TRANSMISSION METHOD AND RECEPTION METHOD FOR OPTICAL COMMUNICATION, AND CORRESPONDING DEVICE.

Abstract

This application discloses a transmission method for optical communication, applicable to various scenarios such as metropolitan area networks, backbone networks, and data center interconnections exceeding 400 Gbps (including 600 Gbps, 800 Gbps, and similar speeds). The method involves generating a superframe containing multiple subframes and transmitting the superframe. Each subframe includes training symbols and pilot symbols, with each training and pilot symbol being one of -A-Aj, -A+Aj, A-Aj, or A+Aj, where A is a real number. Furthermore, the quantities of -A-Aj, -A+Aj, A-Aj, and A+Aj in the training and pilot symbols within each subframe, along with two mutually perpendicular polarization directions, meet specific requirements to achieve DC current balance, enabling the receiver to restore a signal.

Description

A transmission method, a receiving method and corresponding equipment for optical communication

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on April 20, 2021, with application number 202110424596.8 and invention name “A Superframe Transmission Method”, the entire contents of which are incorporated by reference into this application.

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on December 1, 2021, with application number 202111456537.5 and invention name “A transmission method, receiving method and corresponding equipment for optical communication”, the entire contents of which are incorporated by reference into this application.

[0003] This application claims priority to the Chinese patent application filed with the China Patent Office on January 27, 2022, with application number 202210102040.1 and invention name “A transmission method, receiving method and corresponding equipment for optical communication”, the entire contents of which are incorporated by reference into this application. Technical Field

[0004] The present application relates to the field of optical communications, and in particular to a transmission method, a receiving method, and corresponding equipment for optical communications. Background Art

[0005] Driven by 5G, cloud computing, big data, and artificial intelligence, high-speed optical transmission networks are developing towards high capacity, packetization, and intelligence. Coherent optical communication systems utilize the amplitude, phase, polarization, and frequency of light waves to carry information. To combat optical signal distortion caused by dispersion, polarization-related impairments, noise, nonlinear effects, and other factors during transmission and maintain long-distance transmission, coherent optical communication systems typically incorporate a number of designed fixed symbol sequences into the transmitted symbol sequence to facilitate recovery of the transmitted symbols at the receiving end.

[0006] Existing transmission symbol sequences are mainly used in 400Gbps scenarios and cannot adapt to future scenarios above 400Gbps (including 600Gbps, 800Gbps, etc.). In addition, there is a problem of poor cross-correlation between transmission symbol sequences in different polarization directions. These are all problems that need to be solved urgently in the future.

[0007] Summary of the Invention

[0008] The present application provides a transmission method for optical communication, which solves the problem that the existing technology cannot be applied to scenarios above 400Gbps and the symbol sequences in different polarization directions have poor mutual correlation.

[0009] In a first aspect, a transmission method for optical communication is provided, the method comprising: generating a superframe comprising a plurality of subframes, the subframes comprising training symbols and pilot symbols, wherein, in one polarization direction, the sum of the number of the training symbols and the pilot symbols included in the subframe is not less than 5, and there is one symbol that is both a training symbol and a pilot symbol; and each of the training symbols and each of the pilot symbols is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number; and among the training symbols and the pilot symbols included in each subframe, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is respectively And the numbers in the other polarization direction are Among them, N TS N is the number of training symbols in one polarization direction in each subframe. PS N is the number of pilot symbols in each subframe in one polarization direction. TS +N PS is an odd number, and the two polarization directions are orthogonal to each other; the superframe is sent out.

[0010] In a second aspect, a receiving method for optical communication is provided, the method comprising: receiving a superframe comprising a plurality of subframes, the subframes comprising training symbols and pilot symbols, wherein, in one polarization direction, the sum of the number of the training symbols and the pilot symbols included in the subframe is not less than 5, and there is one symbol that is both a training symbol and a pilot symbol; and each of the training symbols and each of the pilot symbols is respectively one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number; and among the training symbols and the pilot symbols included in each subframe, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is respectively And the numbers in the other polarization direction are Among them, N TS N is the number of training symbols in one polarization direction in each subframe. PS N is the number of pilot symbols in each subframe in one polarization direction. TS +N PS is an odd number, and the two polarization directions are orthogonal to each other; the received super frame is decoded.

[0011] In the embodiment of the present application, a subframe includes N in total in each polarization direction. TS +N PS-1 training symbol and pilot symbol, among which the number of -A-Aj, -A+Aj, A-Aj, and A+Aj is no more than 1; and in one subframe, the number of the four complex numbers representing the training symbols and pilot symbols in the two polarization directions is the same, which is (N TS +N PS -1) / 2, effectively ensuring the balance of the number of symbols. In addition, it can also achieve DC balance in the sequence composed of training symbols and pilot symbols, which is beneficial for restoring signal quality at the receiving end.

[0012] In combination with the first aspect or the second aspect, in a first possible implementation, in a subframe, a sequence of training symbols in one polarization direction is different from a sequence of training symbols in another polarization direction, and a sequence of pilot symbols in one polarization direction is different from a sequence of pilot symbols in another polarization direction. This avoids the problem of a receiver being unable to distinguish between the two polarization directions during actual transmission.

[0013] In combination with the above embodiment, in a second possible implementation, the training symbols are arranged continuously in the subframe, wherein, in any polarization direction, the number of consecutive identical real elements in the training symbols included in the subframe is no more than 5, and the number of consecutive identical imaginary elements is no more than 5. Furthermore, in any polarization direction, the number of consecutive identical training symbols in a subframe is no more than 4. The training sequence derived under such conditions facilitates clock recovery, thereby helping to improve the quality of the signal recovered by the receiving end.

[0014] In combination with the above embodiments, in a third possible implementation of the first aspect, the multiple subframes further include a first subframe, the first subframe including consecutively arranged frame synchronization symbols, each frame synchronization symbol being one of -A-Aj, -A+Aj, A-Aj, and A+Aj; in any polarization direction, the number of consecutively identical elements in the real part of the frame synchronization symbols included in the subframe is no more than 5, and the number of consecutively identical elements in the imaginary part is no more than 5. Furthermore, in any polarization direction, the number of consecutively identical frame synchronization symbols in the first subframe does not exceed 4. The frame synchronization sequence derived under such conditions is also conducive to clock recovery, thereby helping to improve the signal quality recovered by the receiving end.

[0015] In combination with the third possible implementation, in a fourth possible implementation, in the frame synchronization symbols included in the first subframe, the numbers of -A-Aj, -A+Aj, A-Aj and A+Aj in one polarization direction are respectively And the numbers in the other polarization direction are Among them, NFAW is the number of the frame synchronization symbols in the first subframe in one polarization direction, N FAW This embodiment ensures that multiple frame synchronization symbols meet DC balance, and the number of the four optional symbols -A-Aj, -A+Aj, A-Aj, and A+Aj differs by no more than 1, which is beneficial for the receiving end to restore signal quality.

[0016] In combination with the above embodiments, in a fifth possible embodiment, N TS is 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 And the numbers in the other polarization direction are

[0017] In combination with the first aspect, the second aspect, and any one of the first to fourth possible implementations, in a sixth possible implementation, N TS is an odd number. Among the training symbols included in each subframe, excluding the training symbol that also serves as the pilot symbol, the numbers of -A-Aj, -A+Aj, A-Aj and A+Aj in one polarization direction are respectively And the numbers in the other polarization direction are

[0018] The two aforementioned embodiments illustrate the number of possible training sequence symbols in different polarization directions under two different conditions. The number of training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj included in a subframe is similar. Furthermore, in each polarization direction, excluding the training symbol that also serves as a pilot symbol (if there is an odd number of training symbols), the sum of the real and imaginary parts of the complex numbers corresponding to the remaining training symbols is zero, achieving DC balance and improving signal quality recovery at the receiving end.

[0019] In combination with the first aspect, the second aspect, and any one of the first to fourth possible implementations, in a seventh possible implementation, N PS is an even number, and in the pilot symbols included in each subframe, the numbers of -A-Aj, -A+Aj, A-Aj and A+Aj in one polarization direction are respectively And the numbers in the other polarization direction are

[0020] In combination with the first aspect, the second aspect, and any one of the first to fourth possible implementations, in an eighth possible implementation, NPS is an odd number. Among the pilot symbols included in each subframe, excluding the pilot symbol that also serves as the training symbol, the numbers of -A-Aj, -A+Aj, A-Aj and A+Aj in one polarization direction are respectively And the numbers in the other polarization direction are

[0021] In combination with the first aspect, the second aspect, and any one of the first to fourth possible implementations, in a ninth possible implementation, in each subframe, the number of pilot symbols in one polarization direction divided by 4 has a remainder of 0, and in the pilot symbols included in each subframe, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is N respectively. PS / 4+1、N PS / 4-1、N PS / 4-1、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、N PS / 4-1; or, the number in both polarization directions is N PS / 4.

[0022] In combination with the first aspect, the second aspect, and any one of the first to fourth possible implementations, in a tenth possible implementation, in each subframe, the number of pilot symbols in one polarization direction divided by 4 has a remainder of 2, and in the pilot symbols included in each subframe, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is (N PS -2) / 4, (N PS -2) / 4+1、(N PS -2) / 4+1、(N PS -2) / 4, and the numbers in the other polarization direction are (N PS -2) / 4+1、(N PS -2) / 4, (N PS -2) / 4, (N PS -2) / 4+1.

[0023] In combination with the first aspect, the second aspect, and any one of the first to fourth possible implementations, in an eleventh possible implementation, in each subframe, the number of pilot symbols in one polarization direction divided by 4 has a remainder of 1, and among the pilot symbols included in each subframe, excluding the pilot symbol that is also a training symbol, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is (N PS -1) / 4+1、(N PS -1) / 4-1、(N PS -1) / 4-1、(N PS -1) / 4+1, and the numbers in the other polarization direction are (N PS -1) / 4-1、(N PS -1) / 4+1、(N PS -1) / 4+1、 (N PS -1) / 4-1; or, the number in both polarization directions is (N PS -1) / 4.

[0024] In combination with the first aspect, the second aspect, and any one of the first to fourth possible implementations, in a twelfth possible implementation, in each subframe, when the number of pilot symbols in one polarization direction is divided by 4 and the remainder is 3, among the pilot symbols included in each subframe, excluding the pilot symbol that is also a training symbol, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is (N PS -3) / 4, (N PS -3) / 4+1、(N PS -3) / 4+1、(N PS -3) / 4, and the numbers in the other polarization direction are (N PS -3) / 4+1、(N PS -3) / 4, (N PS -3) / 4, (N PS -3) / 4+1.

[0025] The seventh to twelfth embodiments described above describe the number of possible pilot sequence symbols in different polarization directions under different circumstances. The number of pilot symbols -A-Aj, -A+Aj, A-Aj, and A+Aj included in a subframe is close to each other, effectively ensuring balance between training symbols. Furthermore, in each polarization direction, excluding the pilot symbol that also serves as a training symbol (if there is an odd number of pilot symbols), the sum of the real parts of the complex numbers corresponding to the remaining pilot symbols is zero, and the sum of the imaginary parts is also zero. This achieves DC balance and improves signal quality recovery at the receiving end.

[0026] In combination with the above embodiment, in a thirteenth possible embodiment, the modulation format of the symbols in the superframe is 16QAM, and the value of A is 1 or 3. In addition, it is also possible to compress the symbols on the constellation diagram, and accordingly, the value of A will also be compressed accordingly. Taking 16QAM as an example, the power of the 16 symbols on the 16QAM constellation diagram is normalized, and the value becomes The value of A is or It should be understood that when the pilot symbols and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj use the outermost four symbols of the constellation diagram, the sensitivity of the training and pilot symbols is high, but the peak to average power ratio is large; when the pilot symbols and training symbols take the values ​​of -A-Aj, -A+Aj, A-Aj, and A+Aj and use the innermost four symbols of the constellation diagram, the noise of the training and pilot symbols is small, but their sensitivity is low.

[0027] 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 on the constellation diagram of the modulation format used. They may be four symbols in the middle area between the outermost four symbols and the innermost four symbols of the constellation diagram. In this case, the noise and sensitivity of the training and pilot symbols are average, but the peak-to-average power ratio is relatively low. Taking 16QAM as an example, the 16 symbols on 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 symbol and training symbol -A-Aj, -A+Aj, A-Aj, and A+Aj can be any four symbols in the middle area between the outermost four symbols and the innermost four symbols of the 16QAM constellation diagram. The specific value of the real number A can be selected according to the actual application scenario to achieve a good compromise between the peak-to-average power ratio, noise, and sensitivity of the training and pilot symbols. For example, the real number The values ​​of pilot symbols and training symbols are In addition, when the 16 symbols on the 16QAM constellation are power normalized and the value is The value of real number A satisfies For example, real numbers The values ​​of pilot symbols and training symbols are

[0028] In combination with the above embodiment, in a fourteenth possible embodiment, in each subframe, a fixed position of every 64 symbols is the pilot symbol. For example, the first symbol of every 64 symbols is the pilot symbol.

[0029] In combination with the first aspect, the second aspect, and any possible implementation manners of the first to thirteenth possible implementation manners, in a fifteenth possible implementation manner, in each subframe, a fixed position of every 48 symbols is the pilot symbol. For example, the first symbol of every 48 symbols is the pilot symbol.

[0030] It should be understood that the above-mentioned implementation modes can be combined with the first aspect or the second aspect, and this application does not limit them.

[0031] In a third aspect, a transmission device for optical communication is provided, the transmission device comprising a processor and a memory, the memory being used to store instructions, and the processor being used to execute the instructions, so that the transmission device executes the method described in the first aspect and any possible implementation method of the first aspect.

[0032] In a fourth aspect, a receiving device for optical communication is provided, wherein the transmitting device includes a processor and a memory, the memory is used to store instructions, and the processor is used to execute the instructions, so that the receiving device executes the method described in the second aspect and any possible implementation method of the second aspect.

[0033] In a fifth aspect, a system for optical communication is provided, the system comprising the transmission device as described in the third aspect, and the receiving device as described in the fourth aspect.

[0034] It should be understood that the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc., and this application does not limit this.

[0035] In a sixth aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores instructions. When the instructions are executed on a terminal device, the terminal device executes the method as described in the first aspect or any possible implementation of the first aspect; or causes the terminal device to execute the method as described in the second aspect or any possible implementation of the second aspect.

[0036] In a seventh aspect, a computer program product comprising instructions is provided that, when executed on a terminal device, causes the terminal device to execute the method as described in the first aspect or any possible implementation of the first aspect; or causes the terminal device to execute the method as described in the second aspect or any possible implementation of the second aspect. It should be understood that the terminal device may be a chip, processor, etc., and this application is not limited thereto.

[0037] In an eighth aspect, a transmission method for optical communication is provided, the method comprising: generating a superframe comprising a plurality of subframes, the subframe comprising a training symbol and a pilot symbol, wherein, in one polarization direction, there is a symbol that is both a training symbol and a pilot symbol, and each training symbol and each pilot symbol are respectively one of -A-Aj, -A+Aj, A-Aj, and A+Aj, where A is a real number; in one polarization direction in each subframe, the pilot symbol is generated by a target polynomial and a seed, and the pilot symbol has N PS , and N TS The combination of training symbols achieves DC balance, N TS is the number of the training symbols in each subframe in one polarization direction, N TS +N PS is an odd number; the target polynomial is one of the following tables;

[0038] Sequence target polynomial 1x 10 +x 9 +x 8 +x 7 +x 6 +12x 10 +x 9 +x 8 +x 6 +x 4 +13x 10 +x 9 +x 7 +x 6 +x 4 +1

[0039] 4x 10 +x 9 +x 6 +x 3 +15x 10 +x 8 +x 5 +x 3 +16x 10 +x 8 +x 6 +x 5 +x 3 +17x 10 +x 8 +x 7 +x4 +x 3 +18x 10 +x 6 +x 5 +x 4 +x 3 +19x 10 +x 9 +x 6 +x 2 +110x 10 +x 7 +x 6 +x 2 +111x 10 +x 7 +x 5 +x 2 +112x 10 +x 8 +x 7 +x 5 +x 2 +113x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +114x 10 +x 7 +x 5 +x 4 +x 2 +115x 10 +x 9 +x 7 +x 5 +x 4 +x 2 +116x 10 +x 9 +x 8 +x 3 +x 2 +117x 10 +x 9 +x 8 +x 7 +x 3 +x 2 +118x 10 +x 7 +x 6 +x 3 +x 2 +119x 10 +x 8 +x 5 +x+120x 10 +x 8 +x 4 +x+121x 10+x 9 +x 8 +x 7 +x 4 +x+122x 10 +x 8 +x 5 +x 4 +x+123x 10 +x 5 +x 3 +x+124x 10 +x 8 +x 6 +x 5 +x 3 +x+125x 10 +x 9 +x 8 +x 7 +x 4 +x 3 +x+126x 10 +x 6 +x 4 +x 3 +x+127x 10 +x 8 +x 7 +x 2 +x+128x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +x+129x 10 +x 9 +x 6 +x 3 +x 2 +x+130x 10 +x 8 +x 6 +x 3 +x 2 +x+131x 10 +x 6 +x 5 +x 3 +x 2 +x+132x 10 +x 4 +x 3 +x 2 +x+133x 10 +x 9 +x 7 +x 3 +134x 10 +x 9 +x 6 +x+135x10 +x 9 +x 4 +x+136x 10 +x 7 +x 3 +x+1

[0040] Send the superframe.

