Transmitting method and receiving method for optical communication and corresponding devices

Abstract

To provide a transmitting method for optical communication that is applied to various scenarios such as metropolitan area networks, backbone networks, and data center interconnections, exceeding 400 Gbps (including 600 Gbps, 800 Gbps, and the like).SOLUTION: A method includes the steps of generating a super-frame including a plurality of sub-frames, and transmitting the super-frame. Each sub-frame includes training symbols and pilot symbols. Each of the training symbols and the pilot symbols is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number. In addition, in the training symbols and pilot symbols included in each sub-frame, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in two mutually perpendicular polarization directions meet a certain requirement, which can achieve DC balance, and is conducive to signal recovery at a receiving end.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present application relates to the field of optical communications, in particular to transmitting and receiving methods for optical communications and corresponding devices. [Background technology]

[0002] Driven by the continuous development of 5G, cloud computing, big data, artificial intelligence, and other technologies, high-speed optical transport 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 address optical signal distortion caused by dispersion, polarization-dependent impairments, noise, nonlinear effects, and other factors in the transmission process and to maintain long-distance transmission, coherent optical communication systems usually add some designed fixed symbol sequences to the transmitted symbol sequence to help the receiving end restore the transmitted symbols.

[0003] Existing transmission symbol sequences are mainly applicable to 400Gbps scenarios and cannot adapt to future scenarios beyond 400Gbps (including 600Gbps, 800Gbps, etc.). In addition, the cross-correlation between transmission symbol sequences in different polarization directions is insufficient. These are issues that need to be urgently solved in the future. Summary of the Invention

[0004] The present application provides a transmission method for optical communication to solve the problems of the inapplicability of prior art to scenarios exceeding 400 Gbps and the insufficient cross-correlation between symbol sequences in different polarization directions.

[0005] According to a first aspect, there is provided a transmission method for optical communication, the method comprising the steps of generating a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, in one polarization direction, a sum of the number of the training symbols and pilot symbols included in the subframe is 5 or more, there is one symbol that is both a training symbol and a pilot symbol, each of the training symbols and pilot symbols is one of -A-Aj, -A+Aj, A-Aj, or A+Aj, where A is a real number, and in the training symbols and pilot symbols included in each subframe, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is respectively

number

number

[0006] According to a second aspect, there is provided a receiving method for optical communication, the method comprising the steps of receiving a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, in one polarization direction, a sum of the number of the training symbols and pilot symbols included in the subframe is 5 or more, there is one symbol that is both a training symbol and a pilot symbol, each of the training symbols and pilot symbols is one of -A-Aj, -A+Aj, A-Aj, or A+Aj, where A is a real number, and in the training symbols and pilot symbols included in each subframe, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is respectively

number

number

[0007] In the embodiment of the present application, in each polarization direction, one subframe is a total of N TS +N PS -1 training symbols and pilot symbols. For these symbols, the difference between the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj is less than or equal to 1. In addition, in one subframe, the number of four complex numbers representing the training symbols and pilot symbols is the same in the two polarization directions, and both are (N TS +N PS−1) / 2, which effectively ensures the balance between the symbol amounts. In addition, the sequence composed of training symbols and the sequence composed of pilot symbols can also achieve DC (direct current) balance, which improves the quality of the signal restored at the receiving end.

[0008] With reference to the first or second aspect, in a first possible implementation form, in one subframe, a sequence of training symbols in one polarization direction is different from a sequence of training symbols in the other polarization direction, and a sequence of pilot symbols in one polarization direction is different from a sequence of pilot symbols in the other polarization direction, thereby avoiding the problem that the receiving end cannot distinguish between the two polarization directions in actual transmission.

[0009] With reference to the above implementation, in a second possible implementation, the training symbols are arranged consecutively in a subframe, and in any polarization direction, the number of consecutive identical real part elements in the training symbols included in the subframe is not more than 5, and the number of consecutive identical imaginary part elements is not more than 5. Furthermore, in any polarization direction, the number of consecutive identical training symbols in one subframe does not exceed 4. The training sequence obtained under this condition facilitates clock recovery, thereby helping to improve the quality of the signal restored at the receiving end.

[0010] With reference to the above implementations, in a third possible implementation of the first aspect, the multiple subframes further include a first subframe, and the first subframe includes consecutively arranged frame alignment word symbols, each of which is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, and in any polarization direction, the number of consecutive identical real part elements in the frame alignment word symbols included in the subframe is not more than 5, and the number of consecutive identical imaginary part elements is not more than 5. Furthermore, in any polarization direction, the number of consecutive identical frame alignment word symbols in the first subframe does not exceed 4. The frame alignment word sequence obtained under this condition also facilitates clock recovery, thereby helping to improve the quality of the signal restored at the receiving end.

[0011] With reference to the third possible implementation form, in a fourth possible implementation form, in the frame alignment word symbols included in the first subframe, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively:

number

number

[0012] With reference to the above implementations, in a fifth possible implementation, N TSis an even number, and in the training symbols included in each subframe, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are, respectively,

number

number

[0013] With reference to the first aspect, the second aspect, or any one of the first to fourth possible implementations, in a sixth possible implementation, TS is an odd number, and in the training symbols included in each subframe, excluding the training symbols also used as pilot symbols, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively

number

number

[0014] The above two embodiments provide several possible symbol numbers of training sequences in different polarization directions in two different cases, and the numbers of training symbols -A-Aj, -A+Aj, A-Aj and A+Aj included in one subframe are close to each other. In addition, in each polarization direction, except for the training symbol that is also used as a pilot symbol (when there is an odd number of training symbols), the sum of the real parts of the complex numbers corresponding to other training symbols is 0, and the sum of their imaginary parts is also 0, so that DC balance can be achieved, and the quality of the signal restored at the receiving end is improved.

[0015] With reference to the first embodiment, the second embodiment, or any one of the first to fourth possible implementations, in a seventh possible implementation, PS is an even number, and the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe are respectively

number

number

[0016] With reference to the first embodiment, the second embodiment, or any one of the first to fourth possible implementations, in an eighth possible implementation, PS is an odd number, and among the pilot symbols included in each subframe, excluding the pilot symbols also used as training symbols, the numbers of −A−Aj, −A+Aj, A−Aj, and A+Aj in one polarization direction are respectively

number

number

[0017] With reference to the first aspect, the second aspect, or any one of the first to fourth possible implementation forms, in a ninth possible implementation form, in each subframe, the remainder when the number of pilot symbols in one polarization direction is divided by 4 is 0, and the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe are respectively N PS / 4+1, N PS / 4-1, N PS / 4-1, and NPS / 4+1, and the number in the other polarization direction is N PS / 4-1, N PS / 4+1, N PS / 4+1, and N PS / 4-1 or the amount in both polarization directions is N PS / 4.

[0018] With reference to the first aspect, the second aspect, or any one of the first to fourth possible implementation forms, in a tenth possible implementation form, in each subframe, the remainder when the number of pilot symbols in one polarization direction is divided by 4 is 2, and the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe are respectively (N PS -2) / 4, (N PS -2) / 4+1, (N PS -2) / 4+1, and (N PS −2) / 4, and the number in the other polarization direction is (N PS -2) / 4+1, (N PS -2) / 4, (N PS -2) / 4, and (N PS -2) / 4+1.

[0019] With reference to the first aspect, the second aspect, or any one of the first to fourth possible implementation forms, in an eleventh possible implementation form, in each subframe, the remainder of the division of the number of pilot symbols in one polarization direction by 4 is 1, and the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe, excluding pilot symbols also used as training symbols, are respectively set to (N PS -1) / 4+1, (N PS -1) / 4-1, (N PS -1) / 4-1, and (N PS -1) / 4+1, and the number in the other polarization direction is (N PS -1) / 4-1, (N PS-1) / 4+1, (N PS -1) / 4+1, and (N PS -1) / 4-1, or their amounts in both polarization directions are (N PS -1) / 4.

[0020] With reference to the first aspect, the second aspect, or any one of the first to fourth possible implementation forms, in a twelfth possible implementation form, in each subframe, the remainder when the number of pilot symbols in one polarization direction is divided by 4 is 3, and the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe, excluding pilot symbols also used as training symbols, are respectively set to (N PS -3) / 4, (N PS -3) / 4+1, (N PS -3) / 4+1, and (N PS -3) / 4, and the number in the other polarization direction is (N PS -3) / 4+1, (N PS -3) / 4, (N PS -3) / 4, and (N PS -3) / 4+1.

[0021] The seventh to twelfth implementation forms provide several possible symbol numbers of pilot sequences of different polarization directions in several different cases, and the numbers of pilot symbols -A-Aj, -A+Aj, A-Aj, and A+Aj included in one subframe are close to each other, thereby effectively ensuring the balance between training symbols. In addition, in each polarization direction, except for the pilot symbols that are also used as training symbols (when there are an odd number of pilot symbols), the sum of the real parts of the complex numbers corresponding to other pilot symbols is 0, and the sum of their imaginary parts is also 0, so that DC balance can be achieved, improving the quality of the signal restored at the receiving end.

[0022] With reference to the above implementations, in a thirteenth possible implementation, the modulation format of the symbols in the superframe is 16QAM, and the value of A is 1 or 3. Alternatively, the symbols in the constellation diagram may be compressed, and the value of A is compressed accordingly. Taking 16QAM as an example, power normalization is performed on 16 symbols in the 16QAM constellation diagram, in which case the value is:

number

number

[0023] It should be noted that in some practical application scenarios, the pilot symbols and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj may not be symbols in the constellation diagram of the modulation format used, but may be four symbols in the intermediate region between the outermost four symbols and the innermost four symbols of the constellation diagram. In this case, the training symbols and pilot symbols have considerable noise and sensitivity, but have a relatively low peak-to-average power ratio. Take 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, the outermost four symbols of the constellation diagram are 3+3j, 3-3j, -3+3j, and -3-3j, and the innermost four symbols of the constellation diagram are 1+1j, 1-1j, -1+1j, and -1-1j. The values ​​of the pilot and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj may be four symbols in the intermediate region between the outermost four symbols and the innermost four symbols of the 16QAM constellation diagram. The specific value of the real number A may be selected according to the actual application scenario, so that the peak-to-average power ratio, noise, and sensitivity of the training and pilot symbols have a good compromise. For example, the real number

number

number

number

number

number

number

[0024] With reference to the above implementations, in a fourteenth possible implementation, in each subframe, a fixed-position symbol of every 64 symbols is a pilot symbol, for example, the first symbol of every 64 symbols is a pilot symbol.

[0025] With reference to the first aspect, the second aspect, or any one of the first to thirteenth possible implementations, in a fifteenth possible implementation, in each subframe, a fixed-position symbol of every 48 symbols is a pilot symbol. For example, the first symbol of every 48 symbols is a pilot symbol.

[0026] It should be understood that all of the above implementations can be combined with the first aspect or the second aspect, and this is not limited in this application.

[0027] According to a third aspect, a transmitting device for optical communication is provided. The transmitting device includes a processor and a memory. The memory is configured to store instructions, and the processor is configured to execute the instructions to cause the transmitting device to perform the method of the first aspect or any one of the possible implementation forms of the first aspect.

[0028] According to a fourth aspect, a receiving device for optical communication is provided. The transmitting device includes a processor and a memory. The memory is configured to store instructions, and the processor is configured to execute the instructions to cause the receiving device to perform the method of the second aspect or any one of the possible implementation forms of the second aspect.

[0029] According to a fifth aspect, there is provided a system for optical communication, the system including a transmitting device according to the third aspect and a receiving device according to the fourth aspect.

[0030] It should be understood that the processor may be a Central Processing Unit (abbreviated as "CPU"), another general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or another programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc. The general-purpose processor may be a microprocessor, the processor may be any conventional processor, etc., which is not limited in the embodiments of the present application.

[0031] According to a sixth aspect, a computer-readable storage medium is provided, the computer-readable storage medium storing instructions that, when executed on a terminal device, cause the terminal device to perform the method of the first aspect or any one of the possible implementations of the first aspect, or cause the terminal device to perform the method of the second aspect or any one of the possible implementations of the second aspect.

[0032] According to a seventh aspect, a computer program product is provided, the computer program product including instructions, when executed on a terminal device, causes the terminal device to execute a method according to the first aspect or any one of the possible implementation forms of the first aspect, or causes the terminal device to execute a method according to the second aspect or any one of the possible implementation forms of the second aspect. It should be understood that the terminal device may be a chip, a processor, etc., which is not limited in this application.

[0033] According to an eighth aspect, a transmission method for optical communication is provided, the method comprising the steps of generating a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, in one polarization direction, there is one symbol that is both a training symbol and a pilot symbol, each of the training symbols and the pilot symbols being one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number, in each subframe, in one polarization direction, the pilot symbols are generated based on a target polynomial and a seed, and N TS N training symbols combined PS There are N pilot symbols, TS is the number of training symbols in each subframe in one polarization direction, and N TS +N PS is an odd integer, the step objective polynomial is one of the entries in the table below, and [Table 1] and transmitting the TIFF2025069189000025.tif51170 superframe.

[0034] According to a ninth aspect, there is provided a receiving method for optical communication. The method includes: receiving a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, in one polarization direction, there is one symbol that is both a training symbol and a pilot symbol, each of the training symbols and the pilot symbols being one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number, in each subframe, in one polarization direction, the pilot symbols are generated based on a target polynomial and a seed, and N TS N training symbols combined PSThere are N pilot symbols, TS is the number of training symbols in each subframe in one polarization direction, and N TS +N PS is odd, and the target polynomial is an item in the table below, with steps and [Table 2] Step TIFF2025069189000027.tif52170: Decoding the received superframe.

[0035] In an eighth or ninth aspect, the pilot symbols are generated based on a target polynomial and a corresponding seed. The target polynomial is any entry in the table above, and the target polynomial and the corresponding seed are generated based on the N PS pilot symbols and N TS The combination of the training symbols can achieve DC balance, that is, in one polarization direction, the sum of the real parts of the complex numbers corresponding to the training symbols and pilot symbols in one subframe is zero, and the sum of the imaginary parts is also zero, which helps the receiving end to better restore the signal, and improves the quality of the signal at the receiving end.

[0036] With reference to the eighth or ninth aspect, in a possible implementation, in one polarization direction, the total number of symbols in a superframe, N F is 175104, and the number of subframes N SF is 24, and the number of symbols in each subframe N S is 7296, and N TS = 11, and N PS = 114, and the number of frame alignment word symbols N FAW and the number of reserved symbols N RES With N FAW +N RESis 96, and the number of pre-framing symbols in the superframe is 172032. Such a superframe structure can help the receiving end to better restore the signal, and improve the quality of the signal at the receiving end.

[0037] With reference to the eighth aspect, the ninth aspect, or any one of the possible implementations, in another possible implementation, when the target polynomial and the hexadecimal seed in two polarization directions are one row of the following table, the normalized amplitude of the side lobe value of the cyclic autocorrelation function of the pilot symbols in the same polarization direction is less than or equal to 0.2, and the normalized amplitude of the cyclic cross-correlation function value of the pilot symbols in different polarization directions is less than or equal to 0.2: [Table 3] TIFF2025069189000029.tif208170 TIFF2025069189000030.tif208170 TIFF2025069189000031.tif61170

[0038] Referring to the eighth aspect, the ninth aspect, or any one of the possible implementations, in another possible implementation, when the target polynomial and hexadecimal seed in two polarization directions are one row of the following table, in one polarization direction, in a combination of 114 pilot symbols and 11 training symbols, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are all 31: [Table 4]

[0039] Referring to the eighth aspect, the ninth aspect, or any one of the possible implementation forms, when the target polynomial is a primitive polynomial, the number of non-zero terms of the target polynomial is five or less, and when the target polynomial and the hexadecimal seed in two polarization directions are one row of the following table, the normalized amplitude of the side lobe value of the cyclic autocorrelation function of the pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the cyclic cross-correlation function value of the pilot symbols in different polarization directions is less than or equal to 0.25: [Table 5]

[0040] Referring to the eighth aspect, the ninth aspect, or any one of the possible implementations, in another possible implementation, the target polynomial is x 10 +x 7 +x 3 When the hexadecimal seeds in the two polarization directions are 0x34E and 0x084, in one polarization direction, in the combination of 114 pilot symbols and 11 training symbols, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are all 31, and the respective 114 pilot symbols in the two polarization directions are shown in the table below: [Table 6]

[0041] Referring to the eighth aspect, the ninth aspect, or any one of the possible implementations, in another possible implementation, the target polynomial is x 10 +x 7 +x 6 +x 2 +1 and the corresponding hexadecimal seeds in the two polarization directions are 0x0BE and 0x1B8, the 114 pilot symbols in each of the two polarization directions are shown in the table below: [Table 7]

[0042] Referring to the eighth aspect, the ninth aspect, or any one of the possible implementations, in another possible implementation, in one polarization direction, the total number of symbols in a superframe N F is 175104, and the number of subframes N SF is 48, and the number of symbols in each subframe N S is 3648, and N TS = 6, and N PS = 57, and the number of frame alignment word symbols N FAW and the number of reserved symbols N RES With N FAW +N RES is 96, and the number of pre-framing symbols in a superframe is 172032.

