Transmission method for optical communication and corresponding device

Abstract

This application discloses a transmission method for optical communication. The method is applicable to multiple scenarios exceeding 400Gbps (including 600Gbps, 800Gbps, etc.), such as metropolitan area networks, backbone networks, and data center interconnects. The method includes the steps of generating a frame including a plurality of symbols, in one polarization direction, the frame being N FAW Frame alignment word symbols, N PS pilot symbols, and N RES reserved symbols, one symbol out of every M symbols in the frame is a pilot symbol, and N FAW +N RES =M or N FAW +N RES +1=M, and each of the frame alignment word symbols and pilot symbols is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number, and transmitting the frame.

Description

[Technical Field]

[0001] This application claims priority to Chinese Patent Application No. 202210504319.2, entitled "Transmission Method and Corresponding Device for Optical Communication," filed with the State Intellectual Property Administration of China on May 10, 2022, which is incorporated herein by reference in its entirety.

[0002] The present application relates to the field of communications technology, and in particular to a transmission method and corresponding device for optical communications. [Background technology]

[0003] Driven by the continuous development of 5G, cloud computing, big data, artificial intelligence, and other technologies, high-speed optical transmission networks are evolving toward high capacity, packet-based, and intelligent. Coherent optical communication systems use the amplitude, phase, polarization, and frequency of light waves to carry information. To resist optical signal distortion caused by dispersion, polarization-dependent impairments, noise, nonlinear effects, and other factors during transmission and maintain long-distance transmission, coherent optical communication systems usually introduce several designed fixed symbol sequences into the transmitted symbol sequence to allow receiving devices to recover the transmitted symbols.

[0004] Existing transmission symbol sequences are mainly applicable to 400Gbps scenarios and cannot be adapted to future scenarios exceeding 400Gbps (including 600Gbps, 800Gbps, etc.). In addition, there are problems of high latency and high complexity, and the quality of the signal restored by the receiving device is poor, which need to be urgently solved in the future. Summary of the Invention

[0005] To solve the problems that existing solutions cannot be applied to scenarios exceeding 400 Gbps, and suffer from high delay and complexity, or poor signal quality recovered by a receiving device, the present application provides a transmission method for optical communication, and further provides corresponding devices, systems, computer-readable storage media, computer program products, etc. [Means for solving the problem]

[0006] A first aspect of the present application provides a transmission method for optical communication, the method comprising the steps of generating a frame including a plurality of symbols, the frame being N FAW Frame alignment word symbols, N PS pilot symbols, and N RES reserved symbols, the two polarization directions are orthogonal to each other, and one symbol out of every M symbols in the frame is a pilot symbol in that polarization direction, where M is an integer greater than 1, and N FAW +N RES =M or N FAW +N RES +1=M, and each of the frame alignment word symbols and pilot symbols is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number, and transmitting the frame.

[0007] In the first aspect, the frame generated by the transmitting device is not further divided into subframes, so that the structure is simple and the transmission delay is small. FAW Frame alignment word symbols, N PS pilot symbols, and N RES The reserved symbols can help the receiving device to better restore the signal quality. Therefore, it can be seen that the frame structure in the transmission method provided in the first aspect has a simple structure and a small transmission delay, which can further improve the quality of the signal restored by the receiving device.

[0008] In one possible implementation of the first aspect, in the polarization direction, there is one symbol in the frame that serves as both a frame alignment word symbol and a pilot symbol, and N FAW +N RES = M and N FAW +N PS is an odd number.

[0009] In this possible implementation, one symbol can function as both a pilot symbol and a frame alignment word symbol. In other words, there is a symbol that functions as a pilot in the frame alignment word symbol. This frame structure can help a receiving device recover the signal quickly.

[0010] In one possible implementation of the first aspect, the pilot symbols are generated using a target polynomial and a seed, and N PS pilot symbols and N FAW Frame alignment word symbols and (N FAW +N PS -1) symbol combinations achieve DC balance.

[0011] In this possible implementation, (N FAW +N PS The (-1) symbols achieve DC balance. Specifically, in each polarization direction, the sum of the real parts of the complex numbers corresponding to the frame alignment word symbols and pilot symbols in a frame is zero, and the sum of the imaginary parts is also zero. Such a frame helps the receiving device to recover the signal better.

[0012] In one possible implementation of the first aspect, in the polarization direction, no symbol in the frame serves as both a frame alignment word symbol and a pilot symbol, and N FAW +N RES +1=M and N FAW +N PS is an even number.

[0013] In this possible implementation, no symbols in a frame serve as both frame alignment word symbols and pilot symbols in one polarization direction. In other words, the symbols serving as pilots are independent of the frame alignment word symbols. This improves the accuracy of signal recovery in the receiving device.

[0014] In one possible implementation of the first aspect, the pilot symbols are generated using a target polynomial and a seed, and N PS pilot symbols and N FAW Frame alignment word symbols and (N FAW +N PS ) symbol combination achieves DC balance.

[0015] In this possible implementation, (N FAW +N PS ) symbols achieve DC balance, and such a frame helps a receiving device to better recover the signal.

[0016] In one possible implementation of the first aspect, N FAW N frame alignment word symbols achieve DC balance, FAW is an even number.

[0017] In this possible implementation, N FAW When is an even number, the effect of DC balancing can be enhanced.

[0018] In one possible implementation of the first aspect, N PS pilot symbols achieve DC balance, and N PS is an even number.

[0019] In this possible implementation, N PS When is an even number, the effect of DC balancing can be enhanced.

[0020] In one possible implementation of the first aspect, N FAWThe value of is 22 or 11.

[0021] In one possible implementation of the first aspect, the symbols in the frame are in a 16QAM modulation format, and the value of A is:

number

[0022] In one possible implementation of the first aspect, the value of M is 64.

[0023] In one possible implementation of the first aspect, the target polynomial is one of the polynomials in the table below.

[0024] [Table 1]

[0025] In one possible implementation of the first aspect, in one polarization direction, N PS =97, N FAW = 22, and N RES = 42, M = 64, and the number of symbols in the frame N F is 6208.

[0026] In one possible implementation of the first aspect, when the target polynomial and hexadecimal seed in two polarization directions are one row in the table below, the normalized amplitude of the sidelobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.25.

[0027] [Table 2]

[0028] In one possible implementation of the first aspect, the target polynomial is x 10 +x 9 +x 4 +x 1+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x0A9 and 0x143, the 97 pilot symbols in the two polarization directions are as shown in the table below.

[0029] [Table 3]

[0030] In one possible implementation of the first aspect, in one polarization direction, N PS =129, N FAW = 11, and N RES = 52, M = 64, and the number of symbols in the frame N F is 8256.

[0031] In one possible implementation of the first aspect, when the target polynomial and hexadecimal seed in two polarization directions are one row in the table below, the normalized amplitude of the sidelobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.17, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.17.

[0032] [Table 4]

[0033] In one possible implementation of the first aspect, the target polynomial is x 10 +x 7 +x 3 +x+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x2E3 and 0x196, the 129 pilot symbols in the two polarization directions are shown in the table below.

[0034] [Table 5]

[0035] In one possible implementation of the first aspect, N FAWThis frame alignment word symbol is a training symbol for link training.

[0036] A second aspect of the present application provides a receiving method for optical communication, the method comprising the steps of receiving a frame including a plurality of symbols, the frame being polarized in one of two polarization directions, N FAW Frame alignment word symbols, N PS pilot symbols, and N RES reserved symbols, the two polarization directions are orthogonal to each other, and one symbol out of every M symbols in the frame is a pilot symbol in that polarization direction, where M is an integer greater than 1, and N FAW +N RES =M or N FAW +N RES +1=M, and each of the frame alignment word symbols and pilot symbols is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number; and decoding the received frame.

[0037] In the second aspect, a frame containing multiple symbols received by a receiving device is not further divided into subframes, which results in a simple structure and a small transmission delay. FAW Frame alignment word symbols, N PS pilot symbols, and N RES The reserved symbols can help the receiving device to better restore the signal quality. Therefore, it can be seen that the frame structure in the transmission method provided in the second aspect has a simple structure and a small transmission delay, which can further improve the quality of the signal restored by the receiving device.

