CN114928409B

CN114928409B - Method, device and system for processing signal

Info

Publication number: CN114928409B
Application number: CN202210838818.5A
Authority: CN
Inventors: 程宁
Original assignee: Innolight Technology Suzhou Ltd
Current assignee: Innolight Technology Suzhou Ltd
Priority date: 2022-07-18
Filing date: 2022-07-18
Publication date: 2022-10-18
Anticipated expiration: 2042-07-18
Also published as: WO2024016870A1; CN114928409A

Abstract

The present disclosure relates to a method, apparatus and system for signal processing. The method comprises the following steps: carrying out direct-current balance coding on a signal sent by a signal source to obtain a coded signal; modulating the coded signal to obtain a modulated signal; and sending the modulation signal to a receiving end to instruct the receiving end to carry out high-pass filtering processing on the received modulation signal to obtain a modulation signal with the frequency higher than a preset value, and carrying out demodulation and decoding processing on the modulation signal with the frequency higher than the preset value to obtain a processed signal. According to the embodiment of the disclosure, the modulation signal with the frequency higher than the preset value is obtained by performing high-pass filtering processing on the received modulation signal at the receiving end, so that the influence of MPI noise on the transmission performance can be effectively reduced, and the tolerance of MPI noise is improved.

Description

Method, device and system for processing signal

Technical Field

The present disclosure relates to the field of communications technologies, and in particular, to a method, an apparatus, and a system for signal processing.

Background

With the development of the communication technology field, high-order Modulation techniques for improving the bit rate, such as Pulse Amplitude Modulation (PAM), duobinary Modulation, and the like, have appeared. However, high-order modulated signals are more susceptible to Multi-path Interference (MPI) effects during transmission. In practical transmission systems, reflections are introduced at the light emitting end, the light receiving end and the fiber connector. The modulated signal passes through a plurality of reflecting end faces in the transmission process to bring a multipath interference effect, and MPI noise generated by the multipath interference effect brings adverse effects relative to the detection of the transmission signal. MPI noise causes the bit error rate to rise significantly, thereby incurring a large optical power penalty for the optical transmission system.

In the related art, the return loss of the optical fiber connector, the optical receiving end and the optical transmitting end is strictly limited, for example, the maximum return loss of the optical fiber connector is reduced to-35 dB from the original-26 dB in international standards such as IEEE802.3 and 100G Lambda MSA. However, in an already deployed actual optical fiber link, because there are many optical fiber connectors and the return loss of the optical fiber connectors is difficult to be controlled below-35 dB, MPI noise in an actual system may bring a large optical power cost to a modulation signal, even in some actual links, even if a complex Forward Error Correction (FEC) is adopted, error-free transmission still cannot be achieved, and how to reduce the influence of multi-channel interference on optical transmission is a problem which is always puzzled in the industry.

Disclosure of Invention

The present disclosure provides a method, an apparatus, and a system for signal processing to at least solve the problem of influence of multipath interference noise on optical transmission in the related art. The technical scheme of the disclosure is as follows:

according to a first aspect of the embodiments of the present disclosure, a method for signal processing is provided, which is applied to a transmitting end, and the method includes:

carrying out direct current balance coding on a signal sent by a signal source to obtain a coded signal;

modulating the coded signal to obtain a modulated signal;

and sending the modulation signal to a receiving end to instruct the receiving end to carry out high-pass filtering processing on the received modulation signal to obtain a modulation signal with the frequency higher than a preset value, and carrying out demodulation and decoding processing on the modulation signal with the frequency higher than the preset value to obtain a processed signal.

In a possible implementation manner, the modulation processing includes pulse amplitude modulation processing, and performing dc balanced encoding on a signal sent by a signal source to obtain an encoded signal includes:

determining the number of demultiplexing signals sent by a signal source according to the modulation order of the pulse amplitude modulation;

demultiplexing the signal into the number of sub-signals;

respectively carrying out direct current balance coding on the sub-signals of the number to obtain the sub-coded signals of the number;

the modulating the coded signal to obtain a modulated signal includes:

and carrying out pulse amplitude modulation according to the sub-coding signals of the number to obtain a modulation signal.

In a possible implementation manner, the performing pulse amplitude modulation according to the number of sub-coded signals to obtain a modulated signal includes:

converting the sub-coding signals of the number into Gray code signals according to a Gray code conversion rule;

and carrying out pulse amplitude modulation according to the Gray code signal to obtain a modulation signal.

In a possible implementation manner, the modulating signal includes a duobinary modulating signal, and the modulating the coded signal to obtain the modulating signal includes:

and carrying out duobinary modulation processing on the coded signal to obtain a duobinary modulation signal.

obtaining a coded signal with a delay of preset bits from the coded signal;

performing exclusive-or processing on the coded signal and the coded signal delayed by the preset bit to obtain a pre-coded signal;

and carrying out precoding processing and duo-binary modulation processing on the precoded signals to obtain duo-binary modulation signals.

In one possible implementation, the dc-balanced encoding includes at least one of:

8B10B coding, MB810 coding, 5S/6S coding, 27S/32S coding.

According to a second aspect of the embodiments of the present disclosure, there is provided a signal processing apparatus including:

the encoding module is used for carrying out direct current balance encoding on the signals sent by the signal source to obtain encoded signals;

the modulation module is used for modulating the coded signal to obtain a modulated signal;

and the processing module is used for sending the modulation signal to a receiving end so as to instruct the receiving end to carry out high-pass filtering processing on the received modulation signal to obtain a modulation signal with the frequency higher than a preset value, and carrying out demodulation and decoding processing on the modulation signal with the frequency higher than the preset value to obtain a processed signal.