[0043] Referring to the eighth aspect, the ninth aspect, or any one of the possible implementations, in another possible implementation, when the target polynomial and the hexadecimal seed in two polarization directions are one row of the following table, the normalized amplitude of the side lobe value of the cyclic autocorrelation function of the pilot symbols in the same polarization direction is not more than 0.23, and the normalized amplitude of the cyclic cross-correlation function value of the pilot symbols in different polarization directions is not more than 0.23: [Table 8]

[0044] Referring to the eighth aspect, the ninth aspect, or any one of the possible implementations, in another possible implementation, the target polynomial is x 10 +x 7 +x 3 +x+1, and the corresponding hexadecimal seeds in the two polarization directions are 0x0B1 and 0x3E9, the 57 pilot symbols in each of the two polarization directions are shown in the table below: [Table 9]

[0045] According to a tenth aspect, a transmitting device for optical communication is provided. The transmitting device includes a processor and a memory. The memory is configured to store instructions, and the processor is configured to execute the instructions to cause the transmitting device to perform the method of the eighth aspect or any one of the possible implementation forms of the eighth aspect.

[0046] According to an eleventh aspect, a receiving device for optical communication is provided. The transmitting device includes a processor and a memory. The memory is configured to store instructions, and the processor is configured to execute the instructions to cause the receiving device to perform the method of the ninth aspect or any one of the possible implementation forms of the ninth aspect.

[0047] According to a twelfth aspect, there is provided a system for optical communication. The system comprises a transmitting device according to the tenth aspect and 11 The present invention also includes a receiving device according to the above aspect.

[0048] It should be understood that the processor may be a Central Processing Unit (abbreviated as "CPU"), another general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or another programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc. The general-purpose processor may be a microprocessor, the processor may be any conventional processor, etc., which is not limited in the embodiments of the present application.

[0049] According to a thirteenth aspect, a computer-readable storage medium is provided, the computer-readable storage medium storing instructions that, when executed on a terminal device, cause the terminal device to perform the method of the eighth aspect or any one of the possible implementations of the eighth aspect, or cause the terminal device to perform the method of the ninth aspect or any one of the possible implementations of the ninth aspect.

[0050] According to a fourteenth aspect, a computer program product is provided, the computer program product including instructions, when executed on a terminal device, causes the terminal device to execute a method according to the eighth aspect or any one of the possible implementation forms of the eighth aspect, or causes the terminal device to execute a method according to the ninth aspect or any one of the possible implementation forms of the ninth aspect. It should be understood that the terminal device may be a chip, a processor, etc., which is not limited in this application.

[0051] According to a fifteenth aspect, there is provided a transmission method for optical communication, comprising the steps of generating a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, and in each subframe, N PS There are N pilot symbols, each of which has a value of −A2−A2j, −A2+A2j, A2−A2j, and A2+A2j, where A2 is a real number, PS is even, and N PS N pilot symbols achieve DC balance and are PS the combination of the pilot symbols achieves DC balance, the pilot symbols being generated based on a target polynomial and a seed, the target polynomial being a primitive polynomial, the target polynomial having five or fewer non-zero terms, and the target polynomial being an item in the following table; [Table 10] and transmitting the superframe.

[0052] According to a sixteenth aspect, there is provided a receiving method for optical communication, comprising the steps of receiving a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, and in each subframe, N PSThere are N pilot symbols, each of which has a value of −A2−A2j, −A2+A2j, A2−A2j, and A2+A2j, where A2 is a real number, PS is even, and N PS N pilot symbols achieve DC balance and are PS the combination of the pilot symbols achieves DC balance, the pilot symbols being generated based on a target polynomial and a seed, the target polynomial being a primitive polynomial, the target polynomial having five or fewer non-zero terms, and the target polynomial being an item in the following table; [Table 11] and decoding the received superframe.

[0053] In a fifteenth or sixteenth aspect, the pilot symbols are generated based on a target polynomial and a seed. The target polynomial is any entry in the table above, and the target polynomial and the corresponding seed are N PS pilot symbols achieve DC balance and the training symbols and N PS The combination of the pilot symbols can meet to achieve DC balance, which helps the receiving end to restore the signal better, and improves the quality of the signal at the receiving end.

[0054] With reference to the fifteenth or sixteenth aspect, in a possible implementation, in one polarization direction, the total number of symbols in a superframe, N F is 175104, and the number of subframes N SF is 24, and the number of symbols in each subframe N S is 7296, and N PS = 114, and the number of frame alignment word symbols N FAW and the number of reserved symbols N RES With N FAW +N RES is 96, the number of pre-framing symbols in a superframe is 172032, When the target polynomial for generating pilot symbols and hexadecimal seeds in two polarization directions is one row of the following table, the normalized amplitude of the side lobe value of the cyclic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the cyclic cross-correlation function value of pilot symbols in different polarization directions is less than or equal to 0.25: [Table 12] TIFF2025069189000041.tif62170

[0055] With reference to the fifteenth aspect, the sixteenth aspect, or any one of the possible implementations, in another possible implementation, the target polynomial is x 10 +x 9 +x 7 +x 6 +1, and the corresponding hexadecimal seeds in the two polarization directions are 0x002 and 0x3C6, the 114 pilot symbols in each of the two polarization directions are shown in the table below: [Table 13]

[0056] With reference to the fifteenth aspect, the sixteenth aspect, or any one of the possible implementation forms, in another possible implementation form, in one polarization direction, in each subframe, when the remainder of dividing the number of pilot symbols by 4 is 0, in pilot symbols included in each subframe, the number of -A2-A2j is equal to the number of A2+A2j, the number of -A2+A2j is equal to the number of A2-A2j, and the number of -A2-A2j is equal to the number of A2-A2j. -A 2 +A 2 j The difference between the numbers is 2, or -A2-A2j, -A2+A2j, A2-A2j, and A2+A2j are equal, When the remainder of dividing the number of pilot symbols by 4 is 2, in the pilot symbols included in each subframe, -A2-A2j is equal to the number of A2+A2j, the number of -A2+A2j is equal to the number of A2-A2j, and the number of -A2-A2j is equal to the number of -A 2 +A 2 j The difference between the numbers is 1.

[0057] According to a seventeenth aspect, a transmitting device for optical communication is provided. The transmitting device includes a processor and a memory. The memory is configured to store instructions, and the processor is configured to execute the instructions to cause the transmitting device to perform the method of the fifteenth aspect or any one of the possible implementation forms of the fifteenth aspect.

[0058] According to an eighteenth aspect, a receiving device for optical communication is provided. The transmitting device includes a processor and a memory. The memory is configured to store instructions, and the processor is configured to execute the instructions to cause the receiving device to perform the method of the sixteenth aspect or any one of the possible implementation forms of the sixteenth aspect.

[0059] According to a nineteenth aspect, there is provided a system for optical communication. The system includes a transmitting device according to the seventeenth aspect and a receiving device according to the eighteenth aspect.

[0060] It should be understood that the processor may be a Central Processing Unit (abbreviated as "CPU"), another general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or another programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc. The general-purpose processor may be a microprocessor, the processor may be any conventional processor, etc., which is not limited in the embodiments of the present application.

[0061] According to a twentieth aspect, a computer-readable storage medium is provided, which stores instructions that, when executed on a terminal device, cause the terminal device to perform the method of the fifteenth aspect or any one of the possible implementations of the fifteenth aspect, or cause the terminal device to perform the method of the sixteenth aspect or any one of the possible implementations of the sixteenth aspect.

[0062] According to a twenty-first aspect, a computer program product is provided, the computer program product including instructions, when executed on a terminal device, causes the terminal device to execute the method in the fifteenth aspect or any one of the possible implementation forms of the fifteenth aspect, or causes the terminal device to execute the method in the sixteenth aspect or any one of the possible implementation forms of the sixteenth aspect. It should be understood that the terminal device may be a chip, a processor, etc., which is not limited in the present application.

[0063] In the above embodiment of the present application, in each polarization direction, the difference between the quantities of -A-Aj, -A+Aj, A-Aj, and A+Aj representing training symbols and pilot symbols is less than or equal to 1, thereby effectively ensuring the equality between symbols. In addition, in each polarization direction, the sum of the real parts of the complex numbers corresponding to the training symbols and pilot symbols in one subframe is 0, and the sum of their imaginary parts is also 0, so that DC balance can be achieved, improving the quality of the signal restored at the receiving end. [Brief description of the drawings]

[0064] [Figure 1] FIG. 1 is a block diagram of a configuration of a communication system. [Diagram 2] FIG. 2 is a schematic diagram of a framing process. [Diagram 3] FIG. 13 is a schematic diagram of another framing process. [Figure 4] 2 is a flow chart of a transmission method for optical communication according to the present application. [Figure 5A]FIG. 2 is a schematic diagram of the location of training or pilot symbols in a constellation diagram for DP-16QAM. [Figure 5B] FIG. 2 is another schematic diagram of the location of training or pilot symbols in a constellation diagram for DP-16QAM. [Figure 6] 1 shows a diagram of a structure of a superframe, a diagram of a structure of a first type of subframe within the superframe, and a diagram of a structure of a second type of subframe within the superframe according to the present application. [Figure 7] 1 shows the mapping relationship between DP-QPSK symbols and bits. [Figure 8] The mapping relationship between DP-16QAM symbols and bits is shown. [Figure 9] 1 illustrates a diagram of a structure of a particular superframe, a first subframe in the superframe, and another subframe other than the first subframe in the superframe, according to an embodiment of the present application. [Figure 10] 1 shows a graph of aperiodic autocorrelation results of a particular frame alignment word sequence in the X polarization direction, a graph of aperiodic autocorrelation results of a particular frame alignment word sequence in the Y polarization direction, and a graph of aperiodic cross-correlation results of a particular frame alignment word sequence in two polarization directions according to an embodiment of the present application. [Figure 11] 1 illustrates a graph of aperiodic autocorrelation results of a specific training sequence in an X polarization direction, a graph of aperiodic autocorrelation results of a specific training sequence in a Y polarization direction, and a graph of aperiodic cross-correlation results of a specific training sequence in two polarization directions according to an embodiment of the present application. [Figure 12] 1 illustrates a graph of cyclic autocorrelation results of a particular pilot sequence in an X polarization direction, a graph of cyclic autocorrelation results of a particular pilot sequence in a Y polarization direction, and a graph of cyclic cross-correlation results of a particular pilot sequence in two polarization directions according to an embodiment of the present application. [Figure 13] 10 shows a spectral diagram of a superframe for DP-16QAM when the superframe structure shown in FIG. 9 is used, and a spectral diagram of a random DP-16QAM signal. [Figure 14] 10 shows a spectral diagram of a superframe for DP-QPSK and a spectral diagram of a random DP-QPSK signal when the superframe structure shown in FIG. 9 is used. [Figure 15] FIG. 1 illustrates a diagram of a structure of a particular superframe, a diagram of a structure of a first subframe within the particular superframe, and a diagram of another subframe structure other than the first subframe within the particular superframe, according to another embodiment of the present application. [Figure 16] 1 shows a graph of aperiodic autocorrelation results of a particular frame alignment word sequence in the X polarization direction, a graph of aperiodic autocorrelation results of a particular frame alignment word sequence in the Y polarization direction, and a graph of aperiodic cross-correlation results of a particular frame alignment word sequence in two polarization directions, according to another embodiment of the present application. [Figure 17] 13 shows a graph of aperiodic autocorrelation results of a specific training sequence in an X polarization direction, a graph of aperiodic autocorrelation results of a specific training sequence in a Y polarization direction, and a graph of aperiodic cross-correlation results of a specific training sequence in two polarization directions according to another embodiment of the present application. [Figure 18] 10 shows a graph of a cyclic autocorrelation result of a specific pilot sequence in an X polarization direction, a graph of a cyclic autocorrelation result of a specific pilot sequence in a Y polarization direction, and a graph of a cyclic cross-correlation result of a specific pilot sequence in two polarization directions according to another embodiment of the present application. [Figure 19] FIG. 16 is a spectral diagram of a superframe for DP-16QAM when the superframe structure shown in FIG. 15 is used. [Figure 20]FIG. 1 illustrates a diagram of a structure of a particular superframe, a diagram of a structure of a first subframe within the particular superframe, and a diagram of another subframe structure other than the first subframe within the particular superframe, according to another embodiment of the present application. [Figure 21] 13 shows a graph of aperiodic autocorrelation results of a specific training sequence in an X polarization direction, a graph of aperiodic autocorrelation results of a specific training sequence in a Y polarization direction, and a graph of aperiodic cross-correlation results of a specific training sequence in two polarization directions according to another embodiment of the present application. [Figure 22] 10 shows a graph of a cyclic autocorrelation result of a specific pilot sequence in an X polarization direction, a graph of a cyclic autocorrelation result of a specific pilot sequence in a Y polarization direction, and a graph of a cyclic cross-correlation result of a specific pilot sequence in two polarization directions according to another embodiment of the present application. [Figure 23] FIG. 21 is a spectral diagram of a superframe for DP-16QAM when the superframe structure shown in FIG. 20 is used. [Figure 24] FIG. 1 illustrates a diagram of a structure of a particular superframe, a diagram of a structure of a first subframe within the particular superframe, and a diagram of another subframe structure other than the first subframe within the particular superframe, according to another embodiment of the present application. [Diagram 25] FIG. 25 is a spectral diagram of a superframe for DP-16QAM when the superframe structure shown in FIG. 24 is used. [Figure 26] FIG. 1 illustrates a diagram of a structure of a particular superframe, a diagram of a structure of a first subframe within the particular superframe, and a diagram of another subframe structure other than the first subframe within the particular superframe, according to another embodiment of the present application. [Figure 27]13 shows a graph of aperiodic autocorrelation results of a specific training sequence in an X polarization direction, a graph of aperiodic autocorrelation results of a specific training sequence in a Y polarization direction, and a graph of aperiodic cross-correlation results of a specific training sequence in two polarization directions according to another embodiment of the present application. [Figure 28] 10 shows a graph of a cyclic autocorrelation result of a specific pilot sequence in an X polarization direction, a graph of a cyclic autocorrelation result of a specific pilot sequence in a Y polarization direction, and a graph of a cyclic cross-correlation result of a specific pilot sequence in two polarization directions according to another embodiment of the present application. [Figure 29] FIG. 27 is a spectral diagram of a superframe for DP-16QAM when the superframe structure shown in FIG. 26 is used. [Diagram 30] FIG. 1 illustrates a diagram of a structure of a particular superframe, a diagram of a structure of a first subframe within the particular superframe, and a diagram of another subframe structure other than the first subframe within the particular superframe, according to another embodiment of the present application. [Diagram 31] FIG. 31 is a spectral diagram of a superframe for DP-16QAM when the superframe structure shown in FIG. 30 is used. [Diagram 32] 2 is a flowchart of a transmission method for optical communication according to an embodiment of the present application. [Diagram 33] 1 illustrates a diagram of a structure of a particular superframe, a first subframe in the superframe, and another subframe other than the first subframe in the superframe, according to an embodiment of the present application. [Diagram 34] 2 is a schematic diagram of a pilot symbol generation structure according to an embodiment of the present application; [Diagram 35] 4 is a schematic diagram of another pilot symbol generation structure according to an embodiment of the present application; [Diagram 36]1 shows a graph of a cyclic autocorrelation result of a particular sequence of pilot symbols in an X polarization direction, a graph of a cyclic autocorrelation result of a particular sequence of pilot symbols in a Y polarization direction, and a graph of a cyclic cross-correlation result of a particular sequence of pilot symbols in two polarization directions according to an embodiment of the present application. [Figure 37] 4 is a schematic diagram of another pilot symbol generation structure according to an embodiment of the present application; [Figure 38] 1 shows a graph of a cyclic autocorrelation result of a particular sequence of pilot symbols in an X polarization direction, a graph of a cyclic autocorrelation result of a particular sequence of pilot symbols in a Y polarization direction, and a graph of a cyclic cross-correlation result of a particular sequence of pilot symbols in two polarization directions according to an embodiment of the present application. [Figure 39] 1 illustrates a diagram of a structure of a particular superframe, a first subframe in the superframe, and another subframe other than the first subframe in the superframe, according to an embodiment of the present application. [Diagram 40] 4 is a schematic diagram of another pilot symbol generation structure according to an embodiment of the present application; [Diagram 41] 1 shows a graph of a cyclic autocorrelation result of a particular sequence of pilot symbols in an X polarization direction, a graph of a cyclic autocorrelation result of a particular sequence of pilot symbols in a Y polarization direction, and a graph of a cyclic cross-correlation result of a particular sequence of pilot symbols in two polarization directions according to an embodiment of the present application. [Diagram 42] 4 is a flowchart of another transmission method for optical communication according to an embodiment of the present application. [Diagram 43] 4 is a schematic diagram of another pilot symbol generation structure according to an embodiment of the present application; [Diagram 44]1 shows a graph of a cyclic autocorrelation result of a particular sequence of pilot symbols in an X polarization direction, a graph of a cyclic autocorrelation result of a particular sequence of pilot symbols in a Y polarization direction, and a graph of a cyclic cross-correlation result of a particular sequence of pilot symbols in two polarization directions according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0065] Before describing the embodiments of the present application in detail, the application scenario of the embodiments of the present application will be described first. Figure 1 is a block diagram of the configuration of a communication system. At the transmitting end, a source provides a data stream to be transmitted. An encoder receives and encodes the data stream. The codeword information obtained by encoding and combining parity bits and information bits is sent to the transmitting end signal processor for framing and transmitted to the receiving end through a channel. After receiving a signal distorted by noise or other impairments in the channel, the receiving end sends the signal to the receiving end signal processor for dispersion compensation, alignment, phase recovery, and other operations. Then, a decoder decodes the signal to restore the original data, and transmits the data to the destination. The encoding method provided in this application is applied to the transmitting end signal processor shown in Figure 1, which is a very important part in a communication system.