[0038] In one possible implementation of the second aspect, in the polarization direction, there is one symbol in the frame that serves as both a frame alignment word symbol and a pilot symbol, and N FAW +N RES = M and NFAW +N PS is an odd number.

[0039] In this possible implementation, one symbol can function as both a pilot symbol and a frame alignment word symbol. In other words, there is a symbol that functions as a pilot in the frame alignment word symbol. This frame structure can help a receiving device recover the signal quickly.

[0040] In one possible implementation of the second aspect, the pilot symbols are generated using a target polynomial and a seed, and N PS pilot symbols and N FAW Frame alignment word symbols and (N FAW +N PS -1) symbol combinations achieve DC balance.

[0041] In this possible implementation, (N FAW +N PS The -1) symbols achieve DC balance, specifically, in each polarization direction, the sum of the real parts of the complex numbers corresponding to the frame alignment word symbols and pilot symbols in one frame is 0, and the sum of the imaginary parts is also 0. This frame helps the receiving device to better restore the signal.

[0042] In one possible implementation of the second aspect, in the polarization direction, no symbol in the frame serves as both a frame alignment word symbol and a pilot symbol, and N FAW +N RES +1=M and N FAW +N PS is an even number.

[0043] In this possible implementation, no symbols in a frame serve as both frame alignment word symbols and pilot symbols in one polarization direction. In other words, the symbols serving as pilots are independent of the frame alignment word symbols. This improves the accuracy of signal recovery in the receiving device.

[0044] In one possible implementation of the second aspect, the pilot symbols are generated using a target polynomial and a seed, and N PS pilot symbols and N FAW Frame alignment word symbols and (N FAW +N PS ) symbol combination achieves DC balance.

[0045] In this possible implementation, (N FAW +N PS ) symbols achieve DC balance, and such a frame helps a receiving device to better recover the signal.

[0046] In one possible implementation of the second aspect, N FAW N frame alignment word symbols achieve DC balance, FAW is an even number.

[0047] In this possible implementation, N FAW When is an even number, the effect of DC balancing can be enhanced.

[0048] In one possible implementation of the second aspect, N PS pilot symbols achieve DC balance, and N PS is an even number.

[0049] In this possible implementation, N PS When is an even number, the effect of DC balancing can be enhanced.

[0050] In one possible implementation of the second aspect, N FAW The value of is 22 or 11.

[0051] In one possible implementation of the second aspect, the symbols in the frame are in a 16QAM modulation format, and the value of A is:

number

[0052] In one possible implementation of the second aspect, the value of M is 64.

[0053] In one possible implementation of the second aspect, in one polarization direction, N PS =97, N FAW = 22, and N RES = 42, M = 64, and the number of symbols in the frame N F is 6208.

[0054] In one possible implementation of the second aspect, when the target polynomial and hexadecimal seed in two polarization directions are one row in the table below, the normalized amplitude of the sidelobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.25.

[0055] [Table 6]

[0056] In one possible implementation of the second aspect, the target polynomial is x 10 +x 9 +x 4 +x 1 +1 and the corresponding hexadecimal seeds in the two polarization directions are 0x0A9 and 0x143, the 97 pilot symbols in the two polarization directions are as shown in the table below.

[0057] [Table 7]

[0058] In one possible implementation of the second aspect, in one polarization direction, N PS =129, N FAW = 11, and N RES = 52, M = 64, and the number of symbols in the frame N F is 6208.

[0059] In one possible implementation of the second aspect, when the target polynomial and hexadecimal seed in two polarization directions are one row in the table below, the normalized amplitude of the sidelobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.17, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.17.

[0060] [Table 8]

[0061] In one possible implementation of the second aspect, the target polynomial is x 10 +x 7 +x 3 +x+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x2E3 and 0x196, the 129 pilot symbols in the two polarization directions are shown in the table below.

[0062] [Table 9]

[0063] In one possible implementation of the second aspect, N FAW This frame alignment word symbol is a training symbol for link training.

[0064] A third aspect of the present application provides a transmitting device for optical communication. The transmitting device is configured to perform the method of the first aspect or any one of the possible implementations of the first aspect. Specifically, the transmitting device includes a module or unit, for example, a processing unit and a transmitting unit, configured to perform the method of the first aspect or any one of the possible implementations of the first aspect.

[0065] A fourth aspect of the present application provides a receiving device for optical communication. The receiving device is configured to perform the method of the second aspect or any one of the possible implementations of the second aspect. Specifically, the receiving device includes a module or unit, for example, a receiving unit and a processing unit, configured to perform the method of the second aspect or any one of the possible implementations of the second aspect.

[0066] According to a fifth aspect of the present application, there is provided a transmitting device for optical communication, the transmitting device including a processor and a memory, the memory configured to store instructions, and the processor configured to execute the instructions to enable the transmitting device to perform the method of the first aspect or any one of possible implementations of the first aspect.

[0067] According to a sixth aspect of the present application, there is provided a receiving device for optical communication, the receiving device including a processor and a memory, the memory configured to store instructions, and the processor configured to execute the instructions to enable the receiving device to perform the method of the second aspect or any one of possible implementations of the second aspect.

[0068] It should be understood that the processor may be a Central Processing Unit (abbreviated "CPU"), or may be another general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, etc. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc. This is not a limitation in this application.

[0069] According to a seventh aspect of the present application, there is provided a computer-readable storage medium storing instructions that, when executed on a transmitting device, enable the transmitting device to perform the method of the first aspect or any one of possible implementations of the first aspect.

[0070] According to an eighth aspect of the present application, there is provided a computer-readable storage medium storing instructions that, when executed on a receiving device, enable the receiving device to perform the method of the second aspect or any one of possible implementations of the second aspect.

[0071] According to a ninth aspect of the present application, there is provided a computer program product including instructions. When the computer program product runs on a transmitting device, the transmitting device is enabled to perform the method of the first aspect or any one of the possible implementations of the first aspect. It should be understood that the transmitting device may be a chip, a processor, etc. This is not limited in the present application.

[0072] According to a tenth aspect of the present application, a computer program product including instructions is provided, or a receiving device is enabled to execute the method of the second aspect or any one of the possible implementations of the second aspect. It should be understood that the receiving device may be a chip, a processor, etc., which is not limited in the present application.

[0073] An eleventh aspect of the present application provides a chip system. The chip system includes one or more interface circuits and one or more processors. The interface circuits are interconnected to the processor through lines. The interface circuits are configured to receive signals from a memory of a terminal device and transmit signals to the processor, the signals including computer instructions stored in the memory. When the processor executes the computer instructions, the transmitting device performs the method of the first aspect or any one of the possible implementations of the first aspect.

[0074] A twelfth aspect of the present application provides a chip system. The chip system includes one or more interface circuits and one or more processors. The interface circuits are interconnected to the processor through lines. The interface circuits are configured to receive signals from a memory of a cloud device and transmit signals to the processor, the signals including computer instructions stored in the memory. When the processor executes the computer instructions, the receiving device performs the method of the second aspect or any one of the possible implementations of the second aspect.

[0075] According to a thirteenth aspect of the present application, there is provided a system for optical communication, the system including the transmitting device of the third aspect and the receiving device of the fourth aspect, or the transmitting device of the fifth aspect and the receiving device of the sixth aspect.

