CN110557195B - Timing error detection method and device based on coherent optical communication - Google Patents

Abstract

Embodiments of the present invention provide a timing error detection method and device based on coherent optical communication. The method includes: determining a symbol period of a received coherent optical signal; sampling the coherent optical signal based on the symbol period, and the sampling period is Half of the symbol period; based on the sampling values of the current sampling symbol and the last sampling symbol, determine whether there is a phase jump between the current sampling symbol and the last sampling symbol; if there is no phase jump, then based on the current sampling symbol The sampled value, the sampled value of the last sampled symbol, the sampled value of the middle sampling time between the sampling time of the current sampled symbol and the sampling time of the last sampled symbol, and the timing error of the last sampled symbol, calculate the timing error of the current sampled symbol. The technical problem that the timing error cannot be accurately calculated if there is no phase jump when using the existing algorithm is solved.

Description

A timing error detection method and device based on coherent optical communication

technical field

The present invention relates to the technical field of optical communication, and in particular, to a timing error detection method and device based on coherent optical communication.

Background technique

With the continuous development of the communication industry, people have put forward higher requirements for the transmission speed, quality, real-time and high efficiency of signals, prompting more researchers to focus on lower transmission damage, wider transmission frequency band, more The optical fiber communication with large communication capacity is continuously explored.

In the field of long-distance and large-capacity optical communication technology, coherent optical communication technology occupies a pivotal position. Compared with the traditional direct detection optical fiber communication system, the coherent optical communication system has the advantages of high detection sensitivity, high spectrum utilization, and large channel capacity.

After the receiving end of the coherent optical communication system receives the signal, the accurate recovery of the clock from the received signal is the first step of demodulation. In order to ensure the reliability of information transmission, the recovery of the synchronous clock should have high accuracy and stability.

The traditional clock recovery scheme has certain limitations. Take the Gardner algorithm as an example to explain. This algorithm samples twice in each symbol, and judges whether there is a timing error based on the sampled value, and can estimate the timing error when there is a timing error. the size of. Specifically, referring to Figs. 1(a)-1(c), arrows indicate sampling moments, n indicates the nth symbol period, and I(n) indicates the sampling value in the nth symbol period. In Fig. 1(a), the sampling time of each symbol period is at the maximum peak value, which means positioning alignment, Fig. 1(b) shows timing lag, Fig. 1(c) shows timing advance, in addition, by sampling The value of the moment can also estimate the value of the timing advance or lag, thereby determining the timing error. However, as shown in Figures 1(a)-1(c), this algorithm is only suitable for the case where there is a phase jump between adjacent symbols. If there is no phase jump, the timing error calculated by this algorithm is wrong of.

It can be seen that the traditional clock recovery scheme cannot accurately detect the timing error between the received signal and the local clock signal when there is no phase jump between adjacent symbols in the signal. Correspondingly, the accuracy of the recovered synchronous clock is also higher. Low.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present invention is to provide a timing error detection method and device based on coherent optical communication, so as to improve the accuracy of detecting the timing error between the received signal and the local clock signal, so as to restore the synchronous clock more accurately. The specific technical solutions are as follows:

To achieve the above object, an embodiment of the present invention provides a timing error detection method based on coherent optical communication, the method comprising:

determining the symbol period of the received coherent optical signal;

sampling the coherent optical signal based on the symbol period, where the sampling period is half of the symbol period;

Based on the sampling values of the current sampling symbol and the last sampling symbol, determine whether there is a phase jump between the current sampling symbol and the last sampling symbol;

If there is no phase jump, based on the sampling value of the current sampling symbol, the sampling value of the last sampling symbol, the sampling value of the sampling instant between the sampling instant of the current sampling symbol and the sampling instant of the last sampling symbol, and the sampling instant of the last sampling symbol Timing error of the symbol, calculates the timing error of the currently sampled symbol.

Optionally, the step of determining the symbol period of the received coherent optical signal includes:

Pre-sampling the received coherent optical signal based on the sampling clock of the preset sampling period to obtain a sampling signal sequence;

performing an interpolation operation on the sampled signal sequence to obtain an interpolated analog signal;

A symbol period of the coherent optical signal is determined based on the analog signal.