[0066] In the transmitting end signal processor, the framing process can be shown in Fig. 2 or Fig. 3. In the framing method, as shown in Fig. 2, symbol mapping, including but not limited to Quadrature Phase Shift Keying (QPSK) and Quadrature Amplitude Modulation (QAM), is performed on the received data sequence, and then polarization symbol distribution is performed to obtain dual-polarization (DP) symbols, for example, DP-QPSK, DP-8QAM, DP-16QAM, DP-32QAM, and DP-64QAM. Framing is performed on a certain number of dual-polarization symbols, inserting frame alignment word symbols, training symbols, reserved symbols, and pilot symbols in the X and Y polarization directions, respectively, to obtain a dual-polarization symbol sequence to be transmitted, which is called a super-frame. It should be noted that after symbol mapping, the symbols may be further interleaved, and the aforementioned framing is performed on the interleaved symbols. In the present application, one dual-polarized symbol may be represented by two symbols, one of which is in the X polarization direction and the other 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 16 complex numbers: ±1±1j, ±1±3j, ±3±1j, and ±3±3j. In some cases, it should be understood that the real and imaginary parts may be normalized, but the essence does not change. Furthermore, a sequence having N dual-polarized symbols may be completely represented by two complex sequences having a length N, one complex sequence representing the symbols on the X polarization and the other complex sequence representing the symbols on the Y polarization. Each complex sequence having a length N is represented by a real part sequence having a length N and an imaginary part sequence having a length N, where N is an integer greater than 1.

[0067] Generally, the received data sequence is the 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, for the received data sequence, according to the symbol mapping rule used, bits corresponding to frame alignment word symbols, training symbols, reserved symbols, and pilot symbols are inserted before symbol mapping, and then symbol mapping and polarization symbol distribution are performed to obtain the same superframe as that obtained in the operation of FIG. 2. In this case, before symbol mapping, interleaving may further be performed on the bit sequence into which bits corresponding to symbols are inserted, and then symbol mapping and polarization symbol distribution are performed to obtain the same superframe as that obtained in the operation of FIG. 2. It should be understood that another framing method is not excluded, and the details are not described in this application.

[0068] An embodiment of the present application provides a transmission method for optical communication. As shown in Figure 4, the transmission method includes the following steps:

[0069] 401: generating a superframe including a plurality of subframes, where one subframe includes training symbols and pilot symbols, each of the training symbols and pilot symbols being one of -A-Aj, -A+Aj, A-Aj, and A+Aj, and in the training symbols and pilot symbols included in each subframe, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively:

number

number

number

[0070] 402: Transmit the superframe.

[0071] In this embodiment of the present application, the value of A is determined by the modulation format used when the symbol is generated. 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 which case A=±1, and each training symbol can be represented by one of -1-1j, -1+1j, 1-1j, and 1+1j. In one subframe, there are all training symbols represented by four complex numbers, and similarly for pilot symbols. When 16QAM is used, there are 16 symbols, in which case A=±1 or ±3. In general, both training symbols and pilot symbols are the outermost four symbols of the constellation diagram, as shown by the hollow symbol in FIG. 5A. In this case, when A=3 or -3, each training symbol can be represented by one of -3-3j, -3+3j, 3-3j, and 3+3j. In one subframe, there are all training symbols represented by four complex numbers, and the same for pilot symbols. Similarly, when 64QAM is used, A=±1, ±3, ±5, or ±7. In general, for the complex numbers representing training symbols and pilot symbols, A=±5 or ±7. Assuming A=5 or -5, each training symbol can be represented by one of -5-5j, -5+5j, 5-5j, and 5+5j. In one subframe, there are all training symbols represented by four complex numbers. Similarly for pilot symbols. Alternatively, higher order modulation formats may be used, and the details are not described in this application. In the actual transmission process, this makes the symbol error probability relatively low and facilitates channel estimation.

[0072] Alternatively, it should be noted that the symbols in the constellation diagram may be compressed, and the value of A is compressed accordingly. Taking 16QAM as an example, power normalization is performed on the 16 symbols in the 16QAM constellation diagram, in which case the value is

number

number

[0073] It should be understood that when the pilot symbols and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj are the outermost four symbols of a constellation diagram, the training symbols and pilot symbols have a relatively high sensitivity but a relatively large peak to average power ratio, and when the values ​​of the pilot symbols and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj are the innermost four symbols of a constellation diagram, the training symbols and pilot symbols have a relatively small noise but a relatively low sensitivity.

[0074] It should be noted that in some practical application scenarios, the pilot symbols and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj may not be symbols in the constellation diagram of the modulation format used, but may be four symbols in the intermediate region between the outermost four symbols and the innermost four symbols of the constellation diagram. In this case, the training symbols and pilot symbols have considerable noise and sensitivity, but have a relatively low peak-to-average power ratio. Take 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. Specifically, as shown in FIG. 5B, the outermost four symbols of the constellation diagram are 3+3j, 3-3j, -3+3j, and -3-3j, and the innermost four symbols of the constellation diagram are 1+1j, 1-1j, -1+1j, and -1-1j. The values ​​of the pilot and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj may be four symbols in the intermediate region between the outermost four symbols and the innermost four symbols of the 16QAM constellation diagram. The specific value of the real number A may be selected according to the actual application scenario, so that the peak-to-average power ratio, noise, and sensitivity of the training and pilot symbols have a good compromise. For example, the real number

number

number

number

number

number

number

[0075] In addition, the two polarization directions are orthogonal to each other. In other words, when one polarization direction is X polarization, the other polarization direction is Y polarization, and when one polarization direction is Y polarization, the other polarization direction is X polarization. In this embodiment of the present application, in one polarization direction, the sum of the number of training symbols and pilot symbols included in one subframe is N TS +N PS −1, which is 5 or more. Since one symbol is both a training symbol and a pilot symbol, the sum of the numbers is N TS +N PS but one less than the sum of the numbers of symbols of the two types.

[0076] In one subframe, the sequence of training symbols in one polarization direction is different from the sequence of training symbols in the other polarization direction, and the sequence of pilot symbols in one polarization direction is different from the sequence of pilot symbols in the other polarization direction. For example, if the sequence of training symbols in one polarization direction is -A-Aj, -A-Aj, A+Aj, and A-Aj, the sequence of training symbols in the other polarization direction cannot be the same according to the same sequence, but can be -A-Aj, -A-Aj, A+Aj, and A+A, that is, one of the symbols is different, so as to avoid the problem that the receiving end cannot distinguish the two polarization directions in actual transmission.

[0077] In the solution of this embodiment of the present application, one subframe is allocated to each polarization direction, for a total of N TS +N PS -1 training symbol and pilot symbol, i.e., the total number of -A-Aj, -A+Aj, A-Aj, and A+Aj representing the training symbols and pilot symbols is N TS +N PS −1, and the difference between the amounts of the four symbols is less than or equal to 1. In addition, in one subframe, the number of four complex numbers (−A−Aj, −A+Aj, A−Aj, and A+Aj) representing the training symbols and pilot symbols is the same in the two polarization directions, and both are (N TS +N PS -1) / 2, which effectively guarantees the symbol quantity balance. In addition, in each polarization direction, the sum of the real parts of the complex numbers corresponding to the training symbols and pilot symbols in one subframe is 0, and the sum of the imaginary parts is also 0, so that DC balance can be achieved, and the quality of the signal restored at the receiving end is improved.

[0078] A superframe in this application, also called a multiframe, includes multiple subframes and has the structure shown in Figure 6(a). Each subframe contains the same number of symbols (N S symbols) in a subframe. There are two main types of subframes. One type of subframe contains a frame alignment word symbol and is usually the first subframe in a superframe, although it is not excluded that the subframe may be located in another position in the superframe. The other subframe is of a second type. The structure of the first type of subframe is shown in Figure 6(b). The first N TS These symbols are training symbols that may be used for link training and / or subframe alignment. Generally, the first symbol of a subframe is both a training symbol and a pilot symbol. Indeed, the first N TSAny of the symbols can be both training symbols and pilot symbols, which is not limited in this application. In addition, in the first type subframe, a symbol at a fixed position every 64 symbols or 48 symbols is a pilot symbol used for carrier phase recovery. In FIG. 6(b), for example, the first symbol every 64 symbols is a pilot symbol, providing a diagram of the frame structure of the first type subframe. The pilot signal is followed by a number of frame alignment word symbols used for inter-superframe alignment. The frame alignment word symbols may be used together with the training symbols for inter-superframe alignment or may be used together with the pilot symbols to implement the same function. The frame alignment word symbols are arranged consecutively and are used as the training symbols. symbol It should be understood that the frame alignment word may be adjacent to the frame alignment word , in which case it is shown in FIG. symbol and training symbol There may be a gap of one or more symbols between the frame alignment word symbols. In addition, after the frame alignment word symbols, there are usually reserved symbols that may be reserved for other purposes in the future. Alternatively, the reserved symbols may be in one of the second type subframes, which is not limited in this application. The remaining symbols are pre-framing symbols that contain information and parity bits, where the pilot symbols do not overlap with the reserved symbols or the pre-framing symbols. For example, there is no symbol that is both a pilot symbol and a pre-framing symbol.

[0079] The frame structure of the second type of subframe is shown in FIG. TS These symbols are also training symbols. In general, the first symbol of a subframe is both a training symbol and a pilot symbol. Indeed, the first N TSAny of the symbols can be both training symbols and pilot symbols, which is not limited in this application. Similar to the first type of subframe, the symbol at a fixed position every 64 symbols or 48 symbols is also a pilot symbol used for carrier phase recovery. In (c) of FIG. 6, for example, the first symbol every 64 symbols is a pilot symbol, providing a diagram of the frame structure of the second type of subframe. Except for the training symbols and pilot symbols, the other symbols are generally pre-framing symbols that contain information and parity bits, and the pilot symbols do not overlap with the pre-framing symbols.

[0080] Additionally, the present application further provides specific possible quantities of symbols for several different cases, examples of some of which are given below:

[0081] (1) Number of symbols before framing, N CW is 175616. For example, a CFEC coding scheme in which a staircase code and a Hamming code are concatenated may be used, or other coding schemes may be used. The first symbol of every 64 symbols is a pilot symbol. In this case, item 1 of Table 1 indicates the following parameters: the number of subframes N SF , the number of training symbols in each subframe N TS and the number of pilot symbols N PS , the number of symbols in each subframe N S , the number of symbols in the superframe N F , the superframe overhead OH, the number of frame alignment word symbols N FAW and the number of reserved symbols N RES and so on, where N FAW is even, and the corresponding N RES >0, and OH=(N F -N CW ) / N CW It is.

[0082] Except for OH, all other parameters are symbol numbers, which may be understood as the number of dual-polarized symbols or as the amount of symbols in one polarization direction. In addition, the amount of different symbols in the two polarization directions is the same. For example, there are 10 training symbols in one polarization direction, and there are also 10 training symbols in the other polarization direction. In total, there are 10 dual-polarized training symbols. All subsequent tables are understood in this way and will not be repeated in this application. [Table 14]

[0083] (2) The number of symbols before framing, N CW is 172032. For example, the Open FEC (OFEC) coding scheme may be used, or another coding scheme may be used. The first symbol of every 64 symbols is a pilot symbol. In this case, item 1 of Table 2 indicates the following parameters: the number of subframes N SF , the number of training symbols in each subframe N TS and the number of pilot symbols N PS , the number of symbols in each subframe N S , the number of symbols in the superframe N F , the superframe overhead OH, the number of frame alignment word symbols N FAW and the number of reserved symbols N RES and so on, where N FAW is even, and the corresponding N RES >0, and OH=(N F -N CW ) / N CW It is. [Table 15]

[0084] (3) Number of symbols before framing, N CWis 175616. For example, a CFEC coding scheme is used. The first symbol of every 48 symbols is a pilot symbol. In this case, item 1 of Table 3 indicates the following parameters: the number of subframes N SF , the number of training symbols in each subframe N TS and the number of pilot symbols N PS , the number of symbols in each subframe N S , the number of symbols in the superframe N F , the superframe overhead OH, the number of frame alignment word symbols N FAW and the number of reserved symbols N RES and so on, where N FAW is even, and the corresponding N RES >0, and OH=(N F -N CW ) / N CW It is. [Table 16] TIFF2025069189000057.tif59170

[0085] (4) Number of symbols before framing, N CW is 172032. For example, an OFEC coding scheme is used. The first symbol of every 48 symbols is a pilot symbol. In this case, item 1 of Table 4 indicates the following parameters: the number of subframes N SF , the number of training symbols in each subframe N TS and the number of pilot symbols N PS , the number of symbols in each subframe N S , the number of symbols in the superframe N F , the superframe overhead OH, the number of frame alignment word symbols N FAW and the number of reserved symbols N RES and so on, where N FAW is even, and the corresponding N RES >0, and OH=(N F -N CW) / N CW It is. [Table 17]

[0086] Optionally, the training symbols are arranged consecutively in a subframe. In one polarization direction, the number of consecutive real part elements "-A" or "A" in the training symbols included in one subframe is less than or equal to M0, and the number of consecutive imaginary part elements "-A" or "A" is less than or equal to M0. In addition, the number of consecutive identical training symbols in one subframe is less than or equal to M1, where both M0 and M1 are positive integers, and 2≦M1≦M0≦5. The training sequence obtained under this condition facilitates clock recovery, thereby helping to improve the quality of the signal restored at the receiving end.

[0087] Furthermore, in one polarization direction, the number of consecutive real part elements "-A" or "A" in the training symbols included in one subframe is not more than 5, and the number of consecutive imaginary part elements "-A" or "A" is not more than 5. For example, there are six training symbols in one polarization direction. For the sequence -A-Aj, -A-Aj, -A-Aj, -A-Aj, -A-Aj, and A+Aj, the real part elements have five consecutive -A, which meets the requirements of this embodiment. However, for the sequence -A-Aj, -A-Aj, -A-Aj, -A-Aj, -A-Aj, and -A+Aj, the real part elements have six consecutive -A, which does not meet the requirements of this embodiment. Furthermore, in one polarization direction, the number of consecutive identical training symbols in one subframe does not exceed four. In this case, the originally satisfying sequences -A-Aj, -A-Aj, -A-Aj, -A-Aj, -A-Aj, and A+Aj no longer satisfy the requirements of this embodiment since there are now five consecutive -A-Aj.

[0088] Optionally, N TSis an even number, that is, when there is an even number of training symbols in one polarization direction in each subframe, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the training symbols included in each subframe are respectively

number

number

number

number

[0089] N TS is an odd number, that is, when there are an odd number of training symbols in one polarization direction in each subframe, the numbers of −A−Aj, −A+Aj, A−Aj, and A+Aj in one polarization direction, excluding the training symbols also used as pilot symbols, in the training symbols included in each subframe, are respectively

number

number

number

number

[0090] In the solution of the above embodiment, in each polarization direction, the numbers of training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj included in one subframe are close to each other. TS When N is an even number, in one subframe, the number of four different symbols (in the form of complex numbers) representing training symbols in the two polarization directions is the same, and the number of all four symbols is N TS / 2, the sum of the real parts of the complex numbers corresponding to the training symbols is 0, and the sum of the imaginary parts is also 0. TS When N is odd, in one subframe, the number of four different symbols (in the form of complex numbers) representing the training symbols in the two polarization directions is the same, except for the training symbols that are also used as pilot symbols, and the number of all four symbols is (N TS -1) / 2, and N TSThe sum of the real parts of the complex numbers corresponding to -1 training symbols is 0, and the sum of their imaginary parts is also 0. This effectively ensures the balance of the quantity of symbols, can achieve DC balance, and improves the quality of the signal restored at the receiving end. It should be understood that the pilot sequence composed of pilot symbols has the same effect.

[0091] Optionally, in each subframe, the number of pilot symbols in one polarization direction, N PS When the remainder when dividing by 4 is 0, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe are N PS / 4+1, N PS / 4-1, N PS / 4-1, and N PS / 4+1, and the number in the other polarization direction is N PS / 4-1, N PS / 4+1, N PS / 4+1, and N PS / 4-1 or the amount in both polarization directions is N PS / 4. N PS When the remainder when dividing by 4 is 2, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe are respectively (N PS -2) / 4, (N PS -2) / 4+1, (N PS -2) / 4+1, and (N PS −2) / 4, and the number in the other polarization direction is (N PS -2) / 4+1, (N PS -2) / 4, (N PS -2) / 4, and (N PS -2) / 4+1. N PS When the remainder when dividing by 4 is 1, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe, excluding the pilot symbols that are also used as training symbols, are respectively (NPS -1) / 4+1, (N PS -1) / 4-1, (N PS -1) / 4-1, and (N PS -1) / 4+1, and the number in the other polarization direction is (N PS -1) / 4-1, (N PS -1) / 4+1, (N PS -1) / 4+1, and (N PS -1) / 4-1, or their amounts in both polarization directions are (N PS -1) / 4. N PS When the remainder when dividing by 4 is 3, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe, excluding the pilot symbols also used as training symbols, are respectively (N PS -3) / 4, (N PS -3) / 4+1, (N PS -3) / 4+1, and (N PS -3) / 4, and the number in the other polarization direction is (N PS -3) / 4+1, (N PS -3) / 4, (N PS -3) / 4, and (N PS -3) / 4+1.