In one possible implementation, the modulation process includes a pulse amplitude modulation process, and the encoding module includes:

the determining submodule is used for determining the number of demultiplexing signals sent by the signal source according to the modulation order of the pulse amplitude modulation;

the demultiplexing submodule is used for demultiplexing the signals into the subsignals with the number;

the encoding submodule is used for respectively carrying out direct-current balanced encoding on the sub-signals of the number to obtain the sub-encoded signals of the number;

the modulation module comprises:

and the first modulation submodule is used for carrying out pulse amplitude modulation according to the sub-coding signals with the number to obtain a modulation signal.

In one possible implementation, the first modulation submodule includes:

the conversion unit is used for converting the sub-coding signals of the number into Gray code signals according to a Gray code conversion rule;

and the modulation unit is used for carrying out pulse amplitude modulation according to the Gray code signal to obtain a modulation signal.

In one possible implementation, the modulation signal includes a duobinary modulation signal, and the modulation module includes:

and the second modulation submodule is used for carrying out duo-binary modulation processing on the coded signal to obtain a duo-binary modulation signal.

the acquisition submodule is used for acquiring a coded signal with preset bit delay from the coded signal;

the processing submodule is used for carrying out XOR processing on the coded signal and the coded signal of the delay preset bit to obtain a pre-coded signal;

and the third modulation submodule is used for carrying out precoding processing and duobinary modulation processing on the precoded signals to obtain duobinary modulation signals.

8B10B coding, MB810 coding, 5S/6S coding, 27S/32S coding.

According to a third aspect of the embodiments of the present disclosure, a system for signal processing is provided, including a transmitting end and a receiving end, where the transmitting end includes:

the encoder is used for carrying out direct current balance encoding on the signal sent by the signal source to obtain an encoded signal;

the modulator is used for modulating the coded signal to obtain a modulated signal;

the modulation laser is used for sending the modulation signal to a receiving end;

the receiving end includes:

a photoelectric receiver for receiving the modulation signal;

the high-pass filter is used for carrying out high-pass filtering processing on the received modulation signal to obtain a modulation signal of which the frequency is higher than a preset value;

and the decoder is used for demodulating and decoding the modulated signal with the frequency higher than the preset value to obtain a processed signal.

According to a third aspect of an embodiment of the present disclosure, there is provided an electronic apparatus including:

a processor;

a memory for storing the processor-executable instructions;

wherein the processor is configured to execute the instructions to implement the method of signal processing according to any one of the embodiments of the present disclosure.

According to a fourth aspect of embodiments of the present disclosure, there is provided a computer-readable storage medium, wherein instructions, when executed by a processor of an electronic device, enable the electronic device to perform the method of signal processing according to any one of the embodiments of the present disclosure.

According to a fifth aspect of embodiments of the present disclosure, there is provided a computer program product including instructions that, when executed by a processor of an electronic device, enable the electronic device to perform the method of signal processing according to any one of the embodiments of the present disclosure.

The technical scheme provided by the embodiment of the disclosure at least brings the following beneficial effects: according to the embodiment of the disclosure, the signal sent by the signal source is subjected to direct current balance coding to obtain a coded signal. The number of high levels and the number of low levels in the signal can be kept equal through direct current balance coding, and after the coded signal is modulated, the energy of the modulated signal in a low frequency band near zero frequency can be very low. Therefore, the embodiment of the disclosure performs high-pass filtering processing on the received modulation signal at the receiving end to obtain the modulation signal with the frequency higher than the preset value, so that the influence of the MPI noise on the transmission performance can be effectively reduced, and the tolerance to the MPI noise is improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure and are not to be construed as limiting the disclosure.

FIG. 1 is a diagram illustrating an application environment for a method of signal processing according to an exemplary embodiment;

FIG. 2 is a flow diagram illustrating a method of signal processing in accordance with an exemplary embodiment;

FIG. 3 is a graphical illustration of an MPI noise spectrum generated by a PAM4 signal transmitted over an optical fiber, according to an exemplary embodiment;

FIG. 4 is a schematic diagram illustrating an MPI noise spectrum generated by transmission of a PAM4 signal over an optical fiber according to another exemplary embodiment;

FIG. 5 is a schematic diagram illustrating an MPI noise spectrum generated by transmission of a PAM4 signal over an optical fiber according to another exemplary embodiment;

FIG. 6 is a system block diagram illustrating a method of signal processing according to another exemplary embodiment;

FIG. 7 is a system block diagram illustrating a method of signal processing in accordance with another exemplary embodiment;

FIG. 8 is a system block diagram illustrating a method of signal processing in accordance with another exemplary embodiment;

FIG. 9 is a system block diagram illustrating a method of signal processing in accordance with another exemplary embodiment;

FIG. 10 is a system block diagram illustrating a method of signal processing in accordance with another exemplary embodiment;

FIG. 11 is a system block diagram illustrating a method of signal processing in accordance with another exemplary embodiment;

fig. 12 is a power spectrum diagram illustrating an 8B10B encoded PAM4 signal, according to an exemplary embodiment;

FIG. 13 is a power spectrum diagram of a duobinary signal shown in accordance with another exemplary embodiment;

FIG. 14 is a schematic diagram illustrating bit error rate curves for a 25Gbaud PAM4 optical signal transmission in accordance with an exemplary embodiment;

FIG. 15 is an optical power cost diagram of a 25Gbaud PAM4 optical transmission system shown at different MPIs, in accordance with another example embodiment;

FIG. 16 is a schematic block diagram of an apparatus for signal processing shown in accordance with an exemplary embodiment;

FIG. 17 is a schematic block diagram illustrating an electronic device in accordance with an exemplary embodiment.