[0076] The transmission method for optical communication provided in this application includes a frame with a new structure. FAW Frame alignment word symbols, N PSN pilot symbols RES The frame contains N reserved symbols and some symbols carrying information. This frame is not further divided into subframes, so it has a simple structure and a small transmission delay. In addition, FAW Frame alignment word symbols, N PS pilot symbols, and N RES The reserved symbols help the receiving device to better restore the signal quality. It can be seen that the frame structure in the transmission method for optical communication provided in the present application has a simple structure and a small transmission delay, which can further improve the quality of the signal restored by the receiving device. [Brief explanation of the drawings]

[0077] [Figure 1] FIG. 1 is a block diagram of a configuration of a communication system. [Figure 2] 1 is a diagram of a framing process according to an embodiment of the present application; [Figure 3] FIG. 10 is a diagram of another framing process according to an embodiment of the present application. [Figure 4] FIG. 1 is a diagram of an embodiment of a transmission method for optical communication according to an embodiment of the present application. [Figure 5A] 1 is a diagram showing the location of frame alignment word symbols or pilot symbols in a constellation diagram for DP-16QAM. [Figure 5B] FIG. 10 is another diagram illustrating the location of frame alignment word symbols or pilot symbols in a constellation diagram for DP-16QAM. [Figure 6A] FIG. 2 is a diagram of a frame structure according to an embodiment of the present application. [Figure 6B] FIG. 2 is another view of the structure of the frame according to an embodiment of the present application. [Figure 7] FIG. 2 is a diagram of a pilot symbol generation structure according to an embodiment of the present application. [Figure 8] FIG. 10 is a diagram of another frame structure according to an embodiment of the present application. [Figure 9]FIG. 2 is a diagram of a pilot symbol generation structure according to an embodiment of the present application. [Figure 10] 1 includes a diagram of a periodic autocorrelation result of a particular pilot symbol sequence in the X polarization direction, a diagram of a periodic autocorrelation result of a particular pilot symbol sequence in the Y polarization direction, and a diagram of a periodic cross-correlation result of a particular pilot symbol sequence in two polarization directions, according to an embodiment of the present application. [Figure 11] FIG. 10 is a diagram of another frame structure according to an embodiment of the present application. [Figure 12] FIG. 2 is a diagram of a pilot symbol generation structure according to an embodiment of the present application. [Figure 13] 1 includes a diagram of a periodic autocorrelation result of a particular pilot symbol sequence in the X polarization direction, a diagram of a periodic autocorrelation result of a particular pilot symbol sequence in the Y polarization direction, and a diagram of a periodic cross-correlation result of a particular pilot symbol sequence in two polarization directions, according to an embodiment of the present application. [Figure 14] FIG. 2 is a diagram of the structure of a transmitting device according to an embodiment of the present application; [Figure 15] FIG. 2 is a diagram of the structure of a receiving device according to an embodiment of the present application; [Figure 16] 1 is a diagram of the structure of a communication device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0078] The following describes embodiments of the present application with reference to the accompanying drawings. It is clear that the described embodiments are only a part, but not all, of the embodiments of the present application. Those skilled in the art can know that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application can also be applied to similar technical problems.

[0079] In the specification, claims, and accompanying drawings of this application, terms such as "first" and "second" are intended to distinguish between similar objects and do not necessarily indicate a particular order or sequence. Such terms, when used in this manner, are interchangeable under appropriate circumstances, and it is understood that the embodiments described herein may be performed in orders other than those illustrated or described herein. Additionally, the terms "include," "have," and any other variants thereof are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or device that includes a list of steps or units is not necessarily limited to the explicitly listed steps or units, but may include other steps or units not explicitly listed, or other steps or units inherent to such process, method, product, or device.

[0080] To solve the problems that transmission methods cannot be applied to scenarios exceeding 400 Gbps, and that they have high delays and complexity, or that the quality of signals restored by receiving devices is poor, embodiments of the present application provide a transmission method for optical communication. The present application also provides corresponding devices, systems, computer-readable storage media, computer program products, etc. Details are described individually below.

[0081] Before describing the embodiments of the present application in detail, we will first explain the application scenario of the embodiments of the present application. Figure 1 is a block diagram of the configuration of a communication system. On the transmitting side, a sender provides a data stream to be transmitted, an encoder receives and encodes the data stream, and the encoded codeword information, which combines parity bits and information bits, is sent to a transmitting signal processor for framing and then transmitted to a receiving device through a channel. After receiving a signal with distortion caused by noise and other impairments on the channel, the receiving device sends the signal to a receiving signal processor for dispersion compensation, synchronization, phase recovery, and other operations. Then, a decoder decodes the signal to restore the original data and transmits the data to the destination. The method provided in the present application is applied to the transmitting signal processor shown in Figure 1, which is a crucial part of the communication system.

[0082] The framing process in the transmitting signal processor can be shown in Figure 2 or 3. In one framing method, symbol mapping and polarization symbol distribution are performed on the received data stream as shown in Figure 2. The symbol mapping includes, but is not limited to, quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM). Then, polarization symbol distribution is performed to obtain dual-polarization (DP) symbols, such as DP-QPSK, DP-8QAM, DP-16QAM, DP-32QAM, and DP-64QAM. The following framing is performed for a certain number of dual-polarization symbols: to obtain a dual-polarization symbol stream to be transmitted, i.e., to obtain a frame, a frame alignment word (FAW) symbol, a reserved symbol (RES), and a pilot symbol (PS) are inserted in each of the X and Y polarization directions. In this application, a frame may also be referred to as a digital signal processing (DPS) frame. Note that after symbol mapping, the symbols may be further interleaved, and the framing described above is performed on the interleaved symbols. In this application, one dual-polarization symbol may be represented by two symbols, one symbol located in the X polarization direction and the other symbol located in the Y polarization direction. Each symbol may be represented by a complex number. For example, a symbol modulated using 16QAM may be represented by any one of the following 16 complex numbers: ±1±1j, ±1±3j, ±3±1j, and ±3±3j. It should be understood that the real and imaginary parts may be normalized in some cases, but the essence remains the same. Furthermore, a string having N dual-polarization symbols may be completely represented by two complex strings of length N, one complex string representing symbols on the X polarization and the other complex string representing symbols on the Y polarization.Each complex sequence of length N is represented by a real sequence of length N and an imaginary sequence of length N, where N is an integer greater than 1.

[0083] Generally, the received data sequence is an information and parity sequence obtained by forward error correction (FEC). The framing operation shown in FIG. 2 is performed on the symbols. Alternatively, as shown in FIG. 3, before symbol mapping, bits corresponding to frame alignment word symbols, reserved symbols, and pilot symbols may be inserted into the received data sequence according to the symbol mapping rule used, and then symbol mapping and polarization symbol distribution are performed to obtain the same frame as that obtained by the operation of FIG. 2. In this case, before symbol mapping, interleaving may be further performed on the bit sequence into which bits corresponding to the aforementioned symbols have been inserted, and then symbol mapping and polarization symbol distribution are performed to obtain the same frame as that obtained by the operation of FIG. 2. It should be understood that other framing schemes are not excluded and will not be described in detail in this application.

[0084] An embodiment of the present application provides a transmission method for optical communication. As shown in Figure 4, one embodiment of the transmission method includes the following steps:

[0085] 401: A transmitting device generates a frame including a plurality of symbols.

[0086] In one of the two polarization directions, this frame has N FAW Frame alignment word symbols, N PS pilot symbols, and N RES reserved symbols, the two polarization directions are orthogonal to each other, one symbol out of every M symbols in the frame is a pilot symbol in that polarization direction, M is an integer greater than 1, and N FAW +N RES =M or N FAW +N RES+1=M, and each of the frame alignment word symbols and pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number.

[0087] 402: A transmitting device transmits a frame including a plurality of symbols. Correspondingly, a receiving device receives the frame including a plurality of symbols.

[0088] 403: The receiving device decodes the frame.

[0089] The transmission method for optical communication provided in this application includes a frame with a new structure. FAW Frame alignment word symbols, N PS N pilot symbols RES The frame contains N reserved symbols and some symbols carrying information. This frame is not further divided into subframes, so it has a simple structure and a small transmission delay. In addition, FAW Frame alignment word symbols, N PS pilot symbols, and N RES The reserved symbols help the receiving device to better restore the signal quality. It can be seen that the frame structure in the transmission method for optical communication provided in the present application has a simple structure and a small transmission delay, which can further improve the quality of the signal restored by the receiving device.