[0092] In the above embodiment, the difference in the amount of pilot symbols -A-Aj, -A+Aj, A-Aj and A+Aj contained in one subframe is relatively small, thereby effectively ensuring the balance between symbols. In addition, in each polarization direction, except for the pilot symbols that are also used as training symbols (when there are an odd number of pilot symbols), the sum of the real parts of the complex numbers corresponding to other pilot symbols is 0, and the sum of their imaginary parts is also 0, so that the DC balance can be achieved, and the quality of the signal restored at the receiving end is improved.

[0093] In the multiple subframe structure included in the superframe, the first type subframe further includes a frame alignment word symbol, as shown in (b) of FIG. 6. The multiple frame alignment word symbols are consecutively arranged in the first type subframe, and each frame alignment word symbol is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, and the value of A corresponding to the frame alignment word symbol is also determined by the modulation format used, which is consistent with the method of determining the value of A corresponding to the training symbol and the pilot symbol described in the previous embodiment, and the details will not be described again here. It should be understood that in some application scenarios, each of the frame alignment word symbols is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, and the value of A corresponding to the frame alignment word symbol may be a real number different from that corresponding to the training symbol and the pilot symbol described in the previous embodiment. For simplicity of explanation, for example, the values ​​of A are equal in this application.

[0094] Optionally, in one polarization direction, in the frame alignment word symbols included in the first type subframe, the number of consecutive real part elements "-A" or "A" is less than or equal to M2, and the number of consecutive imaginary part elements "-A" or "A" is less than or equal to M2. In addition, the number of consecutive same frame alignment word symbols in the first type subframe is less than or equal to M3, where both M2 and M3 are positive integers, and 2≦M3≦M2≦5. The frame alignment word sequence obtained under this condition facilitates clock recovery, thereby helping to improve the quality of the signal restored at the receiving end.

[0095] Furthermore, in one polarization direction, in the frame alignment word symbols included in the first type subframe, the number of consecutive real part elements "-A" or "A" is not more than 5, and the number of consecutive imaginary part elements "-A" or "A" is not more than 5. Optionally, in one polarization direction, the number of consecutive same frame alignment word symbols in the first type subframe is not more than 4. A specific example is described in the example of the training symbol in the preceding embodiment and will not be repeated in this application.

[0096] In a first type subframe, there may be an even number of frame alignment word symbols in one polarization direction, and the following condition may be satisfied: in the frame alignment word symbols included in the first type subframe, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are, respectively:

number

number

[0097] For example, N FAW When N = 22, the numbers of symbols -A-Aj, -A+Aj, A-Aj, and A+Aj in the X polarization direction are 5, 6, 6, and 5, respectively, and the amounts of symbols -A-Aj, -A+Aj, A-Aj, and A+Aj in the Y polarization direction are 6, 5, 5, and 6, respectively, where the two polarization directions are perpendicular to each other. FAWWhen A=24, the number of symbols -A-Aj, -A+Aj, A-Aj, and A+Aj in any polarization direction is 6, and inter-symbol balance and DC balance can be achieved, thereby improving the quality of the signal restored at the receiving end.

[0098] Next, the present application provides several possible symbol sequences, including a frame alignment word sequence composed of frame alignment word symbols in the first type of subframe, a training sequence composed of training symbols in each subframe, and a pilot sequence composed of pilot symbols in each subframe. The training sequences in different subframes are the same, and the pilot sequences in different subframes are also the same.

[0099] First, there may be several possible frame alignment word sequences that can guarantee relatively good cross-correlation between the frame alignment word sequences in the two polarization directions without introducing too much overhead:

[0100] (1)N FAW Assuming that r = 20, the frame alignment word sequence can be any item in Table 5. It should be understood that one index corresponds to a group of frame alignment word sequences in two polarizations, and one item represents a sequence corresponding to one index. In addition, if polarization 1 for any item in the table is X polarization, polarization 2 is Y polarization, and when polarization 1 is Y polarization, polarization 2 is X polarization. The same representation method is applied to the subsequent training sequence and pilot sequence tables, and the details are not described in this application. [Table 18] TIFF2025069189000070.tif208170 TIFF2025069189000071.tif206170 TIFF2025069189000072.tif153170

[0101] (2)N FAW = 22, the frame alignment word sequence can be any item in Table 6. [Table 19] TIFF2025069189000074.tif206170 TIFF2025069189000075.tif70170

[0102] (3)N FAW = 24, the frame alignment word sequence can be any item in Table 7. [Table 20] TIFF2025069189000077.tif206170 TIFF2025069189000078.tif209170 TIFF2025069189000079.tif191170

[0103] Secondly, there may be several possible pilot sequences that can guarantee a relatively good cross-correlation between the pilot sequences in the two polarization directions:

[0104] (1)N PS Assume that N = 48. TS If the remainder when dividing N by 4 is 1, the pilot sequence is one of the items in Table 8-1 below. TS If the remainder when N is divided by 4 is 3, the pilot sequence is one of the items in Table 8-1 or Table 8-2 below. TS +N PS is odd and N PS If is even, then N TS must be odd, N TSWhen you divide by 4, the remainder is always 1 or 3, so N PS If is odd, then N TS must be an even number, and N TS Please understand that when you divide by 4, the remainder will definitely be 0 or 2, and will not be repeated later. [Table 21] TIFF2025069189000081.tif220170 TIFF2025069189000082.tif242170 TIFF2025069189000083.tif250170 TIFF2025069189000084.tif95170 [Table 22] TIFF2025069189000086.tif235170 TIFF2025069189000087.tif235170 TIFF2025069189000088.tif234170 TIFF2025069189000089.tif249170 TIFF2025069189000090.tif234170 TIFF2025069189000091.tif235170 TIFF2025069189000092.tif234170TIFF2025069189000093.tif233170 TIFF2025069189000094.tif91170

[0105] (2)N PS Assume that N = 56. TS If the remainder when N is divided by 4 is 1, the pilot sequence is one of the items in Table 9-1 below. TS If the remainder when divided by 4 is 3, the pilot sequence is one of the items in Table 9-1 or Table 9-2 below. [Table 23] TIFF2025069189000096.tif236170 TIFF2025069189000097.tif234170 TIFF2025069189000098.tif235170 TIFF2025069189000099.tif235170 TIFF2025069189000100.tif233170 TIFF2025069189000101.tif235170 TIFF2025069189000102.tif58170 [Table 24] TIFF2025069189000104.tif233170 TIFF2025069189000105.tif234170 TIFF2025069189000106.tif234170 TIFF2025069189000107.tif189170

[0106] (3)N PS Assume that N = 57. TS If the remainder when divided by 4 is 0, the pilot sequence is one of the items in Table 10-1 below. TS If the remainder when divided by 4 is 2, the pilot sequence is one of the items in Table 10-1 or Table 10-2 below. [Table 25] TIFF2025069189000109.tif248170 TIFF2025069189000110.tif220170 TIFF2025069189000111.tif220170 TIFF2025069189000112.tif66170 [Table 26] TIFF2025069189000114.tif219170 TIFF2025069189000115.tif243170 TIFF2025069189000116.tif155170

[0107] (4)N PS Assume that N = 65. TS If the remainder when dividing N by 4 is 0, the pilot sequence is one of the items in Table 11-1 below. TS If the remainder when divided by 4 is 2, the pilot sequence is one of the items in Table 11-1 or Table 11-2 below. [Table 27] TIFF2025069189000118.tif220170 TIFF2025069189000119.tif218170 TIFF2025069189000120.tif219170 TIFF2025069189000121.tif217170 TIFF2025069189000122.tif218170 TIFF2025069189000123.tif221170 TIFF2025069189000124.tif218170 TIFF2025069189000125.tif118170 [Table 28] TIFF2025069189000127.tif220170 TIFF2025069189000128.tif220170 TIFF2025069189000129.tif218170 TIFF2025069189000130.tif219170 TIFF2025069189000131.tif220170 TIFF2025069189000132.tif218170 TIFF2025069189000133.tif219170 TIFF2025069189000134.tif117170

[0108] (5)N PS Assume that r = 74 and the pilot sequence is one of the items in Table 12-1 below. Alternatively, any item in Table 12-2 below is selected as the pilot sequence for one polarization and any item in Table 12-3 below is selected as the pilot sequence for the other polarization. Alternatively, any item in Table 12-4 below is selected as the pilot sequence for one polarization and any item in Table 12-5 below is selected as the pilot sequence for the other polarization. [Table 29] TIFF2025069189000136.tif249170 TIFF2025069189000137.tif248170 TIFF2025069189000138.tif247170 TIFF2025069189000139.tif72170 [Table 30] TIFF2025069189000141.tif118170 [Table 31] TIFF2025069189000143.tif118170 [Table 32] TIFF2025069189000145.tif117170 [Table 33] TIFF2025069189000147.tif116170

[0109] (6)N PS Assume that N = 76. TS If the remainder when divided by 4 is 1, the pilot sequence is one of the items in Table 13-1 below. TS If the remainder when divided by 4 is 3, the pilot sequence is one of the items in Table 13-1 or Table 13-2 below. [Table 34] TIFF2025069189000149.tif248170 TIFF2025069189000150.tif248170 TIFF2025069189000151.tif248170 TIFF2025069189000152.tif246170 TIFF2025069189000153.tif250170 TIFF2025069189000154.tif249170 TIFF2025069189000155.tif74170 [Table 35] TIFF2025069189000157.tif248170 TIFF2025069189000158.tif248170 TIFF2025069189000159.tif248170 TIFF2025069189000160.tif248170 TIFF2025069189000161.tif248170 TIFF2025069189000162.tif72170

[0110] (7)N PS = 50 and the pilot sequence is one of the items in Table 14 below. [Table 36] TIFF2025069189000164.tif233170 TIFF2025069189000165.tif234170 TIFF2025069189000166.tif235170 TIFF2025069189000167.tif234170 TIFF2025069189000168.tif147170

[0111] (8)N PS When r = 66, the pilot sequence is one of the entries in Table 15-1 below. Alternatively, any entry from Table 15-2 is selected as the pilot sequence for one polarization and any entry from Table 15-3 is selected as the pilot sequence for the other polarization. Alternatively, any entry from Table 15-4 is selected as the pilot sequence for one polarization and any entry from Table 15-5 below is selected as the pilot sequence for the other polarization. [Table 37] [Table 38] TIFF2025069189000171.tif57170 [Table 39] TIFF2025069189000173.tif60170 [Table 40] TIFF2025069189000175.tif57170 [Table 41] TIFF2025069189000177.tif57170

[0112] (9)N PS = 68, N TS If the remainder when divided by 4 is 1, the pilot sequence is an item in Table 16-1. TS If the remainder when divided by 4 is 3, the pilot sequence is an item in Table 16-1 or Table 16-2. [Table 42] TIFF2025069189000179.tif250170 TIFF2025069189000180.tif233170 TIFF2025069189000181.tif250170 TIFF2025069189000182.tif250170 TIFF2025069189000183.tif248170 TIFF2025069189000184.tif249170 [Table 43] TIFF2025069189000186.tif246170 TIFF2025069189000187.tif248170 TIFF2025069189000188.tif248170 TIFF2025069189000189.tif247170 TIFF2025069189000190.tif249170 TIFF2025069189000191.tif248170 TIFF2025069189000192.tif73170

[0113] (10)N PS When = 70, the pilot sequence is one of the items in Table 17 below. [Table 44] TIFF2025069189000194.tif248170 TIFF2025069189000195.tif248170 TIFF2025069189000196.tif250170 TIFF2025069189000197.tif248170 TIFF2025069189000198.tif249170 TIFF2025069189000199.tif73170

[0114] (11)N PS When r = 78, the pilot sequence is an entry in Table 18-1. Alternatively, any entry in Table 18-2 is selected as the pilot sequence in one polarization and any entry in Table 18-3 is selected as the pilot sequence in the other polarization. Alternatively, any entry in Table 18-4 is selected as the pilot sequence in one polarization and any entry in Table 18-5 is selected as the pilot sequence in the other polarization. [Table 45] TIFF2025069189000201.tif210170 TIFF2025069189000202.tif204170 TIFF2025069189000203.tif204170 TIFF2025069189000204.tif192128 TIFF2025069189000205.tif192128 TIFF2025069189000206.tif192128 TIFF2025069189000207.tif197170 TIFF2025069189000208.tif205170 TIFF2025069189000209.tif198170 TIFF2025069189000210.tif193128 TIFF2025069189000211.tif197170 TIFF2025069189000212.tif204170 TIFF2025069189000213.tif198170 TIFF2025069189000214.tif197170 TIFF2025069189000215.tif204170 TIFF2025069189000216.tif248170 TIFF2025069189000217.tif193128 [Table 46] [Table 47] [Table 48] [Table 49]

[0115] (12)N PS When = 94, the pilot sequence is an item in Table 19. [Table 50] TIFF2025069189000223.tif235170 TIFF2025069189000224.tif160170

[0116] (13)N PS When θ = 102, the pilot sequence is one of the entries in Table 20-1 below. Alternatively, any entry from Table 20-2 is selected as the pilot sequence for one polarization, and any entry from Table 20-3 is selected as the pilot sequence for the other polarization. Alternatively, any entry from Table 20-4 is selected as the pilot sequence for one polarization, and any entry from Table 20-5 below is selected as the pilot sequence for the other polarization. [Table 51] TIFF2025069189000226.tif255170 TIFF2025069189000227.tif255170 TIFF2025069189000228.tif192128 TIFF2025069189000229.tif192128 [Table 52] [Table 53] TIFF2025069189000232.tif87170 [Table 54] [Table 55]

[0117] (14)N PS = 49, N TS If the remainder when divided by 4 is 0, the pilot sequence is one of the items in Table 21-1 below. TS If the remainder when divided by 4 is 2, the pilot sequence is one of the items in Table 21-1 or Table 21-2 below. [Table 56] TIFF2025069189000236.tif236170 TIFF2025069189000237.tif191170 [Table 57] TIFF2025069189000239.tif233170 TIFF2025069189000240.tif235170 TIFF2025069189000241.tif235170 TIFF2025069189000242.tif235170 TIFF2025069189000243.tif59170

[0118] (15)N PS When =51, the pilot sequence is one of the items in Table 22 below. [Table 58] TIFF2025069189000245.tif233170 TIFF2025069189000246.tif233170 TIFF2025069189000247.tif234170 TIFF2025069189000248.tif235170 TIFF2025069189000249.tif235170 TIFF2025069189000250.tif232170 TIFF2025069189000251.tif233170 TIFF2025069189000252.tif233170 TIFF2025069189000253.tif233170 TIFF2025069189000254.tif235170 TIFF2025069189000255.tif235170 TIFF2025069189000256.tif232170 TIFF2025069189000257.tif57170

[0119] (16)N PS When N = 61, TS If the remainder when divided by 4 is 0, the pilot sequence is one of the items in Table 23-1 below. TS If the remainder when divided by 4 is 2, the pilot sequence is one of the items in Table 23-1 or Table 23-2 below. [Table 59] TIFF2025069189000259.tif220170 TIFF2025069189000260.tif219170 TIFF2025069189000261.tif218170 [Table 60] TIFF2025069189000263.tif219170 TIFF2025069189000264.tif116170

[0120] (17)N PS When = 67, the pilot sequence is one of the items in Table 24 below. [Table 61] TIFF2025069189000266.tif248170 TIFF2025069189000267.tif246170 TIFF2025069189000268.tif183170

[0121] (18)N PS When N = 72, TSIf the remainder when divided by 4 is 1, the pilot sequence is one of the items in Table 25-1 below. TS If the remainder when divided by 4 is 3, the pilot sequence is an item in Table 25-1 or Table 25-2 below. Alternatively, any item in Table 25-3 below is selected as the pilot sequence for one polarization direction, and any item in Table 25-4 below is selected as the pilot sequence for the other polarization direction. Alternatively, any item in Table 25-5 below is selected as the pilot sequence for one polarization direction, and any item in Table 25-6 below is selected as the pilot sequence for the other polarization direction. [Table 62] TIFF2025069189000270.tif249170 TIFF2025069189000271.tif248170 TIFF2025069189000272.tif248170 TIFF2025069189000273.tif248170 TIFF2025069189000274.tif250170 TIFF2025069189000275.tif248170 TIFF2025069189000276.tif248170 TIFF2025069189000277.tif249170 TIFF2025069189000278.tif248170 TIFF2025069189000279.tif248170 TIFF2025069189000280.tif250170 TIFF2025069189000281.tif252170 TIFF2025069189000282.tif248170 TIFF2025069189000283.tif72170 [Table 63] TIFF2025069189000285.tif73170 [Table 64] [Table 65] [Table 66] [Table 67]

[0122] (19) In particular, N PS When = 75, the pilot sequence is one of the items in Table 26 below. [Table 68] TIFF2025069189000291.tif251170 TIFF2025069189000292.tif248170 TIFF2025069189000293.tif247170 TIFF2025069189000294.tif248170 TIFF2025069189000295.tif248170 TIFF2025069189000296.tif249170 TIFF2025069189000297.tif249170 TIFF2025069189000298.tif250170 TIFF2025069189000299.tif248170 TIFF2025069189000300.tif250170 TIFF2025069189000301.tif250170 TIFF2025069189000302.tif248170 TIFF2025069189000303.tif190170