Optionally, the sampling value based on the current sampling symbol, the sampling value of the last sampling symbol, the sampling value of the sampling instant of the current sampling symbol and the sampling instant of the last sampling symbol, and the sampling value of the last sampling symbol. Timing error, the steps of calculating the timing error of the current sampling symbol, including:

Use the following formula to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol.

Optionally, if there is a phase jump between the current sampling symbol and the previous sampling symbol, the following formula is used to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol.

Optionally, the method further includes:

The sampling period is adjusted based on the timing error of the current sampled symbol.

To achieve the above object, an embodiment of the present invention provides a timing error detection device based on coherent optical communication, the device comprising:

a determining module for determining the symbol period of the received coherent optical signal;

a sampling module, configured to sample the coherent optical signal based on the symbol period, where the sampling period is half of the symbol period;

The judgment module is used to judge whether there is a phase jump between the current sampling symbol and the last sampling symbol based on the sampling values of the current sampling symbol and the last sampling symbol;

The calculation module is used for if the result of the judgment module is no, based on the sampling value of the current sampling symbol, the sampling value of the previous sampling symbol, the sampling moment of the current sampling symbol and the sampling moment of the last sampling symbol The middle sampling moment The sampling value of , and the timing error of the last sampling symbol, calculate the timing error of the current sampling symbol.

Optionally, the determining module is specifically used for:

Pre-sampling the received coherent optical signal based on the sampling clock of the preset sampling period to obtain a sampling signal sequence;

performing an interpolation operation on the sampled signal sequence to obtain an interpolated analog signal;

A symbol period of the coherent optical signal is determined based on the analog signal.

Optionally, the computing module is specifically used for:

Use the following formula to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol.

Optionally, the computing module is further used for:

If the result of the judgment module is yes, the following formula is used to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol.

To achieve the above object, an embodiment of the present invention also provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus;

memory for storing computer programs;

The processor is configured to implement any of the above method steps when executing the program stored in the memory.

To achieve the above object, an embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, any one of the above method steps is implemented.

It can be seen that, by applying the method and device for detecting timing error based on coherent optical communication provided by the embodiments of the present invention, a phase separation error detection method is adopted, that is, whether there is a phase jump between adjacent symbols is first determined. When there is no phase jump between adjacent symbols, it can be based on the sampling value of the current sampling symbol, the sampling value of the previous sampling symbol, and the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol The accurate timing error is calculated, which solves the technical problem that the timing error cannot be accurately calculated if there is no phase jump when using the existing algorithm. In addition, the embodiment of the present invention also introduces the timing error of the last sampled symbol as a reference for the timing error of the current symbol, thereby further improving the accuracy of timing error detection in coherent optical communication and reducing the jitter of the recovered synchronous clock.

Of course, it is not necessary for any product or method to implement the present invention to simultaneously achieve all of the advantages described above.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

Fig. 1(a)-Fig. 1(c) are a kind of schematic diagram of the existing Gardner algorithm to determine the timing error;

FIG. 2 is a schematic flowchart of a timing error detection method based on coherent optical communication provided by an embodiment of the present invention;

FIG. 3 is another schematic flowchart of a timing error detection method based on coherent optical communication provided by an embodiment of the present invention;

Fig. 4 is the simulation schematic diagram of the bit error jitter adopting the traditional Gardner algorithm;

5 is a schematic diagram of a simulation of bit error jitter using a timing error detection method based on coherent optical communication provided by an embodiment of the present invention;

6 is a schematic diagram showing the comparison of bit error rates under different signal-to-noise ratios using the traditional Gardner algorithm and the timing error detection method based on coherent optical communication provided by an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a timing error detection apparatus based on coherent optical communication provided by an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of an electronic device provided by an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In order to improve the accuracy of detecting the timing error between the received signal and the local clock signal, so as to facilitate more accurate recovery of the synchronous clock, embodiments of the present invention provide a timing error detection method, device, electronic device and method based on coherent optical communication. Computer-readable storage medium, the following first describes the timing error detection method based on coherent optical communication provided by the embodiment of the present invention.