Detailed Description

In order to make the technical solutions of the present disclosure better understood by those of ordinary skill in the art, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings.

It should be noted that the terms "first," "second," and the like in the description and claims of the present disclosure and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the disclosure described herein are capable of operation in other sequences than those illustrated or described herein. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

It should be further noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for presentation, analyzed data, etc.) referred to in the present disclosure are information and data authorized by the user or sufficiently authorized by each party.

In order to facilitate those skilled in the art to understand the technical solutions provided in the embodiments of the present disclosure, the following description will first describe a technical environment for implementing the technical solutions.

Aiming at the influence of MPI noise on a high-order modulation signal, a filtering method is adopted in the related art for noise reduction. However, when the MPI noise is large or the high-order modulation signal has large chirp, the MPI noise cannot be effectively filtered. For a high-order modulation signal generated by a Direct Modulated Laser (DML), the signal itself has large chirp, which causes the MPI noise to be spread to a high frequency, and therefore, the filtering method is basically ineffective for reducing the MPI noise. In addition, at a receiving end, direct current drift can be generated after the high-order modulation signal is filtered, and adverse effect is generated on the recovery of the modulation signal.

Based on the practical technical requirements similar to those described above, the embodiments of the present disclosure propose a method, an apparatus and a system for signal processing.

The method for processing signals provided by the present disclosure can be applied to the application environment shown in fig. 1.

Wherein the transmitting end 110 communicates with the receiving end 120 through an optical fiber. The transmitting end 110 may be, but is not limited to, various encoders and Modulated lasers, and the Modulated lasers include, but are not limited to, EML (electro-absorption-Modulated Laser), DML (direct Modulated Laser), MZM (Mach-Zehnder Modulated Laser), and the liketor, electro-optic modulator). The receiving end 120 may be, but is not limited to, various photodiodes, transimpedance amplifiers, high-pass filters, decoders, and the like. And a signal S sent by the signal source is subjected to direct current balance coding and modulation processing, and an optical signal is sent out by modulating a laser. In the process of optical fiber transmission of optical signals, MPI noise is generated due to reflection in a transmitting end, a receiving end and an optical fiber link, the optical signals with the MPI noise are received by a receiving end photodiode, wherein the photodiode is used for converting the optical signals into electric signals, the electric signals are amplified by a transimpedance amplifier (TIA), the low-frequency MPI noise can be filtered by a high-pass filter, the influence of the MPI noise on signal recovery is reduced, and finally, processed signals S are obtained ^’ (recovery signal).

Fig. 2 is a flowchart illustrating a method of signal processing, which is used in a transmitting end, as shown in fig. 2, according to an exemplary embodiment, and includes the following steps.

In step S201, a signal sent by a signal source is subjected to dc balanced encoding to obtain an encoded signal.

In the embodiment of the present disclosure, the signal sent by the signal source is used as data to be transmitted, and the format thereof includes, but is not limited to, binary, octal, and hexadecimal. And carrying out direct current balance coding on the signal, wherein the coding mode of the direct current balance coding comprises but is not limited to 8B10B coding, MB810 coding, 5S/6S coding and 27S/32S coding.

In step S203, the coded signal is modulated to obtain a modulated signal.

In the embodiment of the present disclosure, the encoded signal is modulated, wherein the modulation manner includes, but is not limited to, pulse amplitude modulation PAM-N (N represents a modulation order), duo-binary modulation, non-Return-to-Zero (NRZ), partial response modulation, and a combination of PAM-N and partial response modulation. PAM signal symbols may have multiple levels, e.g., four for PAM4, eight for PAM8, and sixteen for PAM 16. The duobinary encoding can realize the transmission of the same bit rate under the same bandwidth relative to the PAM4 signal, wherein the transmission level of the duobinary encoding is three.

In step S205, the modulation signal is sent to a receiving end to instruct the receiving end to perform high-pass filtering on the received modulation signal to obtain a modulation signal with a frequency higher than a preset value, and the modulation signal with the frequency higher than the preset value is demodulated and decoded to obtain a processed signal.

In the embodiment of the disclosure, the modulation signal may be sent to a receiving end in a manner of optical fiber communication. The modulated signal is susceptible to MPI noise during transmission. The received modulation signal comprises a modulation signal sent by a sending end and an MPI noise signal. At a receiving end, a received modulation signal can be converted into an electric signal through a photodiode, the electric signal is amplified through a transimpedance amplifier, the amplified electric signal is filtered through a high-pass filter, low-frequency MPI noise is filtered, and the filtered signal is processed in a demodulation mode and a decoding mode corresponding to a coding end to obtain a processed signal. For example, the encoding end uses 8B10B encoding, and the decoding end uses 8B10B decoding; the PAM4 modulation is used at the encoding end, and the PAM4 demodulation is used at the decoding end. In the embodiment of the present disclosure, the high pass filter may include any type of high pass filter, such as a first order RC high pass filter or a fourth order bessel high pass filter. The present disclosure is not so limited.