[0123] (20)N PS = 80, N TS If the remainder when divided by 4 is 1, the pilot sequence is an item in Table 27-1. TS If the remainder when divided by 4 is 3, the pilot sequence is an entry in Table 27-1 or Table 27-2. Alternatively, any entry in Table 27-3 is selected as the pilot sequence for one polarization direction and any entry in Table 27-4 is selected as the pilot sequence for the other polarization direction. Alternatively, any entry in Table 27-5 is selected as the pilot sequence for one polarization direction and any entry in Table 27-6 is selected as the pilot sequence for the other polarization direction. [Table 69] TIFF2025069189000305.tif211170 TIFF2025069189000306.tif212170 TIFF2025069189000307.tif211170 TIFF2025069189000308.tif213170 TIFF2025069189000309.tif213170 TIFF2025069189000310.tif212170 TIFF2025069189000311.tif212170 TIFF2025069189000312.tif212170 TIFF2025069189000313.tif214170 TIFF2025069189000314.tif146170 [Table 70] TIFF2025069189000316.tif212170 TIFF2025069189000317.tif213170 TIFF2025069189000318.tif212170 TIFF2025069189000319.tif212170 TIFF2025069189000320.tif212170 TIFF2025069189000321.tif147170 [Table 71] TIFF2025069189000323.tif74170 [Table 72] TIFF2025069189000325.tif72170 [Table 73] TIFF2025069189000327.tif74170 [Table 74] TIFF2025069189000329.tif74170

[0124] (21)N PS When N = 92, TS If the remainder when dividing by 4 is 1, the pilot sequence is an item in Table 28-1. Alternatively, any item in Table 28-2 below is selected as the pilot sequence for one polarization direction, and any item in Table 28-3 below is selected as the pilot sequence for the other polarization direction. Alternatively, any item in Table 28-4 below is selected as the pilot sequence for one polarization direction, and any item in Table 28-5 below is selected as the pilot sequence for the other polarization direction. TSIf the remainder when divided by 4 is 3, the pilot sequence is an entry in Table 28-1 or Table 28-6. Alternatively, any entry in Table 28-2 is selected as the pilot sequence for one polarization direction and any entry in Table 28-3 is selected as the pilot sequence for the other polarization direction. Alternatively, any entry in Table 28-4 is selected as the pilot sequence for one polarization direction and any entry in Table 28-5 is selected as the pilot sequence for the other polarization direction. [Table 75] TIFF2025069189000331.tif235170 TIFF2025069189000332.tif161170 [Table 76] TIFF2025069189000334.tif79170 [Table 77] TIFF2025069189000336.tif79170 [Table 78] TIFF2025069189000338.tif81170 [Table 79] TIFF2025069189000340.tif79170 [Table 80] TIFF2025069189000342.tif234170 TIFF2025069189000343.tif235170 TIFF2025069189000344.tif231170 TIFF2025069189000345.tif234170 TIFF2025069189000346.tif233170 TIFF2025069189000347.tif235170 TIFF2025069189000348.tif233170

[0125] (22) In particular, N PS When N = 96, TS If the remainder when divided by 4 is 1, the pilot sequence is an item in Table 29-1. TS If the remainder when divided by 4 is 3, the pilot sequence is an entry in Table 29-1 or Table 29-2. Alternatively, any entry in Table 29-3 is selected as the pilot sequence for one polarization direction and any entry in Table 29-4 is selected as the pilot sequence for the other polarization direction. Alternatively, any entry in Table 29-5 is selected as the pilot sequence for one polarization direction and any entry in Table 29-6 is selected as the pilot sequence for the other polarization direction. [Table 81] TIFF2025069189000350.tif192128 TIFF2025069189000351.tif255170 TIFF2025069189000352.tif192128 TIFF2025069189000353.tif255170 TIFF2025069189000354.tif192128 TIFF2025069189000355.tif255170 TIFF2025069189000356.tif194128 TIFF2025069189000357.tif96170 [Table 82] TIFF2025069189000359.tif248170 TIFF2025069189000360.tif248170 TIFF2025069189000361.tif193128 TIFF2025069189000362.tif192128 TIFF2025069189000363.tif248170 TIFF2025069189000364.tif248170 [Table 83] TIFF2025069189000366.tif212170 [Table 84] TIFF2025069189000368.tif214170 [Table 85] TIFF2025069189000370.tif213170 [Table 86] TIFF2025069189000372.tif211170

[0126] (23) In particular, N PS = 104, N TS If the remainder when divided by 4 is 1, the pilot sequence is an item in Table 30-1. TS If the remainder when divided by 4 is 3, the pilot sequence is an entry in Table 30-1 or Table 30-2. Alternatively, any entry in Table 30-3 is selected as the pilot sequence for one polarization direction, and any entry in Table 30-4 is selected as the pilot sequence for the other polarization direction. Alternatively, any entry in Table 30-5 is selected as the pilot sequence for one polarization direction, and any entry in Table 30-6 is selected as the pilot sequence for the other polarization direction. [Table 87] TIFF2025069189000374.tif183170 TIFF2025069189000375.tif183170 TIFF2025069189000376.tif191170 TIFF2025069189000377.tif255170 TIFF2025069189000378.tif192128 TIFF2025069189000379.tif193128 TIFF2025069189000380.tif183170 TIFF2025069189000381.tif182170 TIFF2025069189000382.tif193128 TIFF2025069189000383.tif182170 TIFF2025069189000384.tif189170 TIFF2025069189000385.tif182170 TIFF2025069189000386.tif189170 TIFF2025069189000387.tif192128 TIFF2025069189000388.tif175170 TIFF2025069189000389.tif183170 TIFF2025069189000390.tif176170 TIFF2025069189000391.tif182170 TIFF2025069189000392.tif96170

Table 88

[0127] Third, there may be several possible training sequences that can also guarantee a relatively good cross-correlation between the training sequences in the two polarization directions:

[0128] (1)N TS = 6 and the training sequence can be any item in Table 31. [Table 93] TIFF2025069189000406.tif66170

[0129] (2)N TS When = 8, the training sequence is an item in Table 32. [Table 94] TIFF2025069189000408.tif193128 TIFF2025069189000409.tif194128 TIFF2025069189000410.tif194128 TIFF2025069189000411.tif141170

[0130] (3)N TS When =10, the training sequence is one of the items in Table 33 below. [Table 95] TIFF2025069189000413.tif252170 TIFF2025069189000414.tif252170 TIFF2025069189000415.tif250170 TIFF2025069189000416.tif46170

[0131] (4)N TS When = 12, the training sequence is one of the items in Table 34 below. [Table 96] TIFF2025069189000418.tif250170 TIFF2025069189000419.tif250170 TIFF2025069189000420.tif250170 TIFF2025069189000421.tif249170 TIFF2025069189000422.tif251170 TIFF2025069189000423.tif250170 TIFF2025069189000424.tif251170 TIFF2025069189000425.tif45170

[0132] (5)NTS When = 14, the training sequence is one of the items in Table 35 below. [Table 97] TIFF2025069189000427.tif249170 TIFF2025069189000428.tif250170 TIFF2025069189000429.tif250170 TIFF2025069189000430.tif43170

[0133] (6)N TS When = 16, the training sequence is one of the items in Table 36 below. [Table 98] TIFF2025069189000432.tif250170 TIFF2025069189000433.tif250170 TIFF2025069189000434.tif251170 TIFF2025069189000435.tif251170 TIFF2025069189000436.tif250170 TIFF2025069189000437.tif250170 TIFF2025069189000438.tif251170 TIFF2025069189000439.tif43170

[0134] (7)N TS When = 18, the training sequence is one of the items in Table 37 below. [Table 99] TIFF2025069189000441.tif250170 TIFF2025069189000442.tif250170 TIFF2025069189000443.tif249170 TIFF2025069189000444.tif250170 TIFF2025069189000445.tif250170 TIFF2025069189000446.tif249170 TIFF2025069189000447.tif250170 TIFF2025069189000448.tif45170

[0135] (8)N TS When = 7, the training sequence is one of the items in Table 38 below. [Table 100] TIFF2025069189000450.tif193128 TIFF2025069189000451.tif193128 TIFF2025069189000452.tif193128 TIFF2025069189000453.tif192128 TIFF2025069189000454.tif192128 TIFF2025069189000455.tif192128 TIFF2025069189000456.tif193128 TIFF2025069189000457.tif106170

[0136] (9)N TS When = 9, the training sequence TS is one of the items in Table 39 below. [Table 101] TIFF2025069189000459.tif193128 TIFF2025069189000460.tif89170

[0137] (10)N TS When =11, the training sequence is one of the items in Table 40 below. [Table 102] TIFF2025069189000462.tif252170 TIFF2025069189000463.tif250170 TIFF2025069189000464.tif250170 TIFF2025069189000465.tif45170

[0138] (11)N TS When = 13, the training sequence is one of the items in Table 41 below. [Table 103] TIFF2025069189000467.tif250170 TIFF2025069189000468.tif251170 TIFF2025069189000469.tif253170 TIFF2025069189000470.tif45170

[0139] (12)N TS When = 15, the training sequence is one of the items in Table 42 below. [Table 104] TIFF2025069189000472.tif253170 TIFF2025069189000473.tif250170 TIFF2025069189000474.tif250170 TIFF2025069189000475.tif249170 TIFF2025069189000476.tif252170 TIFF2025069189000477.tif45170

[0140] (13)N TS When = 17, the training sequence is one of the items in Table 43 below. [Table 105] TIFF2025069189000479.tif251170 TIFF2025069189000480.tif248170 TIFF2025069189000481.tif248170 TIFF2025069189000482.tif43170

[0141] (14)N TS When = 19, the training sequence is one of the items in Table 44 below. [Table 106] TIFF2025069189000484.tif252170 TIFF2025069189000485.tif94170

[0142] It should be noted that the above-mentioned frame alignment word sequence, pilot sequence, and training sequence are all provided in the form of symbols. Equivalently, they may be provided in the form of bits. For example, Figure 7 and Figure 8 show the mapping relationship between DP-QPSK symbols and bits, and between DP-16QAM symbols and bits, respectively. A QPSK symbol consists of 2 bits. Bit 01 is -1+1j, and 11 is 1+1j. 16QAM consists of 4 bits. 0000 is -3 - 3j, 1010 is 3+3j, and so on. Take QPSK as an example, if the sequence is 1+1j, 1+1j, 1-1j, -1+1j, the corresponding bit sequence is 11111001. The bit sequence undergoes the corresponding modulation and then is converted into a symbol sequence for output.

[0143] The embodiments of the present application further provide some specific superframe formats, which are described below.

[0144] Embodiment 1: The pre-framing symbols are obtained by CFEC encoding. The number of symbols is 175616. The following table shows the parameters N SF , N TS , N PS , N FAW , N RES , N S , N F , and enumerate the OH corresponding to the superframe. [Table 107]

[0145] The superframe structure is shown in FIG. 9. As shown in FIG. 9(a), the superframe includes 49 subframes, each of which includes 3648 symbols. The first subframe is shown in FIG. 9(b), and includes 6 training symbols, 24 frame alignment word symbols, and 74 reserved symbols. The second to 49th subframes also each have 6 training symbols, as shown in FIG. 9(c). In addition, in each subframe, the first symbol of every 64 symbols is a pilot symbol. The frame alignment word sequence having a length of 24 is an item in Table 7. The training sequence having a length of 6 can be an item in Table 31. According to the superframe structure, the pilot sequence having a length of 57 is an item in Table 10-1 or Table 10-2, in which the first symbol is the same as the first symbol of the training sequence used. For example, the frame alignment word sequence having a length of 24 symbols is the following sequence: [Table 108]

[0146] The correlation characteristics corresponding to the frame alignment word sequence are shown in Figure 10. Figure 10(a) shows the aperiodic autocorrelation result of the frame alignment word sequence in the X polarization direction, Figure 10(b) shows the aperiodic autocorrelation result of the frame alignment word sequence in the Y polarization direction, and Figure 10(c) shows the aperiodic cross-correlation result of the frame alignment word sequence in the X and Y polarization directions. The side lobe values ​​of the aperiodic autocorrelation function of the symbol sequence in the two polarization directions are less than or equal to 0.172 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in the two polarization directions are less than or equal to 0.177 (normalized amplitude).

[0147] The training sequence having a symbol length of 6 is the following sequence: [Table 109]

[0148] The correlation characteristics corresponding to the training sequences are shown in Figure 11. Figure 11(a) shows the aperiodic autocorrelation result of the training sequence in the X polarization direction, Figure 11(b) shows the aperiodic autocorrelation result of the training sequence in the Y polarization direction, and Figure 11(c) shows the aperiodic cross-correlation result of the training sequence in the X and Y polarization directions. The side lobe value of the aperiodic autocorrelation function of the symbol sequences in the two polarization directions is less than or equal to 0.34 (normalized amplitude), and the aperiodic cross-correlation function value of the symbol sequences in the two polarization directions is less than or equal to 0.38 (normalized amplitude).

[0149] The pilot sequence having a length of 57 symbols is the following sequence: [Table 110]

[0150] Correlation characteristics corresponding to the pilot sequences are shown in FIG. 12. FIG. 12(a) shows the cyclic autocorrelation result of the pilot sequence in the X polarization direction, FIG. 12(b) shows the cyclic autocorrelation result of the pilot sequence in the Y polarization direction, and FIG. 12(c) shows the cyclic cross-correlation result of the pilot sequence in the X polarization direction and the Y polarization direction. The side lobe value of the cyclic autocorrelation function of the symbol sequence in the two polarization directions is less than or equal to 0.177 (normalized amplitude), and the cyclic cross-correlation function value of the symbol sequence in the two polarization directions is less than or equal to 0.197 (normalized amplitude). It should be understood that for the correlation characteristics of the above sequences, the value of A does not affect the normalized amplitude value of the correlation function, that is, the correlation characteristics do not depend on the modulation format used. Therefore, when the correlation characteristics of the sequences are verified in this embodiment and subsequent embodiments, the value of A is not limited, which is not repeated in this application.

[0151] It can be seen that the frame overhead of the superframe structure provided in this embodiment of the present application is as low as 1.79%, and the designed sequence has relatively good auto-correlation and cross-correlation properties. The frame alignment word sequence can further meet the DC balance, and the training sequence and the pilot sequence can also be combined together to meet the DC balance, which is helpful to improve the quality of the signal restored at the receiving end.

[0152] Based on the received signals in two polarization directions, the receiving end performs signal processing by using the frame alignment word sequence, the training sequence, and the pilot sequence to restore the signal. For example, the polarization directions can be distinguished by calculating the correlation value between the received signals in two polarization directions and the sequence symbols of the training sequence in X polarization and Y polarization respectively, and the subframe alignment can be performed, the superframe alignment is performed by using the frame alignment word sequence, and the carrier phase recovery is performed by using the pilot signal.

[0153] In addition, the three symbol sequences in this embodiment can be expressed in the form of bit sequences. Taking DP-16QAM and DP-QPSK as examples, the bit sequences can be shown in the following table, where b1 to b8 are the corresponding bits in Figures 7 and 8:

[0154] The bit sequence corresponding to the frame alignment word sequence is: [Table 111]

[0155] The bit sequence corresponding to the training sequence is: [Table 112]

[0156] The bit sequence corresponding to the pilot sequence is: [Table 113]

[0157] In addition, in this embodiment, the spectral flatness characteristics of the superframe in different modulation formats are further simulated. Figure 13(a) provides a spectrum diagram of the superframe structure shown in Figure 9, which includes 300 superframes for DP-16QAM. Figure 13(b) is a spectrum diagram of a random DP-16QAM signal of the same length. Figure 14(a) provides a spectrum diagram of the superframe structure shown in Figure 9, which includes 300 superframes for DP-QPSK. Figure 14(b) is a spectrum diagram of a random DP-QPSK signal of the same length. It can be seen that for not only DP-16QAM but also DP-QPSK, there is a very small difference between the spectral flatness characteristics of the superframe structure provided in this embodiment and the spectral flatness characteristics of the random modulation signal of the same length, and there is a very good flatness.

[0158] It should be understood that in this embodiment of the present application, only one polarization direction is used as an example to provide simulation results, since the spectral flatness characteristics of the signals in the two polarization directions are very similar, and the same applies to subsequent embodiments, which will not be repeated in this application.

[0159] Embodiment 2: This embodiment of the present application further provides a specific superframe format. The pre-framing symbols are obtained by CFEC encoding. The number of symbols is 175616. The following table shows the parameters N SF , N TS , N PS , N FAW , N RES , N S , N F, and the OH corresponding to the superframe, etc. are listed. [Table 114]

[0160] The superframe structure is shown in FIG. 15. As shown in FIG. 15(a), the superframe includes 43 subframes, each of which includes 4160 symbols. The first subframe is shown in FIG. 15(b), and includes 10 training symbols, 22 frame alignment word symbols, and 60 reserved symbols. The second to 43rd subframes also each have 10 training symbols, as shown in FIG. 15(c). In addition, in each subframe, the first symbol of every 64 symbols is a pilot symbol. The frame alignment word sequence with a length of 22 is an item in Table 6. The training sequence with a length of 10 can be an item in Table 33. According to the superframe structure, the pilot sequence with a length of 65 is an item in Table 11-1 or Table 11-2, where the first symbol is the same as the first symbol of the training sequence used. For example, the frame alignment word sequence with a length of 22 symbols is the following sequence: [Table 115]

[0161] The correlation characteristics corresponding to the frame alignment word sequence are shown in Figure 16. Figure 16(a) shows the aperiodic autocorrelation result of the frame alignment word sequence in the X polarization direction, Figure 16(b) shows the aperiodic autocorrelation result of the frame alignment word sequence in the Y polarization direction, and Figure 16(c) shows the aperiodic cross-correlation result of the frame alignment word sequence in the X and Y polarization directions. The side lobe values ​​of the aperiodic autocorrelation function of the symbol sequence in the two polarization directions are less than or equal to 0.182 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in the two polarization directions are less than or equal to 0.188 (normalized amplitude).

