Method and system for locating optical multipath interference

Abstract

The present invention provides a method and system for locating optical multipath interference. The method collects a signal and then obtains noise at intervals of a specified number of samples or a specified time. The collected signal and noise are then correlated, or the signal and noise are periodically accumulated and correlated to obtain a relative number of delayed samples. The absolute number of delayed samples is calculated by changing the superposition period and the delay time of the MPI path relative to the signal is obtained. This method greatly reduces the required storage space and achieves accurate MPI positioning.

Description

Technical Field

[0001] The present invention relates to the technical field of positioning optical multipath interference, and in particular to a method and system for positioning optical multipath interference. Background Art

[0002] Multipath interference (MPI) often occurs in fiber optic links. MPI refers to the interference caused by optical signals reflecting back and forth between fiber connection points. If MPI is too high, it can easily lead to increased bit error rates and even communication interruption.

[0003] Patent document CN118233018A discloses a method and related equipment for locating MPIs in an optical fiber link. The method comprises: an MCU obtains a first noise signal based on a signal output by an equalizer; the MCU determines the sign of a windowed average value of the first noise signal; the MCU multiplies the first noise signal by the sign to obtain a second noise signal; and the MCU determines a reflection distance based on the second noise signal. The reflection distance indicates the distance between two optical fiber connection points in the optical fiber link that cause the MPI. However, for longer optical links, the patent requires the DSP chip or MCU to store cross-correlation calculation results on the order of 1e6 to 1e7, which poses a significant challenge to the storage space of the DSP chip or MCU. Furthermore, the patent proposes sending two periodic sequences and using cross-correlation between the sequences and the noise to locate the MPI. However, this method requires sending a special periodic sequence and cannot be implemented based on service signals, which means that the service must be interrupted or the periodic sequence must be sent in addition to the service information. Summary of the Invention

[0004] In view of the defects in the prior art, the present invention aims to provide a method and system for locating optical multipath interference.

[0005] The method for locating optical multipath interference provided by the present invention includes:

[0006] Step 11: Calculate all reflection paths using the known link topology information and the receiver sampling rate.

[0007] Step 12: Determine the number of interval samples or the interval time required to collect the signal and noise by delaying the number of samples or the delay time;

[0008] Step 13: first collect a section of signal as the desired signal, and then collect the noise corresponding to the section of signal as the desired noise after a preset interval time or a preset number of samples;

[0009] Step 14: Process the collected signal and noise separately, including removing DC from the signal, calculating noise power through the noise, and removing DC;

[0010] Step 15: Perform a cross-correlation operation on the processed signal and the noise. The position of the correlation peak indicates the relative delay sample number or relative delay time of the noise relative to the signal.

[0011] Step 16: Calculate the number of samples or delay time of the MPI path relative to the signal by collecting the number of interval samples or the interval time required for collecting the signal and the noise, and the number of samples or the relative delay time of the noise relative to the signal;

[0012] Step 17: Based on the number of delay samples or delay time of the MPI path relative to the signal, compare it with the list of delay samples or delay time experienced by all reflection paths relative to the signal in the known link topology information. The matching reflection path is the detected reflection path, thereby locating the corresponding reflection point.

[0013] Preferably, for any two reflection points at known positions in the known link topology information, the number of delayed samples or the delay time experienced by the formed reflection path relative to the signal is calculated as:

[0014] Number of delayed samples = distance between reflection points × 2 × sampling rate ÷ speed of light in optical fiber;

[0015] Delay time = distance between reflection points × 2 ÷ speed of light in optical fiber.

[0016] Preferably, the acquisition of the noise includes: obtaining a decision signal using an equalizer output signal corresponding to the second segment signal, and then subtracting the decision signal from the equalizer output signal to obtain the noise.

[0017] The method for locating optical multipath interference provided by the present invention includes:

[0018] Step 21: Collect signals and noise;

[0019] Step 22: Processing the signal and the noise separately, including removing DC from the signal, calculating power from the noise, and removing DC;

[0020] Step 23: performing periodic accumulation on the processed signal and noise according to a specified accumulation period to obtain a periodic accumulated signal and a periodic accumulated noise;

[0021] Step 24: performing a correlation operation on the periodically accumulated signal and the periodically accumulated noise to obtain a correlation result;

[0022] Step 25: Repeat steps 22 to 24 multiple times, and accumulate the correlation results obtained each time until a clear correlation peak appears in the accumulated sum of the correlation results, and use the correlation peak to read the relative delayed sample number of the periodically accumulated noise relative to the periodically accumulated signal;

[0023] Step 26: Change the specified accumulation period used for periodic accumulation and repeat steps 22 to 25 to determine the delay time of the MPI path relative to the signal using different specified accumulation periods and their corresponding relative delay sample numbers and the Chinese remainder theorem.