According to the embodiment of the disclosure, the signal sent by the signal source is subjected to direct current balance coding to obtain a coded signal. The number of high levels and the number of low levels in the signal can be kept equal through the direct current balance coding, and after the coded signal is used for optical modulation, the energy of the modulation signal in a low frequency band near zero frequency can be very low (the energy of a power spectrum below the low frequency band (< 100 MHz) is very low). Referring to fig. 3 to 5, in the transmission process of the optical signal generated by EML modulated by the 25Gbaud PAM4 signal at the transmitting end in the optical fiber, MPI noise is generated due to link reflection, fig. 3 corresponds to an MPI noise power spectrum under-36 dB of effective MPI, fig. 4 corresponds to an MPI noise power spectrum under-33 dB of effective MPI, and fig. 5 corresponds to an MPI noise power spectrum under-30 dB of effective MPI. It can be seen that the MIP noise power spectrum is distributed in 0-25GHz, but the main energy is distributed in the low frequency band. Therefore, the embodiment of the disclosure performs high-pass filtering processing on the received modulation signal at the receiving end to obtain the modulation signal with the frequency higher than the preset value, so that most of the MPI noise can be filtered. Therefore, in the embodiment of the present disclosure, the transmitting end uses the dc balance coding, and the receiving end uses the high-pass filtering technology, so that the influence of the MPI noise on the transmission performance can be effectively reduced, and the tolerance to the MPI noise is improved. In addition, because the direct current balance code has no zero frequency component, direct current drift can not be generated after high-pass filtering, and therefore the high-pass filtering can not influence the recovery of the modulation signal.

In a possible implementation manner, the modulation processing includes pulse amplitude modulation processing, and step S201 is to perform dc balanced encoding on a signal sent by a signal source to obtain an encoded signal, including:

demultiplexing the signal into the number of sub-signals;

step S203, performing modulation processing on the encoded signal to obtain a modulated signal, including:

In embodiments of the present disclosure, the pulse amplitude modulation may comprise PAM-N, where N represents a modulation order, such as PAM4, PAM8, PAM16, or higher order PAM codes, for example. According to the modulation order of the pulse amplitude modulation, for example, N, in one example, the number of the demultiplexed signals from the signal source is determined to be log2N. Demultiplexing the signal into the number of sub-signals, for example, splitting the signal into two signals when N is 4; when N is 8, splitting the signal into three paths of signals; when N is 16, the signal is split into four paths of signals. The specific demultiplexing method may include sequentially allocating code streams corresponding to signals sent by the signal source to the number of sub-signals corresponding to the modulation order to obtain the corresponding number of sub-coded signals. In one example, referring to fig. 6, by taking PAM4 as an example, since the modulation order of PAM4 is 4, the number of demultiplexing is 2. The signal sent by the signal source corresponds to a binary code stream of 0101111000100110, the code stream is sequentially allocated to two sub-signal code streams, for example, a first digit 0 is allocated to the first sub-signal 601, a second digit 1 is allocated to the second sub-signal 602, a third digit 0 is allocated to the first sub-signal 601, and a fourth digit 1 is allocated to the second sub-signal 602, and so on, the odd-numbered digits of the binary code stream form the first sub-signal 601, specifically 00110101, and the even-numbered digits of the binary code stream (the underlined digits in the binary code stream) form the second sub-signal 602, specifically 11100010.

In one example, referring to fig. 7, for PAM8 as an example, since the modulation order of PAM8 is 8, the number of demultiplexing is 3. The signal S sent by the signal source is 001011001111100011011101, and the code stream is sequentially distributed to the first sub-signal 701, the second sub-signal 702 and the third sub-signal 703. Specifically, a first digit 0 of the signal S is assigned to the first sub-signal 701 as a first digit of the first sub-signal 701; assigning the second digit 1 of the signal S into the second subsignal 702 as the first digit of the second subsignal 702; assigning the third digit 1 of the signal S into the third subsignal 703 as the first digit of the third subsignal 703; assigning the fourth digit 0 of the signal S into the first subsignal 701 as the second digit of the first subsignal 701; assigning a fifth digit 1 of the signal S into the second subsignal 702 as a second digit of the second subsignal 702; the sixth number 1 of the signal S is distributed to the third sub-signal 703 as the third number of the third sub-signal 703, and so on, to obtain the first sub-signal 701, specifically 00011001; a second sub-signal 702, in particular 01010110; the third sub-signal 703 is specifically 11110111. Similarly, if PAM16 is used, the signal sent by the signal source may be demultiplexed into four paths, and the specific demultiplexing manner is the same as that described above, and is not described herein again.

And respectively carrying out direct current balance coding on the sub-signals of the number to obtain the sub-coded signals of the number. The dc-balanced encoding is exemplified by 8B10B, and in an example, as described with reference to fig. 6, the first sub-signal 601 is subjected to 8B10B encoding to become a first sub-encoded signal 603, specifically: 0011011010. the second sub-signal 602 is encoded by 8B10B to become a second sub-encoded signal 604, specifically: 1110000101. and carrying out pulse amplitude modulation according to the sub-coding signals with the number to obtain a modulation signal. In one example, referring to fig. 6, the first sub-code signal 603 may be the Most Significant Bit (MSB) of PAM4, and the second sub-code signal 604 may be the Least Significant Bit (LSB) of PAM 4. In another example, the first sub-coded signal 603 may be used as the least significant bit of PAM4, and the second sub-coded signal 604 may be used as the most significant bit of PAM 4. Referring to fig. 6, taking the first sub-coded signal 603 as the most significant bit of PAM4 as an example, according to the coding rule corresponding to PAM 4: binary 00 is encoded as symbol 0 of PAM4, binary 01 is encoded as symbol 1 of PAM4, binary 10 is encoded as symbol 2 of PAM4, and binary 11 is encoded as symbol 3 of PAM 4. The first digit 0 of the first sub-coded signal 603 is taken as the most significant bit of the first symbol of PAM4, the first digit 1 of the second sub-coded signal 604 is taken as the least significant bit of the first symbol of PAM4, then the first symbol of PAM4 is 01, and according to the coding rule of PAM4, 01 corresponds to symbol 1, then the first symbol of PAM4 is 1. The second digit 0 of the first sub-coded signal 603 is used as the most significant bit of the second symbol of PAM4, the second digit 1 of the second sub-coded signal 604 is used as the least significant bit of the second symbol of PAM4, and according to the coding rule of PAM4, 01 corresponds to symbol 1, and then the second symbol of PAM4 is 1. By analogy, a PAM4 modulated signal 605, specifically 1132022121, is obtained. Next, the dc balance property of the PAM4 modulated signal 605 will be described.