For ease of understanding, the application scenarios of the present invention are briefly introduced first.

The embodiments of the present invention can be applied to a receiving end of a coherent optical communication system. After receiving the coherent optical signal, the receiving end needs to recover the synchronous clock before demodulation. Those skilled in the art can understand that a synchronous clock means that the sampling clock used by the receiving end and the signal clock modulated by the transmitting end are the same, so that the receiving end can sample at the peak value of each symbol period, thereby obtaining a higher signal-to-noise signal. Compare.

Usually, the clock synchronization process is a dynamic adjustment process. The receiving end can calculate the timing error in real time according to the sampling value, and adjust the sampling clock based on the timing error. The accuracy of the obtained timing error greatly affects the accuracy of the sampling clock.

The timing error detection method based on coherent optical communication provided by the embodiment of the present invention is to improve the accuracy of calculating the timing error, so as to recover the synchronous clock more accurately.

Specifically, referring to FIG. 2, FIG. 2 is a schematic flowchart of a timing error detection method based on coherent optical communication provided by an embodiment of the present invention, and the method may include the following steps:

S201: Determine the symbol period of the received coherent optical signal.

In this embodiment of the present invention, after receiving the coherent optical signal, the receiving end may first determine the symbol period.

In one embodiment of the present invention, determining the symbol period of the received coherent optical signal may include the following refinement steps:

Step 11: Pre-sampling the received coherent optical signal based on the sampling clock of the preset sampling period to obtain a sampling signal sequence.

The receiver can complete the configuration of parameters, including the order configuration of the root raised cosine filter, the configuration of the sampling period, and the configuration of the roll-off coefficient, before the clock synchronization is performed.

The receiving end may pre-sample the received coherent optical signal by using a sampling clock with a preset cycle to obtain a sampling signal sequence. Then, the sampled signal sequence can be stored in a register, waiting for the interpolation filter to complete the interpolation operation.

Step 12: Perform an interpolation operation on the sampled signal sequence to obtain an interpolated analog signal.

The interpolation filter at the receiving end can perform interpolation operation on the sampled signal sequence to restore the analog signal.

Wherein, the process of restoring the analog signal based on the interpolation operation using the signal sequence belongs to the category of the prior art, and will not be repeated here.

Step 13: Determine the symbol period of the coherent optical signal based on the analog signal.

The symbol period of the restored analog signal is the same as that of the coherent optical signal, so that the symbol period of the coherent optical signal can be determined.

Taking Fig. 1(a) as an example, the signal shown in Fig. 1(a) includes two symbol periods.

S202: Sample the coherent optical signal based on the symbol period, where the sampling period is half of the symbol period.

In this embodiment of the present invention, after the symbol period of the coherent optical signal is determined, the sampling period may be reset based on the symbol period. Specifically, the sampling period can be set to be half of the symbol period, that is, sampling twice in one symbol period. The receiving end may sample the received coherent optical signal based on the newly determined sampling period.

S203: Based on the sampling values of the current sampling symbol and the last sampling symbol, determine whether there is a phase jump between the current sampling symbol and the last sampling symbol, and if there is no phase jump, perform S204.

During the sampling process, the symbol decider in the receiving end can determine whether there is a phase jump between the current sampling symbol and the last sampling symbol.

判断是否存在相位跳变。其中(·)^*表示取共轭，Re[·]表示取复数的实部，Im(·)表示取复数的虚部。若计算的判决式结果大于零，则当前符号与上一符号不存在相位跳变，计算的判决式结果不大于零，则当前符号与上一符号存在相位跳变。Specifically, suppose that the current sampling symbol is symbol k, the last sampling symbol is symbol k-1, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling value of the previous sampling symbol, then the decision formula

Determine whether there is a phase jump. Where (·) ^* means taking the conjugate, Re[·] means taking the real part of the complex number, Im(·) means taking the imaginary part of the complex number. If the calculated decision formula result is greater than zero, there is no phase jump between the current symbol and the previous symbol, and the calculated decision formula result is not greater than zero, then there is a phase jump between the current symbol and the previous symbol.

