will cause the decision threshold to fluctuate after convergence. The iterative formula used in this embodiment has the effect of low-pass filtering, and the smaller the iteration coefficient, the narrower the bandwidth. Therefore, this embodiment can set the iteration coefficient α of appropriate size to m and α n This embodiment is experimentally verified with a signal rate B of 1 kbps, a frame length L of 506, and iteration coefficients of 1 / 512 and 1 / 4096 respectively. The verification results are shown in Figure 4 ( Figure 4 shows the convergence of the decision threshold when the iteration coefficient is too large) and Figure 6 ( Figure 6 The convergence of the decision threshold under the appropriate size of the iteration coefficient is shown). Figure 4 and Figure 6 It can be seen that when the iteration coefficient is small enough, the interference of the component with frequency B / 2L can be suppressed. However, when the iteration coefficient is small, the decision threshold takes a long time to converge, and the effect is not good. When the iteration coefficient is 1 / (4 to 16 times the frame length), it can achieve both low-pass filtering effect and faster convergence speed. Therefore, the iteration coefficient can be preferably set to 1 / (4 to 16 times the frame length).

[0143] It can be seen that this embodiment adjusts the proportion of transmitted bits 0 and 1 by alternately encoding each wavelength label signal in positive and negative directions, so that the probability of transmitting bits 0 and 1 per unit time is stabilized at 50%, thereby reducing the impact of non-random signals on the decision threshold, and thus making the calculated decision threshold applicable to the judgment of dynamic random signals and static non-random signals; and through an iterative method, high-precision adaptive adjustment of the decision threshold is achieved, reducing the impact of noise on the decision threshold. In summary, the present application can effectively determine the decision threshold of multiple asynchronous wavelength label signals without the need for a calibration sequence, and the decision threshold can be applied to the judgment of any state signal.

[0144] Furthermore, after the step of calculating the decision threshold corresponding to each bit based on the average signal power value and the noise power value, the method further includes:

[0145] A level decision is performed on each bit according to the magnitude relationship between the decision threshold and the signal power value to obtain a bit sequence after the decision.

[0146] For example, in this embodiment, after determining the decision threshold corresponding to each bit, it is also necessary to perform high-precision signal decision processing according to the exclusive decision threshold of each asynchronous wavelength label channel through the decision module, that is, to make a high or low level decision for each bit. Specifically, the decision can be made based on the relationship between the decision threshold and the signal power value: if the signal power value is less than the decision threshold, the bit is judged as 0, otherwise it is judged as bit 1. For example, the signal power value P[k] corresponding to the kth bit is less than the decision threshold P[k] corresponding to the kth bit. th [k], then the kth bit is judged to be 0. After judging each bit in this way, the judged bit sequence can be obtained.

[0147] Furthermore, after the step of judging each bit according to the magnitude relationship between the judgment threshold and the signal power value to obtain a judged bit sequence, the method further includes:

[0148] Performing a bitwise exclusive OR operation on the preset frame header and the determined bit sequence to obtain a bitwise exclusive OR operation result;

[0149] Extracting the modulation depth according to the bitwise XOR operation result;

[0150] The optical power is calculated based on the modulation depth and the decision threshold.

[0151] Specifically, extracting the modulation depth according to the bitwise XOR operation result includes:

[0152] If the bitwise XOR operation results are all 0, the modulation depth is extracted from the positive frame data;

[0153] If the bitwise XOR operation results are all 1, the inverted frame data is inverted to obtain inverted data, and the modulation depth is extracted from the inverted data.

[0154] For example, the traditional frequency domain monitoring method is affected by the fence effect of FFT operation, and the ADC (Analog-Digital Converter) sampling clock and pilot frequency offset will cause errors in the optical power monitoring results. However, this embodiment calculates the optical power based on a high-precision decision threshold and a modulation depth that is not affected by optical noise, avoiding the fence effect of the frequency shift monitoring scheme and improving robustness. Specifically, this embodiment uses the system-preset frame header sequence and the judged bit sequence output by the decision module to perform threshold comparison through the decoding module; and decodes the data encoded in the alternating positive and negative frames based on the comparison results and implements frame synchronization processing to extract and output the valid data information in the frame. When extracting the frame information, the exclusive modulation depth information of the wavelength label channel obtained is output to the optical power monitoring module; the optical power monitoring module calculates the service channel optical power corresponding to the wavelength label signal based on the high-precision decision threshold output by the threshold update module and the modulation depth information extracted by the decoding module.