[0162] In some practical applications, the frame alignment word sequence with a length of 22 can be an existing symbol sequence, such as the sequence used in OIF-400ZR. However, the sequence has relatively poor cross-correlation in X and Y polarizations, and the receiving end needs to use more symbols to ensure a sufficiently low alignment error probability during alignment.

[0163] The training sequence, which has a length of 10 symbols, is the following sequence: [Table 116]

[0164] The correlation characteristics corresponding to the training sequences are shown in Figure 17. Figure 17(a) shows the aperiodic autocorrelation result of the training sequence in the X polarization direction, Figure 17(b) shows the aperiodic autocorrelation result of the training sequence in the Y polarization direction, and Figure 17(c) shows the aperiodic cross-correlation result of the training sequence in the X and Y polarization directions. The side lobe values ​​of the aperiodic autocorrelation function of the symbol sequences in the two polarization directions are less than or equal to 0.283 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in the two polarization directions are less than or equal to 0.283 (normalized amplitude).

[0165] The pilot sequence having a length of 65 symbols is the following sequence: [Table 117]

[0166] The correlation characteristics corresponding to the pilot sequences are shown in Figure 18. Figure 18(a) shows the cyclic autocorrelation result of the pilot sequence in the X polarization direction, Figure 18(b) shows the cyclic autocorrelation result of the pilot sequence in the Y polarization direction, and Figure 18(c) shows the cyclic cross-correlation result of the pilot sequence in the X and Y polarization directions. The side lobe values ​​of the cyclic autocorrelation function of the symbol sequences in the two polarization directions are less than or equal to 0.161 (normalized amplitude), and the cyclic cross-correlation function values ​​of the symbol sequences in the two polarization directions are less than or equal to 0.173 (normalized amplitude).

[0167] It can be seen that the frame overhead of the superframe structure provided in this embodiment of the present application is also low at 1.86%, and the designed sequence has relatively good autocorrelation and cross-correlation properties. The frame alignment word sequence can further meet the DC balance, and the training sequence and the pilot sequence can also be combined together to meet the DC balance, which is helpful to improve the quality of the signal restored at the receiving end.

[0168] In addition, in this embodiment, taking DP-16QAM as an example, the spectral flatness property of the superframe is further simulated. The result of using the spectrum diagram of the superframe structure shown in Figure 15, which contains 300 superframes, is shown in Figure 19. It can be seen that there is a very small difference between the spectral flatness property of the superframe structure provided in this embodiment and that of the random modulation signal of the same length, and there is a very good flatness.

[0169] Embodiment 3: This embodiment of the present application further provides a specific superframe format. The pre-framing symbols are obtained by CFEC encoding. The number of symbols is 175616. The following table shows the parameters N SF , N TS , N PS , N FAW , N RES , N S , N F , and the OH corresponding to the superframe, etc. are listed. [Table 118]

[0170] The superframe structure is shown in FIG. 20. As shown in FIG. 20(a), the superframe includes 50 subframes, each of which includes 3584 symbols. The first subframe is shown in FIG. 20(b), and includes 15 training symbols, 22 frame alignment word symbols, and 62 reserved symbols. The second to 50th subframes also each have 15 training symbols, as shown in FIG. 20(c). In addition, in each subframe, the first symbol of every 64 symbols is a pilot symbol. The frame alignment word sequence with a length of 22 is an item in Table 6. The training sequence with a length of 15 can be an item in Table 42. According to the superframe structure, the pilot sequence with a length of 56 is an item in Table 9-1 or Table 9-2, in which the first symbol is the same as the first symbol of the training sequence used. For example, considering that a frame alignment word sequence with a symbol length of 22 uses the same sequence as that in embodiment 2, correlation simulation results corresponding to the frame alignment word sequence are shown in FIG.

[0171] The training sequence, which has a length of 15 symbols, uses the following sequence: [Table 119]

[0172] The correlation characteristics corresponding to the training sequences are shown in Figure 21. Figure 21(a) shows the aperiodic autocorrelation result of the training sequence in the X polarization direction, Figure 21(b) shows the aperiodic autocorrelation result of the training sequence in the Y polarization direction, and Figure 21(c) shows the aperiodic cross-correlation result of the training sequence in the X and Y polarization directions. The side lobe values ​​of the aperiodic autocorrelation function of the symbol sequences in the two polarization directions are less than or equal to 0.211 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in the two polarization directions are less than or equal to 0.211 (normalized amplitude).

[0173] The pilot sequence having a length of 56 symbols uses the following sequence: [Table 120]

[0174] The correlation characteristics corresponding to the pilot sequences are shown in Figure 22. Figure 22(a) shows the cyclic autocorrelation result of the pilot sequence in the X polarization direction, Figure 22(b) shows the cyclic autocorrelation result of the pilot sequence in the Y polarization direction, and Figure 22(c) shows the cyclic cross-correlation result of the pilot sequence in the X and Y polarization directions. The side lobe values ​​of the cyclic autocorrelation function of the symbol sequences in the two polarization directions are less than or equal to 0.183 (normalized amplitude), and the cyclic cross-correlation function values ​​of the symbol sequences in the two polarization directions are less than or equal to 0.203 (normalized amplitude).

[0175] It can be seen that the frame overhead of the superframe structure provided in this embodiment of the present application is also low at 2.03%, the training sequence is relatively long so that the receiving end can perform frame alignment, and the designed sequence has relatively good autocorrelation and cross-correlation properties. The frame alignment word sequence can further meet the DC balance, and the training sequence and the pilot sequence can also be combined together to meet the DC balance, which is helpful to improve the quality of the signal restored at the receiving end.

[0176] In addition, in this embodiment, taking DP-16QAM as an example, the spectral flatness property of the superframe is further simulated. The result of using the spectrum diagram of the superframe structure shown in Figure 20, which contains 300 superframes, is shown in Figure 23. It can be seen that there is a very small difference between the spectral flatness property of the superframe structure provided in this embodiment and that of the random modulation signal of the same length, and there is a very good flatness.

[0177] Embodiment 4: This embodiment of the present application provides a specific superframe format. The pre-framing symbols are obtained by Open FEC (OFEC) encoding. The number of symbols is 172032. The following table shows the parameters N SF , N TS , N PS , N FAW , N RES , N S , N F , and the OH corresponding to the superframe, etc. are listed. [Table 121]

[0178] The superframe structure is shown in FIG. 24. As shown in FIG. 24(a), the superframe includes 48 subframes, each of which includes 3648 symbols. The first subframe is shown in FIG. 24(b), and includes 6 training symbols, 24 frame alignment word symbols, and 72 reserved symbols. The second to 48th subframes also each have 6 training symbols, as shown in FIG. 24(c). In addition, in each subframe, the first symbol of every 64 symbols is a pilot symbol. The frame alignment word sequence with a length of 24 is an item in Table 7. The training sequence with a length of 6 can be an item in Table 31. According to the superframe structure, the pilot sequence with a length of 57 is an item in Table 10-1 or Table 10-2, in which the first symbol is the same as the first symbol of the training sequence used. For example, the same frame alignment word sequence, training sequence, and pilot sequence as in the first embodiment are used, and their correlations are shown in FIGS. 10 to 12, respectively.

[0179] In addition, in this embodiment, taking DP-16QAM as an example, the spectral flatness property of the superframe is further simulated. The result of using the spectrum diagram of the superframe structure shown in Figure 24, which contains 300 superframes, is shown in Figure 25. It can be seen that there is a very small difference between the spectral flatness property of the superframe structure provided in this embodiment and that of the random modulation signal of the same length, and there is a very good flatness.

[0180] Embodiment 5: This embodiment of the present application provides a specific superframe format. The pre-framing symbols are obtained by CFEC encoding. The number of symbols is 175616. The following table shows the parameters N SF , N TS , N PS , N FAW , N RES , N S , NF , and the OH corresponding to the superframe, etc. are listed. [Table 122]

[0181] The superframe structure is shown in FIG. 26. As shown in FIG. 26(a), the superframe includes 50 subframes, each of which includes 3600 symbols. The first subframe is shown in FIG. 26(b), and includes 12 training symbols, 22 frame alignment word symbols, and 62 reserved symbols. The second to 50th subframes also each have 12 training symbols, as shown in FIG. 26(c). In addition, in each subframe, the first symbol of every 48 symbols is a pilot symbol. The frame alignment word sequence with a length of 22 is an item in Table 6. The training sequence with a length of 12 can be an item in Table 34. According to the superframe structure, the pilot sequence with a length of 75 is an item in Table 26, in which the first symbol is the same as the first symbol of the training sequence used. For example, considering that a frame alignment word sequence with a symbol length of 22 uses the same sequence as that in embodiment 2, correlation simulation results corresponding to the frame alignment word sequence are shown in FIG.

[0182] The training sequence, which has a length of 12 symbols, uses the following sequence: [Table 123]

[0183] The correlation characteristics corresponding to the training sequences are shown in Figure 27. Figure 27(a) shows the aperiodic autocorrelation result of the training sequence in the X polarization direction, Figure 27(b) shows the aperiodic autocorrelation result of the training sequence in the Y polarization direction, and Figure 27(c) shows the aperiodic cross-correlation result of the training sequence in the X and Y polarization directions. The side lobe values ​​of the aperiodic autocorrelation function of the symbol sequences in the two polarization directions are less than or equal to 0.251 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in the two polarization directions are less than or equal to 0.251 (normalized amplitude).

[0184] The pilot sequence having a length of 75 symbols uses the following sequence: [Table 124]

[0185] The correlation characteristics corresponding to the pilot sequences are shown in Figure 28. Figure 28(a) shows the cyclic autocorrelation result of the pilot sequence in the X polarization direction, Figure 28(b) shows the cyclic autocorrelation result of the pilot sequence in the Y polarization direction, and Figure 28(c) shows the cyclic cross-correlation result of the pilot sequence in the X and Y polarization directions. The side lobe values ​​of the cyclic autocorrelation function of the symbol sequences in the two polarization directions are less than or equal to 0.150 (normalized amplitude), and the cyclic cross-correlation function values ​​of the symbol sequences in the two polarization directions are less than or equal to 0.168 (normalized amplitude).

[0186] The frame overhead of the superframe structure provided in this embodiment of the present application is also low at 2.50%, and the designed sequence has relatively good autocorrelation and cross-correlation properties. The frame alignment word sequence can further meet the DC balance, and the training sequence and the pilot sequence can also be combined together to meet the DC balance, which helps to improve the quality of the signal restored at the receiving end.

[0187] In addition, in this embodiment, taking DP-16QAM as an example, the spectral flatness property of the superframe is further simulated. The result of using the spectrum diagram of the superframe structure shown in Figure 26, which contains 300 superframes, is shown in Figure 29. It can be seen that there is a very small difference between the spectral flatness property of the superframe structure provided in this embodiment and that of the random modulation signal of the same length, and there is a very good flatness.

[0188] Embodiment 6: This embodiment of the present application provides a specific superframe format. The pre-framing symbols are obtained by OFEC encoding. The number of symbols is 172032. The following table shows the parameters N SF , N TS , N PS , N FAW , N RES , N S , N F , OH, and the like corresponding to the superframes. [Table 125]

[0189] The superframe structure is shown in FIG. 30. As shown in FIG. 30(a), the superframe includes 49 subframes, each of which includes 3600 symbols. The first subframe is shown in FIG. 30(b), and includes 12 training symbols, 22 frame alignment word symbols, and 132 reserved symbols. The second to 49th subframes also each have 12 training symbols, as shown in FIG. 30(c). In addition, in each subframe, the first symbol of every 48 symbols is a pilot symbol. The frame alignment word sequence with a length of 22 is an item in Table 6. The training sequence with a length of 12 can be an item in Table 34. According to the superframe structure, the pilot sequence with a length of 75 is an item in Table 26, in which the first symbol is the same as the first symbol of the training sequence used. For example, the same frame alignment word sequence, training sequence, and pilot sequence as in embodiment 5 are used, and their correlations are shown in Figures 16, 27, and 28, respectively.

[0190] The frame overhead of the superframe structure provided in this embodiment of the present application is also low at 2.54%, and the designed sequence has relatively good autocorrelation and cross-correlation properties. The frame alignment word sequence can further meet the DC balance, and the training sequence and the pilot sequence can also be combined together to meet the DC balance, which helps to improve the quality of the signal restored at the receiving end.

[0191] In addition, in this embodiment, taking DP-16QAM as an example, the spectral flatness property of the superframe is further simulated. The result of using the spectrum diagram of the superframe structure shown in Figure 30, which contains 300 superframes, is shown in Figure 31. It can be seen that there is a very small difference between the spectral flatness property of the superframe structure provided in this embodiment and that of the random modulation signal of the same length, and the flatness is very good.

[0192] With reference to the communication system described in the above embodiment corresponding to Fig. 1, and the framing process described in the embodiment corresponding to Fig. 2 or Fig. 3, an embodiment of the present application further provides another transmission method for optical communication. As shown in Fig. 32, the transmission method includes the following steps:

[0193] 3201: A transmitting device generates a superframe including a plurality of subframes, each of the subframes includes a training symbol and a pilot symbol, in one polarization direction, there is one symbol that is both a training symbol and a pilot symbol, each of the training symbol and the pilot symbol is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number, in each subframe, in one polarization direction, the pilot symbol is generated based on a target polynomial and a seed, and N is a number to achieve DC balance. TS N training symbols combined PS There are N pilot symbols, TS is the number of training symbols in each subframe in one polarization direction, and N TS +N PS is odd and the target polynomial is an entry in Table X-1 below. [Table 126] TIFF2025069189000506.tif69170

[0194] 3202: A transmitting device transmits a superframe, and correspondingly, a receiving device receives the superframe including a plurality of subframes.

[0195] 3203: The receiving device decodes the received superframe.

[0196] In this embodiment of the present application, the value of A is determined by the modulation format used when the symbol is generated, which can be understood by referring to the corresponding contents in the embodiment of Figure 4 and Figure 5A. It should be noted that in some practical application scenarios, the pilot symbols and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj may not be symbols in the constellation diagram of the modulation format used, but may be four symbols in the intermediate area between the outermost four symbols and the innermost four symbols of the constellation diagram. In this case, the training symbols and pilot symbols have considerable noise and sensitivity, but have a relatively low peak-to-average power ratio. Take 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. Specifically, as shown in FIG. 5B, the outermost four symbols of the constellation diagram are 3+3j, 3-3j, -3+3j, and -3-3j, and the innermost four symbols of the constellation diagram are 1+1j, 1-1j, -1+1j, and -1-1j. The values ​​of the pilot and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj may be four symbols in the intermediate region between the outermost four symbols and the innermost four symbols of the 16QAM constellation diagram. The specific value of the real number A may be selected according to the actual application scenario, so that the peak-to-average power ratio, noise, and sensitivity of the training and pilot symbols have a good compromise. For example, the real number

number

number

number

number

number

number

[0197] In addition, in this embodiment of the present application, there are two polarization directions, and the two polarization directions are orthogonal to each other. In other words, when one polarization direction is X polarization, the other polarization direction is Y polarization, and when one polarization direction is Y polarization, the other polarization direction is X polarization. The two polarization directions can also be described by polarization 1 and polarization 2. In this embodiment of the present application, in one polarization direction, the sum of the number of training symbols and pilot symbols included in one subframe is N TS +N PS -1. Since one symbol is both a training symbol and a pilot symbol, the sum of the numbers is N TS +N PS but one less than the sum of the numbers of symbols of the two types.

[0198] In the solution of this embodiment of the present application, pilot symbols are generated based on a target polynomial and a seed. The target polynomial can be any item in Table X-1 above, and the target polynomial and the corresponding seed are generated based on the N PS pilot symbols and N TS The combination of the training symbols can achieve DC balance, that is, in one polarization direction, the sum of the real parts of the complex numbers corresponding to the training symbols and pilot symbols in one subframe is zero, and the sum of the imaginary parts is also zero, which helps the receiving end to better restore the signal, and improves the quality of the signal at the receiving end.

[0199] The structure of the superframe provided in this embodiment of the present application can be understood by referring to the corresponding contents of Figures 6(a) to 6(c), and the details will not be described again here.

[0200] The solution provided in this embodiment of the present application is applicable to the rows indexed 18 and 9 of Table 2 in the previous embodiment.

[0201] The two superframe formats are described separately below.

[0202] For the row indexed 18 in Table 2 above, in one polarization direction, the number of symbols before framing is 172032, and the following Table X-2 shows the relationship between the parameter N SF , N PS , N TS , N S , N F , N FAW , N RES , and the OH corresponding to the superframe, etc. are listed. [Table 127]

[0203] The superframe structure is shown in Figure 33(a). The superframe contains 24 subframes, each containing 7296 symbols. The first subframe is shown in Figure 33(b) and contains 11 training symbols and N FAW N frame alignment word symbols and RES reserved symbols, N FAW +N RES = 96. As shown in (c) of Figure 33, the second to 24th subframes also each have 11 training symbols. In addition, in each subframe, the first symbol of every 64 symbols is a pilot symbol, and each subframe contains 114 pilot symbols.