[0090] In the above embodiment, the value of A is determined based on the modulation format used during symbol generation. In some practical application scenarios, -A-Aj, -A+Aj, A-Aj, and A+Aj are symbols in the constellation diagram of the modulation format used. For example, when QPSK is used, there are only four symbols. In this case, A=±1, and each frame alignment word symbol can be represented by one of -1-1j, -1+1j, 1-1j, and 1+1j. In one frame, there are all four frame alignment word symbols represented by four complex numbers, and similarly for the pilot symbols. When 16QAM is used, there are 16 symbols. In this case, A=±1 or ±3. Generally, both the frame alignment word symbols and the pilot symbols are the outermost four symbols in the constellation diagram, as shown by the hollow symbols in FIG. 5A. In this case, if A=3 or −3, each frame alignment word symbol can be represented by one of −3−3j, −3+3j, 3−3j, and 3+3j. A frame also contains frame alignment word symbols represented by four complex numbers, as do pilot symbols. Similarly, if 64QAM is used, A=±1, ±3, ±5, or ±7. Generally, the complex numbers representing frame alignment word symbols and pilot symbols are A=±5 or ±7. Assuming A=5 or −5, each frame alignment word symbol can be represented by one of −5−5j, −5+5j, 5−5j, and 5+5j. A frame contains all frame alignment word symbols represented by four complex numbers. Similarly, the same applies to pilot symbols. Alternatively, higher-order modulation formats may be used, which will not be described in detail in this application. In the actual transmission process, the symbol error probability can be low and the channel estimation can be easy.

[0091] Note that alternatively, the symbols in the constellation diagram may be compressed, with the value of A being compressed accordingly. Using 16QAM as an example, power normalization is performed over 16 symbols in the 16QAM constellation diagram. In this case, the value is

number

number

[0092] It should be understood that when the pilot symbols and frame alignment word symbols, -A-Aj, -A+Aj, A-Aj, and A+Aj, are the four outermost symbols in the constellation diagram, the frame alignment word symbols and pilot symbols have high sensitivity but a large peak to average power ratio. When the pilot symbols and frame alignment word symbols, -A-Aj, -A+Aj, A-Aj, and A+Aj, are the four innermost symbols in the constellation diagram, the frame alignment word symbols and pilots have low noise but low sensitivity.

[0093] Note that in some practical application scenarios, the pilot symbols and frame alignment word symbols, -A-Aj, -A+Aj, A-Aj, and A+Aj, may not necessarily be symbols in the constellation diagram of the modulation format used, but may be the four symbols in the middle of the outermost four symbols and the innermost four symbols in the constellation diagram. In this case, the frame alignment word symbols and pilot symbols have good noise and sensitivity, but a low peak-to-average power ratio. Using 16QAM as an example, the values ​​of the 16 symbols in the 16QAM constellation diagram are {±1±1j, ±1±3j, ±3±1j, ±3±3j}, and the value of the real number A satisfies 1≦A≦3. More specifically, as shown in FIG. 5B, the four outermost symbols in the constellation diagram are 3+3j, 3-3j, -3+3j, and -3-3j, and the four innermost symbols in the constellation diagram are 1+1j, 1-1j, -1+1j, and -1-1j. The values ​​of the pilot symbols and frame alignment word symbols, -A-Aj, -A+Aj, A-Aj, and A+Aj, may be the four symbols in the middle of the four outermost symbols and the four innermost symbols in the 16QAM constellation diagram. The specific value of the real number A may be selected based on the actual application scenario to achieve a good compromise between the peak-to-average power ratio, noise, and sensitivity of the frame alignment word symbols and pilots. For example, the real number

number

number

number

number

number

number

[0094] In addition, the two polarization directions are orthogonal to each other: specifically, if one polarization direction is X-polarized, the other polarization direction is Y-polarized, or vice versa.

[0095] In one frame, the columns containing the frame alignment word symbols in one polarization direction are different from the columns containing the frame alignment word symbols in the other polarization direction, and the columns containing the pilot symbols in one polarization direction are different from the columns containing the pilot symbols in the other polarization direction. For example, if the columns containing the frame alignment word symbols in one polarization direction are -A-Aj, -A-Aj, A+Aj, and A-Aj, the columns containing the frame alignment word symbols in the other polarization direction cannot be the same as the columns in the same order, but can be -A-Aj, -A-Aj, A+Aj, and A+Aj. There is one different symbol. This avoids the problem of a receiving device being unable to distinguish between the two polarization directions in actual transmission.

[0096] The frame structure provided in this embodiment of the present application can generally be of two types. In one type, there is one symbol in the frame that serves as both a frame alignment word symbol and a pilot symbol, and in the other type, there is no symbol in the frame that serves as both a frame alignment word symbol and a pilot symbol. The two types of frame structure will be described separately below.

[0097] 1. One symbol in the frame that acts as both the frame alignment word symbol and the pilot symbol In this embodiment of the present application, in one polarization direction, there is one symbol in the frame that serves as both a frame alignment word symbol and a pilot symbol, and N FAW +N RES = M and N FAW +N PS is an odd number.

[0098] For the frame structure in this case, please refer to Figure 6A for understanding. As shown in Figure 6A, the frame is PS N pilot symbols FAW Frame alignment word symbols, N RES Reserved symbols and a number of pre-framing symbols, where the pre-framing symbols include information and parity symbols. There is one pilot symbol for every M symbols in the frame, where the first symbol of the first M symbols is both a frame alignment word symbol and a pilot symbol, and the remaining symbols are frame alignment word symbols and reserved symbols. Or, of course, the first N FAW Any one of the N symbols may be both a frame alignment word symbol and a pilot symbol. This is not a limitation in this application. In addition, a symbol at a fixed position every M symbols is a pilot symbol and is used for carrier phase recovery. FAWAfter the frame alignment word symbols, there are N symbols that may be reserved for other purposes in the future. RES There are typically N reserved symbols, e.g., representing measured link end-to-end transmission delay data, FAW +N RES =M. For every M following symbols, the first symbol is a pilot symbol, and the remaining (M-1) symbols are pre-framing symbols. Note that in this application, pilot symbols do not overlap with reserved symbols, and pilot symbols do not overlap with pre-framing symbols. For example, no symbol is both a pilot symbol and a pre-framing symbol.

[0099] In an embodiment in which the frame structure shown in FIG. 6A is used, the sum of the number of frame alignment word symbols and pilot symbols included in one frame in one polarization direction is (N FAW +N PS −1), which is even. Since one symbol is both a frame alignment word symbol and a pilot symbol, this sum is (N FAW +N PS ) is not. Therefore, this sum is one less than the sum of the two types of symbols. In each polarization direction, the number of symbols in one frame including the frame alignment word symbols and pilot symbols (N FAW +N PS The sum of the real parts of the complex numbers corresponding to the −1) symbols is 0, and the sum of the imaginary parts is also 0. This achieves DC balance and helps receiving devices restore signal quality.

[0100] In one DSP frame, N consecutively arranged FAWThis symbol is a frame alignment word symbol and can be used for frame alignment words and / or link training. In some application scenarios, the FAW frame alignment word sequence is also called a training sequence (TS). For FAW in other contents of this application, please refer to this section for understanding. Details will not be repeated below.

[0101] Based on the frame structure shown in FIG. 6A, a frame can be divided into multiple symbol subsets starting from the first symbol, and each symbol subset includes M symbols. It should be understood that the symbol division into frames in this specification is merely a concept introduced for ease of explanation, and that in actual applications, a frame may not be divided. In each symbol subset including M symbols, one symbol is a pilot symbol. One symbol subset in a frame includes pilot symbols, frame alignment word symbols, and reserved symbols. Another symbol subset includes pilot symbols and pre-framing symbols. It should be understood that in the frame structure shown in FIG. 6A, the first symbol subset includes pilot symbols, frame alignment word symbols, and reserved symbols. This is merely an example. Alternatively, the last symbol subset may include pilot symbols, frame alignment word symbols, and reserved symbols. This is not a limitation of this specification. In the frame structure shown in FIG. 6A, there are no pre-framing symbols in the first symbol subset. This frame structure may facilitate hardware implementation and have low delay and low complexity characteristics. Based on the frame structure shown in FIG. 6A, one frame has M×N PS symbols, and the number of symbols before framing is (M-1) × (N PS It should be understood that (M-1) × (N PS -1) symbols are (N PS-1) groups, each containing (M-1) symbols, with one pilot symbol inserted before each group of (M-1) symbols, resulting in M×(N PS −1) symbols are obtained, and M×(N PS -1) symbols are inserted before or after M symbols, and M symbols are inserted into N FAW Frame alignment word symbols and N RES and reserved symbols.