[0155] It is understandable that a bitwise XOR operation can be performed between the preset frame header and the judged bit sequence, and frame information can be extracted based on the result of the bitwise XOR operation. The decoding strategy is that the frame data is not changed for the positive frame, and the entire frame data (including the frame header) is inverted for the inverted frame. Specifically, if the bitwise XOR result is all 0, the frame header of the positive frame is found, the intra-frame data of this frame is directly output, and the modulation depth information is extracted; if the bitwise XOR result is all 1, the frame header of the inverted frame is found, all the data of this frame is inverted and output, and the modulation depth information that is not affected by optical noise is extracted. That is, the modulation depth obtained by the receiving end is exactly the same as the modulation depth preset by the transmitting end, and there is no error.

[0156] For example, the preset frame header is 0110, and the bit sequence after judgment is 1110011011011011. The preset frame header 0110 is first subjected to a bitwise exclusive OR operation with 1110 in the bit sequence after judgment, and the result is 1000. Since it is neither all 0 nor all 1, 1110 is not a frame header. The preset frame header 0110 is then subjected to a bitwise exclusive OR operation with 0110 in the sequence after judgment, and the result is 0000. Since it is all 0, it indicates that 0110 is the frame header of a positive frame. The entire frame data including the frame header is directly output, and the modulation depth is extracted from the output information.

[0157] For another example, the preset frame header is 0110, and the bit sequence after judgment is 1110100111011011. The preset frame header 0110 is first subjected to a bitwise exclusive OR operation with 1110 in the bit sequence after judgment, and the result is 1000. Since it is neither all 0 nor all 1, 1110 is not a frame header. The preset frame header 0110 is then subjected to a bitwise exclusive OR operation with 1001 in the sequence after judgment, and the result is 1111. Since it is all 1, it indicates that 1001 is the frame header of the inverted frame. The entire frame data including the frame header is then inverted and output, and the modulation depth is extracted from the output information.

[0158] Then, the decision threshold and the extracted modulation depth are substituted into the following formula to calculate the power of the service optical signal.

[0159]

[0160] Where R represents the responsivity of the photodetector, G represents the gain coefficient of the electrical amplifier, and M represents the modulation depth. However, in actual systems, since the values ​​of R and G vary to a certain extent on different single-board hardware, experimental testing and calibration are required. Therefore, for quick application, in this embodiment, an initial calibration coefficient k can be used for initial calibration to achieve the same result, which can be obtained:

[0161]

[0162] It can be seen that this embodiment achieves high-precision level judgment and optical power monitoring of multi-channel asynchronous non-random wavelength label signals, avoiding the interference of the transmitted non-random bit information and noise on the judgment threshold, so that the high-precision level judgment method proposed in this embodiment is applicable to any static non-random sequence and dynamic random signal and has no requirements for the frame format. This embodiment specifically uses the positive and negative frame-by-frame alternating coding technology to achieve a stable probability of bit 0 and bit 1 of 50%, and matching the corresponding decoding strategy at the receiving end not only achieves error-free demodulation, but also achieves the effect of high-precision adaptive adjustment of the judgment threshold without the need for calibration bytes. At the same time, the optical power monitoring method proposed in this embodiment avoids the influence of clock offset, frequency offset, FFT fence effect, modulation code type, modulation depth error and non-random transmission sequence. Compared with the traditional monitoring method based on frequency amplitude, it has higher accuracy and better robustness.