[0041] In a ninth aspect, a receiving method for optical communication is provided, the method comprising:

[0042] A superframe comprising multiple subframes is received, each subframe comprising training symbols and pilot symbols, wherein, in one polarization direction, there is a symbol that is both a training symbol and a pilot symbol, and each training symbol and each pilot symbol are one of -A-Aj, -A+Aj, A-Aj, and A+Aj, respectively, where A is a real number; in each subframe, in one polarization direction, the pilot symbol is generated by a target polynomial and a seed, and the pilot symbol has N PS , and N TS The combination of training symbols achieves DC balance, N TS is the number of the training symbols in each subframe in one polarization direction, N TS +N PS is an odd number; the target polynomial is one of the following tables;

[0043] Sequence target polynomial 1x 10 +x 9 +x 8 +x 7 +x 6 +12x 10 +x 9 +x 8 +x 6 +x 4 +13x 10 +x 9 +x 7 +x 6 +x 4 +14x 10 +x 9 +x 6 +x 3 +15x 10 +x 8 +x 5 +x 3 +16x 10 +x 8 +x 6 +x 5 +x 3 +17x 10 +x 8 +x 7 +x4 +x 3 +18x 10 +x 6 +x 5 +x 4 +x 3 +19x 10 +x 9 +x 6 +x 2 +110x 10 +x 7 +x 6 +x 2 +111x 10 +x 7 +x 5 +x 2 +112x 10 +x 8 +x 7 +x 5 +x 2 +113x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +114x 10 +x 7 +x 5 +x 4 +x 2 +115x 10 +x 9 +x 7 +x 5 +x 4 +x 2 +116x 10 +x 9 +x 8 +x 3 +x 2 +117x 10 +x 9 +x 8 +x 7 +x 3 +x 2 +118x 10 +x 7 +x 6 +x 3 +x 2 +119x 10 +x 8 +x 5 +x+120x 10 +x 8 +x 4 +x+121x 10+x 9 +x 8 +x 7 +x 4 +x+122x 10 +x 8 +x 5 +x 4 +x+123x 10 +x 5 +x 3 +x+124x 10 +x 8 +x 6 +x 5 +x 3 +x+125x 10 +x 9 +x 8 +x 7 +x 4 +x 3 +x+126x 10 +x 6 +x 4 +x 3 +x+127x 10 +x 8 +x 7 +x 2 +x+128x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +x+129x 10 +x 9 +x 6 +x 3 +x 2 +x+130x 10 +x 8 +x 6 +x 3 +x 2 +x+131x 10 +x 6 +x 5 +x 3 +x 2 +x+132x 10 +x 4 +x 3 +x 2 +x+1

[0044] 33x 10 +x 9 +x 7 +x 3 +134x 10 +x9 +x 6 +x+135x 10 +x 9 +x 4 +x+136x 10 +x 7 +x 3 +x+1

[0045] Decode the received superframe.

[0046] In the eighth or ninth aspect, the pilot symbol is generated according to a target polynomial and a corresponding seed, the target polynomial is any one of the items in the above table, and the target polynomial and the corresponding seed can satisfy the generated N PS pilot symbols and N TS The combination of training symbols achieves DC balance, that is, in one subframe and in one polarization direction, the sum of the real parts of the complex numbers corresponding to the training symbols and pilot symbols is 0, and the sum of the imaginary parts is also 0. This is conducive to better signal recovery at the receiving end and improves the signal quality at the receiving end.

[0047] In combination with the eighth or ninth aspect, in a possible implementation, in one polarization direction, the total number of symbols N in the superframe is F =175104, number of subframes N SF =24, the number of symbols in each subframe N S =7296, N TS =11, N PS =114, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW +N RES =96, and the number of symbols before super-frame formation is 172032. This super-frame structure can better facilitate signal recovery at the receiving end and improve the signal quality at the receiving end.

[0048] In combination with the eighth aspect or the ninth aspect or any possible implementation manner, in another possible implementation manner, when the target polynomial and the hexadecimal seeds in the two polarization directions are a row in the following table, the normalized amplitude of the periodic autocorrelation function sidelobe value of the pilot symbol in the same polarization direction is not greater than 0.2, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbol in different polarization directions is not greater than 0.2,

[0049]

[0050]

[0051]

[0052]

[0053] In combination with the eighth aspect, the ninth aspect, or any possible implementation manner, in another possible implementation manner, when the target polynomial and the hexadecimal seeds in two polarization directions are a row in the following table, in one polarization direction, in the combination of 114 pilot symbols and 11 training symbols, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is 31;

[0054] Serial number Target polynomial Seed in polarization direction 1 Seed in polarization direction 2 1x 10 +x 9 +x 8 +x 7 +x 6 +10x0460x3842x 10 +x 9 +x 8 +x 7 +x 6 +10x0460x3C43x 10 +x 9 +x 6 +x 3 +10x0760x07C4x 10 +x 8 +x 7 +x 4 +x 3 +10x1A20x3305x 10 +x 8 +x 7 +x 4 +x 3 +10x2E60x3306x 10 +x 8 +x 7 +x 2 +x+10x2260x3DC7x 10 +x 9 +x 6 +x 3 +x 2 +x+10x13A0x3308x 10 +x 4 +x 3 +x 2 +x+10x3220x3689x 10 +x 4 +x 3 +x 2 +x+10x3220x0E410x 10 +x 4+x 3 +x 2 +x+10x0E20x36811x 10 +x 4 +x 3 +x 2 +x+10x0E20x0E412x 10 +x 4 +x 3 +x 2 +x+10x04E0x2F0.

[0055] In combination with the eighth aspect, the ninth aspect, or any possible implementation method, when the target polynomial is a primitive polynomial and its non-zero term is not greater than 5, the target polynomial and the hexadecimal seeds in the two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbol in the same polarization direction is not greater than 0.25, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbol in different polarization directions is not greater than 0.25.

[0056] Serial number Target polynomial Seed in polarization direction 1 Seed in polarization direction 2

[0057] 1x 10 +x 9 +x 7 +x 3 +10x23E0x0942x 10 +x 7 +x 6 +x 2 +10x0BE0x1B83x 10 +x 9 +x 6 +x+10x0020x2104x 10 +x 9 +x 6 +x+10x0020x3085x 10 +x 9 +x 6 +x+10x0020x1846x 10 +x 9 +x 6 +x+10x1C20x0407x 10 +x 8 +x 5 +x+10x3FE0x0E08x 10 +x 8 +x 5 +x+10x3FE0x2709x 10 +x 8 +x 5+x+10x3FE0x30410x 10 +x 9 +x 4 +x+10x3B60x1A011x 10 +x 9 +x 4 +x+10x3B60x0D012x 10 +x 9 +x 4 +x+10x3B60x05813x 10 +x 9 +x 4 +x+10x3B60x22C14x 10 +x 7 +x 3 +x+10x34E0x084.

[0058] In combination with the eighth aspect, the ninth aspect or any possible implementation manner, in another possible implementation manner, when the target polynomial is x 10 +x 7 +x 3 +x+1, and the corresponding hexadecimal seeds in the two polarization directions are 0x34E and 0x084, then in one polarization direction, in the combination of 114 pilot symbols and 11 training symbols, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction is 31. The 114 pilot symbols in each of the two polarization directions are shown in the following table:

[0059]

[0060]

[0061] In combination with the eighth aspect, the ninth aspect or any possible implementation manner, in another possible implementation manner, when 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 the two polarization directions are as shown in the following table:

[0062]

[0063] In combination with the eighth aspect, the ninth aspect or any possible implementation manner, in another possible implementation manner, in one polarization direction, the total number of symbols N in the superframe is F =175104, number of subframes N SF=48, the number of symbols in each subframe N S =3648, N TS =6, N PS =57, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW +N RES =96, the number of symbols before superframe framing is 172032.

[0064] In combination with the eighth aspect, the ninth aspect, or any possible implementation manner, in another possible implementation manner, when the target polynomial and the hexadecimal seeds in the two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbol in the same polarization direction is not greater than 0.23, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbol in different polarization directions is not greater than 0.23,

[0065] Serial number Target polynomial Seed in polarization direction 1 Seed in polarization direction 2 1x 10 +x 7 +x 3 +x+10x2040x2792x 10 +x 7 +x 3 +x+10x0B10x3E93x 10 +x 7 +x 3 +x+10x0B10x279.

[0066] In combination with the eighth aspect, the ninth aspect or any possible implementation manner, in another possible implementation manner, when 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 the two polarization directions are as shown in the following table:

[0067]

[0068] In the tenth aspect, a transmission device for optical communication is provided, the transmission device including a processor and a memory, the memory being used to store instructions, and the processor being used to execute instructions, so that the transmission device executes the method as in the eighth aspect and any possible implementation method of the eighth aspect.

[0069] In the eleventh aspect, a receiving device for optical communication is provided, and the transmitting device includes a processor and a memory, the memory is used to store instructions, and the processor is used to execute instructions, so that the receiving device executes the method as in the ninth aspect and any possible implementation method of the ninth aspect.

[0070] In a twelfth aspect, a system for optical communication is provided, the system comprising the transmission device as in the tenth aspect, and the receiving device as in the eleventh aspect.

[0071] It should be understood that the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc., and this application does not limit this.

[0072] In the thirteenth aspect, a computer-readable storage medium is provided, which stores instructions. When the instructions are executed on a terminal device, the terminal device executes a method such as the eighth aspect or any possible implementation of the eighth aspect; or causes the terminal device to execute a method such as the ninth aspect or any possible implementation of the ninth aspect.

[0073] In a fourteenth aspect, a computer program product comprising instructions is provided. When executed on a terminal device, the computer program product causes the terminal device to execute the method according to the eighth aspect or any possible implementation of the eighth aspect; or causes the terminal device to execute the method according to the ninth aspect or any possible implementation of the ninth aspect. It should be understood that the terminal device may be a chip, a processor, etc., and this application is not limited thereto.

[0074] In a fifteenth aspect, a transmission method for optical communication is provided, comprising: generating a superframe comprising a plurality of subframes, wherein the subframe comprises a training symbol and a pilot symbol; in each subframe, in one polarization direction, the pilot symbol has N PS The value is one of -A2-A2j, -A2+A2j, A2-A2j, A2+A2j, where A2 is a real number, N PS is an even number; N PS The pilot symbols achieve DC balance; the training symbols and N PS The combination of the pilot symbols achieves DC balance; the pilot symbols are generated by a target polynomial and a seed, the target polynomial is a primitive polynomial, and its non-zero terms are not greater than 5; the target polynomial is one of the following table;

[0075] Sequence target polynomial 1x10 +x 9 +x 7 +x 6 +12x 10 +x 9 +x 7 +x 3 +13x 10 +x 8 +x 4 +x 3 +14x 10 +x 7 +x 6 +x 2 +15x 10 +x 9 +x 6 +x+16x 10 +x 9 +x 4 +x+17x 10 +x 7 +x 3 +x+18x 10 +x 4 +x 3 +x+1

[0076] The superframe is sent out.

[0077] In a sixteenth aspect, a receiving method for optical communication is provided, comprising: receiving a superframe comprising a plurality of subframes, wherein the subframe comprises a training symbol and a pilot symbol; in each subframe, in one polarization direction, the pilot symbol has N PS The value is one of -A2-A2j, -A2+A2j, A2-A2j, A2+A2j, where A2 is a real number, N PS is an even number; N PS The pilot symbols achieve DC balance; the training symbols and N PS The combination of the pilot symbols achieves DC balance; the pilot symbols are generated by a target polynomial and a seed, the target polynomial is a primitive polynomial, and its non-zero terms are not greater than 5; the target polynomial is one of the following table;

[0078] Sequence target polynomial 1x 10 +x 9 +x 7 +x 6 +12x 10 +x 9 +x 7 +x 3 +13x 10 +x 8 +x 4 +x 3 +1

[0079] 4x 10 +x 7 +x 6 +x 2 +15x 10 +x 9 +x 6 +x+16x 10 +x 9 +x 4 +x+17x 10 +x 7 +x 3 +x+18x 10 +x 4 +x 3 +x+1

[0080] The received superframe is decoded.

[0081] In the fifteenth aspect or the sixteenth aspect, the pilot symbol is generated according to a target polynomial and a corresponding seed, the target polynomial is any one of the items in the above table, and the target polynomial and the corresponding seed can satisfy N PS pilot symbols to achieve DC balance, training symbols and N PS The combination of pilot symbols achieves DC balance, which is beneficial for the receiving end to better recover the signal and improve the quality of the signal at the receiving end.

[0082] In combination with the fifteenth or sixteenth aspect, in a possible implementation, in one polarization direction, the total number of symbols N in the superframe is F =175104, number of subframes N SF =24, the number of symbols in each subframe N S =7296, N PS =114, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW +N RES =96, the number of symbols before the superframe is formed is 172032;

[0083] When the target polynomial for generating the pilot symbol and the seeds expressed in hexadecimal in two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbol in the same polarization direction is not greater than 0.25, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.25,

[0084] Serial number Target polynomial Seed in polarization direction 1 Seed in polarization direction 2 1x 10 +x 9 +x7 +x 6 +10x0020x3C62x 10 +x 9 +x 7 +x 6 +10x0020x38D3x 10 +x 9 +x 7 +x 3 +10x0940x11F4x 10 +x 9 +x 7 +x 3 +10x1290x11F5x 10 +x 8 +x 4 +x 3 +10x07A0x1676x 10 +x 8 +x 4 +x 3 +10x07A0x2CF7x 10 +x 7 +x 6 +x 2 +10x1B80x22F8x 10 +x 7 +x 6 +x 2 +10x1B80x05F9x 10 +x 9 +x 6 +x+10x0400x21010x 10 +x 9 +x 6 +x+10x0400x30811x 10 +x 9 +x 6 +x+10x0400x18412x 10 +x 9 +x 6 +x+10x0400x0C213x 10 +x 9 +x 6 +x+10x0400x0E114x 10 +x 9 +x 6 +x+10x0400x0D7

[0085] 15x 10 +x 9 +x 6 +x+10x0400x1AF16x 10+x 9 +x 6 +x+10x2100x20117x 10 +x 9 +x 6 +x+10x3080x20118x 10 +x 9 +x 6 +x+10x1840x20119x 10 +x 9 +x 6 +x+10x0C20x20120x 10 +x 9 +x 6 +x+10x2010x0E121x 10 +x 9 +x 6 +x+10x2010x0D722x 10 +x 9 +x 6 +x+10x2010x1AF23x 10 +x 9 +x 4 +x+10x1A00x2D924x 10 +x 9 +x 4 +x+10x1A00x3DB25x 10 +x 9 +x 4 +x+10x0D00x2D926x 10 +x 9 +x 4 +x+10x0D00x3DB27x 10 +x 9 +x 4 +x+10x0580x2D928x 10 +x 9 +x 4 +x+10x0580x3DB29x 10 +x 9 +x 4 +x+10x22C0x2D930x 10 +x 9 +x 4 +x+10x22C0x3DB31x 10 +x 9 +x 4 +x+10x2D20x2D932x 10 +x 9 +x 4+x+10x2D20x3DB33x 10 +x 9 +x 4 +x+10x2D90x1A534x 10 +x 9 +x 4 +x+10x2D90x3DD35x 10 +x 9 +x 4 +x+10x1A50x3DB36x 10 +x 9 +x 4 +x+10x3DD0x3DB37x 10 +x 7 +x 3 +x+10x0840x1A738x 10 +x 7 +x 3 +x+10x1090x1A739x 10 +x 4 +x 3 +x+10x3650x3EB40x 10 +x 4 +x 3 +x+10x2CB0x3EB.

[0086] In combination with the fifteenth aspect or the sixteenth aspect or any possible implementation thereof, in another possible implementation, when 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 as shown in the following table:

[0087]

[0088]

[0089] In combination with the above-mentioned fifteenth aspect or sixteenth aspect or any possible implementation manner therein, in another possible implementation manner, in each subframe, in one polarization direction, when the remainder of the number of pilot symbols divided by 4 is 0, among the 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 difference between the number of -A2-A2j and the number of is 2; or, the number of -A2-A2j, -A2+A2j, A2-A2j, and A2+A2j are equal.

[0090] When the remainder of the number of pilot symbols divided by 4 is 2, among the 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 difference between the number of -A2-A2j and the number of

[0091] In the seventeenth aspect, a transmission device for optical communication is provided, the transmission device including a processor and a memory, the memory being used to store instructions, and the processor being used to execute instructions, so that the transmission device executes the method as in the fifteenth aspect and any possible implementation method of the fifteenth aspect.

[0092] In the eighteenth aspect, a receiving device for optical communication is provided, and the transmitting device includes a processor and a memory, the memory is used to store instructions, and the processor is used to execute instructions, so that the receiving device executes the method as in the sixteenth aspect and any possible implementation method of the sixteenth aspect.

[0093] In a nineteenth aspect, a system for optical communication is provided, the system comprising the transmission device as in the seventeenth aspect, and the receiving device as in the eighteenth aspect.

[0094] It should be understood that the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc., and this application does not limit this.

[0095] In the twentieth aspect, a computer-readable storage medium is provided, which stores instructions. When the instructions are executed on a terminal device, the terminal device executes a method as in the fifteenth aspect or any possible implementation of the fifteenth aspect; or causes the terminal device to execute a method as in the sixteenth aspect or any possible implementation of the sixteenth aspect.