S204: Based on the sampling value of the current sampling symbol, the sampling value of the previous sampling symbol, the sampling value at the intermediate sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, and the timing error of the previous sampling symbol, calculate Timing error of the currently sampled symbol.

In this embodiment of the present invention, if there is no phase jump between the current sampling symbol and the last sampling symbol, the sampling time of the current sampling symbol and the last sampling time may be based on the sampling value of the current sampling symbol, the sampling value of the last sampling symbol, and the The sampling value at the middle sampling time of the sampling time of the sampling symbol, and the timing error of the last sampling symbol, calculate the timing error of the current sampling symbol.

In an embodiment of the present invention, the following formula can be used to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol.

Specifically, the embodiment of the present invention introduces a step function ε(t) to detect timing errors. The characteristics of this function are: when the independent variable t is less than zero, the function outputs zero, when the independent variable t is equal to zero, the function outputs 1/2, and when the independent variable t is greater than zero, the function outputs 1. After introducing the step function, the timing error detection algorithm can be expressed as:

且

代入上式即可得到：If there is no phase jump between the current sampling symbol and the previous sampling symbol,

and

Substitute into the above formula to get:

It can be seen that, by applying the timing error detection method based on coherent optical communication provided by the embodiment of the present invention, a phase separation error detection method is adopted, that is, it is first determined whether there is a phase jump between adjacent symbols. When there is no phase jump between adjacent symbols, it can be based on the sampling value of the current sampling symbol, the sampling value of the previous sampling symbol, and the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol The accurate timing error is calculated, which solves the technical problem that the timing error cannot be accurately calculated if there is no phase jump when using the existing algorithm. In addition, the embodiment of the present invention also introduces the timing error of the last sampled symbol as a reference for the timing error of the current symbol, thereby further improving the accuracy of timing error detection in coherent optical communication and reducing the jitter of the recovered synchronous clock.

In an embodiment of the present invention, if there is a phase jump between the current sampling symbol and the previous sampling symbol, the following formula can be used to calculate the timing error of the current sampling symbol:

代入上式即可得到：Specifically, if there is a phase jump between the current sampling symbol and the previous sampling symbol, then

Substitute into the above formula to get:

It can be seen that if there is a phase jump between the current sampling symbol and the last sampling symbol, compared with the existing method, the embodiment of the present invention also introduces a control factor and a timing error of the last sampling symbol, so that the coherent light can be improved. The accuracy of timing error detection in communication and the jitter of the recovered synchronous clock are reduced.

In an embodiment of the present invention, after the timing error of the current sampling symbol is determined, the sampling period may be adjusted based on the timing error. Specifically, a loop filter can be used to remove high-frequency components first, and then a numerically controlled oscillator can be used to change the sampling frequency. This process belongs to the category of the prior art and will not be described in detail here.

For ease of understanding, the following further describes the timing error detection method based on coherent optical communication provided by the embodiment of the present invention with reference to FIG. 3 . FIG. 3 is another schematic flowchart of the timing error detection method based on coherent optical communication provided by the embodiment of the present invention. , including the following steps:

S301: The receiving end pre-samples the coherent optical signal according to the local clock.

S302: Restore the analog signal through interpolation operation, and determine the symbol period.

S303: Use half of the symbol period as the sampling period, and perform resampling.

S304: Determine whether there is a phase jump between the current sampling symbol and the previous sampling symbol, if not, execute S305; if so, execute S306.

S305: Conjugate the sampling value of the current sampling symbol and make a difference, multiply the sampling value at the middle sampling point, and then subtract the product of the control factor and the timing error of the previous sampling symbol.

Specifically, the timing error can be calculated using the following formula:

S306: Subtract the sampling value of the current sampling symbol from the sampling value of the previous sampling symbol, multiply the sampling value at the middle sampling point, and then subtract the product of the control factor and the timing error of the previous sampling symbol.