[0102] Another specific framing task is as follows: (M-1) × (N PS -1) symbols are inserted before or after M symbols, and M symbols are inserted into N FAW Frame alignment word symbols and N RES reserved symbols, and (M-1)×(N PS -1) symbols are (N PS 6A is divided into (M-1) groups, each group containing (M-1) symbols, and one pilot symbol is inserted before the (M-1) symbols in each group. It will be appreciated that the frame structure shown in FIG. 6A is characterized by low delay and low complexity.

[0103] 2. There are no symbols in the frame that serve as both frame alignment word symbols and pilot symbols.

[0104] In this embodiment of the present application, in one polarization direction, there is no symbol in the frame that serves as both a frame alignment word symbol and a pilot symbol, and N FAW +N RES +1=M and N FAW +N PS is an even number.

[0105] For the frame structure in this case, please refer to Figure 6B for understanding. As shown in Figure 6B, the frame is PS N pilot symbols FAWFrame alignment word symbols, N RES 6A , the frame includes M reserved symbols and a plurality of pre-framing symbols, where the pre-framing symbols include information and parity symbols. Unlike the structure of FIG. 6A , there is one pilot symbol for every M symbols in the frame, and the first symbol of the first M symbols is a pilot symbol, but it is not a frame alignment word symbol; instead, it is followed by a frame alignment word symbol and a reserved symbol. Of course, the position of the pilot symbol is not limited to the first position, and may be after the frame alignment word symbol or after the reserved symbol. This is not a limitation of the present application.

[0106] In one polarization direction, the sum of the number of frame alignment word symbols and pilot symbols in one frame is (N FAW +N PS ) and is an even number. In each polarization direction, the number of symbols including the frame alignment word symbol and the pilot symbol in one frame (N FAW +N PS ) symbols, the real parts of the complex numbers corresponding to them sum to 0, and the imaginary parts also sum to 0. This achieves DC balance and helps receiving devices restore signal quality.

[0107] Based on the frame structure shown in FIG. 6B , a frame can be divided into multiple symbol subsets starting from the first symbol, with each symbol subset including M symbols. It should be understood that the symbol division into frames in this document is merely a concept introduced for ease of explanation, and that in actual applications, a frame may not be divided. In each symbol subset including M symbols, one symbol is a pilot symbol. One symbol subset in a frame includes pilot symbols, frame alignment word symbols, and reserved symbols. Another symbol subset includes pilot symbols and pre-framing symbols. It should be understood that in the frame structure shown in FIG. 6B , the first symbol subset includes pilot symbols, frame alignment word symbols, and reserved symbols. This is merely an example. Alternatively, the last symbol subset may include pilot symbols, frame alignment word symbols, and reserved symbols. This is not a limitation of this document. In the frame structure shown in FIG. 6B , the first symbol subset does not include pre-framing symbols. This may facilitate hardware implementation and have low delay and low complexity characteristics. Based on the frame structure shown in FIG. 6B, one frame has M×N PS symbols, and the number of symbols before framing is (M-1) × (N PS It should be understood that the specific DSP framing operations are as follows: FAW Frame alignment word symbols and N RES (M-1) symbols including the reserved symbols are (M-1) × (N PS -1) symbols are inserted before or after the PS symbols are obtained, and the (M-1)×N PS N symbols PS6B is divided into (M-1) groups, each group containing (M-1) symbols, and one pilot symbol is inserted before the (M-1) symbols in each group. It will be appreciated that the frame structure shown in Figure 6B is characterized by low delay and low complexity.

[0108] The pilot symbols mentioned above are generated using a target polynomial and a seed. In this embodiment of the present application, a 10th order polynomial is used as the target polynomial, which can be expressed as: x 10 +a9×x 9 +a8×x 8 +a7×x 7 +a6×x 6 +a5×x 5 +a4×x 4 +a3×x 3 +a2×x 2 +a1×x+1, where the values ​​of a9...a1 can be 0 or 1.

[0109] For an understanding of the pilot symbol generation structure, please refer to Figure 7. As shown in Figure 7, the seeds can be represented in binary form as m9, m8, m7, m6, m5, m4, m3, m2, m1, and m0. Of course, the seeds may alternatively be represented in hexadecimal or decimal form and need to be converted to binary form during operation with the target polynomial. For example, 0110111000 is represented in hexadecimal form as 0x1B8 and in decimal form as 440.

[0110] In this embodiment of the present application, the same target generator polynomial may be used for the pilot symbols of the two orthogonal polarization directions, but because the seeds are different, the pilot symbols output in the two polarization directions are correspondingly not completely identical.

[0111] As shown in Figure 7, N PS In a scenario where pilot symbols need to be generated, 2N PS A bit string with a continuous length of

number

number

[0112] In this embodiment of the present application, the target polynomial and seed may be determined by designing the values ​​of the coefficients a9...a1 in the polynomial so that the generated pilot symbols have good autocorrelation properties of the symbol sequences on the X and Y polarizations and good cross-correlation properties of the symbol sequences on the two polarizations. Generally, the target polynomial may be one of the following target polynomials in Table 0:

[0113] [Table 10]

[0114] In particular, the target polynomial is x 10 +x 7 +x 3 +x+1 or x 10 +x 8 +x 4 +x 3 +1.

[0115] In addition, by choosing an appropriate target polynomial and seed, the solution shown in Figure 6A can achieve N FAW Frame alignment word symbols and N PS and (N FAW +N PS -1) The symbols achieve DC balance, which can help the receiving device restore signal quality.

[0116] In the solution shown in FIG. 6A in the embodiment of the present application, one frame is generated for each polarization direction, totaling (N FAW +N PS −1) frame alignment word symbols and pilot symbols, and the difference in the numbers of −A−Aj, −A+Aj, A−Aj, and A+Aj in these symbols is equal to or less than 1. In addition, in one frame, the number of four complex numbers representing the frame alignment word symbols and pilot symbols in the two polarization directions is the same, i.e., (N FAW +N PS -1) / 2. This effectively guarantees a balance between the number of symbols. In addition, the sequence including the frame alignment word symbols and pilot symbols can further achieve DC balance, so that the receiving device can restore the signal quality. A specific example is as follows: in the frame alignment word symbols and pilot symbols included in each frame, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively:

number

number

number

[0117] In addition, in the solution shown in Figure 6B, N FAW Frame alignment word symbols and N PS and (N FAW +N PS ) symbols achieve DC balance to help the receiving device restore signal quality.

[0118] In the solution shown in FIG. 6B in the embodiment of the present application, one frame is generated for each polarization direction, totaling (N FAW +N PS ) frame alignment word symbols and pilot symbols, and the difference in the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in these symbols is 1 or less. In addition, in one frame, the number of four complex numbers representing the frame alignment word symbols and pilot symbols in the two polarization directions is the same, i.e., (N FAW +N PS ) / 2. This effectively guarantees a balance between the number of symbols. In addition, the sequence including the frame alignment word symbols and pilot symbols can further achieve DC balance, so that the receiving device can restore the signal quality. A specific example is as follows: in the frame alignment word symbols and pilot symbols included in each frame, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively:

number

number

number

[0119] 6A and 6B above illustrate frames with two different structures. In order to better understand the solution of the present application, the following describes the pilot symbol generation process in different frame structures with reference to specific examples.

[0120] In one polarization direction, the number of symbols before framing is 6048, and the following Table 1 shows the N corresponding frame structure. PS , N F , NFAW , N RES , OH, and M are listed.

[0121] [Table 11]

[0122] For an understanding of this frame structure, please refer to Figure 8. The frame contains 6208 symbols, there is one pilot symbol every 64 symbols, the first 22 symbols of the first 64 symbols are frame alignment word symbols, the first frame alignment word symbol is also a pilot symbol, and the following 42 symbols are reserved symbols, i.e., N FAW +N RES =22+42=64. The first symbol of every subsequent 64 symbols is a pilot symbol, so 6208 / 64=97, there are 97 pilot symbols. The frame redundancy of this structure is 2.65%.

[0123] The 22 frame alignment word symbols can be understood with reference to Table 2 below.