[0024] Step 27: Determine a corresponding reflection point based on the delay time of the MPI path relative to the signal and in combination with link topology information.

[0025] Preferably, the noise is obtained by obtaining a decision signal from a signal output by an equalizer, and then obtaining the noise by subtracting the decision signal from the signal output by the equalizer.

[0026] The system for locating optical multipath interference provided by the present invention includes:

[0027] Module M11: Calculates all reflection paths using known link topology information and the receiver sampling rate;

[0028] Module M12: Determines the number of interval samples or the interval time required to collect signals and noise by delaying the number of samples or the delay time;

[0029] Module M13: first collects a section of signal as the desired signal, and then collects the noise corresponding to the section of signal as the desired noise after a preset interval time or number of interval samples;

[0030] Module M14: processes the collected signal and noise separately, including removing DC from the signal, calculating the noise power through the noise, and removing DC;

[0031] Module M15: Perform cross-correlation operation on the processed signal and noise. The position of the correlation peak indicates the relative delay sample number or relative delay time of the noise relative to the signal.

[0032] Module M16: Calculate the number of samples or delay time of the MPI path relative to the signal by collecting the number of interval samples or the interval time required for the signal and the noise, and the number of samples or the relative delay time of the noise relative to the signal;

[0033] Module M17: Based on the number of delay samples or delay time of the MPI path relative to the signal, a list of the number of delay samples or delay time experienced by all reflection paths relative to the signal in the known link topology information is compared. The matching reflection path is the detected reflection path, thereby locating the corresponding reflection point.

[0034] Preferably, for any two reflection points at known positions in the known link topology information, the number of delayed samples or the delay time experienced by the formed reflection path relative to the signal is calculated as:

[0035] Number of delayed samples = distance between reflection points × 2 × sampling rate ÷ speed of light in optical fiber;

[0036] Delay time = distance between reflection points × 2 ÷ speed of light in optical fiber.

[0037] Preferably, the acquisition of the noise includes: obtaining a decision signal using an equalizer output signal corresponding to the second segment signal, and then subtracting the decision signal from the equalizer output signal to obtain the noise.

[0038] The system for locating optical multipath interference provided by the present invention includes:

[0039] Module M21: collects signals and noise;

[0040] Module M22: processing the signal and the noise separately, including removing DC from the signal, calculating power from the noise and removing DC;

[0041] Module M23: performing periodic accumulation on the processed signal and noise according to a specified accumulation period to obtain a periodic accumulated signal and a periodic accumulated noise;

[0042] Module M24: performing correlation operation on the periodically accumulated signal and the periodically accumulated noise to obtain a correlation result;

[0043] Module M25: repeatedly triggering modules M22 to M24 multiple times, and accumulating the correlation results obtained each time until a clear correlation peak appears in the accumulated sum of the correlation results, and using the correlation peak to read the relative delayed sample number of the periodically accumulated noise relative to the periodically accumulated signal;

[0044] Module M26: Changes the specified accumulation period used for periodic accumulation, repeatedly triggers modules M22 to M25, and determines the delay time of the MPI path relative to the signal through different specified accumulation periods and their corresponding relative delay sample numbers and the Chinese remainder theorem.

[0045] Module M27: Determine a corresponding reflection point according to the delay time of the MPI path relative to the signal and in combination with link topology information.

[0046] Preferably, the noise is obtained by obtaining a decision signal from a signal output by an equalizer, and then obtaining the noise by subtracting the decision signal from the signal output by the equalizer.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The present invention processes the received service signal to obtain the signal and the noise, without the need to send a special periodic sequence or special code pattern, thereby achieving the effect of not interrupting the service;

[0049] (2) Solution 1 of the present invention achieves the effect of greatly reducing the requirement for storage space by first storing the shorter signal, then storing the noise of the same or equivalent length after a fixed number of symbols (or a fixed time, or a fixed number of bits).

[0050] (3) The second solution of the present invention achieves the effect of greatly reducing the requirement for storage space size by performing periodic accumulation operations on the processed signal and noise according to a specified accumulation period. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0052] Figure 1 Flowcharts of the first and second invention schemes;

[0053] Figure 2 This is a specific implementation example of the second solution of the present invention. DETAILED DESCRIPTION

[0054] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0055] Example

[0056] like Figure 1 and Figure 2 The present invention provides a method for locating optical multipath interference, comprising:

[0057] Option 1:

[0058] Step 1: Using the known link topology information and the receiver sampling rate, calculate the number of delayed samples (or delay time) experienced by all possible reflection paths relative to the signal. For any two reflection points at known locations in the known link topology information, the number of delayed samples (or delay time) experienced by the possible reflection paths relative to the signal can be calculated as:

[0059] Number of delayed samples = distance between reflection points × 2 × sampling rate ÷ speed of light in the fiber.