Each symbol of PAM4 is represented by a different level, for example, symbol 0 of PAM4 is represented by-3V, symbol 1 of PAM4 is represented by-1V, symbol 2 is represented by 1V, and symbol 3 is represented by 3V. For the PAM4 modulated signal 605, specifically 1132022121, the number of high levels (e.g.: 1V, 3V) and low levels (e.g.: 1V, -3V) are equal, and therefore, the DC balance is achieved.

And respectively carrying out direct-current balance coding on the sub-signals of the number to obtain the sub-coded signals of the number. The dc balanced encoding is exemplified by 8B10B, and in an example, as described with reference to fig. 7, the first sub-signal 701 is subjected to 8B10B encoding to obtain a first sub-encoded signal 704, specifically 1100110010; the second sub-signal 702 is 8B10B encoded to obtain a second sub-encoded signal 705, specifically 0101011100; the third sub-signal 703 is encoded by 8B10B to obtain a third sub-encoded signal 706, specifically 0101110001. The first digit 1 of the first sub-coded signal 704, the first digit 0 of the second sub-coded signal 702, and the first digit 0 of the third sub-coded signal 703 are respectively selected to form 100, according to the coding rule of PAM8, 100 corresponds to symbol 4, and then 4 is used as the first symbol of PAM8, and so on, to obtain a modulation signal 707 of PAM8, specifically 4703572241.

In the above, how to encode the binary code stream into a dc-balanced PAM code stream is discussed, at the receiving end, inverse transformation is performed according to the encoding process, and the binary code stream is recovered. Taking PAM4 encoded by 8B10B as an example, after receiving the PAM4 modulated signal after the filtering process, the receiving end obtains the first sub-encoded signal 603 and the second sub-encoded signal 604 by PAM4 decoding. 8B10B decoding is performed on the first sub-coded signal 603 to obtain a first sub-signal 601, 8B10B decoding is performed on the second sub-coded signal 604 to obtain a second sub-signal 602, and the first sub-signal 601 and the second sub-signal 602 are multiplexed together in a multiplexing manner corresponding to the time phase of coding to obtain a processed signal S ^’ 。

In the embodiment of the present disclosure, after a common binary code stream is encoded by 8B10B, MB810, or other dc balance encoding, dc balance can be achieved. However, if the final line code is PAM code (such as PAM4, PAM8, PAM16 or higher order PAM codes), the dc balanced binary code stream may partially or even completely lose the dc balanced characteristic due to the PAM coding rule. Taking the original code stream 0101111000100110 in fig. 6 as an example, if the original code stream is not subjected to the demultiplexing step, direct current balance coding (8B 10B) is directly performed to obtain 01011001101010011, and then PAM4 coding is performed to obtain 1123031103, the number of high levels and low levels in the obtained PAM4 signal is not equal, so that the direct current balanced binary code stream partially or even completely loses the characteristic of direct current balance when subjected to PAM coding.

Therefore, for the pulse amplitude modulation processing, the number of the demultiplexed sub-signals is determined according to the modulation order of the pulse amplitude modulation, then the number of the demultiplexed sub-signals is respectively subjected to the direct current balance coding to obtain the number of the sub-coded signals, the pulse amplitude modulation is performed according to the number of the sub-coded signals to obtain the modulated signals, and the finally obtained modulated signals can be ensured to have the property of direct current balance. And a subsequent receiving end adopts a high-pass filtering technology, so that the influence of MPI noise on the transmission performance can be effectively reduced, and the tolerance of the MPI noise is improved.

Performing pulse amplitude modulation according to the number of the sub-coded signals to obtain a modulated signal, including:

In the embodiment of the present disclosure, the gray code is also referred to as a cyclic binary code or a reflective binary code. Taking PAM4 and 8B10B codes as examples, a code stream corresponding to a signal S sent by a signal source, specifically 010111100100100110, may demultiplex the code stream into a first sub-signal 601, specifically 00110101, and a second sub-signal 602, specifically 11100010, according to the method disclosed in the foregoing embodiments. The first sub-signal 601 and the second sub-signal 602 are respectively 8B10B encoded to obtain a first sub-encoded signal 603, specifically 0011011010, and a second sub-encoded signal 604, specifically 1110000101. According to the gray code conversion rule, the bits of the second sub-coded signal 604 are inverted according to the bit of the first sub-coded signal 603 being 0 or 1,that is, if the bit of the first sub-encoded signal 603 is 1, the bit of the second sub-encoded signal 604 is inverted; if the bit of the first sub-encoded signal 603 is 0, the bit of the second sub-encoded signal 604 is not inverted. This process may be implemented by xoring the first sub-encoded signal 603 and the second sub-encoded signal 604, as shown with reference to figure 8,

i.e. representing exclusive or logic (i.e. 0)

0 = 0, 0

1 = 1, 1

0 = 1, 1

1 = 0). Gray code signal 801 is obtained by gray code conversion of the first sub-coded signal and the second sub-coded signal. Further, PAM4 encoding is performed on the gray code signal to obtain a modulation signal 802. Specifically, if the first sub-code (MSB) is 0, the second sub-code (LSB) is 0, and PAM4 generated through gray code conversion is encoded as 0; if the first sub-code is 0 and the second sub-code is 1, the PAM4 code generated by Gray code conversion is 1; if the first sub-code is 1, the second sub-code is 1, PAM4 generated by gray code conversion is 2, and if the first sub-code is 1, the second sub-code is 0, PAM4 generated by gray code conversion is 3.