[0124] [Table 12]

[0125] The 97 pilot symbols are determined based on a target polynomial and a corresponding seed. In this embodiment of the present application, the structure of pilot symbol generation using the target polynomial and the seed can be understood with reference to FIG.

[0126] In the scenario where 97 pilot symbols are generated, the bit sequence b0, b1, b2, ... b 193 The bit string b0, b1, b2, ... b 193 Every two consecutive bits of b are mapped to one symbol, and2t and b 2t+1 is one symbol (2b 2t -1)A+(2b 2t+1 -1)Aj. 2t -1)A+(2b 2t+1 -1) Note that Aj does not have to be a symbol in the constellation diagram of the modulation format used, but may be the four symbols in the middle between the four outermost and four innermost symbols of the constellation diagram of the modulation format used.

[0127] When the target polynomial and hexadecimal seed for two polarization directions are one row in Table 3 below, the normalized amplitude of the sidelobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.25.

[0128] [Table 13]

[0129] The target polynomial is x 10 +x 9 +x 4 +x 1 +1 and the corresponding hexadecimal seeds represented in the two polarization directions are 0x0A9 and 0x143, i.e., row 1 with sequence number 11 in Table 2, the process of generating 97 pilot symbols can be understood with reference to FIG. 9.

[0130] As shown in FIG. 9, for polarization direction 1, the input polarization seed is 0x0A9, which becomes 0010101001 after being converted into a binary sequence, i.e., values ​​m9 to m0. When two bits 1 and 0 are output consecutively in sequence, the pilot symbol for the X polarization direction is A-Aj. When two bits 0 and 0 are output consecutively in sequence, the pilot symbol for the X polarization direction is -A-Aj. When two bits 1 and 1 are output consecutively in sequence, the pilot symbol for the X polarization direction is A+Aj. When two bits 0 and 1 are output consecutively in sequence, the pilot symbol for the X polarization direction is -A+Aj. By analogy, 97 pilot symbols for the X polarization direction can be obtained.

[0131] As shown in FIG. 9, for polarization direction 2, the input polarization seed is 0x143, which becomes 0101000011 after being converted into a binary sequence, i.e., values ​​m9 to m0. When two bits 1 and 0 are output consecutively in sequence, the pilot symbol for the Y polarization direction is A-Aj. When two bits 0 and 0 are output consecutively in sequence, the pilot symbol for the Y polarization direction is -A-Aj. When two bits 1 and 1 are output consecutively in sequence, the pilot symbol for the Y polarization direction is A+Aj. When two bits 0 and 1 are output consecutively in sequence, the pilot symbol for the Y polarization direction is -A+Aj. By analogy, 97 pilot symbols for the Y polarization direction can be obtained.

[0132] Therefore, we can obtain the 97 pilot symbols shown in Table 4 below.

[0133] [Table 14]

[0134] Figure 10 shows the correlation characteristics corresponding to the pilot symbols. Figure 10(a) shows the periodic autocorrelation results of the pilot symbol sequence in the X polarization direction, Figure 10(b) shows the periodic autocorrelation results of the pilot symbol sequence in the Y polarization direction, and Figure 10(c) shows the periodic cross-correlation results of the pilot symbol sequence in the X and Y polarization directions. The normalized amplitudes of the side lobe values ​​of the periodic autocorrelation functions of the symbol sequence in the two polarization directions are less than 0.190, and the normalized amplitudes of the side lobe values ​​of the periodic cross-correlation functions of the symbol sequence in the two polarization directions are less than 0.206.

[0135] Based on the received signals of the two polarization directions, the receiving device performs DSP and recovers the signal using the FAW frame alignment word sequence and the PS pilot sequence. For example, by separately calculating the correlation value between the received signal and the column symbols of the frame alignment word sequence for X and Y polarization, the polarization direction can be distinguished, frame alignment word alignment can be performed, and carrier phase recovery can be performed using the PS pilot signal.

[0136] The designed pilot symbol sequence has good autocorrelation and cross-correlation properties, and the frame alignment word sequence and the pilot symbol sequence are combined to achieve DC balance, which helps the receiving device improve the quality of the recovered signal.

[0137] An example of a frame structure has been described above with reference to FIG. 6A, and below, an example of a frame structure will be described with reference to FIG. 6B.

[0138] In this frame structure, the number of symbols before framing is 8064, and Table 5 below shows the N symbols corresponding to this frame structure. PS , N F , N FAW , N RES , OH, and M are listed.

[0139] [Table 15]

[0140] This frame structure can be understood with reference to Figure 11. The frame contains 8256 symbols, with one pilot symbol every 64 symbols, the first of the first 64 symbols being a pilot symbol, followed by 11 frame alignment word symbols, followed by 52 reserved symbols, i.e., N FAW +N RES +1 = 11 + 52 + 1 = 64. The first symbol of every subsequent 64 symbols is a pilot symbol, so 8256 / 64 = 129, or 129 pilot symbols. The frame redundancy of this structure is 2.38%.

[0141] The 11 frame alignment word symbols can be understood with reference to Table 6 below.

[0142] [Table 16]

[0143] The 129 pilot symbols are determined based on a target polynomial and a corresponding seed. When the target polynomial and hexadecimal seed for two polarization directions are one row in Table 7 below, the normalized amplitude of the side lobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is 0.21 or less, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is 0.21 or less.

[0144] [Table 17]

[0145] The target polynomial is x 10 +x 7 +x 3+x+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x2E3 and 0x196, i.e., one row with sequence number 4 in Table 4, the process of generating 129 pilot symbols can be understood with reference to Figure 12. The 129 pilot symbols shown in Table 8 below can be obtained.

[0146] [Table 18]

[0147] Figure 13 shows the correlation characteristics corresponding to the pilot symbols. Figure 13(a) shows the periodic autocorrelation results of the pilot symbol sequence in the X polarization direction, Figure 13(b) shows the periodic autocorrelation results of the pilot symbol sequence in the Y polarization direction, and Figure 13(c) shows the periodic cross-correlation results of the pilot symbol sequence in the X and Y polarization directions. The normalized amplitudes of the side lobe values ​​of the periodic autocorrelation functions of the symbol sequence in the two polarization directions are 0.175 or less, and the normalized amplitudes of the side lobe values ​​of the periodic cross-correlation functions of the symbol sequence in the two polarization directions are 0.160 or less.

[0148] Based on the received signals of the two polarization directions, the receiving device performs DSP and recovers the signal using the FAW frame alignment word sequence and the PS pilot sequence. For example, by separately calculating the correlation value between the received signal and the column symbols of the frame alignment word sequence for X and Y polarization, the polarization direction can be distinguished, frame alignment word alignment can be performed, and carrier phase recovery can be performed using the PS pilot signal.

[0149] The designed pilot symbol sequence has good autocorrelation and cross-correlation properties, and the frame alignment word sequence and the pilot symbol sequence are combined to achieve DC balance, which helps the receiving device improve the quality of the recovered signal.

[0150] The technical solution of this application uses a frame architecture with low latency and complexity, including a frame alignment word symbol and a reserved symbol. This helps resolve polarization direction arbitrariness and measurement dispersion during signal processing at the receiving end. The designed sequence has good autocorrelation and cross-correlation properties. The FAW frame alignment word sequence satisfies DC balance, and the combination of the frame alignment word sequence and the PS pilot sequence also satisfies DC balance. This helps the receiving device restore signal quality.

[0151] Please note that the above are only some examples. In the embodiment of the present application, different pilot symbols can be obtained by using different target polynomials and corresponding seeds. For the principle, please refer to the above contents of Figure 9 and Figure 12 for understanding.

[0152] The above describes the transmission method and corresponding frame structure for optical communication. Hereinafter, the devices provided in the embodiments of the present application will be described with reference to the accompanying drawings.