[0096] In a twenty-first aspect, a computer program product comprising instructions is provided that, when executed on a terminal device, causes the terminal device to execute the method according to the fifteenth aspect or any possible implementation of the fifteenth aspect; or causes the terminal device to execute the method according to the sixteenth aspect or any possible implementation of the sixteenth aspect. It should be understood that the terminal device may be a chip, a processor, etc., and this application is not limited thereto.

[0097] In the above-described embodiment of the present application, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj representing training symbols and pilot symbols in each polarization direction does not differ by more than 1, effectively ensuring balance between symbols. Furthermore, in each polarization direction, the sum of the real parts of the complex numbers corresponding to the training symbols and pilot symbols in a subframe is 0, and the sum of the imaginary parts is also 0, achieving DC balance and facilitating signal quality recovery at the receiving end. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] FIG1 is a block diagram of a communication system;

[0099] FIG2 is a schematic diagram of a framing process;

[0100] FIG3 is a schematic diagram of another framing process;

[0101] FIG4 is a flow chart of a transmission method for optical communication provided by the present application;

[0102] FIG5A is a schematic diagram showing the position of training symbols or pilot symbols in a constellation diagram under DP-16QAM;

[0103] FIG5B is a schematic diagram showing another position of training symbols or pilot symbols in a constellation diagram under DP-16QAM;

[0104] FIG6 is a diagram of a superframe structure, a diagram of a first type of subframe structure, and a diagram of a second type of subframe structure provided by the present application;

[0105] Figure 7 shows the mapping relationship between DP-QPSK symbols and bits;

[0106] Figure 8 shows the mapping relationship between DP-16QAM symbols and bits;

[0107] FIG9 is a structural diagram of a specific superframe and its first subframe and other subframes except the first subframe provided in an embodiment of the present application;

[0108] FIG10 is a graph showing the non-periodic autocorrelation results in the X polarization direction, the non-periodic autocorrelation results in the Y polarization direction, and the non-periodic cross-correlation results in the two polarization directions of a specific frame synchronization sequence provided in an embodiment of the present application;

[0109] FIG11 is a diagram showing the non-periodic autocorrelation results in the X polarization direction, the non-periodic autocorrelation results in the Y polarization direction, and the non-periodic cross-correlation results in the two polarization directions of a specific training sequence provided in an embodiment of the present application;

[0110] FIG12 is a diagram showing the periodic autocorrelation results of a specific pilot sequence in the X polarization direction, a diagram showing the periodic autocorrelation results in the Y polarization direction, and a diagram showing the periodic cross-correlation results in the two polarization directions according to an embodiment of the present application;

[0111] FIG13 is a spectrum diagram of a superframe under DP-16QAM using the superframe structure shown in FIG9 , and a spectrum diagram of a random DP-16QAM signal;

[0112] FIG14 is a spectrum diagram of a superframe under DP-QPSK and a spectrum diagram of a random DP-QPSK signal using the superframe structure shown in FIG9 ;

[0113] FIG15 is a diagram illustrating a specific superframe structure according to another embodiment of the present application, a diagram illustrating a structure of the first subframe in a specific superframe, and diagrams illustrating structures of subframes other than the first subframe;

[0114] FIG16 is a diagram showing the aperiodic autocorrelation results of a specific frame synchronization sequence in the X polarization direction, a diagram showing the aperiodic autocorrelation results of a specific frame synchronization sequence in the Y polarization direction, and a diagram showing the aperiodic cross-correlation results of the two polarization directions according to another embodiment of the present application;

[0115] FIG17 is a diagram showing the aperiodic autocorrelation results of a specific training sequence in the X polarization direction, a diagram showing the aperiodic autocorrelation results of a specific training sequence in the Y polarization direction, and a diagram showing the aperiodic cross-correlation results of the two polarization directions according to another embodiment of the present application;

[0116] FIG18 is a diagram showing periodic autocorrelation results of a specific pilot sequence in the X polarization direction, a diagram showing periodic autocorrelation results in the Y polarization direction, and a diagram showing periodic cross-correlation results in the two polarization directions, according to another embodiment of the present application;

[0117] FIG19 is a superframe spectrum diagram under DP-16QAM using the superframe structure shown in FIG15 ;

[0118] FIG20 is a diagram illustrating a specific superframe structure, a diagram illustrating a structure of the first subframe in a specific superframe, and diagram illustrating structures of subframes other than the first subframe in a specific superframe, provided in yet another embodiment of the present application;

[0119] FIG21 is a diagram showing the aperiodic autocorrelation results of a specific training sequence in the X polarization direction, a diagram showing the aperiodic autocorrelation results of a specific training sequence in the Y polarization direction, and a diagram showing the aperiodic cross-correlation results of the two polarization directions according to another embodiment of the present application;

[0120] FIG22 is a diagram showing the periodic autocorrelation results of a specific pilot sequence in the X polarization direction, the periodic autocorrelation results in the Y polarization direction, and the periodic cross-correlation results in the two polarization directions, provided in yet another embodiment of the present application;

[0121] FIG23 is a superframe spectrum diagram under DP-16QAM using the superframe structure shown in FIG20 ;

[0122] FIG24 is a diagram illustrating a specific superframe structure, a diagram illustrating a structure of the first subframe in a specific superframe, and a diagram illustrating a structure of subframes other than the first subframe in a specific superframe, provided in yet another embodiment of the present application;

[0123] FIG25 is a superframe spectrum diagram under DP-16QAM using the superframe structure shown in FIG24 ;

[0124] FIG26 is a diagram illustrating a specific superframe structure, a diagram illustrating a structure of the first subframe in a specific superframe, and diagram illustrating structures of subframes other than the first subframe in a specific superframe, provided by yet another embodiment of the present application;

[0125] FIG27 is a diagram showing the aperiodic autocorrelation results of a specific training sequence in the X polarization direction, a diagram showing the aperiodic autocorrelation results of a specific training sequence in the Y polarization direction, and a diagram showing the aperiodic cross-correlation results of the two polarization directions according to another embodiment of the present application;

[0126] FIG28 is a diagram showing the periodic autocorrelation results of a specific pilot sequence in the X polarization direction, the periodic autocorrelation results in the Y polarization direction, and the periodic cross-correlation results in the two polarization directions, provided in yet another embodiment of the present application;

[0127] FIG29 is a superframe spectrum diagram under DP-16QAM using the superframe structure shown in FIG26 ;

[0128] FIG30 is a diagram illustrating a specific superframe structure, a diagram illustrating a structure of the first subframe in a specific superframe, and diagram illustrating structures of subframes other than the first subframe in a specific superframe, provided in yet another embodiment of the present application;

[0129] FIG31 is a superframe spectrum diagram under DP-16QAM using the superframe structure shown in FIG30 ;

[0130] FIG32 is a flow chart of a transmission method for optical communication provided in an embodiment of the present application;

[0131] FIG33 is a structural diagram of a specific superframe and its first subframe and other subframes except the first subframe provided in an embodiment of the present application;

[0132] FIG34 is a schematic diagram of a pilot symbol generation structure provided in an embodiment of the present application;

[0133] FIG35 is a schematic diagram of another pilot symbol generation structure provided in an embodiment of the present application;

[0134] FIG36 is a diagram showing periodic autocorrelation results in the X polarization direction, periodic autocorrelation results in the Y polarization direction, and periodic cross-correlation results in the two polarization directions for a specific pilot symbol sequence provided in an embodiment of the present application;

[0135] FIG37 is a schematic diagram of another pilot symbol generation structure provided in an embodiment of the present application;

[0136] FIG38 is a diagram showing periodic autocorrelation results in the X polarization direction, a diagram showing periodic autocorrelation results in the Y polarization direction, and a diagram showing periodic cross-correlation results in the two polarization directions for a specific pilot symbol sequence provided in an embodiment of the present application;

[0137] FIG39 is a structural diagram of a specific superframe and its first subframe and other subframes except the first subframe provided in an embodiment of the present application;

[0138] FIG40 is a schematic diagram of another pilot symbol generation structure provided in an embodiment of the present application;

[0139] FIG41 is a diagram showing periodic autocorrelation results in the X polarization direction, periodic autocorrelation results in the Y polarization direction, and periodic cross-correlation results in the two polarization directions for a specific pilot symbol sequence provided in an embodiment of the present application;

[0140] FIG42 is a flow chart of another transmission method for optical communication provided in an embodiment of the present application;

[0141] FIG43 is a schematic diagram of another pilot symbol generation structure provided in an embodiment of the present application;

[0142] FIG44 is a diagram showing the periodic autocorrelation results of a sequence of specific pilot symbols provided in an embodiment of the present application in the X-polarization direction, a diagram showing the periodic autocorrelation results in the Y-polarization direction, and a diagram showing the periodic cross-correlation results in the two polarization directions. DETAILED DESCRIPTION

[0143] Before explaining the embodiments of the present application in detail, the application scenarios of the embodiments of the present application are first explained. Figure 1 shows a structural block diagram of a communication system. At the transmitting end, the information source provides a data stream to be sent; the encoder receives the data stream and encodes it. The codeword information obtained by encoding the check bits and information bits is sent to the transmitting end signal processor for framing, and is transmitted through the channel to the receiving end; after the receiving end receives the distorted signal caused by noise or other damage in the channel, it is sent to the receiving end signal processor for dispersion compensation, synchronization, phase recovery and other operations, and then decoded by the decoder to restore the original data and send it to the destination. Among them, the encoding method provided by the present application is applied to the transmitting end signal processor shown in Figure 1, which is a very important link in the communication system.

[0144] In the transmitting signal processor, the framing process can be shown in Figure 2 or Figure 3. In one framing method, as shown in Figure 2, the received data sequence is symbol mapped, including but not limited to Quadrature Phase Shift Keying (QPSK) and Quadrature Amplitude Modulation (QAM), and then polarization symbol division is performed to obtain dual-polarization (DP) symbols, such as DP-QPSK, DP-8QAM, DP-16QAM, DP-32QAM and DP-64QAM; a certain number of dual-polarization symbols are framed as follows: frame synchronization symbols, training symbols, reserved symbols and pilot symbols are inserted in the X and Y polarization directions respectively to obtain a dual-polarization symbol sequence to be transmitted, called a super-frame. It should be noted that after symbol mapping, the symbols can also be interleaved, and the interleaved symbols are subjected to the above-mentioned framing process. In the present application, a dual-polarization symbol can be represented by two symbols, one of which is located in the X polarization direction and the other is located in the Y polarization direction. Each symbol can be represented by a complex number. For example, the symbol obtained by 16QAM modulation can be represented by any one of the following 16 complex numbers: ±1±1j, ±1±3j, ±3±1j, and ±3±3j. It should be understood that in some cases, the real and imaginary parts are normalized, but the essence does not change. Furthermore, a sequence with N dual-polarization symbols can be completely represented by two complex number sequences of length N, one of which represents the symbol on the X polarization and the other represents the symbol on the Y polarization. Each complex number sequence of length N is represented by a real part sequence of length N and an imaginary part sequence of length N, where N is an integer greater than 1.

[0145] Normally, the received data sequence is the information and check sequence obtained by the forward error correction code (FEC). The framing operation shown in FIG2 is performed on the symbols. As shown in FIG3 , the received data sequence can be inserted with the bits corresponding to the frame synchronization symbol, training symbol, reserved symbol and pilot symbol before the symbol mapping according to the adopted symbol mapping rule, and then the symbol mapping and polarization symbol division are performed to obtain the same superframe as the operation in FIG2 . At this time, before the symbol mapping, the bit sequence after the bits corresponding to the above symbols are inserted can also be interleaved, and then the symbol mapping and polarization symbol division are performed to obtain the same superframe as the operation in FIG2 . It should be understood that other framing methods are not excluded, and this application will not go into details.

[0146] An embodiment of the present application provides a transmission method for optical communication, as shown in FIG4 , the transmission method comprising:

[0147] 401. Generate a superframe including multiple subframes, where one subframe includes training symbols and pilot symbols, and each training symbol and each pilot symbol are one of -A-Aj, -A+Aj, A-Aj, and A+Aj; among 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 And the numbers in the other polarization direction are Among them, N TS N is the number of training symbols in one polarization direction in each subframe. PS N is the number of pilot symbols in one polarization direction in each subframe. TS +N PS is an odd number, here Indicates rounding down the positive real number a.

[0148] 402. Send the superframe.

[0149] In the embodiment of the present application, the value of A is determined by the modulation format used when generating the symbol. In some practical application scenarios, -A-Aj, -A+Aj, A-Aj and A+Aj are symbols on the constellation diagram of the modulation format used. For example, when QPSK is used, there are only four symbols. At this time, A=±1. Each training symbol can be represented by one of -1-1j, -1+1j, 1-1j and 1+1j. In a subframe, the four complex-numbered training symbols will exist, as will the pilot symbols. When 16QAM is used, there are 16 symbols. A=±1 or ±3. Normally, the training symbols and pilot symbols are the outermost four symbols on the constellation diagram, as shown by the hollow symbols in Figure 5A. At this time, when A=3 or -3, each training symbol can be represented by one of -3-3j, -3+3j, 3-3j and 3+3j. In a subframe, the four complex-numbered training symbols will also exist, as will the pilot symbols. Similarly, using 64QAM, A = ±1 or ±3 or ±5 or ±7. Normally, in 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 a subframe, these four complex numbers will represent training symbols. Similarly, the pilot symbols meet the same conditions. Higher-order modulation formats can also be used, which will not be described in detail in this application. In the actual transmission process, the probability of symbol error can be reduced, which facilitates channel estimation.

[0150] It should be noted that it is also possible to compress the symbols on the constellation diagram. Correspondingly, the value of A will also be compressed accordingly. Taking 16QAM as an example, the power of the 16 symbols on the 16QAM constellation diagram is normalized. At this time, the value becomes The value of A is or Other normalization methods may also be used, which are not limited in this application.

[0151] It should be understood that when the pilot symbols and training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj use the outermost four symbols of the constellation diagram, the sensitivity of the training and pilot symbols is high, but the peak to average power ratio is large; when the pilot symbols and training symbols take the values ​​of -A-Aj, -A+Aj, A-Aj, and A+Aj and use the innermost four symbols of the constellation diagram, the noise of the training and pilot symbols is small, but their sensitivity is low.

[0152] 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 on the constellation diagram of the modulation format used. They may be four symbols in the middle area between the outermost four symbols and the innermost four symbols of the constellation diagram. In this case, the noise and sensitivity of the training and pilot symbols are average, but the peak-to-average power ratio is relatively low. Taking 16QAM as an example, the 16 symbols on the 16QAM constellation diagram are {±1±1j, ±1±3j, ±3±1j, ±3±3j}, and the value of the real number A satisfies 1≤A≤3. More specifically, as shown in Figure 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 pilot symbol and training symbol values ​​-A-Aj, -A+Aj, A-Aj, and A+Aj can be any four symbols in the middle area between the outermost four symbols and the innermost four symbols of the 16QAM constellation diagram. The specific value of the real number A can be selected according to the actual application scenario to achieve a good compromise between the peak-to-average power ratio, noise, and sensitivity of the training and pilot symbols. For example, the real number The values ​​of pilot symbols and training symbols are In addition, when the 16 symbols on the 16QAM constellation are power normalized and the value is The value of real number A satisfies For example, real numbers The values ​​of pilot symbols and training symbols are

[0153] In addition, the two polarization directions are orthogonal to each other, that is, when one of the polarization directions is X polarization, the other polarization direction is Y polarization; when one of the polarization directions is Y polarization, the other polarization direction is X polarization. In the embodiment of the present application, the sum of the number of training symbols and pilot symbols included in one subframe in one polarization direction is N TS +N PS -1, which is not less than 5; the reason why it is not N TS +N PS The reason is that there is a symbol that is both a training symbol and a pilot symbol, so the sum of their numbers is one less than the sum of the two symbols.

[0154] In a 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, A-Aj, then the sequence of training symbols in the other polarization direction, following the same order, cannot be the same. Instead, it can be -A-Aj, -A-Aj, A+Aj, A+Aj. This difference prevents the receiver from being unable to distinguish between the two polarization directions during actual transmission.

[0155] In the embodiment of the present application, a subframe includes N TS +N PS -1 training symbol and pilot symbol, that is, the total number of -A-Aj, -A+Aj, A-Aj, and A+Aj of training symbols and pilot symbols is N TS +N PS -1, the number of the four symbols differs by no more than 1; moreover, in one subframe, the number of the four complex numbers (-A-Aj, -A+Aj, A-Aj, A+Aj) representing the training symbols and pilot symbols in the two polarization directions is the same, and the number is (N TS +N PS -1) / 2; this effectively ensures a balanced number of symbols. Furthermore, in each polarization direction, the sum of the real and imaginary parts of the complex numbers corresponding to the training and pilot symbols in a subframe is zero, achieving DC balance and facilitating signal quality recovery at the receiving end.