[0204] In FIG. 33(b), N FAW =22 and N RES = 74 is used as an example for illustration purposes. The sequence of the 22 frame alignment word symbols can be understood by referring to Table X-3 below. [Table 128]

[0205] The sequence of 11 training symbols can be understood by reference to Table X-4 below. [Table 129]

[0206] In this example, the 114 pilot symbols are determined based on a target polynomial and a corresponding seed. In this embodiment of the present application, the target polynomial is a 10th order polynomial, which may be expressed as:

number

[0207] The pilot symbol generation structure can be understood by referring to Figure 34. As shown in Figure 34, the seeds can be represented in binary form as m9, m8, m7, m6, m5, m4, m3, m2, m1, and m0. Indeed, the seeds may also be represented in hexadecimal or decimal form, and when calculated with the target polynomial, the seeds need to be converted to binary form. For example, 0110111000 is represented in hexadecimal as 0x1B8 and in decimal as 440.

[0208] In this embodiment of the present application, the same target generator polynomial can be used for pilot symbols in two orthogonal polarization directions, but due to different seeds, the pilot symbols output in the two polarization directions are accordingly not completely the same.

[0209] As shown in FIG. 34, for a scenario in which 114 pilot symbols need to be generated, a bit sequence b0, b1, b2, ... b 227 is obtained based on the target polynomial and the seed. 227 Every two consecutive bits in b are mapped to one symbol, where b 2t and b 2t+1 is one symbol (2b 2t -1)A+(2b 2t+1 −1)Aj, where 0≦t<114. 2t -1)A+(2b 2t+1-1) Note that Aj may not be a symbol in the constellation diagram of the modulation format used, but may be four symbols in the intermediate region between the outermost four symbols and the innermost four symbols of the constellation diagram of the modulation format used. In this case, the training symbols and pilot symbols have considerable noise and sensitivity, but have a relatively low peak-to-average power ratio. Take 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. The specific value of the real number A may be selected according to the actual application scenario, so that the peak-to-average power ratio, noise, and sensitivity of the training symbols and pilot symbols have a good compromise. For example, the real number

number

number

number

number

number

number

[0210] In this embodiment of the present application, the target polynomial and the seed can be determined by designing the values ​​of the coefficients a9...a1 in the polynomial so that the symbol sequence of the generated pilot symbol in the X polarization or the Y polarization has relatively good autocorrelation properties, and the symbol sequence in the two polarizations has relatively good cross-correlation properties. In particular, the normalized amplitude of the side lobe value of the periodic autocorrelation function of the symbol sequence in the two polarization directions is less than or equal to a preset value T0, and the normalized amplitude of the periodic cross-correlation function value of the symbol sequence in the two polarization directions is less than or equal to a preset value T1.

[0211] When the target polynomial and hexadecimal seed in two polarization directions are one row of Table X-5 below, the normalized amplitude of the side lobe value of the cyclic autocorrelation function of the pilot symbols in the same polarization direction is less than or equal to 0.2, and the normalized amplitude of the cyclic cross-correlation function value of the pilot symbols in different polarization directions is less than or equal to 0.2, i.e., T0=0.2 and T1=0.2. [Table 130] TIFF2025069189000524.tif193128 TIFF2025069189000525.tif194128 TIFF2025069189000526.tif131170

[0212] When the target polynomial and hexadecimal seed in two polarization directions are one row of Table X-6 below (Table X-6 is a subset of Table X-5), in one polarization direction, in a combination of 114 pilot symbols and 11 training symbols, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are all 31. [Table 131]

[0213] Considering that the sequence generated when the target polynomial is a primitive polynomial generally has relatively good randomness, and more non-zero terms in the target polynomial indicate more complex implementation, when the target polynomial uses a primitive polynomial, the non-zero terms in the target polynomial are 5 or less, and the target polynomial and the hexadecimal seed in two polarization directions are one row in the following Table X-7, the normalized amplitude of the side lobe value of the cyclic autocorrelation function of the pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the cyclic cross-correlation function value of the pilot symbols in different polarization directions is less than or equal to 0.25; [Table 132]

[0214] In Table X-7, in the row indexed 14, the target polynomial, sometimes called the primitive polynomial, is x 10 +x 7 +x 3 +x+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x34E and 0x084, the process of generating 114 pilot symbols can be understood by referring to FIG.

[0215] As shown in FIG. 35, in the X polarization direction, the input polarization seed is 0x34E, which is 1101001110 after being converted into a binary sequence, that is, the value of m9 to m0. When two bits 1 and 0 are output in succession in sequence, the pilot symbol in the X polarization direction is A-Aj. When two bits 0 and 0 are output in succession in sequence, the pilot symbol in the X polarization direction is -A-Aj. When two bits 1 and 1 are output in succession in sequence, the pilot symbol in the X polarization direction is A+Aj. When two bits 0 and 1 are output in succession in sequence, the pilot symbol in the X polarization direction is -A+Aj. By analogy, 114 pilot symbols in the X polarization direction can be obtained.

[0216] As shown in FIG. 35, in the Y polarization direction, the input polarization seed is 0x084, which is 0010000100 after being converted into a binary sequence, that is, the value of m9 to m0. When two bits 1 and 0 are output in succession in sequence, the pilot symbol in the Y polarization direction is A-Aj. When two bits 0 and 0 are output in succession in sequence, the pilot symbol in the Y polarization direction is -A-Aj. When two bits 1 and 1 are output in succession in sequence, the pilot symbol in the Y polarization direction is A+Aj. When two bits 0 and 1 are output in succession in sequence, the pilot symbol in the Y polarization direction is -A+Aj. By analogy, 114 pilot symbols in the Y polarization direction can be obtained.

[0217] The polarization seed of the X polarization direction may be exchanged with the polarization seed of the Y polarization direction, and thus, 114 pilot symbols may be obtained as shown in Table X-8 below. [Table 133]

[0218] In the above Table X-8, in one polarization direction, in a combination of 114 pilot symbols and 11 training symbols, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are all 31.

[0219] In the solution of Table X-8 above, the correlation characteristics corresponding to the pilot symbols are shown in Figure 36. Figure 36(a) shows the cyclic autocorrelation result of the sequence of pilot symbols in the X polarization direction, Figure 36(b) shows the cyclic autocorrelation result of the sequence of pilot symbols in the Y polarization direction, and Figure 36(c) shows the cyclic cross-correlation result of the sequence of pilot symbols in the X polarization direction and the Y polarization direction. The normalized amplitude of the side lobe value of the cyclic autocorrelation function of the symbol sequence in the two polarization directions is less than or equal to 0.167, and the normalized amplitude of the side lobe value of the cyclic cross-correlation function of the symbol sequence in the two polarization directions is less than or equal to 0.202. The frame overhead of the superframe structure provided in this embodiment of the present application is also as low as 1.79%, and the sequence of pilot symbols has relatively good autocorrelation and cross-correlation characteristics. The training symbols and pilot symbols can also be combined together to meet DC balance, which helps to improve the quality of the signal restored at the receiving end.

[0220] Another example of the above-mentioned superframe structure is further provided below. 10 +x 7 +x 6 +x 2 The process of generating pilot symbols in two polarization directions when the first hex seed is +1 and the corresponding hexadecimal seeds in the two polarization directions are 0x0BE and 0x1B8 can be understood by referring to FIG.

[0221] As shown in FIG. 37, in the X polarization direction, the input polarization seed is 0x0BE, which is 0010111110 after being converted into a binary sequence, that is, the value of m9 to m0. When two bits 1 and 0 are output in succession in sequence, the pilot symbol in the X polarization direction is A-Aj. When two bits 0 and 0 are output in succession in sequence, the pilot symbol in the X polarization direction is -A-Aj. When two bits 1 and 1 are output in succession in sequence, the pilot symbol in the X polarization direction is A+Aj. When two bits 0 and 1 are output in succession in sequence, the pilot symbol in the X polarization direction is -A+Aj. By analogy, 114 pilot symbols in the X polarization direction can be obtained.

[0222] As shown in FIG. 37, in the Y polarization direction, the input polarization seed is 0x1B8, which is 0110111000 after being converted into a binary sequence, that is, the value of m9 to m0. When two bits 1 and 0 are output in succession in sequence, the pilot symbol in the Y polarization direction is A-Aj. When two bits 0 and 0 are output in succession in sequence, the pilot symbol in the Y polarization direction is -A-Aj. When two bits 1 and 1 are output in succession in sequence, the pilot symbol in the Y polarization direction is A+Aj. When two bits 0 and 1 are output in succession in sequence, the pilot symbol in the Y polarization direction is -A+Aj. By analogy, 114 pilot symbols in the Y polarization direction can be obtained.

[0223] The polarization seed of the X polarization direction may be exchanged with the polarization seed of the Y polarization direction, and thus, 114 pilot symbols may be obtained as shown in Table X-9 below. [Table 134]

[0224] In the above Table X-9, the correlation characteristics corresponding to the pilot symbols are shown in Figure 38. Figure 38(a) shows the cyclic autocorrelation result of the sequence of pilot symbols in the X polarization direction, Figure 38(b) shows the cyclic autocorrelation result of the sequence of pilot symbols in the Y polarization direction, and Figure 38(c) shows the cyclic cross-correlation result of the sequence of pilot symbols in the X polarization direction and the Y polarization direction. The normalized amplitude of the side lobe value of the cyclic autocorrelation function of the symbol sequence in the two polarization directions is less than or equal to 0.162, and the normalized amplitude of the side lobe value of the cyclic cross-correlation function of the symbol sequence in the two polarization directions is less than or equal to 0.185. The frame overhead of the superframe structure provided in this embodiment of the present application is also as low as 1.79%, and the designed sequence of pilot symbols has relatively good autocorrelation and cross-correlation characteristics. The training sequence and the sequence of pilot symbols can also be combined together to meet the DC balance, which helps to improve the quality of the signal restored at the receiving end.

[0225] The contents of the superframe structure and the process for generating its pilot symbols corresponding to the row indexed 18 in the above Table 2. The corresponding contents of the superframe corresponding to the row indexed 9 in the above Table 2 are described below.

[0226] For the row indexed 9 in Table 2 above, the number of symbols before framing is 172032, and Table X-10 below shows the relationship between the parameter N SF , N PS , N TS , N S , N F , N FAW , N RES , and the OH corresponding to the superframe, etc. are listed. [Table 135]

[0227] The superframe structure is shown in Figure 39(a). The superframe contains 48 subframes, each containing 3648 symbols. The first subframe is shown in Figure 39(b) and contains 6 training symbols and N FAW N frame alignment word symbols and RES reserved symbols, N FAW +N RES = 96. As shown in (c) of Figure 39, the second to 48th subframes also each have 6 training symbols. In addition, in each subframe, the first symbol of every 64 symbols is a pilot symbol, and each subframe contains 57 pilot symbols.

[0228] In FIG. 39(b), N FAW =22 and N RES = 74 is used as an example for illustration. The sequence of the 22 frame alignment word symbols can be understood by referring to Table X-3. It is considered that the starting symbol of the 6 training symbols needs to be the same as the starting symbol of the 57 pilot symbols. In FIG. 39(b), the sequence of the 6 training symbols can be understood by referring to Table X-11 below. [Table 136]

[0229] In this example, 57 pilot symbols are determined based on a target polynomial and a corresponding seed. In this embodiment of the present application, the structure for generating pilot symbols based on a target polynomial and a seed can be understood by referring to the corresponding content of FIG.

[0230] For a scenario in which 57 pilot symbols need to be generated, a bit sequence b0, b1, b2, ... b 113is obtained based on the target polynomial and the seed. 113 Every two consecutive bits in b are mapped to one symbol, where b 2t and b 2t+1 is one symbol (2b 2t -1)A+(2b 2t+1 -1)Aj. Symbol (2b 2t -1)A+(2b 2t+1 -1) Note that Aj may not be a symbol in the constellation diagram of the modulation format used, but may be four symbols in the intermediate region between the outermost four symbols and the innermost four symbols of the constellation diagram of the modulation format used. In this case, the training symbols and pilot symbols have considerable noise and sensitivity, but have a relatively low peak-to-average power ratio. Take 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. The specific value of the real number A may be selected according to the actual application scenario, so that the peak-to-average power ratio, noise, and sensitivity of the training symbols and pilot symbols have a good compromise. For example, the real number

number

number

number

number

number

number

[0231] When the target polynomial and hexadecimal seed in two polarization directions are one row of Table X-12 below, the normalized amplitude of the side lobe value of the cyclic autocorrelation function of pilot symbols in the same polarization direction is less than or equal to 0.23, and the normalized amplitude of the cyclic cross-correlation function value of pilot symbols in different polarization directions is less than or equal to 0.23. [Table 137]

[0232] The target polynomial is x 10 +x 7 +x 3 +x+1 and the corresponding hexadecimal seeds in the two polarization directions are 0x0B1 and 0x3E9, i.e., the row indexed 2 in Table X-12 above, the process of generating 57 pilot symbols can be understood by reference to FIG. 40.

[0233] As shown in FIG. 40, in the X polarization direction, the input polarization seed is 0x0B1, which is 0010110001 after being converted into a binary sequence, that is, the value of m9 to m0. When two bits 1 and 0 are output in succession in sequence, the pilot symbol in the X polarization direction is A-Aj. When two bits 0 and 0 are output in succession in sequence, the pilot symbol in the X polarization direction is -A-Aj. When two bits 1 and 1 are output in succession in sequence, the pilot symbol in the X polarization direction is A+Aj. When two bits 0 and 1 are output in succession in sequence, the pilot symbol in the X polarization direction is -A+Aj. By analogy, 57 pilot symbols in the X polarization direction can be obtained.

[0234] As shown in FIG. 40, in the Y polarization direction, the input polarization seed is 0x3E9, which is 1111101001 after being converted into a binary sequence, that is, the value of m9 to m0. When two bits 1 and 0 are output in succession in sequence, the pilot symbol in the Y polarization direction is A-Aj. When two bits 0 and 0 are output in succession in sequence, the pilot symbol in the Y polarization direction is -A-Aj. When two bits 1 and 1 are output in succession in sequence, the pilot symbol in the Y polarization direction is A+Aj. When two bits 0 and 1 are output in succession in sequence, the pilot symbol in the Y polarization direction is -A+Aj. By analogy, 57 pilot symbols in the Y polarization direction can be obtained.

[0235] The polarization seed of the X polarization direction may be exchanged with the polarization seed of the Y polarization direction, and thus the 57 pilot symbols shown in Table X-13 below may be obtained. [Table 138]

[0236] In the above Table X-13, the correlation characteristics corresponding to the pilot symbols are shown in Figure 41. Figure 41(a) shows the cyclic autocorrelation result of the sequence of pilot symbols in the X polarization direction, Figure 41(b) shows the cyclic autocorrelation result of the sequence of pilot symbols in the Y polarization direction, and Figure 41(c) shows the cyclic cross-correlation result of the sequence of pilot symbols in the X polarization direction and the Y polarization direction. The normalized amplitude of the side lobe value of the cyclic autocorrelation function of the symbol sequence in the two polarization directions is less than or equal to 0.206, and the normalized amplitude of the side lobe value of the cyclic cross-correlation function of the symbol sequence in the two polarization directions is less than or equal to 0.212. The frame overhead of the superframe structure provided in this embodiment of the present application is also as low as 1.79%, and the designed sequence of pilot symbols has relatively good autocorrelation and cross-correlation characteristics. The training sequence and the sequence of pilot symbols can also be combined together to meet the DC balance, which helps to improve the quality of the signal restored at the receiving end.

[0237] With reference to the communication system described in the above embodiment corresponding to Fig. 1, and the framing process described in the embodiment corresponding to Fig. 2 or Fig. 3, an embodiment of the present application further provides another transmission method for optical communication. As shown in Fig. 42, the transmission method includes the following steps:

[0238] 3301: A transmitting device generates a superframe including a plurality of subframes, where the subframe includes a training symbol and a pilot symbol.

[0239] In each subframe, one polarization direction has N PS There are N pilot symbols, each of which has a value of −A2−A2j, −A2+A2j, A2−A2j, and A2+A2j, where A2 is a real number, PS is an even number. PS N pilot symbols achieve DC balance and are PSThe combination of pilot symbols achieves DC balance.

[0240] The pilot symbols are generated based on a target polynomial and a seed. The target polynomial is a primitive polynomial, and the target polynomial has five or fewer nonzero terms. The target polynomial is an entry in Table Y-1 below. [Table 139]

[0241] 3302: A transmitting device transmits a superframe, and correspondingly, a receiving device receives the superframe including a plurality of subframes.

[0242] 3303: The receiving device decodes the received superframe.

[0243] In the solution of this embodiment of the present application, pilot symbols are generated based on a target polynomial and a seed. The target polynomial can be any item in Table Y-1 above, and the target polynomial and the corresponding seed are generated based on the N PS N pilot symbols achieve DC balance and the training symbols and N PS The combination with the pilot symbols satisfies achieving DC balance, which helps the receiving end to restore the signal better and improves the quality of the signal at the receiving end.

[0244] The structure of the superframe provided in this embodiment of the present application can be understood by referring to the corresponding contents of Figures 33(a) to 33(c), and the details will not be described again here.