[0153] As shown in FIG. 14, the structure of the transmitting device 140 provided in one embodiment of the present application includes: A processing unit 1401 configured to generate a frame comprising a plurality of symbols, the frame comprising N symbols in one of two polarization directions. FAW Frame alignment word symbols, N PS pilot symbols, and N RES reserved symbols, the two polarization directions are orthogonal to each other, and one symbol out of every M symbols in the frame is a pilot symbol in that polarization direction, where M is an integer greater than 1, and N FAW +N RES =M or N FAW +N RES+1=M, and each of the frame alignment word symbols and pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number, and the processing unit 1401 is configured to perform step 401 in the above method embodiment; a transmitting unit 1402 configured to transmit a frame, the transmitting unit 1402 being configured to perform step 402 in the embodiment of the method described above; Includes:

[0154] As shown in FIG. 15, the structure of a receiving device 150 provided in one embodiment of the present application includes: A receiving unit 1501 configured to receive a frame comprising a plurality of symbols, the frame being N in one of two polarization directions. FAW Frame alignment word symbols, N PS pilot symbols, and N RES reserved symbols, the two polarization directions are orthogonal to each other, and one symbol out of every M symbols in the frame is a pilot symbol in that polarization direction, where M is an integer greater than 1, and N FAW +N RES =M or N FAW +N RES +1=M, and each of the frame alignment word symbols and pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number, and the receiving unit 1501 is configured to perform step 402 in the method embodiment; a processing unit 1502 configured to decode a received frame, the processing unit 1502 being configured to perform step 403 in the embodiment of the method described above; Includes:

[0155] In this embodiment of the present application, the frame generated by the transmitting device is not further divided into subframes, so that the structure is simple and the transmission delay is small. FAW Frame alignment word symbols, N PS pilot symbols, and N RES The reserved symbols help the receiving device to better restore the signal quality. Therefore, it can be seen that the frame structure in the transmission method provided in this embodiment has a simple structure and a small transmission delay, which can further improve the quality of the signal restored by the receiving device.

[0156] Optionally, in one polarization direction, there is one symbol in the frame that serves as both the frame alignment word symbol and the pilot symbol, and N FAW +N RES = M and N FAW +N PS is an odd number.

[0157] Optionally, pilot symbols are generated using a target polynomial and a seed, N PS pilot symbols and N FAW Frame alignment word symbols and (N FAW +N PS -1) symbol combinations achieve DC balance.

[0158] Optionally, in that polarization direction, the frame does not have a symbol that is both a frame alignment word symbol and a pilot symbol, and N FAW +N RES +1=M and N FAW +N PS is an even number.

[0159] Optionally, pilot symbols are generated using a target polynomial and a seed, N PS pilot symbols and N FAW Frame alignment word symbols and (N FAW +NPS ) symbol combination achieves DC balance.

[0160] Optionally, N FAW N frame alignment word symbols achieve DC balance, FAW is an even number.

[0161] Optionally, N PS pilot symbols achieve DC balance, and N PS is an even number.

[0162] Optionally, N FAW The value of is 22 or 11.

[0163] Optionally, the symbols in the frame are in 16QAM modulation format, and the value of A is

number

[0164] An arbitrary choice for the value of M is 64.

[0165] Optionally, in the polarization direction, N PS =97, N FAW = 22, and N RES = 42, M = 64, and the number of symbols in the frame N F is 6208.

[0166] Optionally, if the target polynomial and hexadecimal seed for two polarization directions are one row in the table below, the normalized amplitude of the side lobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.25.

[0167] [Table 19]

[0168] Optionally, the target polynomial is x 10 +x 9 +x 4 +x 1 +1 and the corresponding hexadecimal seeds in the two polarization directions are 0x0A9 and 0x143, the 97 pilot symbols in the two polarization directions are as shown in the table below.

[0169] [Table 20]

[0170] Optionally, in the polarization direction, N PS =129, N FAW = 11, and N RES = 52, M = 64, and the number of symbols in the frame N F is 8256.

[0171] Optionally, if the target polynomial and hexadecimal seed for two polarization directions are one row in the table below, the normalized amplitude of the side lobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.17, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.17.

[0172] [Table 21]

[0173] Optionally, the target polynomial is x 10 +x 7 +x 3 +x+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x2E3 and 0x196, the 129 pilot symbols in the two polarization directions are shown in the table below.

[0174] [Table 22]

[0175] Optionally, N FAW This frame alignment word symbol is a training symbol for link training.

[0176] In the embodiment of the present application, the operations performed by the units in the transmitting device and the receiving device are similar to those described in the embodiment shown in Figures 4 to 13. The details will not be described again here.

[0177] FIG. 16 is a diagram of a possible logical structure of a communication device according to an embodiment of the present application. The communication device may be a transmitting device or a receiving device, and the communication device may be a terminal device or a network device. As shown in FIG. 16, the communication device 160 provided in this embodiment of the present application includes a processor 1601, a communication interface 1602, a memory 1603, and a bus 1604. The processor 1601, the communication interface 1602, and the memory 1603 are connected to each other through the bus 1604. In this embodiment of the present application, the processor 1601 is configured to control and manage the operation of the communication device 160. For example, the processor 1601 is configured to perform a frame generation process or a frame decoding process. The communication interface 1602 is configured to assist the communication device 160 in communication. For example, the communication interface 1602 can perform steps of transmitting and receiving data in the aforementioned method embodiments. The memory 1603 is configured to store program codes and data for the communication device 160.

[0178] The processor 1601 may be a central processing unit, a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The processor 1601 may implement or execute various exemplary logic blocks, modules, and circuits described with reference to the subject matter disclosed herein. Alternatively, the processor may be a combination of processors that perform computing functions, such as a combination of one or more microprocessors, or a combination of a digital signal processor and a microprocessor. The bus 1604 may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. Buses may be categorized into address buses, data buses, control buses, and the like. For ease of representation, only one bold line is used to represent a bus in FIG. 16, but this does not imply that there is only one bus or only one type of bus.

[0179] In another embodiment of the present application, a computer-readable storage medium is further provided, which stores computer-executable instructions, which, when executed by a processor of a terminal, cause a transmitting device to perform the steps performed by the transmitting device in Figures 4 to 13.

[0180] In another embodiment of the present application, a computer-readable storage medium is further provided, which stores computer-executable instructions, which, when executed by a processor of a terminal, cause a receiving device to perform the steps performed by the receiving device in Figures 4 to 13.

[0181] In another embodiment of the present application, there is further provided a computer program product, which includes computer program code, which, when executed on a computer, causes the computing device to perform the steps performed by the terminal in Figures 4 to 13.

[0182] In another embodiment of the present application, a chip system is further provided. The chip system includes one or more interface circuits and one or more processors. The interface circuits and the processors are interconnected through lines. The interface circuits are configured to receive signals from a memory of the terminal and transmit signals to the processor, the signals including computer instructions stored in the memory. When the processor executes the computer instructions, the terminal performs the steps performed by the transmitting device in Figures 4 to 13. In one possible design, the chip system further includes a memory. The memory is configured to store program instructions and data required for the control device. The chip system may include a chip, or may include a chip and other discrete components.

[0183] In some embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the described device embodiments are merely examples. For example, the division into units is merely a logical division of function, and actual implementation may involve other divisions. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not implemented. In addition, the shown or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces. Indirect couplings or communication connections between devices or units may be implemented in electrical, mechanical, or other forms.

[0184] The units described as separate parts may or may not be physically separate, and the parts shown as units may or may not be physical units, and may be located in one place or distributed over multiple network units. Some or all of the units may be selected based on actual requirements to achieve the objectives of the solutions of the embodiments.

[0185] In addition, the functional units of the embodiments of the present application may be integrated into one processing unit, and each of the units may exist physically alone, or two or more units may be integrated into one unit. All or part of the integrated units may be implemented using software, hardware, firmware, or any combination thereof.