[0156] The superframe of the present application, which may also be referred to as a multiframe, includes multiple subframes, and its structure is shown in (a) of FIG6 . Each subframe includes the same number of symbols (N SSymbols), subframes are mainly divided into two categories. One type of subframe includes frame synchronization symbols, which is usually the first subframe in a superframe, but it is not excluded that it is located in other positions in the superframe. Other subframes are the second type; Among them, the structure of the first type of subframe is shown in (b) of Figure 6. The first N subframes in the subframe TS The first N symbols are training symbols, which can be used for link training and / or subframe synchronization. Usually, the first symbol of a subframe is both a training symbol and a pilot symbol. Of course, it can also be the first N symbols. TS Any of the symbols can be both a training symbol and a pilot symbol, which is not limited in this application. In addition, in the first type of subframe, a symbol at a fixed position in every 64 symbols or 48 symbols is a pilot symbol, which is used for carrier phase recovery. Figure 6 (b) takes the first symbol in every 64 symbols as a pilot symbol as an example to show the frame structure diagram of the first type of subframe. Following the pilot signal are multiple frame synchronization symbols, which are used for synchronization between superframes. The frame synchronization symbols can be used together with the training symbols for synchronization between superframes, or together with the pilot symbols to achieve the same function. It should be understood that the frame synchronization symbols are arranged continuously and can be next to the training signal. Figure 6 (b) shows this situation. There can also be one or more symbol intervals between the frame synchronization signal and the training signal. In addition, after the multiple frame synchronization symbols, there are usually multiple reserved symbols, which can be reserved for other future uses. The reserved symbols can also be located in one of the multiple second type subframes, which is not limited in this application. The remaining symbols are pre-framing symbols containing information and checksums, wherein there is no overlap between pilot symbols and reserved symbols, and between pilot symbols and pre-framing symbols. For example, there is no symbol that is both a pilot symbol and a pre-framing symbol.

[0157] The frame structure of the second type of subframe is shown in (c) of Figure 6. TS The first symbol of a subframe is also a training symbol. Usually, the first symbol of a subframe is both a training symbol and a pilot symbol. Of course, it may also be the first N TS Any one of the symbols is both a training symbol and a pilot symbol, which is not limited in this application. Similar to the first type of subframe, the symbols at fixed positions in every 64 symbols or 48 symbols are also pilot symbols, which are used for carrier phase recovery. Figure 6 (c) takes the first symbol in every 64 symbols as a pilot symbol as an example to show the frame structure diagram of the second type of subframe. In addition to the training symbols and pilot symbols, under normal circumstances, the remaining symbols are pre-framing symbols containing information and checksums, where the pilot symbols do not overlap with the pre-framing symbols.

[0158] Furthermore, this application also provides the possible specific number of each symbol for several different situations, and examples of several situations are as follows:

[0159] (1) Number of symbols before framing NCW =175616, for example, a CFEC encoding method using a staircase code and a Hamming code concatenated together, or other encoding methods; the first symbol in every 64 symbols is a pilot symbol, and in this case, the number of subframes N SF , the number of training symbols in each subframe N TS , 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 , superframe redundancy OH, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum of the parameters is as shown in Table 1, where N FAW is an even number, the corresponding N RES >0, OH=(N F -N CW ) / N CW .

[0160] Except for OH, all other parameters are symbol counts, which can be understood as the number of dual-polarization symbols or the number of symbols in one polarization direction. Moreover, the number of different symbols in the two polarization directions is the same. For example, if there are 10 training symbols in one polarization direction and 10 training symbols in the other polarization direction, overall, there are 10 dual-polarization training symbols. Subsequent tables can be understood in this way and will not be repeated in this application.

[0161] Serial number N SF N PS N S N F OHN TS N FAW +N RES1883220481802242.62%192082853321121795202.22%121643803522401792002.04%10644783623041797122.33%151965743824321799682.48%192086723924961797122.33%162087723924961797122.33%18648704025601792002.04%118497 04025601792002.04%922410654327521788801.86%614411614629441795842.26%196412614629441795842.26%1718613574931361787521.79%65814565032001792002.04%1311215565032001792002.04%1122416555132641795202.22%18164

[0162] 17505635841792002.04%158418505635841792002.04%1318419495736481787521.79%69820436541601788801.86%108221407044801792002.04%196422407044801792002.04%1714423407044801792002.04%1522424358051201792002.04%1915425358051201792002.04%17224

[0163] Table 1

[0164] (2) Number of symbols before framing N CW =172032, for example, an open code (Open FEC, OFEC) encoding method is used, and other encoding methods can also be used; the first symbol in every 64 symbols is a pilot symbol. In this case, the number of subframes N SF , the number of training symbols in each subframe N TS , 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 , superframe redundancy OH, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum of the parameters is as shown in Table 2, where N FAWis an even number, the corresponding N RES >0, OH=(N F -N CW ) / N CW .

[0165] Serial number N SF N PS N S N F OHN TS N FAW +N RES 1833321121752961.90%61102743723681752321.86%6923674126241758082.19%141584614528801756802.12%141105564931361756162.08%141126564931361756162.08%122247495635841756 162.08%17568495635841756162.08%151549485736481751041.79%69610456139041756802.12%1813811387246081751041.79%710812377447361752321.86%119213377447361752321.86%9166

[0166] 14367648641751041.79%94815338353121752961.90%149616338353121752961.90%12162172411472961751041.79%1348182411472961751041.79%11961924114729617510 41.79%9144202411472961751041.79%7192212311976161751681.82%1654222311976161751681.82%14100232311976161751681.82%12146242311976161751681.82%10192

[0167] Table 2

[0168] (3) Number of symbols before framing N CW =175616. For example, if CFEC encoding is used, the first symbol in every 48 symbols is a pilot symbol. In this case, the number of subframes N is SF , the number of training symbols in each subframe NTS , 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 , superframe redundancy OH, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum of the parameters is as shown in Table 3, where N FAW is an even number, the corresponding N RES >0, OH=(N F -N CW ) / N CW .

[0169] Serial number N SF N PS N S N F OHN TS N FAW +N RES 11213114881800482.52%67621143315841805762.82%101723993818241805762.82%112084944019201804802.77%111645804722561804802.77%146468047225618 04802.77%122247755024001800002.50%71848755024001800002.50%9349715325441806242.85%183810715325441806242.85%1618011675626881800962.55%9192

[0170] 12675626881800962.55%115813665727361805762.82%1620814665727361805762.82%187615576631681805762.82%1917216566732161800962.55%1022417566732161800962.55%121121852723456179 7122.33%74019507536001800002.50%128420507536001800002.50%1018421487837441797122.33%76422399646081797122.33%94023399646081797122.33%7118243610449921797122.33%9642536104 49921797122.33%7136263510751361797602.36%1084273510751361797602.36%8154283510751361797602.36%6224293211756161797122.33%1064303211756161797122.33%8128313211756161797122 .33%6192323112158081800482.52%2092333112158081800482.52%18154343112158081800482.52%16216353012560001800002.50%2064363012560001800002.50%18124373012560001800002.50%16184

[0171] Table 3

[0172] (4) Number of symbols before framing N CW =172032. For example, if OFEC encoding is used, the first symbol in every 48 symbols is a pilot symbol. In this case, the number of subframes N is SF , the number of training symbols in each subframe N TS , 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 , superframe redundancy OH, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum of the parameters is as shown in Table 4, where N FAW is an even number, the corresponding NRES > 0, OH = (N F -N CW ) / N CW .

[0173] Serial number N SF N PS N S N F OHN TS N FAW +N RES 11193114881770722.93% 124221053516801764002.54% 61683973818241769282.85% 13464924019201766402.68% 91925904119681771202.96% 16486824521601771202.96% 161687804622081766402.68% 111288754923521764002.54% 81689725124481762562.46% 84810725124481762562.46% 619211685425921762562.46% 714412675526401768802.82% 1615813556732161768802.82% 2011814546832641762562.46% 912015517234561762562.46% 114216517234561762562.46% 914417497536001764002.54% 145618497536001764002.�4% 1215419468038401766402.68% 1910020468038401766402.68% 1719221409244161766402.68% 1920822399445121759682.29% 736233610248961762562.46% 1548243610248961762562.46% 13120

[0174] 253610248961762僟46% 11192263510550401764002.54% 1898273510550401764002.54% 16168283410851841762562.46% 1576293410851841762562.46% 13144303410851841762562.46% 11212

[0175] Table 4

[0176] Optionally, the training symbols are arranged continuously in a subframe. In one polarization direction, the number of consecutive "-A" or "A" real-part elements in the training symbols included in a subframe is no more than M0, and the number of consecutive "-A" or "A" imaginary-part elements is no more than M0. In addition, the number of consecutive identical training symbols in a subframe does not exceed M1, where M0 and M1 are both positive integers and 2≤M1≤M0≤5. The training sequence derived under these conditions facilitates clock recovery, thereby helping to improve the quality of the signal recovered by the receiving end.

[0177] Furthermore, in a training symbol included in a subframe in one polarization direction, the number of consecutive "-A"s or "A"s in the real part element is no more than 5, and the number of consecutive "-A"s or "A"s in the imaginary part element is no more than 5. Taking six training symbols in one polarization direction as an example, in the sequences -A-Aj, -A-Aj, -A-Aj, -A-Aj, -A-Aj, and A+Aj, the real part elements contain five consecutive -As, which meets the requirements of this embodiment. However, if the sequences are -A-Aj, -A-Aj, -A-Aj, -A-Aj, -A-Aj, and -A+Aj, the real part elements contain six consecutive -As, which does not meet the requirements of this embodiment. Furthermore, in one polarization direction, the number of consecutive identical training symbols in a subframe does not exceed 4. At this time, the sequences -A-Aj, -A-Aj, -A-Aj, -A-Aj, -A-Aj and A+Aj that originally met the requirements no longer meet the requirements of this embodiment due to the presence of 5 consecutive -A-Aj.

[0178] Optionally, when N TS When it is an even number, that is, in each subframe, there are an even number of training symbols in one polarization direction. At this time, 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 And the numbers in the other polarization direction are Since N TS +N PS is an odd number, and N TS is an even number, then N PS It must be an odd number, that is, in each subframe, there is an odd number of pilot symbols in one polarization direction. At this time, among the pilot symbols included in each subframe, excluding the pilot symbol that is also a training symbol, -A-Aj, -A+Aj, A-Aj and A+Aj can also meet the following conditions: the number in one polarization direction is respectively And the numbers in the other polarization direction are

[0179] When N TS When it is an odd number, that is, in each subframe, there are an odd number of training symbols in one polarization direction. At this time, among the training symbols included in each subframe, excluding the training symbol that also serves as a pilot symbol, the numbers of -A-Aj, -A+Aj, A-Aj and A+Aj in one polarization direction are respectively The numbers in the other polarization direction are Since N TS +N PS is an odd number, and N TS is an odd number, then N PS It must be an even number, that is, in each subframe, there are an even number of pilot symbols in one polarization direction. At this time, among the pilot symbols included in each subframe, -A-Aj, -A+Aj, A-Aj and A+Aj can also meet the following conditions: the number in one polarization direction is respectively And the numbers in the other polarization direction are

[0180] In the above embodiment, in each polarization direction, the number of training symbols -A-Aj, -A+Aj, A-Aj, and A+Aj included in a subframe is close to each other; moreover, when N TS When it is an even number, in one subframe, the number of four different symbols (complex form) representing training symbols in the two polarization directions is the same, and the number of the four symbols is N TS / 2, the sum of the real part of the complex number corresponding to the training symbol is 0, and the sum of the imaginary part is also 0; when N TS When it is an odd number, in one subframe, excluding the training symbol which is also a pilot symbol, the number of the four different symbols (complex form) representing the training symbols in the two polarization directions is the same, and the number of the four symbols is (N TS -1) / 2,N TS The sum of the real and imaginary parts of the complex numbers corresponding to -1 training symbol is 0, and the sum of the imaginary parts is also 0. This effectively ensures a balance in the number of symbols and achieves DC balance, which facilitates signal quality recovery at the receiving end. It should be understood that the pilot sequence composed of pilot symbols also has a similar effect.

[0181] Optionally, in each subframe, when the number of pilot symbols in one polarization direction is N PS When the remainder after division by 4 is 0, the number of pilot symbols in each subframe, -A-Aj, -A+Aj, A-Aj and A+Aj in one polarization direction is N respectively. PS / 4+1、N PS / 4-1、N PS / 4-1、NPS / 4+1, and the number in the other polarization direction is N PS / 4-1、N PS / 4+1、N PS / 4+1、N PS / 4-1; or, the number in both polarization directions is N PS / 4. When N PS When the remainder after division by 4 is 2, the number of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction in the pilot symbols included in each subframe is (N PS -2) / 4, (N PS -2) / 4+1、(N PS -2) / 4+1、(N PS -2) / 4, and the numbers in the other polarization direction are (N PS -2) / 4+1、(N PS -2) / 4, (N PS -2) / 4, (N PS -2) / 4+1. When N PS When the remainder after division by 4 is 1, among the pilot symbols included in each subframe, excluding the pilot symbol that also serves as a training symbol, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are (N PS -1) / 4+1、(N PS -1) / 4-1、(N PS -1) / 4-1、(N PS -1) / 4+1, and the numbers in the other polarization direction are (N PS -1) / 4-1、(N PS -1) / 4+1、(N PS -1) / 4+1、(N PS -1) / 4-1; or, the number in both polarization directions is (N PS -1) / 4. When N PS When the remainder after division by 4 is 3, among the pilot symbols included in each subframe, excluding the pilot symbol that also serves as a training symbol, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are (N PS -3) / 4, (N PS -3) / 4+1、(N PS -3) / 4+1、(N PS -3) / 4, and the numbers in the other polarization direction are (N PS -3) / 4+1、(N PS -3) / 4, (N PS -3) / 4, (NPS -3) / 4+1.

[0182] In the above embodiment, the number of pilot symbols -A-Aj, -A+Aj, A-Aj, and A+Aj included in a subframe is relatively small, effectively ensuring symbol balance. Furthermore, in each polarization direction, excluding the pilot symbol that also serves as a training symbol (if there is an odd number of pilot symbols), the sum of the real and imaginary parts of the complex numbers corresponding to the remaining pilot symbols is zero, achieving DC balance and improving signal quality at the receiving end.

[0183] In the multiple subframe structures included in the superframe, the first type of subframe also includes a frame synchronization symbol, as shown in (b) in Figure 6, multiple frame synchronization symbols are arranged continuously in the first type of subframe, and each frame synchronization symbol is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, wherein the A value corresponding to the frame synchronization symbol is also determined by the modulation format adopted, which is consistent with the A value corresponding to the training symbols and pilot symbols described in the previous embodiment, and this application will not go into details here. It should be understood that in some application scenarios, each frame synchronization symbol is one of -A-Aj, -A+Aj, A-Aj, and A+Aj, and its corresponding A value can be a different real number from the A value corresponding to the training symbols and pilot symbols described in the previous embodiment. For the sake of simplicity, this application takes the example of the two taking equal values ​​for description.

[0184] Optionally, in one polarization direction, in the frame synchronization symbols included in the first type of subframe, the number of consecutive real-part elements of "-A" or "A" is no more than M2, and the number of consecutive imaginary-part elements of "-A" or "A" is no more than M2. Furthermore, the number of consecutive identical frame synchronization symbols in the first type of subframe does not exceed M3, where M2 and M3 are both positive integers and 2≤M3≤M2≤5. The frame synchronization sequence derived under these conditions facilitates clock recovery, thereby helping to improve the quality of the signal recovered by the receiving end.

[0185] Furthermore, in a polarization direction, in a frame synchronization symbol included in a first-type subframe, the number of consecutive real-part elements of "-A" or "A" is no more than 5, and the number of consecutive imaginary-part elements of "-A" or "A" is no more than 5. Optionally, in a polarization direction, the number of consecutive identical frame synchronization symbols in a first-type subframe does not exceed 4. Specific examples have been described in the example of training symbols in the previous embodiment and will not be repeated here.

[0186] In the first type of subframe, there is an even number of frame synchronization symbols in one polarization direction, and the following conditions can be met: among the frame synchronization symbols included in the first type of subframe, the numbers of -A-Aj, -A+Aj, A-Aj and A+Aj in one polarization direction are respectively And the numbers in the other polarization direction are Among them, N FAW The number of frame synchronization symbols in the first type of subframe in one polarization direction. This condition ensures that multiple frame synchronization symbols are DC balanced and that the number of the four optional symbols -A-Aj, -A+Aj, A-Aj, and A+Aj differs by no more than 1, which helps the receiver restore signal quality.

[0187] For example, when N FAW = 22, the number of symbols -A-Aj, -A+Aj, A-Aj, A+Aj in the X polarization direction is 5, 6, 6, 5 respectively, and the number of symbols -A-Aj, -A+Aj, A-Aj, A+Aj in the Y polarization direction is 6, 5, 5, 6 respectively; the two polarization directions are perpendicular to each other. When N FAW When ∑ = 24, the number of symbols -A-Aj, -A+Aj, A-Aj, and A+Aj in any polarization direction is 6. This can achieve inter-symbol balance and DC balance, which is beneficial for restoring signal quality at the receiving end.

[0188] Next, the present application provides some possible symbol sequences, including a frame synchronization sequence composed of frame synchronization 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, wherein the training sequences in different subframes are the same as each other, and the pilot sequences in different subframes are also the same as each other.

[0189] First, the frame synchronization sequence can have the following possibilities, which can ensure that the frame synchronization sequences in the two polarization directions have good mutual correlation and not too much redundancy:

[0190] (1) Assume N FAW =20, the frame synchronization sequence can be any item in Table 5. It should be understood that one sequence number corresponds to a set of frame synchronization sequences on two polarizations, and one item represents a sequence corresponding to one sequence number; and when polarization 1 of any item in the table is X polarization, polarization 2 is Y polarization; when polarization 1 is Y polarization, polarization 2 is X polarization; the subsequent training sequence and pilot sequence tables are expressed in the same way and are not described in detail in this application.