[0060] Delay time = distance between reflection points × 2 ÷ speed of light in optical fiber.

[0061] Step 2: Determine the number of interval samples (or interval time) required to collect the signal and noise based on the number of delayed samples (or delay time). There is no strict relationship between the number of interval samples (or interval time) and the number of delayed samples (or delay time) (this can be determined based on specific implementation circumstances), but the two should be close to each other to ensure that in subsequent steps, in two signal segments collected at the interval of the number of interval samples (or interval time), the length of the partial sequence showing correlation accounts for a sufficiently large proportion of the total length of the collected signal sequence.

[0062] Step 3: First, a segment of the signal is collected as the collected signal. Then, after the interval time or the number of samples, the noise corresponding to the segment of the signal is collected as the noise. The noise is obtained by obtaining a decision signal using the equalizer output signal corresponding to the second segment of the signal. The noise is then obtained by subtracting the decision signal from the equalizer output signal.

[0063] Step 4: Perform certain processing on the signal and the noise respectively, for example (but not limited to), removing the DC from the signal, calculating the noise power from the noise, and removing the DC.

[0064] Step 5: Perform a cross-correlation operation on the signal and noise after the above processing. The position of the correlation peak indicates the relative delayed sample number (or relative delayed time) of the noise relative to the signal.

[0065] Step 6: Calculate the number of delayed samples (or delay time) of the MPI path relative to the signal by using the number of interval samples (or interval time) required to acquire the signal and noise, and the number of relatively delayed samples (or relative delay time) of the noise relative to the signal.

[0066] Step 7: Based on the number of delay samples (or delay time) of the MPI path relative to the signal, compare it with a list of the number of delay samples (or delay time) experienced by all possible reflection paths in the known link topology information relative to the signal. The matching reflection path is the detected reflection path, thereby locating the corresponding reflection point.

[0067] Option 2:

[0068] Step 1: Collecting signals and noise. The noise is obtained by obtaining a decision signal from the signal output by the equalizer, and then subtracting the decision signal from the signal output by the equalizer to obtain the noise.

[0069] Step 2: Perform certain processing on the signal and the noise respectively, for example (but not limited to), removing the DC from the signal, calculating the power from the noise, and removing the DC.

[0070] Step 3: Perform periodic accumulation on the signal and noise after the above processing according to a specified accumulation period to obtain a periodic accumulated signal and a periodic accumulated noise.

[0071] Step 4: Perform a correlation operation (such as but not limited to cyclic correlation) on the periodically accumulated signal and the periodically accumulated noise to obtain a correlation result.

[0072] Step 5: Repeat steps 2 to 4 above multiple times, and accumulate the correlation results obtained each time until a clear correlation peak appears in the cumulative sum of the correlation results. Use the correlation peak to read the relative delayed sample number of the periodically accumulated noise relative to the periodically accumulated signal.

[0073] Step 6: Change the specified accumulation period used for periodic accumulation and repeat steps 2 to 5. Determine the delay time of the MPI path relative to the signal by using different specified accumulation periods and their corresponding relative delay sample numbers and the Chinese remainder theorem.

[0074] Step 7: Determine the corresponding reflection point based on the delay time of the MPI path relative to the signal and the link topology information.

[0075] Those skilled in the art will appreciate that, in addition to implementing the system, device, and various modules provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, and the like by logically programming the method steps. Therefore, the system, device, and various modules provided by the present invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; the modules for implementing various functions can also be considered both software programs for implementing the method and structures within the hardware component.

[0076] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for locating optical multipath interference, characterized in that: include: Step 11: Calculate all reflection paths using the known link topology information and the receiver sampling rate. Step 12: Determine the number of interval samples or the interval time required to collect the signal and noise by delaying the number of samples or the delay time; Step 13: first collect a section of signal as the desired signal, and then collect the noise corresponding to the section of signal as the desired noise after a preset interval time or a preset number of samples; Step 14: Process the collected signal and noise separately, including removing DC from the signal, calculating noise power through the noise, and removing DC; Step 15: Perform a cross-correlation operation on the processed signal and the noise. The position of the correlation peak indicates the relative delay sample number or relative delay time of the noise relative to the signal. Step 16: Calculate the number of samples or delay time of the MPI path relative to the signal by collecting the number of interval samples or the interval time required for collecting the signal and the noise, and the number of samples or the relative delay time of the noise relative to the signal; Step 17: Based on the number of delay samples or delay time of the MPI path relative to the signal, compare it with the list of delay samples or delay time experienced by all reflection paths relative to the signal in the known link topology information. The matching reflection path is the detected reflection path, thereby locating the corresponding reflection point.