[0186] When software is used to implement an integrated unit, all or a portion of the integrated unit may be implemented in the form of a computer program product. This computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the procedures or functions according to the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, optical fiber, or digital subscriber line (DSL)) or wireless (e.g., infrared, radio wave, or microwave) transmission. The computer-readable storage medium may be any available medium accessible by a computer, or a data storage device, such as a server or data center, that integrates one or more available media. The available media may be magnetic media (e.g., floppy disk, hard disk, or magnetic tape), optical media (e.g., DVD), or semiconductor media (e.g., solid state disk (SSD)). [Explanation of symbols]

[0187] 140 transmitting device 1401 Processing Unit 1402 transmitting unit 150 receiving devices 1501 receiving unit 1502 Processing Unit 160 Communication Devices 1601 processor 1602 Communication Interface 1603 memory 1604 Bus

Claims

1. A transmitting device for optical communications comprising one or more memories and one or more processors, wherein the one or more processors: A frame including a plurality of symbols is generated, and in one of two polarization directions, the frame is ＦＡＷ Frame alignment word symbols, N ＰＳ pilot symbols, and N ＲＥＳ reserved symbols, the two polarization directions being orthogonal to each other, in which one symbol out of every M symbols in the frame is a pilot symbol, M being an integer greater than 1, and N ＦＡＷ +N ＲＥＳ = M or N ＦＡＷ +N ＲＥＳ +1=M, and each of the frame alignment word symbols and the pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number; Transmit the frame a transmitting device configured to:

2. In the polarization direction, there is one symbol in the frame that functions as both a frame alignment word symbol and a pilot symbol, and N ＦＡＷ +N ＲＥＳ = M and N ＦＡＷ +N ＰＳ The transmitting device of claim 1 , wherein is an odd number.

3. The pilot symbols are generated using a target polynomial and a seed, and the N ＰＳ pilot symbols and the N ＦＡＷ frame alignment word symbols and (N ＦＡＷ +N ＰＳ 3. The transmitting device of claim 2, wherein a combination of -1) symbols achieves DC balance.

4. In the polarization direction, there is no symbol in the frame that functions as both a frame alignment word symbol and a pilot symbol, and N ＦＡＷ +N ＲＥＳ +1=M and N ＦＡＷ +N ＰＳ The transmitting device of claim 1 , wherein is an even number.

5. The pilot symbols are generated using a target polynomial and a seed, and the N ＰＳ pilot symbols and the N ＦＡＷ frame alignment word symbols and (N ＦＡＷ +N ＰＳ 5. The transmitting device of claim 4, wherein a combination of symbols achieves DC balance.

6. N ＦＡＷ The transmitting device of claim 1 , wherein the value of is 22 or 11.

7. The symbols in the frame are in a 16QAM modulation format, and the value of A is [Equation 1] The transmitting device of claim 1 , wherein:

8. The transmitting device of claim 1 , wherein the value of M is 64.

9. The transmitting device of claim 3 , wherein the target polynomial is one of the polynomials in the following table: Table 1

10. In the polarization direction, N ＰＳ = 97, N ＦＡＷ = 22, and N ＲＥＳ = 42, M = 64, and the number of symbols in the frame N Ｆ The transmitting device of claim 9, wherein: is 6208.

11. 11. The transmitting device of claim 10, wherein when the target polynomial and hexadecimal seed in the two polarization directions are one row in the following table, normalized amplitudes of sidelobe values ​​of periodic autocorrelation functions of pilot symbols in the same polarization direction are less than or equal to 0.25, and normalized amplitudes of periodic cross-correlation function values ​​of pilot symbols in different polarization directions are less than or equal to 0.

25. Table 2

12. The target polynomial is x １０ +x ９ +x ４ +x １ 12. The transmitting device of claim 11, wherein when the hexadecimal seeds are 0x0A9 and 0x143, and the corresponding hexadecimal seeds in the two polarization directions are 0x0A9 and 0x143, the 97 pilot symbols in the two polarization directions are as shown in the following table: Table 3

13. In the polarization direction, N ＰＳ = 129, N ＦＡＷ = 11, N ＲＥＳ = 52, M = 64, and the number of symbols in the frame N Ｆ 10. The transmitting device of claim 9, wherein: is 8256.

14. 14. The transmitting device of claim 13, wherein when the target polynomial and hexadecimal seed in the two polarization directions are one row in the following table, the normalized amplitudes of sidelobe values ​​of periodic autocorrelation functions of pilot symbols in the same polarization direction are less than or equal to 0.17, and the normalized amplitudes of periodic cross-correlation function values ​​of pilot symbols in different polarization directions are less than or equal to 0.

17. Table 4

15. The target polynomial is x １０ +x ７ +x ３ +x+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x2E3 and 0x196, the 129 pilot symbols in the two polarization directions are as shown in the following table: Table 5

16. The N ＦＡＷ The transmitting device of claim 1 , wherein the frame alignment word symbols are training symbols.

17. A transmitting device for optical communications comprising one or more memories and one or more processors, wherein the one or more processors: A frame including a plurality of symbols is received, and in one of two polarization directions, the frame is ＦＡＷ Frame alignment word symbols, N ＰＳ pilot symbols, and N ＲＥＳ reserved symbols, the two polarization directions being orthogonal to each other, in which one symbol out of every M symbols in the frame is a pilot symbol, M being an integer greater than 1, and N ＦＡＷ +N ＲＥＳ = M or N ＦＡＷ +N ＲＥＳ +1=M, and each of the frame alignment word symbols and the pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number; Decoding the received frame a transmitting device configured to:

18. 1. A system for optical communication, the system comprising a transmitting device and a receiving device, the transmitting device comprising: generating a frame including a plurality of symbols, the frame including N FAW frame alignment word symbols, N PS pilot symbols, and N RES reserved symbols in one of two polarization directions, the two polarization directions being orthogonal to each other, one symbol out of M symbols in the frame being a pilot symbol in the polarization direction, M being an integer greater than 1, N FAW +N RES =M or N FAW +N RES +1=M, each of the frame alignment word symbols and the pilot symbols being one of −A−Aj, −A+Aj, A−Aj, and A+Aj, and A is a real number; transmitting the frame; the receiving device: receiving the frame; Decoding the received frame The system is configured as follows:

19. The system of claim 18, wherein in the polarization direction there is one symbol in the frame that functions as both a frame alignment word symbol and a pilot symbol, N FAW +N RES =M, and N FAW +N PS is an odd number.

20. The system of claim 19, wherein the pilot symbols are generated using a target polynomial and a seed, and a (N FAW +N PS -1) symbol combination of the N PS pilot symbols and the N FAW frame alignment word symbols achieves DC balance.

21. The system of claim 18, wherein in the polarization direction, no symbol in the frame functions as both a frame alignment word symbol and a pilot symbol, N FAW +N RES +1=M, and N FAW +N PS is an even number.

22. The system of claim 21, wherein the pilot symbols are generated using a target polynomial and a seed, and wherein a (N FAW +N PS ) symbol combination of the N PS pilot symbols and the N FAW frame alignment word symbols achieves DC balance.

23. The system of claim 18, wherein the value of N FAW is 22 or 11.

24. The plurality of symbols in the frame are modulated in a 16QAM format, and the value of A is: [Equation 2] 20. The system of claim 18, wherein:

25. The system of claim 18, wherein the value of M is 64.

26. The system of claim 20, wherein the target polynomial is one of the polynomials in the following table: Table 6 27. The system of claim 26, wherein in the polarization direction, N PS =97, N FAW =22, and N RES =42 in the frame, M=64, and the number of symbols in the frame, N F , is 6208.

28. The system described in claim 27, wherein when the target polynomial and hexadecimal seed in the two polarization directions are one row in the table below, the normalized amplitude of the side lobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.

25. Table 7 29. The system of claim 28, wherein when the target polynomial is x10+x9+x4+x1+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x0A9 and 0x143, the 97 pilot symbols in the two polarization directions are as shown in the following table: Table 8 30. The system of claim 26, wherein in the polarization direction, N PS =129, N FAW =11, N RES =52 in the frame, M=64, and the number of symbols in the frame, N F , is 8256.

31. The system described in claim 30, wherein when the target polynomial and hexadecimal seed in the two polarization directions are one row in the table below, the normalized amplitude of the side lobe values ​​of the periodic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.17, and the normalized amplitude of the periodic cross-correlation function values ​​of pilot symbols in different polarization directions is less than or equal to 0.

17. Table 9 32. The system of claim 31, wherein when the target polynomial is x10+x7+x3+x+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x2E3 and 0x196, the 129 pilot symbols in the two polarization directions are as shown in the following table: Table 10 33. The system of claim 18, wherein the N FAW frame alignment word symbols are training symbols.

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