[0191]

[0192]

[0193]

[0194]

[0195] Table 5

[0196] (2) Assume N FAW =22, the frame synchronization sequence can be any one of the items in Table 6.

[0197]

[0198]

[0199]

[0200]

[0201] Table 6

[0202] (3) Assume N FAW =24, the frame synchronization sequence can be any one of the items in Table 7.

[0203]

[0204]

[0205]

[0206]

[0207]

[0208] Table 7

[0209] Secondly, the pilot sequence can have the following possibilities to ensure good mutual correlation between the pilot sequences in the two polarization directions:

[0210] (1) Assume N PS =48, if N TS The remainder when divided by 4 is 1, and the pilot sequence is one of the items in Table 8-1 below. If N TS The remainder when divided by 4 is 3, and the pilot sequence is one of the items in Table 8-1 or 8-2 below. TS +N PS is an odd number, if N PS is an even number, then N TS It must be an odd number, and the remainder when divided by 4 must be 1 or 3; if N PS is an odd number, then N TS It must be an even number, and the remainder obtained by dividing it by 4 must be 0 or 2. I will not go into details later.

[0211]

[0212]

[0213]

[0214]

[0215]

[0216] Table 8-1

[0217]

[0218]

[0219]

[0220]

[0221]

[0222]

[0223]

[0224]

[0225]

[0226]

[0227]

[0228] Table 8-2

[0229] (2) Assume N PS =56, if N TS The remainder when divided by 4 is 1, and the pilot sequence is one of the items in Table 9-1 below. If N TS The remainder when divided by 4 is 3, and the pilot sequence is one of the items in Table 9-1 or 9-2 below.

[0230]

[0231]

[0232]

[0233]

[0234]

[0235]

[0236]

[0237]

[0238]

[0239] Table 9-1

[0240]

[0241]

[0242]

[0243]

[0244]

[0245] Table 9-2

[0246] (3) Assume N PS =57, if N TS The remainder when divided by 4 is 0, and the pilot sequence is one of the items in Table 10-1 below. If N TS The remainder when divided by 4 is 2, and the pilot sequence is one of the items in Table 10-1 or 10-2 below.

[0247]

[0248]

[0249]

[0250]

[0251]

[0252] Table 10-1

[0253]

[0254]

[0255]

[0256]

[0257] Table 10-2

[0258] (4) Assume N PS =65, if N TS The remainder when divided by 4 is 0, and the pilot sequence is one of the items in Table 11-1 below. If N TSThe remainder when divided by 4 is 2, and the pilot sequence is one of the items in Table 11-1 or 11-2 below.

[0259]

[0260]

[0261]

[0262]

[0263]

[0264]

[0265]

[0266]

[0267] Table 11-1

[0268]

[0269]

[0270]

[0271]

[0272]

[0273]

[0274]

[0275]

[0276] Table 11-2

[0277] (5) Assume N PS =74, the pilot sequence is one of the items in Table 12-1 below; or any item in Table 12-2 below is selected as the pilot sequence on one polarization, and any item in Table 12-3 below is selected as the pilot sequence on the other polarization; or any item in Table 12-4 below is selected as the pilot sequence on one polarization, and any item in Table 12-5 below is selected as the pilot sequence on the other polarization.

[0278]

[0279]

[0280]

[0281]

[0282]

[0283] Table 12-1

[0284]

[0285]

[0286]

[0287] Table 12-2

[0288]

[0289]

[0290]

[0291] Table 12-3

[0292]

[0293]

[0294] Table 12-4

[0295]

[0296]

[0297]

[0298] Table 12-5

[0299] (6) Assume N PS =76, if N TS The remainder when divided by 4 is 1, and the pilot sequence is one of the items in Table 13-1 below. If N TS The remainder when divided by 4 is 3, and the pilot sequence is one of the items in Table 13-1 or 13-2 below.

[0300]

[0301]

[0302]

[0303]

[0304]

[0305]

[0306]

[0307]

[0308]

[0309] Table 13-1

[0310]

[0311]

[0312]

[0313]

[0314]

[0315]

[0316]

[0317] Table 13-2

[0318] (7) Assume N PS =50, the pilot sequence is one of the items in Table 14 below.

[0319]

[0320]

[0321]

[0322]

[0323]

[0324]

[0325] Table 14

[0326] (8) When N PSWhen =66, the pilot sequence is one of the items in Table 15-1 below; or any item in Table 15-2 is selected as the pilot sequence on one polarization, and any item in Table 15-3 is selected as the pilot sequence on the other polarization; or any item in Table 15-4 is selected as the pilot sequence on one polarization, and any item in Table 15-5 is selected as the pilot sequence on the other polarization.

[0327]

[0328]

[0329] Table 15-1

[0330]

[0331]

[0332] Table 15-2

[0333]

[0334]

[0335] Table 15-3

[0336]

[0337]

[0338] Table 15-4

[0339]

[0340]

[0341] Table 15-5

[0342] (9) When N PS =68, if N TS Divide by 4 and the remainder is 1, the pilot sequence is one of the items in Table 16-1. If N TS When divided by 4, the remainder is 3, and the pilot sequence is one of the items in Table 16-1 or 16-2.

[0343]

[0344]

[0345]

[0346]

[0347]

[0348]

[0349]

[0350]

[0351] Table 16-1

[0352]

[0353]

[0354]

[0355]

[0356]

[0357]

[0358]

[0359]

[0360] Table 16-2

[0361] (10) When N PS =70, the pilot sequence is one of the items in Table 17 below.

[0362]

[0363]

[0364]

[0365]

[0366]

[0367]

[0368]

[0369] Table 17

[0370] (11) When N PSWhen =78, the pilot sequence is one of the items in Table 18-1; or any item in Table 18-2 is selected as the pilot sequence on one polarization, and any item in Table 18-3 is selected as the pilot sequence on the other polarization; or any item in Table 18-4 is selected as the pilot sequence on one polarization, and any item in Table 18-5 is selected as the pilot sequence on the other polarization.

[0371]

[0372]

[0373]

[0374]

[0375]

[0376]

[0377]

[0378]

[0379]

[0380]

[0381]

[0382]

[0383]

[0384]

[0385]

[0386]

[0387] Table 18-1

[0388]

[0389]

[0390] Table 18-2

[0391]

[0392]

[0393] Table 18-3

[0394]

[0395]

[0396] Table 18-4

[0397]

[0398]

[0399] Table 18-5

[0400] (12) When N PS When =94, the pilot sequence is one of the items in Table 19.

[0401]

[0402]

[0403]

[0404]

[0405] Table 19

[0406] (13) When N PS When ∈R=102, the pilot sequence is one of the items in Table 20-1 below; or any item in Table 20-2 is selected as the pilot sequence on one polarization, and any item in Table 20-3 is selected as the pilot sequence on the other polarization; or any item in Table 20-4 is selected as the pilot sequence on one polarization, and any item in Table 20-5 is selected as the pilot sequence on the other polarization.

[0407]

[0408]

[0409]

[0410]

[0411]

[0412]

[0413] Table 20-1

[0414]

[0415]

[0416] Table 20-2

[0417]

[0418]

[0419] Table 20-3

[0420]

[0421]

[0422] Table 20-4

[0423]

[0424]

[0425]

[0426] Table 20-5

[0427] (14) When N PS =49, if N TS The remainder when divided by 4 is 0, and the pilot sequence is one of the items in Table 21-1 below. If N TS When divided by 4, the remainder is 2, and the pilot sequence is one of the items in Table 21-1 or 21-2 below.

[0428]

[0429]

[0430]

[0431] Table 21-1

[0432]

[0433]

[0434]

[0435]

[0436]

[0437]

[0438] Table 21-2

[0439] (15) When N PS =51, the pilot sequence is one of the items in Table 22 below.

[0440]

[0441]

[0442]

[0443]

[0444]

[0445]

[0446]

[0447]

[0448]

[0449]

[0450]

[0451]

[0452]

[0453] Table 22

[0454] (16) When N PS =61, if N TS The remainder when divided by 4 is 0, and the pilot sequence is one of the items in Table 23-1 below. If N TS When divided by 4, the remainder is 2, and the pilot sequence is one of the items in Table 23-1 or 23-2 below.

[0455]

[0456]

[0457]

[0458]

[0459] Table 23-1

[0460]

[0461]

[0462]

[0463] Table 23-2

[0464] (17) When N PS =67, the pilot sequence is one of the items in Table 24 below.

[0465]

[0466]

[0467]

[0468]

[0469] Table 24

[0470] (18) When N PS =72, if N TS The remainder is 1 when divided by 4, and the pilot sequence is one of the items in Table 25-1 below; if N TS If the remainder is 3 when divided by 4, the pilot sequence is one of the items in Table 25-1 or 25-2 below; or any item in Table 25-3 below is selected as the pilot sequence for one polarization direction, and any item in Table 25-4 is selected as the pilot sequence for the other polarization direction; or any item in Table 25-5 below is selected as the pilot sequence for one polarization direction, and any item in Table 25-6 is selected as the pilot sequence for the other polarization direction.

[0471]

[0472]

[0473]

[0474]

[0475]

[0476]

[0477]

[0478]

[0479]

[0480]

[0481]

[0482]

[0483]

[0484]

[0485]

[0486] Table 25-1

[0487]

[0488]

[0489] Table 25-2

[0490]

[0491]

[0492] Table 25-3

[0493]

[0494]

[0495] Table 25-4

[0496]

[0497]

[0498] Table 25-5

[0499]

[0500]

[0501] Table 25-6

[0502] (19) In particular, when N PS =75, the pilot sequence is one of the items in Table 26 below.

[0503]

[0504]

[0505]

[0506]

[0507]

[0508]

[0509]

[0510]

[0511]

[0512]

[0513]

[0514]

[0515]

[0516]

[0517] Table 26

[0518] (20) When N PS =80, if N TS The remainder when divided by 4 is 1, and the pilot sequence is one of the items in Table 27-1; if N TS If the remainder is 3 when divided by 4, the pilot sequence is one of the items in Table 27-1 or 27-2; or any item in Table 27-3 is selected as the pilot sequence for one polarization direction, and any item in Table 27-4 is selected as the pilot sequence for the other polarization direction; or any item in Table 27-5 is selected as the pilot sequence for one polarization direction, and any item in Table 27-6 is selected as the pilot sequence for the other polarization direction.

[0519]

[0520]

[0521]

[0522]

[0523]

[0524]

[0525]

[0526]

[0527]

[0528] Table 27-1

[0529]

[0530]

[0531]

[0532]

[0533]

[0534]

[0535] Table 27-2

[0536]

[0537]

[0538] Table 27-3

[0539]

[0540]

[0541] Table 27-4

[0542]

[0543]

[0544] Table 27-5

[0545]

[0546]

[0547] Table 27-6

[0548] (21) When N PS =92, if N TS If the remainder is 1 when divided by 4, the pilot sequence is one of the items in Table 28-1; or any item in Table 28-2 is selected as the pilot sequence for one polarization direction, and any item in Table 28-3 is selected as the pilot sequence for another polarization direction; or any item in Table 28-4 is selected as the pilot sequence for one polarization direction, and any item in Table 28-5 is selected as the pilot sequence for another polarization direction. TSIf the remainder is 3 when divided by 4, the pilot sequence is one of the items in Table 28-1 or 28-6; or any item in Table 28-2 is selected as the pilot sequence for one polarization direction, and any item in Table 28-3 is selected as the pilot sequence for the other polarization direction; or any item in Table 28-4 is selected as the pilot sequence for one polarization direction, and any item in Table 28-5 is selected as the pilot sequence for the other polarization direction.

[0549]

[0550]

[0551]

[0552] Table 28-1

[0553]

[0554]

[0555]

[0556] Table 28-2

[0557]

[0558]

[0559] Table 28-3

[0560]

[0561]

[0562] Table 28-4

[0563]

[0564]

[0565] Table 28-5

[0566]

[0567]

[0568]

[0569]

[0570]

[0571]

[0572]

[0573]

[0574] Table 28-6

[0575] (22) In particular, when N PS =96, if N TS If the remainder is 1 when divided by 4, the pilot sequence is one of the items in Table 29-1. TS If the remainder when divided by 4 is 3, the pilot sequence is one of the items in Table 29-1 or 29-2, or any item in Table 29-3 is selected as the pilot sequence for one polarization direction, and any item in Table 29-4 is selected as the pilot sequence for the other polarization direction; or any item in Table 29-5 is selected as the pilot sequence for one polarization direction, and any item in Table 29-6 is selected as the pilot sequence for the other polarization direction.

[0576]

[0577]

[0578]

[0579]

[0580]

[0581]

[0582]

[0583]

[0584] Table 29-1

[0585]

[0586]

[0587]

[0588]

[0589]

[0590]

[0591]

[0592]

[0593] Table 29-2

[0594]

[0595]

[0596]

[0597] Table 29-3

[0598]

[0599]

[0600]

[0601] Table 29-4

[0602]

[0603]

[0604] Table 29-5

[0605]

[0606]

[0607]

[0608] Table 29-6

[0609] (23) In particular, when N PS =104, if N TS If the remainder is 1 when divided by 4, the pilot sequence is one of the items in Table 30-1. TS If the remainder when divided by 4 is 3, the pilot sequence is one of the items in Table 30-1 or 30-2, or any item in Table 30-3 is selected as the pilot sequence for one polarization direction, and any item in Table 30-4 is selected as the pilot sequence for the other polarization direction; or any item in Table 30-5 is selected as the pilot sequence for one polarization direction, and any item in Table 30-6 is selected as the pilot sequence for the other polarization direction.

[0610]

[0611]

[0612]

[0613]

[0614]

[0615]

[0616]

[0617]

[0618]

[0619]

[0620]

[0621]

[0622]

[0623]

[0624]

[0625]

[0626]

[0627] Table 30-1

[0628]

[0629]

[0630]

[0631]

[0632] Table 30-2

[0633]

[0634]

[0635]

[0636] Table 30-3

[0637]

[0638]

[0639]

[0640] Table 30-4

[0641]

[0642]

[0643]

[0644] Table 30-5

[0645]

[0646]

[0647]

[0648] Table 30-6

[0649] Again, the training sequence can be of the following possibilities, which can also ensure good mutual correlation between the training sequences in the two polarization directions:

[0650] (1) Assume N TS =6, the training sequence can be any one of the items in Table 31.

[0651]

[0652]

[0653] Table 31

[0654] (2) When N TS =8, the training sequence is one of the items in Table 32.

[0655]

[0656]

[0657]

[0658]

[0659]

[0660]

[0661]

[0662]

[0663]

[0664]

[0665] Table 32

[0666] (3) When N TS =10, the training sequence is one of the items in Table 33 below.

[0667]

[0668]

[0669]

[0670]

[0671]

[0672]

[0673] Table 33

[0674] (4) When N TS =12, the training sequence is one of the items in Table 34 below.

[0675]

[0676]

[0677]

[0678]

[0679]

[0680]

[0681]

[0682]

[0683]

[0684]

[0685] Table 34

[0686] (5) When N TS =14, the training sequence is one of the items in Table 35 below.

[0687]

[0688]

[0689]

[0690]

[0691]

[0692]

[0693] Table 35

[0694] (6) When N TS =16, the training sequence is one of the items in Table 36 below.

[0695]

[0696]

[0697]

[0698]

[0699]

[0700]

[0701]

[0702]

[0703]

[0704]

[0705] Table 36

[0706] (7) When N TS =18, the training sequence is one of the items in Table 37 below.

[0707]

[0708]

[0709]

[0710]

[0711]

[0712]

[0713]

[0714]

[0715]

[0716]

[0717] Table 37

[0718] (8) When N TS =7, the training sequence is one of the items in Table 38 below.

[0719]

[0720]

[0721]

[0722]

[0723]

[0724]

[0725]

[0726]

[0727]

[0728]

[0729]

[0730]

[0731]

[0732]

[0733]

[0734]

[0735]

[0736]

[0737]

[0738] Table 38

[0739] (9) When N TS =9, the TS training sequence is one of the items in Table 39 below.

[0740]

[0741]

[0742]

[0743]

[0744]

[0745] Table 39

[0746] (10) When N TS =11, the training sequence is one of the items in Table 40 below.

[0747]

[0748]

[0749]

[0750]

[0751]

[0752]

[0753] Table 40

[0754] (11) When N TS =13, the training sequence is one of the items in Table 41 below.

[0755]

[0756]

[0757]

[0758]

[0759]

[0760]

[0761] Table 41

[0762] (12) When N TS =15, the training sequence is one of the items in Table 42 below.

[0763]

[0764]

[0765]

[0766]

[0767]

[0768]

[0769]

[0770]

[0771] Table 42

[0772] (13) When N TS =17, the training sequence is one of the items in Table 43 below.

[0773]

[0774]

[0775]

[0776]

[0777]

[0778] Table 43

[0779] (14) When N TS =19, the training sequence is one of the items in Table 44 below.

[0780]

[0781]

[0782]

[0783]

[0784]

[0785] Table 44

[0786] It should be noted that the above-mentioned frame synchronization sequence, pilot sequence, and training sequence are all given in the form of symbols, and can also be given in the form of bits. The two are equivalent. For example, Figures 7 and 8 respectively give the mapping relationship between DP-QPSK symbols and DP-16QAM symbols and bits, where the 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; taking QPSK as an example, if a sequence is 1+1j, 1+1j, 1-1j, -1+1j, then the corresponding bit sequence is 11111001. After corresponding modulation, the bit sequence will become a symbol sequence output.