2. The method for locating optical multipath interference according to claim 1, wherein: For any two reflection points at known locations in the known link topology information, the number of delayed samples or delay time experienced by the reflected path relative to the signal is calculated as: Number of delayed samples = distance between reflection points × 2 × sampling rate ÷ speed of light in optical fiber; Delay time = distance between reflection points × 2 ÷ speed of light in optical fiber.

3. The method for locating optical multipath interference according to claim 1, wherein: The noise is obtained by using an equalizer output signal corresponding to the second segment signal to obtain a decision signal, and then subtracting the decision signal from the equalizer output signal to obtain the noise.

4. A method for locating optical multipath interference, characterized in that: include: Step 21: Collect signals and noise; Step 22: Processing the signal and the noise separately, including removing DC from the signal, calculating power from the noise, and removing DC; Step 23: performing periodic accumulation on the processed signal and noise according to a specified accumulation period to obtain a periodic accumulated signal and a periodic accumulated noise; Step 24: performing a correlation operation on the periodically accumulated signal and the periodically accumulated noise to obtain a correlation result; Step 25: Repeat steps 22 to 24 multiple times, and accumulate the correlation results obtained each time until a clear correlation peak appears in the accumulated sum of the correlation results, and use the correlation peak to read the relative delayed sample number of the periodically accumulated noise relative to the periodically accumulated signal; Step 26: Change the specified accumulation period used for periodic accumulation and repeat steps 22 to 25 to determine the delay time of the MPI path relative to the signal using different specified accumulation periods and their corresponding relative delay sample numbers and the Chinese remainder theorem. Step 27: Determine a corresponding reflection point based on the delay time of the MPI path relative to the signal and in combination with link topology information.

5. The method for locating optical multipath interference according to claim 4, characterized in that: The noise acquisition includes: acquiring a decision signal through a signal output by an equalizer, and then subtracting the decision signal from the signal output by the equalizer to acquire the noise.

6. A system for locating optical multipath interference, characterized in that: include: Module M11: Calculates all reflection paths using known link topology information and the receiver sampling rate; Module M12: Determines the number of interval samples or the interval time required to collect signals and noise by delaying the number of samples or the delay time; Module M13: first collects a section of signal as the desired signal, and then collects the noise corresponding to the section of signal as the desired noise after a preset interval time or number of interval samples; Module M14: processes the collected signal and noise separately, including removing DC from the signal, calculating the noise power through the noise, and removing DC; Module M15: Perform cross-correlation operation on the processed signal and noise. The position of the correlation peak indicates the relative delay sample number or relative delay time of the noise relative to the signal. Module M16: Calculate the number of samples or delay time of the MPI path relative to the signal by collecting the number of interval samples or the interval time required for the signal and the noise, and the number of samples or the relative delay time of the noise relative to the signal; Module M17: Based on the number of delay samples or delay time of the MPI path relative to the signal, a list of the number of delay samples or delay time experienced by all reflection paths relative to the signal in the known link topology information is compared. The matching reflection path is the detected reflection path, thereby locating the corresponding reflection point.

7. The system for locating optical multipath interference according to claim 6, wherein: For any two reflection points at known locations in the known link topology information, the number of delayed samples or delay time experienced by the reflected path relative to the signal is calculated as: Number of delayed samples = distance between reflection points × 2 × sampling rate ÷ speed of light in optical fiber; Delay time = distance between reflection points × 2 ÷ speed of light in optical fiber.

8. The system for locating optical multipath interference according to claim 6, wherein: The noise is obtained by using an equalizer output signal corresponding to the second segment signal to obtain a decision signal, and then subtracting the decision signal from the equalizer output signal to obtain the noise.

9. A system for locating optical multipath interference, characterized in that: include: Module M21: collects signals and noise; Module M22: processing the signal and the noise separately, including removing DC from the signal, calculating power from the noise and removing DC; Module M23: performing periodic accumulation on the processed signal and noise according to a specified accumulation period to obtain a periodic accumulated signal and a periodic accumulated noise; Module M24: performing correlation operation on the periodically accumulated signal and the periodically accumulated noise to obtain a correlation result; Module M25: repeatedly triggering modules M22 to M24 multiple times, and accumulating the correlation results obtained each time until a clear correlation peak appears in the accumulated sum of the correlation results, and using the correlation peak to read the relative delayed sample number of the periodically accumulated noise relative to the periodically accumulated signal; Module M26: Changes the specified accumulation period used for periodic accumulation, repeatedly triggers modules M22 to M25, and determines the delay time of the MPI path relative to the signal through different specified accumulation periods and their corresponding relative delay sample numbers and the Chinese remainder theorem. Module M27: Determine a corresponding reflection point according to the delay time of the MPI path relative to the signal and in combination with link topology information.

10. The system for locating optical multipath interference according to claim 9, characterized in that: The noise acquisition includes: acquiring a decision signal through a signal output by an equalizer, and then subtracting the decision signal from the signal output by the equalizer to acquire the noise.

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