Referring to fig. 9, after recovering the PAM4 code stream, the receiving end decodes the PAM4 code stream to obtain two binary code streams, i.e., an MSB code stream 901 and an LSB code stream 902, and then xors the LSB code stream 902 and the MSB code stream 901 to form a new LSB code stream 903. After 8B10B decoding is performed on the MSB code stream 901 and the new LSB code stream 903, they are multiplexed into a binary code stream, which is the original binary code stream S.

In the embodiment of the present disclosure, the sub-coded signals are converted into gray code signals according to a gray code conversion rule. Taking PAM4 encoding as an example, a common PAM4 encoding rule is: binary 00 is coded as symbol 0 of PAM, binary 01 is coded as symbol 1 of PAM, binary 10 is coded as symbol 2 of PAM, and binary 11 is coded as symbol 3 of PAM; for PAM4 using gray code, the coding rule is: binary 00 is encoded as symbol 0 of PAM, binary 01 is encoded as symbol 1 of PAM, binary 11 is encoded as symbol 2 of PAM, and binary 10 is encoded as symbol 3 of PAM. According to the PAM4 modulation adopting the Gray code, binary codes represented by two adjacent PAM4 code elements only have one bit different, error code elements generated by symbol misjudgment are often adjacent code elements, and the error rate of two bits caused by each code element error is very low, so that the bit error rate is lower than that of the common PAM4 modulation.

In a possible implementation manner, the modulating signal includes a duobinary modulating signal, and step S203 performs modulation processing on the coded signal to obtain a modulating signal, including:

In the embodiment of the disclosure, duobinary modulation processing is performed on the coded signal to obtain a duobinary modulation signal. The duobinary modulated signal is a duobinary code. The duobinary code is to convert the logic signal "1" or "0" in the original binary into the logic signals "+1", "-1", and "0" according to a certain rule, so that the spectrum bandwidth of the signal is reduced to half of the original spectrum bandwidth. The double binary modulation can reduce the occupied bandwidth of the signal, improve the utilization rate of frequency and increase the transmission distance of the optical signal in the optical fiber.

In the embodiment of the disclosure, the coded signal is subjected to duobinary modulation, and duobinary transmission has better MPI tolerance compared with a PAM4 modulated signal. At a transmitting end, signals transmitted by an information source are subjected to direct current balanced coding, and are subjected to duobinary modulation, and a receiving end adopts high-pass filtering processing, so that MPI noise interference can be reduced better.

The modulation signal includes a duobinary modulation signal, and step S203 is performed to modulate the coded signal to obtain a modulation signal, including:

acquiring a coded signal with preset bit delay from the coded signal;

carrying out XOR processing on the coded signal and the coded signal delaying the preset bit to obtain a pre-coded signal;

and carrying out precoding processing and duobinary modulation processing on the precoded signals to obtain duobinary modulation signals.

In the embodiment of the present disclosure, before duobinary modulation processing, referring to precoding and duobinary coding 1002 in fig. 10, the precoding signal is subjected to precoding processing and duobinary modulation processing to obtain a duobinary modulation signal. The pre-coding processing comprises delaying the pre-coded signal by preset bit to obtain a delayed pre-coded signal; and carrying out XOR processing on the delayed pre-coding signal and the pre-coding signal. Through the precoding processing, the judgment of the receiving end is simpler, and the error rate in the duobinary transmission can be reduced. However, the precoding process may destroy the dc balance characteristic of the encoded signal, and therefore, referring to the xor process 1001 in fig. 10, the embodiment of the disclosure obtains the encoded signal with a delay of a preset bit from the encoded signal, and performs the xor process on the encoded signal and the encoded signal with the delay of the preset bit to obtain the precoded signal. Through the exclusive-or processing, the final duobinary modulation signal can have a direct current balance property. In the context of figure 10 of the drawings,

represents exclusive OR logic, z ^-1 Meaning that the delay is one bit,

representing the algebraic sum.

Referring to fig. 11, at the receiving end, duo-binary decoding is performed on the duo-binary modulated signal after high-pass filtering, and exclusive-or processing 1101 is performed on the obtained binary code stream to obtain an 8B10B coded binary code stream, and finally, the 8B10B coded binary code stream is decoded to obtain an original binary code stream. In one example, the decoding method of duobinary decoding may include: if the received duobinary +/-1 code element is determined to be bit 0; if the duo-binary 0 symbol is decided as bit 1, the original binary code stream is restored by the above-mentioned manner, and pre-decoding may not be required.

The embodiment of the disclosure provides a direct current balanced duobinary coding mode, and the method can reduce the duobinary coding error rate, and the duobinary code stream is subjected to high-pass filtering processing at a receiving end to obtain a processed signal. The tolerance of the duo-binary code stream to MPI noise is improved.

In one possible implementation, the dc-balanced encoding includes at least one of: 8B10B coding, MB810 coding, 5S/6S coding, 27S/32S coding.