[0787] The present application also provides several specific superframe formats, which are described as follows:

[0788] Example 1: The symbols before framing are obtained by CFEC encoding. The number of symbols is 175616, and the corresponding N SF 、N TS 、N PS 、N FAW 、N RES 、N S 、N F , OH and other parameters are shown in the following table:

[0789] N SF N PS N S N F OHN FAW N TS N RES 495736481787521.79%24674

[0790] Its superframe architecture is shown in Figure 9. The superframe includes 49 subframes, and each subframe includes 3648 symbols, as shown in (a) in Figure 9; the first subframe is shown in (b) in Figure 9, with 6 training symbols, 24 frame synchronization symbols, and 74 reserved symbols; in the 2nd to 49th subframes, there are also 6 training symbols, as shown in (c) in Figure 9; and in each subframe, the first symbol of every 64 symbols is a pilot symbol. The frame synchronization sequence with a length of 24 uses one of the items in Table 7. The training sequence with a length of 6 can use one of the items in Table 31. The pilot sequence with a length of 57, according to the superframe structure, selects the one in Table 10-1 or Table 10-2 whose first symbol is the same as the first symbol of the training sequence used. For example, the frame synchronization sequence with a symbol length of 24 uses the following sequence:

[0791]

[0792]

[0793] The corresponding correlation characteristics are shown in Figure 10. Figure 10(a) shows the aperiodic autocorrelation result of the frame synchronization sequence in the X polarization direction, Figure 10(b) shows the aperiodic autocorrelation result of the frame synchronization sequence in the Y polarization direction, and Figure 10(c) shows the aperiodic cross-correlation result of the frame synchronization sequence in both polarization directions. The sidelobe values ​​of the aperiodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.172 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.177 (normalized amplitude).

[0794] The training sequence with a symbol length of 6 uses the following sequence:

[0795] Polarization training sequence

[0796] The corresponding correlation characteristics 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 sequences in both polarization directions. The sidelobe values ​​of the aperiodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.34 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.38 (normalized amplitude).

[0797] The pilot sequence with a symbol length of 57 uses the following sequence:

[0798]

[0799]

[0800] The corresponding correlation characteristics are shown in Figure 12, where (a) in Figure 12 shows the periodic autocorrelation result of the pilot sequence in the X polarization direction, (b) in Figure 12 shows the periodic autocorrelation result of the pilot sequence in the Y polarization direction, and (c) in Figure 12 shows the periodic cross-correlation result of the pilot sequence in the X and Y polarization directions. The sidelobe value of the periodic autocorrelation function of the symbol sequence in the two polarization directions is not greater than 0.177 (normalized amplitude), and the periodic cross-correlation function value of the symbol sequence in the two polarization directions is not greater than 0.197 (normalized amplitude). It should be understood that for the correlation characteristics of the above-mentioned sequence, the value of A does not affect the normalized amplitude value of the correlation function, that is, it has nothing to do with the modulation format adopted. Therefore, this embodiment and subsequent embodiments do not limit the value of A when verifying the correlation characteristics of the sequence, and this application will not go into details.

[0801] It can be seen that the frame redundancy of the superframe architecture provided in the embodiment of the present application is as low as 1.79%, and the designed sequence autocorrelation and cross-correlation characteristics are good. The frame synchronization sequence can also meet the DC balance, and the training sequence and pilot sequence combined can also meet the DC balance, which is beneficial to improving the quality of the recovered signal at the receiving end.

[0802] The receiver processes the received signals in both polarization directions using the frame synchronization sequence, training sequence, and pilot sequence to recover the signal. For example, by calculating the correlation between the received signals in both polarization directions and the sequence symbols of the training sequence in the X and Y polarization directions, the polarization direction can be distinguished and subframe synchronization can be performed. The frame synchronization sequence is used for superframe synchronization, and the pilot signal is used for carrier phase recovery.

[0803] In addition, the three symbol sequences of this embodiment can be represented in the form of bit sequences. Taking DP-16QAM and DP-QPSK as an example, the bit sequences can be shown in the following tables, where b1-b8 correspond to the bits in FIG. 7 and FIG. 8 respectively:

[0804] The bit sequence corresponding to the frame synchronization sequence is as follows:

[0805]

[0806]

[0807] The bit sequence corresponding to the training sequence is as follows:

[0808]

[0809] The bit sequence corresponding to the pilot sequence is as follows:

[0810]

[0811]

[0812] Furthermore, this embodiment also simulates the spectral flatness characteristics of the superframe under different modulation formats. Figure 13 (a) shows the spectrum diagram of 300 superframes under DP-16QAM using the superframe architecture shown in Figure 9, and Figure 13 (b) is the spectrum diagram of a random DP-16QAM signal of the same length; Figure 14 (a) shows the spectrum diagram of 300 superframes under DP-QPSK using the superframe architecture shown in Figure 9, and Figure 14 (b) is the spectrum diagram of a random DP-QPSK signal of the same length; it can be seen that, whether it is DP-16QAM or DP-QPSK, the spectral flatness characteristics of the superframe structure provided by this embodiment are very close to those of the random modulation signal of the same length, and the flatness is very good.

[0813] It should be understood that since the spectral flatness characteristics of the signal are very similar in the two polarization directions, the embodiment of the present application only takes one polarization direction as an example and gives the simulation results. The same is true for the subsequent embodiments, and this application will not go into details.

[0814] Example 2: This embodiment of the present application also provides a specific superframe format. The symbols before framing are obtained by CFEC encoding. The number of symbols is 175616, and its corresponding N SF 、N TS 、N PS 、N FAW 、N RES 、N S 、N F , OH and other parameters are shown in the following table:

[0815] N SF N PS N S N F OHN FAW N TS N RES 436541601788801.86%221060

[0816] Its superframe architecture is shown in Figure 15. The superframe includes 43 subframes, and each subframe includes 4160 symbols, as shown in (a) in Figure 15; the first subframe is shown in (b) in Figure 15, with 10 training symbols, 22 frame synchronization symbols, and 60 reserved symbols; in the 2nd to 43rd subframes, there are also 10 training symbols, as shown in (c) in Figure 15; and in each subframe, the first symbol of every 64 symbols is a pilot symbol. The frame synchronization sequence with a length of 22 uses one of the items in Table 6. The training sequence with a length of 10 can use one of the items in Table 33. The pilot sequence with a length of 65, according to the superframe structure, selects the one in Table 11-1 or Table 11-2 whose first symbol is the same as the first symbol of the training sequence used; for example, the frame synchronization sequence with a symbol length of 22 uses the following sequence:

[0817]

[0818] The corresponding correlation characteristics are shown in Figure 16. Figure 16 (a) shows the aperiodic autocorrelation result of the frame synchronization sequence in the X polarization direction, Figure 16 (b) shows the aperiodic autocorrelation result of the frame synchronization sequence in the Y polarization direction, and Figure 16 (c) shows the aperiodic cross-correlation result of the frame synchronization sequence in both polarization directions. The sidelobe values ​​of the aperiodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.182 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.188 (normalized amplitude).

[0819] In some practical applications, the frame synchronization sequence of length 22 can use an existing symbol sequence, such as the sequence used by OIF-400ZR. However, this sequence has poor cross-correlation in X-polarization and Y-polarization. Therefore, the receiver needs to use more symbols during synchronization to ensure a sufficiently low synchronization error probability.

[0820] The training sequence with a symbol length of 10 uses the following sequence:

[0821]

[0822] The corresponding correlation characteristics 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 sequences in both polarization directions. The sidelobe values ​​of the aperiodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.283 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.283 (normalized amplitude).

[0823] The pilot sequence with a symbol length of 65 uses the following sequence:

[0824]

[0825]

[0826] The corresponding correlation characteristics are shown in Figure 18. Figure 18 (a) shows the periodic autocorrelation result of the pilot sequence in the X polarization direction, Figure 18 (b) shows the periodic autocorrelation result of the pilot sequence in the Y polarization direction, and Figure 18 (c) shows the periodic cross-correlation result of the pilot sequences in both polarization directions. The sidelobe values ​​of the periodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.161 (normalized amplitude), and the periodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.173 (normalized amplitude).

[0827] It can be seen that the frame redundancy of the superframe architecture provided in the embodiment of the present application is also relatively low, at 1.86%, and the designed sequence autocorrelation and cross-correlation characteristics are good. The frame synchronization sequence can also meet the DC balance, and the training sequence and pilot sequence combined can also meet the DC balance, which is beneficial to improving the quality of the recovered signal at the receiving end.

[0828] Furthermore, this embodiment also takes DP-16QAM as an example to simulate the spectral flatness characteristics of the superframe. The results are shown in Figure 19, which adopts the superframe architecture shown in Figure 15 and includes a spectrum diagram of 300 superframes. It can be seen that the spectral flatness characteristics of the superframe structure provided by this embodiment are very close to those of a randomly modulated signal of the same length, and the flatness is very good.

[0829] Example 3: This embodiment of the present application also provides a specific superframe format. The symbols before framing are obtained by CFEC encoding. The number of symbols is 175616, and its corresponding N SF 、N TS 、N PS 、N FAW 、N RES 、N S 、N F , OH and other parameters are shown in the following table:

[0830] N SF N PS N S N F OHN FAW N TS N RES 505635841792002.04%221562

[0831] Its superframe architecture is shown in Figure 20. The superframe includes 50 subframes, each of which includes 3584 symbols, as shown in Figure 20 (a). The first subframe, as shown in Figure 20 (b), has 15 training symbols, 22 frame synchronization symbols, and 62 reserved symbols. Subframes 2 to 50 also have 15 training symbols, as shown in Figure 20 (c). In each subframe, the first symbol of every 64 symbols is a pilot symbol. A frame synchronization sequence with a length of 22 uses one of the items in Table 6. A training sequence with a length of 15 can use one of the items in Table 42. A pilot sequence with a length of 56, based on the superframe structure, selects the item in Table 9-1 or Table 9-2 whose first symbol is the same as the first symbol of the training sequence used. For example, considering a frame synchronization sequence with a symbol length of 22 using the same sequence as in Example 2, the corresponding correlation simulation results are shown in Figure 16.

[0832] Considering a training sequence with a symbol length of 15, the following sequence is used:

[0833]

[0834] The corresponding correlation characteristics 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 sequences in both polarization directions. The sidelobe values ​​of the aperiodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.211 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.211 (normalized amplitude).

[0835] Considering the pilot sequence with a symbol length of 56, the following sequence is used:

[0836]

[0837] The corresponding correlation characteristics are shown in Figure 22. Figure 22(a) shows the periodic autocorrelation result of the pilot sequence in the X polarization direction, Figure 22(b) shows the periodic autocorrelation result of the pilot sequence in the Y polarization direction, and Figure 22(c) shows the periodic cross-correlation result of the pilot sequences in both polarization directions. The sidelobe values ​​of the periodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.183 (normalized amplitude), and the periodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.203 (normalized amplitude).

[0838] It can be seen that the frame redundancy of the superframe architecture provided in the embodiment of the present application is also low, at 2.03%; the training sequence is longer, which facilitates frame synchronization at the receiving end; and the designed sequence autocorrelation and cross-correlation characteristics are good. The frame synchronization sequence can also meet the DC balance, and the combination of the training sequence and the pilot sequence can also meet the DC balance, which is beneficial to improving the quality of the signal recovered by the receiving end.

[0839] Furthermore, this embodiment also takes DP-16QAM as an example to simulate the spectral flatness characteristics of the superframe. The results are shown in Figure 23, which adopts the superframe architecture shown in Figure 20 and includes a spectrum diagram of 300 superframes. It can be seen that the spectral flatness characteristics of the superframe structure provided by this embodiment are very close to those of the randomly modulated signal of the same length, and the flatness is very good.

[0840] Example 4: This embodiment of the present application provides a specific superframe format. The symbols before framing are obtained by open code (Open FEC, OFEC) encoding. The number of symbols is 172032, and its corresponding N SF 、N TS 、N PS 、N FAW 、N RES 、N S 、N F , OH and other parameters are shown in the following table:

[0841] N SF N PS N S N F OHN FAW N TS N RES 485736481751041.79%24672

[0842] Its superframe architecture is shown in Figure 24. The superframe includes 48 subframes, each of which includes 3648 symbols, as shown in Figure 24 (a). The first subframe, as shown in Figure 24 (b), has 6 training symbols, 24 frame synchronization symbols, and 72 reserved symbols. In the second to 48th subframes, there are also 6 training symbols, as shown in Figure 24 (c). In each subframe, the first symbol of every 64 symbols is a pilot symbol. The frame synchronization sequence with a length of 24 uses one of the items in Table 7. The training sequence with a length of 6 can use one of the items in Table 31. The pilot sequence with a length of 57, based on the superframe structure, selects the item in Table 10-1 or Table 10-2 whose first symbol is the same as the first symbol of the training sequence used. For example, the same frame synchronization sequence, training sequence, and pilot sequence as in Example 1 are used, and their correlation is shown in Figure 10-12.

[0843] Furthermore, this embodiment also takes DP-16QAM as an example to simulate the spectral flatness characteristics of the superframe. The results are shown in Figure 25, which adopts the superframe architecture shown in Figure 24 and contains a spectrum diagram of 300 superframes. It can be seen that the spectral flatness characteristics of the superframe structure provided by this embodiment are very close to those of the random modulation signal of the same length, and the flatness is very good.

[0844] Example 5: This embodiment of the present application provides a specific superframe format. The symbols before framing are obtained by CFEC encoding. The number of symbols is 175616, and its corresponding N SF 、N TS 、N PS 、N FAW 、N RES 、N S 、N F , OH and other parameters are shown in the following table:

[0845] N SF N PS N S N F OHN FAW N TS N RES 507536001800002.50%221262

[0846] Its superframe architecture is shown in Figure 26. The superframe includes 50 subframes, each of which includes 3600 symbols, as shown in Figure 26 (a). The first subframe, as shown in Figure 26 (b), has 12 training symbols, 22 frame synchronization symbols, and 62 reserved symbols. In the second to 50th subframes, there are also 12 training symbols, as shown in Figure 26 (c). In each subframe, the first symbol of every 48 symbols is a pilot symbol. The frame synchronization sequence with a length of 22 uses one of the items in Table 6. The training sequence with a length of 12 can use one of the items in Table 34. The pilot sequence with a length of 75, based on the superframe structure, selects the item in Table 26 whose first symbol is the same as the first symbol of the training sequence used. For example, considering a frame synchronization sequence with a symbol length of 22 using the same sequence as in Example 2, the corresponding correlation simulation results are shown in Figure 16.

[0847] Considering a training sequence with a symbol length of 12, the following sequence is used:

[0848]

[0849] The corresponding correlation characteristics 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 sequences in both polarization directions. The sidelobe values ​​of the aperiodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.251 (normalized amplitude), and the aperiodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.251 (normalized amplitude).

[0850] Considering the pilot sequence with a symbol length of 75, the following sequence is used:

[0851]

[0852] The corresponding correlation characteristics are shown in Figure 28. Figure 28 (a) shows the periodic autocorrelation result of the pilot sequence in the X polarization direction, Figure 28 (b) shows the periodic autocorrelation result of the pilot sequence in the Y polarization direction, and Figure 28 (c) shows the periodic cross-correlation result of the pilot sequences in both polarization directions. The sidelobe values ​​of the periodic autocorrelation function of the symbol sequences in both polarization directions are no greater than 0.150 (normalized amplitude), and the periodic cross-correlation function values ​​of the symbol sequences in both polarization directions are no greater than 0.168 (normalized amplitude).

[0853] The frame redundancy of the superframe architecture provided in the embodiment of the present application is also relatively low, at 2.50%, and the designed sequence autocorrelation and cross-correlation characteristics are good. The frame synchronization sequence can also meet the DC balance, and the training sequence and pilot sequence combined can also meet the DC balance, which is beneficial to improving the quality of the recovered signal at the receiving end.

[0854] Furthermore, this embodiment also takes DP-16QAM as an example to simulate the spectral flatness characteristics of the superframe. The results are shown in Figure 29, which adopts the superframe architecture shown in Figure 26 and contains a spectrum diagram of 300 superframes. It can be seen that the spectral flatness characteristics of the superframe structure provided by this embodiment are very close to those of the random modulation signal of the same length, and the flatness is very good.

[0855] Example 6: This embodiment of the present application provides a specific superframe format. The symbols before framing are obtained by OFEC encoding. The number of symbols is 172032, and its corresponding N SF 、N TS 、N PS 、N FAW 、N RES 、N S 、N F , OH and other parameters are shown in the following table:

[0856] NSF N PS N S N F OHN FAW N TS N RES 497536001764002.54%2212132

[0857] Its superframe architecture is shown in Figure 30. The superframe includes 49 subframes, each of which includes 3600 symbols, as shown in Figure 30 (a). The first subframe, as shown in Figure 30 (b), has 12 training symbols, 22 frame synchronization symbols, and 132 reserved symbols. Subframes 2 to 49 also have 12 training symbols, as shown in Figure 30 (c). In each subframe, the first symbol of every 48 symbols is a pilot symbol. The frame synchronization sequence with a length of 22 uses one of the items in Table 6. The training sequence with a length of 12 can use one of the items in Table 34. The pilot sequence with a length of 75, based on the superframe structure, selects the item in Table 26 whose first symbol is the same as the first symbol of the training sequence used. For example, the same frame synchronization sequence, training sequence, and pilot sequence as in Example 5 are used, and their correlations are shown in Figures 16, 27, and 28, respectively.