Specifically, the timing error can be calculated using the following formula:

S307: Eliminate high-frequency components through a loop filter.

S308: Change the sampling frequency through the numerical control oscillator, return to S303, and continue sampling based on the changed sampling frequency.

S309: Output the synchronous clock signal in real time.

The receiver can calculate the timing error in real time according to the sampling value, adjust the sampling clock based on the timing error, and output the clock signal that has been synchronized in real time.

It can be seen that the method for detecting timing error based on coherent optical communication provided by the embodiment of the present invention adopts the method of phase separation error detection, that is, it is first determined whether there is a phase jump between adjacent symbols. There are two cases: there is no phase jump between adjacent symbols and there is a phase jump. Different calculation methods are used to determine the timing error. Compared with the existing algorithm, the accuracy of the timing error can be improved, thereby improving the synchronization clock. accuracy. In addition, the embodiment of the present invention also introduces the timing error of the last sampled symbol as a reference for the timing error of the current symbol, thereby further improving the accuracy of timing error detection in coherent optical communication and reducing the jitter of the recovered synchronous clock.

The following is a further description in conjunction with the simulation experiment diagram.

Referring to Fig. 4, Fig. 5, Fig. 4 is the schematic diagram of the bit error jitter using the traditional Gardner algorithm; Fig. 5 is the schematic diagram of the bit error jitter adopting the timing error detection method based on coherent optical communication provided by the embodiment of the present invention; Fig. 4 and Figure 5 shows the bit error jitter at the receiving end after 1000 symbols are transmitted over 100km. The abscissa of Figure 4 and Figure 5 represents the symbol number, and the ordinate represents the bit error at the sampling time corresponding to each symbol. It can be seen that this The timing error detection method based on coherent optical communication provided by the embodiment of the invention can effectively improve the bit error jitter.

Referring to FIG. 6 , FIG. 6 is a schematic diagram of comparison of bit error rates under different signal-to-noise ratios using the traditional Gardner algorithm and the timing error detection method based on coherent optical communication provided by the embodiment of the present invention. The abscissa represents the signal-to-noise ratio, the ordinate represents the bit error rate, the solid square connecting line represents the simulation result of the traditional Gardner algorithm, and the hollow square connecting line represents the simulation of the timing error detection method based on coherent optical communication provided by the embodiment of the present invention result. FIG. 6 shows the bit error rate of a quadrature amplitude modulation (Quadrature Amplitude Modulation, 4QAM) signal after 100km transmission. It can be seen that under different signal-to-noise ratios, the timing error detection method based on coherent optical communication provided by the embodiment of the invention has a lower bit error rate than the traditional Gardner algorithm, which is more obvious in the case of low signal-to-noise ratio.

Based on the same inventive concept, according to the above embodiment of the method for detecting timing error based on coherent optical communication, an embodiment of the present invention also provides a device for detecting timing error based on coherent optical communication. Referring to FIG. 7 , FIG. 7 is an embodiment of the present invention. Provided is a schematic structural diagram of a timing error detection device based on coherent optical communication, which may include the following modules:

The determining module 701 is configured to determine the symbol period of the received coherent optical signal.

A sampling module 702, configured to sample the coherent optical signal based on the symbol period, where the sampling period is half of the symbol period.

The judgment module 703 is configured to judge whether there is a phase jump between the current sampling symbol and the last sampling symbol based on the sampling values of the current sampling symbol and the last sampling symbol.

The calculation module 704 is used for if the result of the judgment module is no, based on the sampling value of the current sampling symbol, the sampling value of the last sampling symbol, the sampling time of the current sampling symbol and the sampling time of the last sampling symbol. The sampling value at the moment, and the timing error of the last sampling symbol, calculate the timing error of the current sampling symbol.