[0163] The present application also provides a system for determining a decision threshold for a multi-channel asynchronous wavelength label signal, including:

[0164] A signal demodulation module is used to demodulate the target wavelength label signal obtained after positive and negative alternating encoding when receiving the target wavelength label signal, and obtain the signal power value corresponding to each bit in the target wavelength label signal;

[0165] A threshold updating module is used to perform iterative calculation based on the signal power value to obtain the average signal power value and noise power value corresponding to each bit; and to calculate the decision threshold corresponding to each bit based on the average signal power value and the noise power value.

[0166] Furthermore, the system further includes a decision module, which is configured to:

[0167] A level decision is performed on each bit according to the magnitude relationship between the decision threshold and the signal power value to obtain a bit sequence after the decision.

[0168] Furthermore, the system further includes an encoding module, which is used to:

[0169] Combining a wavelength label signal to be sent and a modulation depth corresponding to the wavelength label signal to be sent into a frame;

[0170] The framed data is encoded alternately in forward and reverse order frame by frame to obtain the target wavelength label signal.

[0171] Furthermore, the system also includes a decoding module and an optical power monitoring module; the decoding module is used to perform a bit-wise XOR operation on the preset frame header and the bit sequence after the judgment to obtain a bit-wise XOR operation result; the modulation depth is extracted according to the bit-wise XOR operation result; the optical power monitoring module is used to calculate the optical power based on the modulation depth and the judgment threshold.

[0172] Furthermore, the decoding module is specifically used to:

[0173] If the bitwise XOR operation results are all 0, the modulation depth is extracted from the positive frame data;

[0174] If the bitwise XOR operation results are all 1, the inverted frame data is inverted to obtain inverted data, and the modulation depth is extracted from the inverted data.

[0175] Furthermore, the threshold updating module is specifically configured to:

[0176] Substituting the signal power value into the first iterative calculation formula to obtain an average signal power value;

[0177] Substituting the signal power value into the second iterative calculation formula to obtain the noise power value;

[0178] The first iterative calculation formula is:

[0179] P m [k] = (1-α m )P m [k-1]+α m P[k]

[0180] The second iteration calculation formula is:

[0181] P n [k] = (1-α n )P n [k-1]+α n P[k]

[0182] Where, P m [k] represents the average signal power value of the kth bit, P m [k-1] represents the average signal power value of the k-1th bit, P[k] represents the signal power value of the kth bit, P n [k] represents the noise power value of the kth bit, P n [k-1] represents the noise power value of the k-1th bit, α m and α n Both represent iteration coefficients.

[0183] Furthermore, the iteration coefficient α m and the iteration coefficient α n The value range is (1 / 4 times the frame length to 1 / 16 times the frame length).

[0184] Furthermore, when calculating the noise power value of the k-th bit, the threshold updating module is further configured to:

[0185] Determine whether the signal power value of the k-th bit is less than the decision threshold of the k-1-th bit;

[0186] If yes, updating the noise power value based on the signal power value of the k-th bit and the second iterative calculation formula to obtain the noise power value of the k-th bit;

[0187] If not, the noise power value of the k-1th bit is used as the noise power value of the kth bit.

[0188] Furthermore, the signal demodulation module is specifically used to:

[0189] Demodulating the target wavelength label signal to obtain a label baseband signal corresponding to each bit;

[0190] The tag baseband signal corresponding to each bit is squared to obtain the signal power value corresponding to each bit.

[0191] It should be noted that those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and each module described above can refer to the corresponding process in the aforementioned embodiment of the method for determining the decision threshold of multiple asynchronous wavelength label signals, and will not be repeated here.

[0192] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0193] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for determining a decision threshold for multi-channel asynchronous wavelength label signals, characterized in that: The following steps are involved: When receiving the target wavelength label signal obtained after the forward and reverse alternating encoding, demodulating the target wavelength label signal to obtain a signal power value corresponding to each bit in the target wavelength label signal; Performing iterative calculation based on the signal power value to obtain an average signal power value and a noise power value corresponding to each bit; Calculate a decision threshold corresponding to each bit based on the average signal power value and the noise power value; The iterative calculation based on the signal power value to obtain the average signal power value and the noise power value corresponding to each bit includes: Substituting the signal power value into the first iterative calculation formula to obtain an average signal power value; Substituting the signal power value into the second iterative calculation formula to obtain the noise power value; The first iterative calculation formula is: The second iteration calculation formula is: Where, represents the average signal power value of the kth bit, represents the average signal power value of the k-1th bit, represents the signal power value of the kth bit, represents the noise power value of the kth bit, represents the noise power value of the k-1th bit, and Both represent iteration coefficients.