[0858] The frame redundancy of the superframe architecture provided in the embodiment of the present application is also low, at 2.54%, and the designed sequence autocorrelation and cross-correlation characteristics are good. The frame synchronization sequence can also meet the DC balance, and the training sequence and pilot sequence combined can also meet the DC balance, which is beneficial to improving the quality of the recovered signal at the receiving end.

[0859] Furthermore, this embodiment also takes DP-16QAM as an example to simulate the spectral flatness characteristics of the superframe. The results are shown in Figure 31, which adopts the superframe architecture shown in Figure 30 and includes a spectrum diagram of 300 superframes. It can be seen that the spectral flatness characteristics of the superframe structure provided by this embodiment are very close to those of the random modulation signal of the same length, and the flatness is very good.

[0860] In combination with the communication system described in the embodiment corresponding to FIG. 1 and the framing process described in the embodiment corresponding to FIG. 2 or FIG. 3 , the embodiment of the present application further provides another transmission method for optical communication, as shown in FIG. 32 , the transmission method includes:

[0861] 3201. The transmission device generates a superframe comprising multiple subframes, each of which includes a training symbol and a pilot symbol. In one polarization direction, there is a symbol that is both a training symbol and a pilot symbol, and each training symbol and each pilot symbol are respectively 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 by the target polynomial and the seed, and the pilot symbol has N PS , and N TS The combination of training symbols achieves DC balance, N TS is the number of the training symbols in each subframe in one polarization direction, N TS +N PS is an odd number; the target polynomial is one of the following Table X-1.

[0862] Table X-1

[0863] Sequence target polynomial 1x 10 +x 9 +x 8 +x 7 +x 6 +12x 10 +x 9 +x 8 +x 6 +x 4 +13x 10 +x 9 +x 7 +x 6 +x 4 +14x 10 +x 9 +x 6 +x 3 +15x 10 +x 8 +x 5 +x 3 +16x 10 +x 8 +x 6 +x 5 +x 3 +17x 10 +x 8 +x 7 +x 4 +x 3 +18x 10 +x 6 +x 5 +x 4 +x 3 +19x 10 +x 9 +x 6 +x 2+110x 10 +x 7 +x 6 +x 2 +111x 10 +x 7 +x 5 +x 2 +112x 10 +x 8 +x 7 +x 5 +x 2 +113x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +114x 10 +x 7 +x 5 +x 4 +x 2 +115x 10 +x 9 +x 7 +x 5 +x 4 +x 2 +116x 10 +x 9 +x 8 +x 3 +x 2 +117x 10 +x 9 +x 8 +x 7 +x 3 +x 2 +118x 10 +x 7 +x 6 +x 3 +x 2 +119x 10 +x 8 +x 5 +x+120x 10 +x 8 +x 4 +x+121x 10 +x 9 +x 8 +x 7 +x 4 +x+122x 10 +x 8 +x 5 +x 4 +x+123x 10 +x 5 +x3 +x+124x 10 +x 8 +x 6 +x 5 +x 3 +x+125x 10 +x 9 +x 8 +x 7 +x 4 +x 3 +x+126x 10 +x 6 +x 4 +x 3 +x+127x 10 +x 8 +x 7 +x 2 +x+128x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +x+129x 10 +x 9 +x 6 +x 3 +x 2 +x+130x 10 +x 8 +x 6 +x 3 +x 2 +x+131x 10 +x 6 +x 5 +x 3 +x 2 +x+132x 10 +x 4 +x 3 +x 2 +x+133x 10 +x 9 +x 7 +x 3 +134x 10 +x 9 +x 6 +x+135x 10 +x 9 +x 4 +x+136x 10 +x 7 +x 3 +x+1

[0864] 3202. The transmission device sends out a superframe, and correspondingly, the receiving device receives the superframe containing multiple subframes.

[0865] 3203. The receiving device decodes the received superframe.

[0866] In the embodiment of the present application, the value of A is determined by the modulation format used when generating the symbols, and can be understood by referring to the corresponding contents of the embodiment section of Figures 4 and 5A above. It should be noted that in some practical application scenarios, the pilot symbols and training symbols -A-Aj, -A+Aj, A-Aj, A+Aj may not be symbols on the constellation diagram of the modulation format used, but may be 4 symbols in the middle area between the outermost 4 symbols and the innermost 4 symbols of the constellation diagram. At this time, the noise and sensitivity of the training and pilot symbols are average, but the peak-to-average power ratio is relatively low. Taking 16QAM as an example, the 16 symbols on the 16QAM constellation diagram are {±1±1j, ±1±3j, ±3±1j, ±3±3j}, and the value of the real number A satisfies 1≤A≤3. More specifically, as shown in FIG5B , the outermost four symbols of the constellation are 3+3j, 3-3j, -3+3j, -3-3j, and the innermost four symbols of the constellation are 1+1j, 1-1j, -1+1j, -1-1j. The pilot symbol and training symbol values ​​-A-Aj, -A+Aj, A-Aj, and A+Aj can be four symbols in the middle area between the outermost four symbols and the innermost four symbols of the 16QAM constellation. The specific value of the real number A can 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 The values ​​of pilot symbols and training symbols are In addition, when the 16 symbols on the 16QAM constellation are power normalized and the value is The value of real number A satisfies For example, real numbers The values ​​of pilot symbols and training symbols are

[0867] In addition, in the embodiment of the present application, there are two polarization directions, which are orthogonal to each other, that is, when one of the polarization directions is X polarization, the other polarization direction is Y polarization; when one of the polarization directions is Y polarization, the other polarization direction is X polarization. These two polarization directions can also be described as polarization one and polarization two. In the embodiment of the present application, in one polarization direction, the sum of the number of training symbols and pilot symbols included in a subframe is N TS +N PS -1, the reason why it is not N TS +N PS The reason is that there is a symbol that is both a training symbol and a pilot symbol, so the sum of their numbers is one less than the sum of the two symbols.

[0868] In the embodiment of the present application, the pilot symbol is generated by a target polynomial and a seed. The target polynomial is any one of the items in Table X-1 above. The target polynomial and the corresponding seed can satisfy the generated N PS the pilot symbols and N TS The combination of training symbols achieves DC balance, that is, in one subframe and in one polarization direction, the sum of the real parts of the complex numbers corresponding to the training symbols and pilot symbols is 0, and the sum of the imaginary parts is also 0. This is conducive to better signal recovery at the receiving end and improves the signal quality at the receiving end.

[0869] The structure of the superframe provided in the embodiment of the present application can be understood by referring to the corresponding contents of parts (a) to (c) in Figure 6 above, and will not be repeated here.

[0870] The solution provided in the embodiment of the present application can be applied to the row numbered 18 and the row numbered 9 in Table 2 in the aforementioned embodiment.

[0871] The following introduces these two superframe formats respectively.

[0872] For the row numbered 18 in Table 2 above, in one polarization direction, the number of symbols before framing is 172032, and its corresponding N SF 、N PS 、N TS 、N S 、N F 、N FAW 、N RES , OH and other parameters are shown in Table X-2 below:

[0873] Table X-2

[0874] N SF N PS N S N F OHN TS N FAW +N RES 2411472961751041.79%1196

[0875] The superframe structure is shown in (a) of FIG33 . The superframe includes 24 subframes, and each subframe includes 7296 symbols. The first subframe is shown in (b) of FIG33 , which has 11 training symbols. FAW frame synchronization symbols, N RES reserved symbols, N FAW +N RES=96; as shown in (c) in Figure 33, there are also 11 training symbols in the 2nd to 24th subframes; and in each subframe, the first symbol in every 64 symbols is a pilot symbol, and each subframe contains 114 pilot symbols.

[0876] In (b) of FIG33, N FAW =22, N RES =74 as an example, the sequence of 22 frame synchronization symbols can be understood by referring to the following Table X-3:

[0877] Table X-3

[0878]

[0879] The sequence of 11 training symbols can be understood by referring to Table X-4 below:

[0880] Table X-4

[0881]

[0882] In this example, 114 pilot symbols are determined based on a target polynomial and a corresponding seed. In the embodiment of the present application, the target polynomial is a 10th-order polynomial, which can be expressed as:

[0883] x 10 +a9×x 9 +a8×x 8 +a7×x 7 +a6×x 6 +a5×x 5 +a4×x 4 +a3×x 3 +a2×x 2 +a1×x+1

[0884] Among them, a9...a1 can take the value of 0 or 1.

[0885] The pilot symbol generation structure can be understood by referring to Figure 34. As shown in Figure 34, the seed can be expressed in binary form as m9, m8, m7, m6, m5, m4, m3, m2, m1, and m0. Of course, the seed can also be expressed in hexadecimal or decimal. When operating with the target polynomial, it needs to be converted into binary form, such as: 0110111000 is expressed as 0x1B8 in hexadecimal and 440 in decimal.

[0886] In the embodiment of the present application, the same target generating polynomial may be used for the pilot symbols in two orthogonal polarization directions. However, due to different seeds, the pilot symbols output in the two polarization directions are not exactly the same.

[0887] As shown in FIG34 , for a scenario where 114 pilot symbols need to be generated, a bit sequence b0, b1, b2, ... b with a continuous length of 228 is obtained according to the target polynomial and the seed. 227 The bit sequence b0, b1, b2, ...b 227 Every two consecutive bits are mapped into a symbol, where b 2t and b 2t+1 Mapped to a symbol (2b 2t -1)A+(2b 2t+1 -1)Aj, 0≤t<114. It should be noted that the symbol (2b 2t -1)A+(2b 2t+1 -1)Aj may not be a symbol on the constellation diagram of the modulation format used, but may be a certain 4 symbols in the middle area between the outermost 4 symbols and the innermost 4 symbols of the constellation diagram of the modulation format used. At this time, the noise and sensitivity of the training and pilot symbols are average, but the peak-to-average power ratio is relatively low. Taking 16QAM as an example, the 16 symbols on 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 can 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 The values ​​of pilot symbols and training symbols are In addition, when the 16 symbols on the 16QAM constellation are power normalized and the value is The value of real number A satisfies For example, real numbers The values ​​of pilot symbols and training symbols are

[0888] In the 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 generated pilot symbols have good autocorrelation characteristics in the symbol sequences of X polarization and Y polarization, and good cross-correlation characteristics in the symbol sequences of the two polarizations. In particular, the normalized amplitude of the sidelobe values ​​of the periodic autocorrelation function of the symbol sequences in the two polarization directions is no greater than a preset value T0, and the normalized amplitude of the periodic cross-correlation function values ​​of the symbol sequences in the two polarization directions is no greater than a preset value T1.

[0889] When the target polynomial and the seeds expressed in hexadecimal in two polarization directions are a row in the following Table X-5, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbol in the same polarization direction is not greater than 0.2, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.2, that is, T0 = 0.2, T1 = 0.2.

[0890] Table X-5

[0891] Serial number Target polynomial Seed in polarization direction 1 Seed in polarization direction 2 1x 10 +x 9 +x 8 +x 7 +x 6 +10x1220x0E42x 10 +x 9 +x 8 +x 7 +x 6 +10x1220x06C3x 10 +x 9 +x 8 +x 7 +x 6 +10x3620x1C44x 10 +x 9 +x 8 +x 7 +x 6 +10x3620x0DC5x 10 +x 9 +x 8 +x 7 +x 6 +10x31A0x0E46x 10 +x 9 +x 8 +x 7 +x 6 +10x31A0x06C7x 10 +x 9 +x 8 +x 7 +x 6 +10x0460x3848x 10 +x 9 +x 8 +x 7 +x 6 +10x0460x3C49x 10 +x 9 +x 8 +x 7 +x 6 +10x0460x2DC

[0892] 10x 10 +x 9 +x 8 +x 7 +x 6 +10x2460x34811x 10 +x 9 +x 8 +x 7 +x 6 +10x2460x1C412x 10 +x 9 +x 8 +x 7 +x 6 +10x2460x0DC13x 10 +x 9 +x 8 +x 7 +x 6 +10x0F60x38414x 10 +x 9 +x 8 +x 7 +x 6 +10x0F60x1C415x 10 +x 9 +x 8 +x 7 +x 6 +10x0F60x0DC16x 10 +x 9 +x 8 +x 7 +x 6 +10x08E0x0E417x 10 +x 9 +x 8 +x 7 +x 6 +10x08E0x06C18x 10 +x 9 +x 8 +x 6 +x 4 +10x0220x08019x 10 +x 9 +x 8 +x 6 +x 4 +10x0220x22020x 10 +x 9 +x 8 +x 6 +x 4 +10x0220x1FC21x 10 +x9 +x 7 +x 6 +x 4 +10x3A20x1A422x 10 +x 9 +x 7 +x 6 +x 4 +10x03A0x1A423x 10 +x 9 +x 6 +x 3 +10x0760x07C24x 10 +x 8 +x 5 +x 3 +10x3CE0x19C25x 10 +x 8 +x 6 +x 5 +x 3 +10x1860x04826x 10 +x 8 +x 6 +x 5 +x 3 +10x1860x03427x 10 +x 8 +x 7 +x 4 +x 3 +10x1A20x2A028x 10 +x 8 +x 7 +x 4 +x 3 +10x1A20x33029x 10 +x 8 +x 7 +x 4 +x 3 +10x10A0x33430x 10 +x 8 +x 7 +x 4 +x 3 +10x10A0x08C31x 10 +x 8 +x 7 +x 4 +x 3 +10x3EA0x35032x 10 +x 8 +x 7 +x 4 +x 3+10x3EA0x18433x 10 +x 8 +x 7 +x 4 +x 3 +10x2E60x2A034x 10 +x 8 +x 7 +x 4 +x 3 +10x2E60x33035x 10 +x 6 +x 5 +x 4 +x 3 +10x1660x0CC36x 10 +x 9 +x 6 +x 2 +10x21E0x02837x 10 +x 9 +x 6 +x 2 +10x21E0x01438x 10 +x 7 +x 6 +x 2 +10x0BE0x1B839x 10 +x 7 +x 5 +x 2 +10x3420x16C40x 10 +x 8 +x 7 +x 5 +x 2 +10x0D60x0CC41x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +10x16A0x0DC42x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +10x2A60x0DC43x 10 +x 7 +x 5 +x 4 +x 2 +10x18A0x32444x 10 +x 7 +x 5 +x4 +x 2 +10x1C60x32445x 10 +x 9 +x 7 +x 5 +x 4 +x 2 +10x26E0x38C46x 10 +x 9 +x 7 +x 5 +x 4 +x 2 +10x26E0x27C

[0893] 47x 10 +x 9 +x 8 +x 3 +x 2 +10x1020x1F048x 10 +x 9 +x 8 +x 3 +x 2 +10x0220x1AC49x 10 +x 9 +x 8 +x 3 +x 2 +10x00A0x14450x 10 +x 9 +x 8 +x 3 +x 2 +10x14A0x07C51x 10 +x 9 +x 8 +x 3 +x 2 +10x0A60x07C52x 10 +x 9 +x 8 +x 3 +x 2 +10x1760x1AC53x 10 +x 9 +x 8 +x 3 +x 2 +10x0BE0x07C54x 10 +x 9 +x 8 +x 7 +x 3 +x 2 +10x0820x26455x10 +x 7 +x 6 +x 3 +x 2 +10x2020x17056x 10 +x 7 +x 6 +x 3 +x 2 +10x2020x3F457x 10 +x 7 +x 6 +x 3 +x 2 +10x1420x2E058x1 0 +x 7 +x 6 +x 3 +x 2 +10x1420x05459x 10 +x 7 +x 6 +x 3 +x 2 +10x1420x07C60x 10 +x 7 +x 6 +x 3 +x 2 +10x2EA0x15061x 10 +x 7 +x 6 +x 3 +x 2 +10x3060x22062x 10 +x 7 +x 6 +x 3 +x 2 +10x3060x09463x 10 +x 8 +x 5 +x+10x3FE0x0E064x 10 +x 8 +x 4 +x+10x28E0x0F465x 10 +x 9 +x 8 +x 7 +x 4 +x+10x1020x24866x 10 +x 8 +x 5 +x 4 +x+10x10A0x0EC67x 10+x 5 +x 3 +x+10x1C60x07C68x 10 +x 8 +x 6 +x 5 +x 3 +x+10x2460x24C69x 10 +x 9 +x 8 +x 7 +x 4 +x 3 +x+10x1C60x13070x 10 +x 6 +x 4 +x 3 +x+10x25A0x23C71x 10 +x 6 +x 4 +x 3 +x+10x2F60x23C72x 10 +x 8 +x 7 +x 2 +x+10x0220x1CC73x 10 +x 8 +x 7 +x 2 +x+10x0220x3DC74x 10 +x 8 +x 7 +x 2 +x+10x2260x1CC75x 10 +x 8 +x 7 +x 2 +x+10x2260x3DC76x 10 +x 8 +x 7 +x 2 +x+10x3160x1C477x 10 +x 8 +x 7 +x 2 +x+10x3160x2EC78x 10 +x 8 +x 7 +x 2 +x+10x12E0x1C479x 10 +x 8 +x 7 +x 2 +x+10x12E0x2EC80x10 +x 9 +x 8 +x 7 +x 4 +x 2 +x+10x38A0x07C81x 10 +x 9 +x 6 +x 3 +x 2 +x+10x2520x39882x 10 +x 9 +x 6 +x 3 +x 2 +x+10x13A0x33083x 10 +x 9 +x 6 +x 3 +x 2 +x+10x13A0x398

[0894] 84x 10 +x 8 +x 6 +x 3 +x 2 +x+10x31A0x31085x 10 +x 8 +x 6 +x 3 +x 2 +x+10x31A0x1C486x 10 +x 6 +x 5 +x 3 +x 2 +x+10x2620x3A487x 10 +x 6 +x 5 +x 3 +x 2 +x+10x2920x36C88x 10 +x 4 +x 3 +x 2 +x+10x2220x04889x 10 +x 4 +x 3 +x 2 +x+10x2220x13890x 10 +x 4 +x 3 +x 2 +x+10x3220x36891x 10 +x4 +x 3 +x 2 +x+10x3220x1D892x 10 +x 4 +x 3 +x 2 +x+10x3220x0E493x 10 +x 4 +x 3 +x 2 +x+10x0E20x36894x 10 +x 4 +x 3 +x 2 +x+10x0E20x1D895x 10 +x 4 +x 3 +x 2 +x+10x0E20x0E496x 10 +x 4 +x 3 +x 2 +x+10x07A0x2C497x 10 +x 4 +x 3 +x 2 +x+10x07A0x3B498x 10 +x 4 +x 3 +x 2 +x+10x04E0x2F099x 10 +x 4 +x 3 +x 2 +x+10x04E0x224100x 10 +x 4 +x 3 +x 2 +x+10x36E0x2C4101x 10 +x 4 +x 3 +x 2 +x+10x36E0x0EC102x 10 +x 4 +x 3 +x 2 +x+10x21E0x368103x 10 +x 4 +x 3 +x 2 +x+10x21E0x1D8

[0895] When the target polynomial and the seed expressed in hexadecimal in two polarization directions are a row in the following Table X-6 (Table X-6 is a subset of Table X-5), in one polarization direction, in the combination of 114 pilot symbols and 11 training symbols, the number of -A-Aj, -A+Aj, A-Aj and A+Aj in one polarization direction is 31.