Referring to FIG. 12, curve 1203 represents the power spectral density of an NRZ signal at 50Gbaud/s, curve 1201 represents the power spectral density of a PAM4 signal at 25Gbaud/s, and curve 1202 represents the power spectral density of a 25Gbaud/s signal at 8B10B + PAM4. The bit rates for the three signals are all 50Gb/s, but the power spectral densities of 25Gbaud/s PAM4 and 25Gbaud/s 8B10B + PAM4 are only half the bandwidth of 50Gbaud/s NRZ signals. While the 25Gbaud/s 8B10B + PAM4 signal has no zero frequency component and is therefore a DC balanced signal.

Referring to FIG. 13, curve 1303 represents the power spectral density of an NRZ signal at 50Gbaud/s, curve 1301 represents the power spectral density of a 25Gbaud/s duobinary signal, and curve 1302 represents the power spectral density of a 25Gbaud/s duobinary encoded +8B10B signal. The bit rates of these three signals are all 50Gb/s, with the 25Gbaud/s duobinary signal and the 25Gbaud/s duobinary encoded +8B10B signal being only half of the NRZ signal at 50 Gbaud. The 25Gbaud/s duobinary coded +8B10B signal has no zero frequency component and is therefore a DC balanced signal.

Referring to fig. 14, fig. 14 shows the variation of the bit error rate of the 25Gbuad PAM4 optical transmission with the received optical power. Where MPI =0 indicates the error rate without MPI in the fiber link, MPI = -28dB is the error rate with an equivalent MPI of-28 dB in the fiber link. It can be seen that MPI = -28dB has a large impact on the error rate, which is orders of magnitude different than without MPI. MPI = -28,7.5MHz HPF is the error rate after traditional PAM4 signal is transmitted through optical fiber, the receiving end adopts high pass filter, the high pass filter can partially filter MPI noise, but certain signal distortion (such as baseline drift) can be caused to traditional MPI signal, so the cut-off frequency of the high pass filter needs to be optimized to reach the minimum error rate. In the figure, MPI = -28, and 7.5MHz HPF is the error rate after the cut-off frequency (7.5 MHz) of the high-pass filter is optimized, and compared with the error rate without the filter (black round points), the performance is slightly improved. In the figure, MPI = -28,8B10B &31MHz HPF is the bit error rate after equivalent MPI = -28dB, an 8B10B coded PAM4 signal is transmitted by an optical fiber, and because a high-pass filter (31 MHz after cutoff frequency optimization) is adopted at a receiving end, MPI noise can be furthest filtered, the influence on the PAM4 signal is small, and the bit error rate is improved by several orders of magnitude relative to the bit error rate without filtering.

Referring to FIG. 15, there is shown the optical power penalty for 25Gbaud/s PAM4 optical transmission versus optical transmission without MPI at different effective MPIs. The round point PAM4 is the optical power cost of PAM4 transmission under different MPIs traditionally, and if the optical power cost is limited to be less than or equal to 1 dB, the tolerance of 25Gbaud/s PAM4 optical transmission to the MPI is about-32 dB. The method has the advantages that PAM4 and HPF are 25Gbaud/s PAM4, the optical power cost is obtained after the transmission through optical fibers and the high-pass filtering at a receiving end; the receiving end adopts the high-pass filtering with the cut-off frequency of 7.5MHz, the tolerance of the transmission system to the MPI is about-31 dB, and compared with the condition that the receiving end does not have the high-pass filter, the MPI tolerance is improved by 1 dB. In the figure, a triangle is PAM4&8B10BEncoding + HPF is the optical power cost when the transmitting end adopts 8B10B PAM4 coding and the receiving end adopts a high-pass filter with the cut-off frequency of 31MHz, the tolerance of the system to MPI is about-27 dB, and compared with the condition that no 8B10B coding exists and no high-pass filtering exists at the receiving end (as shown by circular dots), the tolerance of the MPI is improved by 5dB. Therefore, the tolerance of the optical communication system to MPI can be effectively improved through the dc balanced encoding (such as 8B10B or MB 810) at the transmitting end and the high-pass filtering at the receiving end.

It should be understood that, although the steps in the flowchart are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in the figures may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of execution of the steps or stages is not necessarily sequential, but may be performed alternately or in alternation with other steps or at least some of the other steps or stages.

It is understood that the same/similar parts between the embodiments of the method described above in this specification can be referred to each other, and each embodiment focuses on the differences from the other embodiments, and it is sufficient that the relevant points are referred to the descriptions of the other method embodiments.

Fig. 16 is a schematic block diagram illustrating a signal processing apparatus according to an example embodiment. Referring to fig. 16, the apparatus 1600 includes:

the encoding module 1601 is configured to perform direct-current balanced encoding on a signal sent by a signal source to obtain an encoded signal;

a modulation module 1603, configured to perform modulation processing on the encoded signal to obtain a modulated signal;

the processing module 1605 is configured to send the modulation signal to a receiving end, so as to instruct the receiving end to perform high-pass filtering on the received modulation signal, so as to obtain a modulation signal with a frequency higher than a preset value, and perform demodulation and decoding on the modulation signal with the frequency higher than the preset value, so as to obtain a processed signal.

the encoding sub-module is used for respectively carrying out direct-current balanced encoding on the sub-signals of the number to obtain the sub-encoded signals of the number;

the modulation module comprises:

In one possible implementation manner, the first modulation submodule includes:

the acquisition submodule is used for acquiring the coded signal with the delay of preset bits from the coded signal;

the processing submodule is used for carrying out XOR processing on the coded signal and the coded signal delaying the preset bit to obtain a pre-coded signal;

8B10B coding, MB810 coding, 5S/6S coding, 27S/32S coding.

the encoder is used for carrying out direct-current balance encoding on the signal sent by the signal source to obtain an encoded signal;

the receiving end includes:

a photoelectric receiver for receiving the modulation signal;

With regard to the apparatus in the above embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be described in detail here.