[0245] In this embodiment of the present application, the following specific superframe format is considered: The number of symbols before framing is 172032, and the symbols are coding symbols. The coding scheme may be multiple coding using Open FEC (OFEC) or using a Hamming code with a code length of 128 bits, or another coding scheme may be used. The following table shows the relationship between the parameter N SF , N TS , N PS , N FAW , N RES , N S , N F , and the OH corresponding to the superframe, etc. are listed. [Table 140]

[0246] As shown in (a) of Figure 33, the superframe includes 24 subframes, each of which includes 7296 symbols. The first subframe is shown in (b) of Figure 33 and includes 11 training symbols and N FAW N frame alignment word symbols and RES reserved symbols, N FAW +N RES = 96. As shown in (c) of Figure 33, the second to 24th subframes also each include 11 training symbols. In addition, in each subframe, the first symbol of every 64 symbols is a pilot symbol. Each subframe includes 114 pilot symbols.

[0247] where the number of frame alignment word symbols, N FAW = 22 and the number of reserved symbols N RES =74 is used as an example for illustration purposes, as shown in FIG.

[0248] A frame alignment word sequence having a length of 22 is shown in Table Y-2 below, where FAWThe value of is not particularly limited. The value can be selected according to the actual application scenario so that the peak-to-average power ratio, noise, and sensitivity of the FAW symbol have a good compromise. Taking 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 real number A FAW The value of A is 1≦A FAW ≦3. For example, real numbers

number

number

[0249] The 114 pilot symbols are determined based on a target polynomial and a corresponding seed. In this embodiment of the present application, the target polynomial is a 10th order polynomial, which may be expressed as follows:

number

[0250] The pilot symbol generation structure can be understood by referring to Figure 34 above. As shown in Figure 34, the seeds can be represented in binary form as m9, m8, m7, m6, m5, m4, m3, m2, m1, and m0. Indeed, the seeds may also be represented in hexadecimal or decimal form, and when calculated with the target polynomial, the seeds need to be converted to binary form. For example, 0110111000 is represented in hexadecimal as 0x1B8 and in decimal as 440.

[0251] In this embodiment of the present application, the same target generator polynomial can be used for pilot symbols in two orthogonal polarization directions, but due to different seeds, the pilot symbols output in the two polarization directions are accordingly not completely the same.

[0252] As shown in FIG. 34, for a scenario in which 114 pilot symbols need to be generated, a bit sequence b0, b1, b2, ... b 227 is obtained based on the target polynomial and the seed. 227 Every two consecutive bits in b are mapped to one symbol, where b 2t and b 2t+1 is one symbol (2b 2t -1)A2+(2b 2t+1 −1) A2j, where 0≦t<114.

[0253] It should be understood that when the pilot symbols are the outermost four symbols of the constellation diagram, the pilot symbols have a relatively high sensitivity but a relatively large peak to average power ratio, and when the pilot symbol values ​​are the innermost four symbols of the constellation diagram, the training symbols and pilot symbols have a relatively low noise but a relatively low sensitivity.

[0254] It should be noted that the pilot symbols may not be symbols in the constellation diagram of the used modulation format, but may be four symbols in the intermediate region between the outermost four symbols and the innermost four symbols of the constellation diagram of the used modulation format. In this case, the pilot symbols have considerable noise and sensitivity, but have a relatively low peak-to-average power ratio. Take 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 A2 satisfies 1≦A2≦3. The specific value of the real number A2 may be selected according to the actual application scenario, so that the peak-to-average power ratio, noise, and sensitivity of the training symbols or pilot symbols have a good compromise. For example, the real number

number

number

number

number

number

number

[0255] Considering that the sequence generated when the target polynomial is a primitive polynomial generally has relatively good randomness, and more non-zero terms in the target polynomial indicate more complex implementation, when the target polynomial uses a primitive polynomial, the non-zero terms in the target polynomial are 5 or less, and the target polynomial and the hexadecimal seed in two polarization directions are one row in the following Table Y-3, the normalized amplitude of the side lobe value of the cyclic autocorrelation function of the pilot symbols in the same polarization direction is less than or equal to 0.25, and the normalized amplitude of the cyclic cross-correlation function value of the pilot symbols in different polarization directions is less than or equal to 0.25; [Table 142] TIFF2025069189000554.tif113170

[0256] In table Y-3, in the row indexed 1, the primitive polynomial used by the goal polynomial is x 10 +x 9 +x 7 +x 6 +1 and the corresponding hexadecimal seeds in the two polarization directions are 0x002 and 0x3C6, the process of generating 114 pilot symbols can be understood by referring to FIG.

[0257] As shown in FIG. 43, in the X polarization direction, the input polarization seed is 0x002, which is 0000000010 after being converted into a binary sequence, i.e., the value of m9 to m0. When two bits 1 and 0 are output in succession in sequence, the pilot symbol in the X polarization direction is A2-A2j. When two bits 0 and 0 are output in succession in sequence, the pilot symbol in the X polarization direction is -A2-A2j. When two bits 1 and 1 are output in succession in sequence, the pilot symbol in the X polarization direction is A2+A2j. When two bits 0 and 1 are output in succession in sequence, the pilot symbol in the X polarization direction is -A2+A2j. By analogy, 114 pilot symbols in the X polarization direction can be obtained.

[0258] As shown in FIG. 43, in the Y polarization direction, the input polarization seed is 0x3C6, which is 0010000100 after being converted into a binary sequence, that is, the value of m9 to m0. When two bits 1 and 0 are output in succession in sequence, the pilot symbol in the Y polarization direction is A2-A2j. When two bits 0 and 0 are output in succession in sequence, the pilot symbol in the Y polarization direction is -A2-A2j. When two bits 1 and 1 are output in succession in sequence, the pilot symbol in the Y polarization direction is A2+A2j. When two bits 0 and 1 are output in succession in sequence, the pilot symbol in the Y polarization direction is -A2+A2j. By analogy, 114 pilot symbols in the Y polarization direction can be obtained.

[0259] The polarization seed of the X polarization direction may be exchanged with the polarization seed of the Y polarization direction, and thus 114 pilot symbols may be obtained as shown in Table Y-4 below. [Table 143]

[0260] In the above table Y-4, in one polarization direction, -A2-A2j, -A2+A2j, A2-A2j, and A2+A2j in 114 pilot symbols are 28, 29, 29, and 28, respectively. In one polarization direction, -A2-A2j, -A2+A2j, A2-A2j, and A2+A2j in pilot symbols included in one subframe are close to each other. In addition, in one polarization direction, the sum of 114 pilot symbols in one subframe is 0, which can achieve DC balance and improve the quality of the signal restored at the receiving end.

[0261] In this embodiment of the present application, the first symbol of each subframe is used as both a pilot symbol and a training symbol. The first symbol of the considered 11 training symbols is the same as the first symbol of the 114 pilot symbols. In one polarization direction, each subframe further includes 10 training symbols in addition to the first symbol. The value of each of the 10 training symbols is one of -A1-A1j, -A1+A1j, A1-A1j, and A1+A1j, where A1 is a real number. The specific value of the real number A1 can be selected according to the actual application scenario, so that the peak-to-average power ratio, noise, and sensitivity of the training symbols and pilot symbols have a good compromise. A1 may not be equal to A2. Taking 16QAM as an example, the values ​​of the 16 symbols in the 16QAM constellation are {±1±1j, ±1±3j, ±3±1j, ±3±3j}, and the value of the real number A1 satisfies 1≦A1≦3. For example, the real number

number

number

number

number

number

number

[0262] In Figure 33(b), the training sequence having a length of 11 may be an item in Table 40 where the start symbol in two polarizations is -A+Aj, the real number A used in the start symbol in each polarization direction is set to A2, and the real number A used in the remaining 10 symbols excluding the start symbol is set to A1. The training sequence is an item indexed 15 in Table 40, as shown in Table Y-5 below. [Table 144]

[0263] In the case of the above-mentioned 114 pilot symbols and 11 training symbols, the combination of pilot symbols and training symbols included in one subframe in one polarization direction satisfies DC balance.

[0264] It should be noted that when the values ​​of the real numbers A1 and A2 are not equal, the 11 training symbols in the above Table Y-5 are -A2+A2j, which is not equal to any of the values ​​of the following 10 training symbols -A1-A1j, -A1+A1j, A1-A1j, and A1+A1j. In some practical application scenarios, in order to facilitate implementation, in one polarization direction, the first symbol in each subframe is only used as a pilot symbol and is no longer used as a training symbol. In this case, the number of training symbols in a subframe is reduced to 10, and the value of the training symbol is one of -A1-A1j, -A1+A1j, A1-A1j, and A1+A1j, which facilitates the implementation of equalisation. In this case, the training sequence with a length of 10 can be one item of Table 33, and the real number A is set to A1.

[0265] In the above solution, the correlation characteristics corresponding to the pilot symbols are shown in the following Figure 44. Figure 44(a) shows the cyclic autocorrelation result of the sequence of pilot symbols in the X polarization direction, Figure 44(b) shows the cyclic autocorrelation result of the sequence of pilot symbols in the Y polarization direction, and Figure 44(c) shows the cyclic cross-correlation result of the sequence of pilot symbols in the X polarization direction and the Y polarization direction. The normalized amplitude of the side lobe value of the cyclic autocorrelation function of the symbol sequence in the two polarization directions is less than or equal to 0.167, and the normalized amplitude of the side lobe value of the cyclic cross-correlation function of the symbol sequence in the two polarization directions is less than or equal to 0.176. The frame overhead of the superframe structure provided in this embodiment of the present application is also as low as 1.79%, and the sequence of pilot symbols has relatively good autocorrelation and cross-correlation characteristics. The training symbols and pilot symbols can also be combined together to meet the DC balance, which helps to improve the quality of the signal restored at the receiving end.

[0266] Those skilled in the art should understand that the embodiments of the present application may be provided as a method or a computer program product. Thus, the present application may be in the form of a hardware-only embodiment, a software-only embodiment, or an embodiment having a combination of software and hardware. In addition, the present application may be in the form of a computer program product embodied on one or more computer usable storage media (including, but not limited to, disk memory, CD-ROM, optical memory, etc.) that contain computer usable program code.

[0267] The preceding description is merely an embodiment of the technical solutions of the present application, and is not intended to limit the protection scope of the present application. Nohara Any modifications, equivalent replacements, improvements, etc. within the scope of protection of this application shall fall within the scope of protection of this application.

Claims

1. A transmission method for optical communication, comprising: generating a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, in one polarization direction, there is one symbol that is both a training symbol and a pilot symbol, in each subframe, in the one polarization direction, N ＰＳ pilot symbols and N ＴＳ There are N training symbols, ＰＳ is 114, and N ＴＳ is 111, each of the training symbols and the pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number, and the 114 pilot symbols in each of the two polarization directions are as shown in the table below: 【Table 1】 transmitting the superframe; A transmission method including:

2. In one polarization direction, the total number of symbols in the superframe, N Ｆ is 175104, and the number of subframes N ＳＦ is 24, and the number of symbols in each subframe N Ｓ 2. The transmission method of claim 1 , wherein the number of pre-framing symbols in the superframe is 172032.

3. Number of frame alignment word symbols N ＦＡＷ and the number of reserved symbols N ＲＥＳ With N ＦＡＷ +N ＲＥＳ The transmission method according to claim 2 , wherein:

4. 2. The transmission method of claim 1, wherein in each subframe, a fixed-position symbol out of every 64 symbols is the pilot symbol, or in each subframe, a fixed-position symbol out of every 48 symbols is the pilot symbol.

5. 10. The transmission method of claim 1, wherein the first symbol in each subframe is both a training symbol and a pilot symbol.

6. The modulation format of the symbols in the superframe is 16QAM, and the value of A is ±1, ±3, or [0010] The transmission method according to claim 1 ,

7. The transmission method of claim 1 , wherein a modulation format of the symbols in the superframe is QPSK and the value of A is ±1.

8. A receiving method for optical communication, comprising the steps of: receiving a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, in one polarization direction, there is one symbol that is both a training symbol and a pilot symbol, in each subframe, in the one polarization direction, N ＰＳ pilot symbols and N ＴＳ There are N training symbols, ＰＳ is 114, and N ＴＳ is 111, each of the training symbols and the pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number, and the 114 pilot symbols in each of the two polarization directions are as shown in the following table: 【Table 2】 decoding the received superframe; A receiving method including:

9. In one polarization direction, the total number of symbols in the superframe, N Ｆ is 175104, and the number of subframes N ＳＦ is 24, and the number of symbols in each subframe N Ｓ 9. The method of claim 8, wherein the number of pre-framing symbols in the superframe is 172032.

10. Number of frame alignment word symbols N ＦＡＷ and the number of reserved symbols N ＲＥＳ With N ＦＡＷ +N ＲＥＳ 10. The receiving method according to claim 9, wherein:

11. 9. The receiving method according to claim 8, wherein in each subframe, a fixed-position symbol out of every 64 symbols is the pilot symbol, or in each subframe, a fixed-position symbol out of every 48 symbols is the pilot symbol.

12. 9. The method of claim 8, wherein the first symbol in each subframe is both a training symbol and a pilot symbol.

13. The modulation format of the symbols in the superframe is 16QAM, and the value of A is ±1, ±3, or [0025] The receiving method according to claim 8, wherein:

14. The receiving method according to claim 8, wherein the modulation format of the symbols in the superframe is QPSK and the value of A is ±1.

15. A transmission method for optical communication, comprising: generating a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, in one polarization direction, there is one symbol that is both a training symbol and a pilot symbol, in each subframe, in the one polarization direction, N ＰＳ pilot symbols and N ＴＳ There are N training symbols, ＰＳ is 114, and N ＴＳ is 111, each of the training symbols and the pilot symbols is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number, and in one polarization direction, in a combination of 114 pilot symbols and 11 training symbols, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in the one polarization direction are all 31; transmitting the superframe; A transmission method including:

16. In one polarization direction, the total number of symbols in the superframe, N Ｆ is 175104, and the number of subframes N ＳＦ is 24, and the number of symbols in each subframe N Ｓ 16. The transmission method of claim 15, wherein the number of pre-framing symbols in the superframe is 172032.

17. Number of frame alignment word symbols N ＦＡＷ and the number of reserved symbols N ＲＥＳ With N ＦＡＷ +N ＲＥＳ The transmission method according to claim 16, wherein:

18. Each of the training symbols and the pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number, and in one polarization direction, in a combination of 114 pilot symbols and 11 training symbols, each of the 114 pilot symbols in two polarization directions is shown in the following table: 【Table 3】 The transmission method according to claim 15.

19. 16. The transmission method of claim 15, wherein in each subframe, a fixed-position symbol out of every 64 symbols is the pilot symbol, or in each subframe, a fixed-position symbol out of every 48 symbols is the pilot symbol.

20. 16. The transmission method of claim 15, wherein the first symbol in each subframe is both a training symbol and a pilot symbol.

21. The modulation format of the symbols in the superframe is 16QAM, and the value of A is ±1, ±3, or [0030] The transmission method according to claim 15,

22. The transmission method of claim 15, wherein a modulation format of the symbols in the superframe is QPSK and the value of A is ±1.

23. A receiving method for optical communication, comprising the steps of: receiving a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, in one polarization direction, there is one symbol that is both a training symbol and a pilot symbol, in each subframe, in the one polarization direction, N ＰＳ pilot symbols and N ＴＳ There are N training symbols, ＰＳ is 114, and N ＴＳ is 111, each of the training symbols and the pilot symbols is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number, and in one polarization direction, in a combination of 114 pilot symbols and 11 training symbols, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in the one polarization direction are all 31; decoding the received superframe; A receiving method including:

24. In one polarization direction, the total number of symbols in the superframe, N Ｆ is 175104, and the number of subframes N ＳＦ is 24, and the number of symbols in each subframe N Ｓ 24. The method of claim 23, wherein the number of pre-framing symbols in the superframe is 172032.

25. Number of frame alignment word symbols N ＦＡＷ and the number of reserved symbols N ＲＥＳ With N ＦＡＷ +N ＲＥＳ 25. The receiving method according to claim 24, wherein:

26. Each of the training symbols and the pilot symbols is one of −A−Aj, −A+Aj, A−Aj, and A+Aj, where A is a real number, and in one polarization direction, in a combination of 114 pilot symbols and 11 training symbols, the respective 114 pilot symbols in two polarization directions are shown in the following table: 【Table 4】 24. The receiving method according to claim 23.

27. 24. The receiving method of claim 23, wherein in each subframe, a fixed-position symbol out of every 64 symbols is the pilot symbol, or in each subframe, a fixed-position symbol out of every 48 symbols is the pilot symbol.

28. 24. The method of claim 23, wherein the first symbol in each subframe is both a training symbol and a pilot symbol.

29. The modulation format of the symbols in the superframe is 16QAM, and the value of A is ±1, ±3, or [0045] The receiving method according to claim 23,

30. 24. The receiving method of claim 23, wherein the modulation format of the symbols in the superframe is QPSK and the value of A is ±1.

31. A communication device for optical communication, said communication device configured to perform a method according to any one of claims 1 to 30.

32. A system for optical communication, the system comprising a transmitting device and a receiving device, the transmitting device configured to perform a method according to any one of claims 1 to 7 and 15 to 22, and the receiving device configured to perform a method according to any one of claims 8 to 14, 23 to 30.

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