2. The method for determining a decision threshold for a multi-channel asynchronous wavelength label signal according to claim 1, wherein: After the step of calculating the decision threshold corresponding to each bit based on the average signal power value and the noise power value, the method further includes: A level decision is performed on each bit according to the magnitude relationship between the decision threshold and the signal power value to obtain a bit sequence after the decision.

3. The method for determining a decision threshold for multi-channel asynchronous wavelength label signals according to claim 2, wherein: Before the step of receiving the wavelength label signal obtained after the forward and reverse alternating encoding, the method further includes: Combining a wavelength label signal to be sent and a modulation depth corresponding to the wavelength label signal to be sent into a frame; The framed data is encoded alternately in forward and reverse order frame by frame to obtain the target wavelength label signal.

4. The method for determining a decision threshold for multi-channel asynchronous wavelength label signals according to claim 3, wherein: After the step of judging each bit according to the magnitude relationship between the judgment threshold and the signal power value to obtain a judged bit sequence, the method further includes: Performing a bitwise exclusive OR operation on the preset frame header and the determined bit sequence to obtain a bitwise exclusive OR operation result; Extracting the modulation depth according to the bitwise XOR operation result; The optical power is calculated based on the modulation depth and the decision threshold.

5. The method for determining a decision threshold for multi-channel asynchronous wavelength label signals according to claim 4, wherein: Extracting the modulation depth according to the bitwise XOR operation result includes: If the bitwise XOR operation results are all 0, the modulation depth is extracted from the positive frame data; If the bitwise XOR operation results are all 1, the inverted frame data is inverted to obtain inverted data, and the modulation depth is extracted from the inverted data.

6. The method for determining a decision threshold for multi-channel asynchronous wavelength label signals according to claim 1, wherein: The iteration coefficient and the iteration coefficient The value range is 1 / 4 times the frame length to 1 / 16 times the frame length.

7. The method for determining a decision threshold for multi-channel asynchronous wavelength label signals according to claim 1, wherein: When calculating the noise power value of the k-th bit, determining whether the signal power value of the k-th bit is less than the decision threshold of the k-1-th bit; If yes, updating the noise power value based on the signal power value of the k-th bit and the second iterative calculation formula to obtain the noise power value of the k-th bit; If not, the noise power value of the k-1th bit is used as the noise power value of the kth bit.

8. The method for determining a decision threshold for multi-channel asynchronous wavelength label signals according to claim 1, wherein: The demodulating the target wavelength label signal to obtain a signal power value corresponding to each bit in the target wavelength label signal includes: Demodulating the target wavelength label signal to obtain a label baseband signal corresponding to each bit; The tag baseband signal corresponding to each bit is squared to obtain the signal power value corresponding to each bit.

9. A multi-channel asynchronous wavelength label signal decision threshold determination system, characterized in that: include: A signal demodulation module is used to demodulate the target wavelength label signal obtained after positive and negative alternating encoding when receiving the target wavelength label signal, and obtain the signal power value corresponding to each bit in the target wavelength label signal; a threshold updating module, configured to perform iterative calculation based on the signal power value to obtain an average signal power value and a noise power value corresponding to each bit; and calculate a decision threshold corresponding to each bit based on the average signal power value and the noise power value; The threshold updating module is specifically configured to: Substituting the signal power value into the first iterative calculation formula to obtain an average signal power value; Substituting the signal power value into the second iterative calculation formula to obtain the noise power value; The first iterative calculation formula is: The second iteration calculation formula is: Where, represents the average signal power value of the kth bit, represents the average signal power value of the k-1th bit, represents the signal power value of the kth bit, represents the noise power value of the kth bit, represents the noise power value of the k-1th bit, and Both represent iteration coefficients.

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