It can be seen that, by applying the timing error detection device based on coherent optical communication provided by the embodiment of the present invention, a phase-separated error detection method is adopted, that is, it is first determined whether there is a phase jump between adjacent symbols. When there is no phase jump between adjacent symbols, it can be based on the sampling value of the current sampling symbol, the sampling value of the previous sampling symbol, and the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol The accurate timing error is calculated, which solves the technical problem that the timing error cannot be accurately calculated if there is no phase jump when using the existing algorithm. In addition, the embodiment of the present invention also introduces the timing error of the last sampled symbol as a reference for the timing error of the current symbol, thereby further improving the accuracy of timing error detection in coherent optical communication and reducing the jitter of the recovered synchronous clock.

In an embodiment of the present invention, the determining module 701 may be specifically used for:

Pre-sampling the received coherent optical signal based on the sampling clock of the preset sampling period to obtain a sampling signal sequence;

performing an interpolation operation on the sampled signal sequence to obtain an interpolated analog signal;

A symbol period of the coherent optical signal is determined based on the analog signal.

In an embodiment of the present invention, the computing module 704 may be specifically used for:

Use the following formula to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol.

In an embodiment of the present invention, the computing module 704 can also be specifically used for:

If the result of the judgment module is yes, the following formula is used to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol.

Based on the same inventive concept, according to the above-mentioned embodiment of the method for detecting timing error based on coherent optical communication, the embodiment of the present invention further provides an electronic device, as shown in FIG. 8 , including a processor 801 , a communication interface 802 , a memory 803 and A communication bus 804, wherein the processor 801, the communication interface 802, and the memory 803 complete the communication with each other through the communication bus 804,

a memory 803 for storing computer programs;

When the processor 801 is used to execute the program stored in the memory 803, the following steps are implemented:

determining the symbol period of the received coherent optical signal;

sampling the coherent optical signal based on the symbol period, where the sampling period is half of the symbol period;

Based on the sampling values of the current sampling symbol and the last sampling symbol, determine whether there is a phase jump between the current sampling symbol and the last sampling symbol;

If there is no phase jump, based on the sampling value of the current sampling symbol, the sampling value of the last sampling symbol, the sampling value of the sampling instant between the sampling instant of the current sampling symbol and the sampling instant of the last sampling symbol, and the sampling instant of the last sampling symbol Timing error of the symbol, calculates the timing error of the currently sampled symbol.

The communication bus mentioned in the above electronic device may be a peripheral component interconnect standard (Peripheral Component Interconnect, PCI) bus or an Extended Industry Standard Architecture (Extended Industry Standard Architecture, EISA) bus or the like. The communication bus can be divided into an address bus, a data bus, a control bus, and the like. For convenience of representation, only one thick line is used in FIG. 8, but it does not mean that there is only one bus or one type of bus.

The communication interface is used for communication between the above electronic device and other devices.

The memory may include random access memory (Random Access Memory, RAM), and may also include non-volatile memory (Non-Volatile Memory, NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

The above-mentioned processor may be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU), a network processor (Network Processor, NP), etc.; may also be a digital signal processor (Digital Signal Processing, DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), Field-Programmable Gate Array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

By applying the electronic device provided by the embodiment of the present invention, a phase-separation error detection method is adopted, that is, it is firstly judged whether there is a phase jump between adjacent symbols. When there is no phase jump between adjacent symbols, it can be based on the sampling value of the current sampling symbol, the sampling value of the previous sampling symbol, and the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol The accurate timing error is calculated, which solves the technical problem that the timing error cannot be accurately calculated if there is no phase jump when using the existing algorithm. In addition, the embodiment of the present invention also introduces the timing error of the last sampled symbol as a reference for the timing error of the current symbol, thereby further improving the accuracy of timing error detection in coherent optical communication and reducing the jitter of the recovered synchronous clock.