Fig. 17 is a block diagram illustrating an electronic device 1700 for signal processing according to an example embodiment. For example, the electronic device 1700 may be a server. Referring to fig. 17, an electronic device 1700 includes a processing component 1720, which further includes one or more processors, and memory resources, represented by memory 1722, for storing instructions, such as applications, that may be executed by the processing component 1720. The application programs stored in memory 1722 may include one or more modules that each correspond to a set of instructions. Further, processing component 1720 is configured to execute instructions to perform the above-described methods.

The electronic device 1700 may further include: the power component 1724 is configured to perform power management of the electronic device 1700, the wired or wireless network interface 1726 is configured to connect the electronic device 1700 to a network, and the input output (I/O) interface 1728. The electronic device 1700 may operate based on an operating system stored in the memory 1722, such as Windows Server, mac OS X, unix, linux, freeBSD, or the like.

In an exemplary embodiment, a computer-readable storage medium comprising instructions, such as the memory 1722 comprising instructions, executable by a processor of the electronic device 1700 to perform the above-described method is also provided. The storage medium may be a computer-readable storage medium, which may be, for example, a ROM, a Random Access Memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

In an exemplary embodiment, a computer program product is also provided, which includes instructions executable by a processor of the electronic device 1700 to perform the above-described method.

It should be noted that the descriptions of the above apparatus, the electronic device, the computer-readable storage medium, the computer program product, and the like according to the method embodiments may also include other embodiments, and specific implementation manners may refer to the descriptions of the related method embodiments, which are not described in detail herein.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It will be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for signal processing, applied to a transmitting end, the method comprising:

modulating the coded signal to obtain a modulated signal;

sending the modulation signal to a receiving end to instruct the receiving end to perform high-pass filtering processing on the received modulation signal to obtain a modulation signal with the frequency higher than a preset value, and performing demodulation and decoding processing on the modulation signal with the frequency higher than the preset value to obtain a processed signal;

under the condition that the modulation processing includes pulse amplitude modulation processing, performing direct current balance coding on the signal sent by the signal source to obtain a coded signal, including:

demultiplexing the signal into the number of sub-signals;

and respectively carrying out direct current balance coding on the sub-signals of the number to obtain the sub-coded signals of the number.

2. The method according to claim 1, wherein, in the case where the modulation process includes a pulse amplitude modulation process,

the modulating the coded signal to obtain a modulated signal includes:

3. The method of claim 2, wherein performing pulse amplitude modulation on the sub-coded signals according to the number to obtain a modulated signal comprises:

4. The method of claim 1, wherein the modulation signal comprises a duobinary modulation signal, and the modulating the encoded signal to obtain the modulation signal comprises:

5. The method of claim 1, wherein the modulation signal comprises a duobinary modulation signal, and wherein modulating the encoded signal to obtain the modulation signal comprises:

acquiring a coded signal with preset bit delay from the coded signal;

6. The method of any one of claims 1 to 5, wherein the DC-balanced encoding comprises at least one of:

8B10B coding, MB810 coding, 5S/6S coding, 27S/32S coding.

7. A signal processing apparatus, characterized by comprising:

the processing module is used for sending the modulation signal to a receiving end to instruct the receiving end to carry out high-pass filtering processing on the received modulation signal so as to obtain a modulation signal with the frequency higher than a preset value, and carrying out demodulation and decoding processing on the modulation signal with the frequency higher than the preset value so as to obtain a processed signal;

in a case where the modulation process includes a pulse amplitude modulation process, the encoding module includes:

and the coding sub-module is used for respectively carrying out direct-current balance coding on the sub-signals with the number to obtain the sub-coded signals with the number.

8. The apparatus according to claim 7, wherein, in a case where the modulation process includes a pulse amplitude modulation process,

the modulation module comprises:

and the first modulation submodule is used for carrying out pulse amplitude modulation according to the sub-coding signals of the number to obtain a modulation signal.

9. The apparatus of claim 8, wherein the first modulation submodule comprises:

10. The apparatus of claim 7, wherein the modulation signal comprises a duobinary modulation signal, and wherein the modulation module comprises:

11. The apparatus of claim 7, wherein the modulation signal comprises a duobinary modulation signal, and wherein the modulation module comprises:

12. The apparatus according to any one of claims 7 to 11, wherein the dc-balanced encoding comprises at least one of:

8B10B coding, MB810 coding, 5S/6S coding, 27S/32S coding.

13. A system for processing a signal, comprising a transmitting end and a receiving end, wherein the transmitting end comprises:

the receiving end includes:

a photoelectric receiver for receiving the modulation signal;

the high-pass filter is used for carrying out high-pass filtering processing on the received modulation signal to obtain a modulation signal with the frequency higher than a preset value;

14. An electronic device, comprising:

a processor;

a memory for storing the processor-executable instructions;

wherein the processor is configured to execute the instructions to implement the method of signal processing of any of claims 1 to 6.

15. A computer-readable storage medium, wherein instructions in the computer-readable storage medium, when executed by a processor of an electronic device, enable the electronic device to perform the method of signal processing of any of claims 1-6.