Based on the same inventive concept, according to the above-mentioned embodiment of the method for detecting timing error based on coherent optical communication, in another embodiment provided by the present invention, a computer-readable storage medium is also provided, and the computer-readable storage medium stores There is a computer program, and when the computer program is executed by the processor, any of the above-mentioned steps of the coherent optical communication-based timing error detection method shown in FIGS. 2-3 are implemented.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

Each embodiment in this specification is described in a related manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments of the timing error detection apparatus based on coherent optical communication, the electronic device embodiments, and the computer storage medium embodiments, since they are basically similar to the embodiments of the timing error detection method based on coherent optical communication, the description is relatively simple. , and for relevant details, please refer to the partial description of the embodiment of the method for detecting timing error based on coherent optical communication.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims (8)

1. A timing error detection method based on coherent optical communication, wherein the method comprises: determining the symbol period of the received coherent optical signal; sampling the coherent optical signal based on the symbol period, where the sampling period is half of the symbol period; Based on the sampling values of the current sampling symbol and the last sampling symbol, determine whether there is a phase jump between the current sampling symbol and the last sampling symbol; If there is no phase jump, based on the sampling value of the current sampling symbol, the sampling value of the last sampling symbol, the sampling value of the sampling instant between the sampling instant of the current sampling symbol and the sampling instant of the last sampling symbol, and the sampling instant of the last sampling symbol Timing error of the symbol, calculate the timing error of the currently sampled symbol; Described based on the sampling value of the current sampling symbol, the sampling value of the previous sampling symbol, the sampling value of the intermediate sampling moment between the sampling moment of the current sampling symbol and the sampling moment of the previous sampling symbol, and the timing error of the last sampling symbol, calculate The steps of the timing error of the currently sampled symbol include: Use the following formula to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol. 2. The method according to claim 1, wherein the step of determining the symbol period of the received coherent optical signal comprises: Pre-sampling the received coherent optical signal based on the sampling clock of the preset sampling period to obtain a sampling signal sequence; performing an interpolation operation on the sampled signal sequence to obtain an interpolated analog signal; A symbol period of the coherent optical signal is determined based on the analog signal. 3. method according to claim 1, is characterized in that, if there is phase jump between current sampling symbol and last sampling symbol, then adopt following formula to calculate the timing error of current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor, and τ _{old_err} represents the timing error of the last sampled symbol. 4. The method according to claim 1, wherein the method further comprises: The sampling period is adjusted based on the timing error of the current sampled symbol. 5. A timing error detection device based on coherent optical communication, wherein the device comprises: a determining module for determining the symbol period of the received coherent optical signal; a sampling module, configured to sample the coherent optical signal based on the symbol period, where the sampling period is half of the symbol period; The judgment module is used to judge whether there is a phase jump between the current sampling symbol and the last sampling symbol based on the sampling values of the current sampling symbol and the last sampling symbol; The calculation module is used for if the result of the judgment module is no, based on the sampling value of the current sampling symbol, the sampling value of the previous sampling symbol, the sampling moment of the current sampling symbol and the sampling moment of the last sampling symbol The middle sampling moment The sampling value of , and the timing error of the last sampling symbol, calculate the timing error of the current sampling symbol; The computing module is specifically used for: Use the following formula to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol. 6. The device according to claim 5, wherein the determining module is specifically configured to: Pre-sampling the received coherent optical signal based on the sampling clock of the preset sampling period to obtain a sampling signal sequence; performing an interpolation operation on the sampled signal sequence to obtain an interpolated analog signal; A symbol period of the coherent optical signal is determined based on the analog signal. 7. The device according to claim 5, wherein the computing module is further used for: If the result of the judgment module is yes, the following formula is used to calculate the timing error of the current sampling symbol:

Among them, τ _err represents the timing error of the current sampling symbol, Re[ ] represents the real part of the complex number, k represents the current sampling symbol, y _k represents the sampling value of the current sampling symbol, and y _k-1 represents the sampling of the previous sampling symbol value, y _k-1/2 represents the sampling value at the middle sampling time between the sampling time of the current sampling symbol and the sampling time of the previous sampling symbol, (·) ^* means taking the conjugate, E{·} means taking the average value, λ represents the control factor and τ _{old_err} represents the timing error of the last sampled symbol. 8. An electronic device, characterized in that it comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface, and the memory complete mutual communication through the communication bus; memory for storing computer programs; The processor is configured to implement the method steps described in any one of claims 1-4 when executing the program stored in the memory.

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