[0896] Table X-6

[0897] Serial number Target polynomial Seed in polarization direction 1 Seed in polarization direction 2 1x 10 +x 9 +x 8 +x 7 +x 6 +10x0460x3842x 10 +x 9 +x 8 +x 7 +x 6 +10x0460x3C43x 10 +x 9 +x 6 +x 3 +10x0760x07C4x 10 +x 8 +x 7 +x 4 +x 3 +10x1A20x3305x 10 +x 8 +x 7 +x 4 +x 3 +10x2E60x3306x 10 +x 8 +x 7 +x 2 +x+10x2260x3DC7x 10 +x 9 +x 6 +x 3 +x 2 +x+10x13A0x3308x 10 +x 4 +x 3 +x 2 +x+10x3220x3689x 10 +x 4 +x 3 +x 2 +x+10x3220x0E410x 10 +x 4 +x 3 +x 2+x+10x0E20x36811x 10 +x 4 +x 3 +x 2 +x+10x0E20x0E412x 10 +x 4 +x 3 +x 2 +x+10x04E0x2F0

[0898] Taking into account that the sequence generated when the target polynomial is a primitive polynomial generally has better randomness, and taking into account that the more non-zero terms the target polynomial has, the more complex the implementation is, when the target polynomial adopts a primitive polynomial and its non-zero terms are not greater than 5, when the target polynomial and the seeds expressed in hexadecimal in the two polarization directions are a row in Table X-7 below, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbol in the same polarization direction is not greater than 0.25, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.25.

[0899] Table X-7

[0900] Serial number Target polynomial Seed in polarization direction 1 Seed in polarization direction 2 1x 10 +x 9 +x 7 +x 3 +10x23E0x0942x 10 +x 7 +x 6 +x 2 +10x0BE0x1B83x 10 +x 9 +x 6 +x+10x0020x2104x 10 +x 9 +x 6 +x+10x0020x3085x 10 +x 9 +x 6 +x+10x0020x1846x 10 +x 9 +x 6 +x+10x1C20x0407x 10 +x 8 +x 5 +x+10x3FE0x0E08x 10 +x 8 +x 5 +x+10x3FE0x2709x 10 +x 8 +x 5+x+10x3FE0x30410x 10 +x 9 +x 4 +x+10x3B60x1A011x 10 +x 9 +x 4 +x+10x3B60x0D012x 10 +x 9 +x 4 +x+10x3B60x05813x 10 +x 9 +x 4 +x+10x3B60x22C14x 10 +x 7 +x 3 +x+10x34E0x084

[0901] In the row numbered 14 in Table X-7, the target polynomial, also known as the primitive polynomial, is x 10 +x 7 +x 3 +x+1, when the seeds expressed in hexadecimal in the corresponding two polarization directions are 0x34E and 0x084, the generation process of 114 pilot symbols can be understood by referring to Figure 35.

[0902] As shown in Figure 35, in the X-polarization direction, the input polarization seed is 0x34E, which, after conversion to the binary sequence, is 1101001110, which is the value from m9 to m0. If the two bits 1 and 0 are output sequentially, the pilot symbol in the X-polarization direction is A-Aj. If the two bits 0 and 0 are output sequentially, the pilot symbol in the X-polarization direction is -A-Aj. If the two bits 1 and 1 are output sequentially, the pilot symbol in the X-polarization direction is A+Aj. If the two bits 0 and 1 are output sequentially, the pilot symbol in the X-polarization direction is -A+Aj. Similarly, 114 pilot symbols in the X-polarization direction are obtained.

[0903] As shown in Figure 35, in the Y polarization direction, the input polarization seed is 0x084, which, after conversion to the binary sequence, is 0010000100, which is the value from m9 to m0. If the two bits are output sequentially, 1 and 0, the pilot symbol in the Y polarization direction is A-Aj. If the two bits are output sequentially, 0 and 0, the pilot symbol in the Y polarization direction is -A-Aj. If the two bits are output sequentially, 1 and 1, the pilot symbol in the Y polarization direction is A+Aj. If the two bits are output sequentially, 0 and 1, the pilot symbol in the Y polarization direction is -A+Aj. Similarly, 114 pilot symbols in the Y polarization direction are obtained.

[0904] The polarization seeds in the X polarization direction and the polarization seeds in the Y polarization direction can be interchanged, so 114 pilot symbols as shown in the following Table X-8 can be obtained.

[0905] Table X-8

[0906]

[0907] In the above Table X-8, in one polarization direction, in the combination of 114 pilot symbols and 11 training symbols, the number of -A-Aj, -A+Aj, A-Aj and A+Aj in the said one polarization direction is 31.

[0908] In the above-mentioned X-8 scheme, the correlation characteristics corresponding to the pilot symbols are shown in Figure 36. (a) in Figure 36 shows the periodic autocorrelation result of the sequence of pilot symbols in the X polarization direction, (b) in Figure 36 shows the periodic autocorrelation result of the sequence of pilot symbols in the Y polarization direction, and (c) in Figure 36 shows the periodic cross-correlation result of the sequence of pilot symbols in the X and Y polarization directions. The normalized amplitude of the sidelobe value of the periodic autocorrelation function of the symbol sequence in the two polarization directions is not greater than 0.167, and the normalized amplitude of the sidelobe value of the periodic cross-correlation function of the symbol sequence in the two polarization directions is not greater than 0.202. The frame redundancy of the superframe architecture provided in the embodiment of the present application is also low, at 1.79%, and the sequence autocorrelation and cross-correlation characteristics of the pilot symbols are good. The combination of training symbols and pilot symbols can also meet DC balance, which is beneficial to improving the signal recovery at the receiving end and improving the quality of the recovered signal.

[0909] Next, another example of the above superframe structure is provided. When the target polynomial is x 10 +x 7 +x 6 +x 2 +1, when the corresponding seeds expressed in hexadecimal in the two polarization directions are 0x0BE and 0x1B8, the generation process of the pilot symbols in the two polarization directions can be understood by referring to Figure 37.

[0910] As shown in Figure 37, in the X-polarization direction, the input polarization seed is 0x0BE, which, after conversion to the binary sequence, is 0010111110, which is the value from m9 to m0. If the two bits 1 and 0 are output sequentially, the pilot symbol in the X-polarization direction is A-Aj. If the two bits 0 and 0 are output sequentially, the pilot symbol in the X-polarization direction is -A-Aj. If the two bits 1 and 1 are output sequentially, the pilot symbol in the X-polarization direction is A+Aj. If the two bits 0 and 1 are output sequentially, the pilot symbol in the X-polarization direction is -A+Aj. Similarly, 114 pilot symbols in the X-polarization direction are obtained.

[0911] As shown in Figure 37, in the Y polarization direction, the input polarization seed is 0x1B8, which, after conversion to the binary sequence, is 0110111000, which is the value from m9 to m0. If the two bits 1 and 0 are output sequentially, the pilot symbol in the Y polarization direction is A-Aj. If the two bits 0 and 0 are output sequentially, the pilot symbol in the Y polarization direction is -A-Aj. If the two bits 1 and 1 are output sequentially, the pilot symbol in the Y polarization direction is A+Aj. If the two bits 0 and 1 are output sequentially, the pilot symbol in the Y polarization direction is -A+Aj. Similarly, 114 pilot symbols in the Y polarization direction are obtained.

[0912] The polarization seeds in the X polarization direction and the polarization seeds in the Y polarization direction can be interchanged, so 114 pilot symbols as shown in the following Table X-9 can be obtained.

[0913] Table X-9

[0914]

[0915]

[0916] In the above-mentioned Figure X-9, the correlation characteristics corresponding to the pilot symbols are shown in Figure 38, and Figure 38 (a) shows the periodic autocorrelation result of the sequence of pilot symbols in the X polarization direction, and Figure 38 (b) shows the periodic autocorrelation result of the sequence of pilot symbols in the Y polarization direction. Figure 38 (c) shows the periodic cross-correlation result of the sequence of pilot symbols in the X and Y polarization directions. The normalized amplitude of the sidelobe value of the periodic autocorrelation function of the symbol sequence in the two polarization directions is not greater than 0.162, and the normalized amplitude of the sidelobe value of the periodic cross-correlation function of the symbol sequence in the two polarization directions is not greater than 0.185. The frame redundancy of the superframe architecture provided in the embodiment of the present application is also low, at 1.79%, and the sequence autocorrelation and cross-correlation characteristics of the designed pilot symbols are good. The combination of the training sequence and the pilot symbol sequence can also meet the DC balance, which is beneficial to improving the signal recovery at the receiving end and improving the quality of the recovered signal.

[0917] The above describes the superframe structure of the row with sequence number 18 in Table 2 and the content of the generation process of its pilot symbols. The following describes the corresponding content of the superframe of the row with sequence number 9 in Table 2.

[0918] For the row with sequence number 9 in Table 2 above, the number of symbols before framing is 172032, and its corresponding N SF 、N PS 、N TS 、N S 、N F 、N FAW 、N RES , OH and other parameters are shown in Table X-10 below:

[0919] Table X-10

[0920] N SF N PS N S N F OHN TS N FAW +N RES 485736481751041.79%696

[0921] The superframe structure is shown in (a) of FIG39 . The superframe includes 48 subframes, each of which includes 3648 symbols. The first subframe is shown in (b) of FIG39 , which has 6 training symbols, N FAW frame synchronization symbols, N RES reserved symbols, N FAW +N RES=96; as shown in (c) in Figure 39, there are also 6 training symbols in the 2nd to 48th subframes; and in each subframe, the first symbol in every 64 symbols is a pilot symbol, and each subframe contains 57 pilot symbols.

[0922] In (b) of FIG39, N FAW =22, N RES =74 as an example, the sequence of 22 frame synchronization symbols can be understood by referring to Table X-3 below: Considering that the first symbol of the 6 training symbols needs to be the same as the first symbol of the 57 pilot symbols. In (b) of Figure 39, the sequence of the 6 training symbols can be understood by referring to Table X-11 below:

[0923] Table X-11

[0924] Sequence of polarization training symbols Polarization one A-Aj, A+Aj, A+Aj, -A-Aj, -A-Aj, -A+Aj Polarization two A-Aj, -A-Aj, -A+Aj, A-Aj, A+Aj, -A+Aj

[0925] In this example, 57 pilot symbols are determined by the target polynomial and the corresponding seed. In the embodiment of the present application, the structure of the target polynomial and the seed generating the pilot symbols can be understood by referring to the corresponding content of the aforementioned FIG. 34 .

[0926] For the scenario where 57 pilot symbols need to be generated, a continuous bit sequence of length 114 b0, b1, b2, ...b is obtained according to the target polynomial and the seed. 113 The bit sequence b0, b1, b2, ...b 113 Every two consecutive bits are mapped into a symbol, where b 2t and b 2t+1 Mapped to a symbol (2b 2t -1)A+(2b 2t+1 -1)Aj. It should be noted that the symbol (2b 2t -1)A+(2b 2t+1 -1)Aj may not be a symbol on the constellation diagram of the modulation format used, but may be a certain 4 symbols in the middle area between the outermost 4 symbols and the innermost 4 symbols of the constellation diagram of the modulation format used. At this time, the noise and sensitivity of the training and pilot symbols are average, but the peak-to-average power ratio is relatively low. Taking 16QAM as an example, the 16 symbols on 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 can 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 The values ​​of pilot symbols and training symbols are In addition, when the 16 symbols on the 16QAM constellation are power normalized and the value is The value of real number A satisfies For example, real numbers The values ​​of pilot symbols and training symbols are

[0927] When the target polynomial and the seeds expressed in hexadecimal in two polarization directions are a row in Table X-12 below, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is not greater than 0.23, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.23.

[0928] Table X-12

[0929] Serial number target polynomial Seed for one polarization direction Seed for another polarization direction 1x 10 +x 7 +x 3 +x+10x2040x2792x 10 +x 7 +x 3 +x+10x0B10x3E93x 10 +x 7 +x 3 +x+10x0B10x279

[0930] When the target polynomial is x 10 +x 7 +x 3 +x+1, when the seeds expressed in hexadecimal in the corresponding two polarization directions are 0x0B1 and 0x3E9, that is, when the row with sequence number 2 in the above Table X-12 is used, the generation process of 57 pilot symbols can be understood by referring to Figure 40.

[0931] As shown in Figure 40, in the X-polarization direction, the input polarization seed is 0x0B1, which, after conversion to the binary sequence, is 0010110001, which is the value from m9 to m0. If the two bits 1 and 0 are output sequentially, the pilot symbol in the X-polarization direction is A-Aj. If the two bits 0 and 0 are output sequentially, the pilot symbol in the X-polarization direction is -A-Aj. If the two bits 1 and 1 are output sequentially, the pilot symbol in the X-polarization direction is A+Aj. If the two bits 0 and 1 are output sequentially, the pilot symbol in the X-polarization direction is -A+Aj. Similarly, 57 pilot symbols in the X-polarization direction are obtained.

[0932] As shown in Figure 40, in the Y polarization direction, the input polarization seed is 0x3E9, which, after conversion to the binary sequence, is 1111101001, which is the value from m9 to m0. If the two bits 1 and 0 are output sequentially, the pilot symbol in the Y polarization direction is A-Aj. If the two bits 0 and 0 are output sequentially, the pilot symbol in the Y polarization direction is -A-Aj. If the two bits 1 and 1 are output sequentially, the pilot symbol in the Y polarization direction is A+Aj. If the two bits 0 and 1 are output sequentially, the pilot symbol in the Y polarization direction is -A+Aj. Similarly, 57 pilot symbols in the Y polarization direction are obtained.

[0933] The polarization seeds in the X polarization direction and the polarization seeds in the Y polarization direction can be interchanged, so 57 pilot symbols as shown in the following Table X-13 can be obtained.

[0934] Table X-13

[0935]

[0936] In the above Figure X-13, the correlation characteristics corresponding to the pilot symbols are shown in Figure 41. (a) in Figure 41 shows the periodic autocorrelation result of the sequence of pilot symbols in the X polarization direction, (b) in Figure 41 shows the periodic autocorrelation result of the sequence of pilot symbols in the Y polarization direction, and (c) in Figure 41 shows the periodic cross-correlation result of the sequence of pilot symbols in the X and Y polarization directions. The normalized amplitude of the sidelobe value of the periodic autocorrelation function of the symbol sequence in the two polarization directions is not greater than 0.206, and the normalized amplitude of the sidelobe value of the periodic cross-correlation function of the symbol sequence in the two polarization directions is not greater than 0.212. The frame redundancy of the superframe architecture provided in the embodiment of the present application is also low, at 1.79%, and the designed sequence autocorrelation and cross-correlation characteristics of the pilot symbols are good. The combination of the training sequence and the pilot symbol sequence can also meet the DC balance, which is beneficial to improving the signal recovery at the receiving end and improving the quality of the recovered signal.

[0937] In combination with the communication system described in the embodiment corresponding to FIG. 1 and the framing process described in the embodiment corresponding to FIG. 2 or FIG. 3 , the embodiment of the present application further provides another transmission method for optical communication, as shown in FIG. 42 , the transmission method includes:

[0938] 3301. The transmitting device generates a superframe comprising a plurality of subframes, wherein the subframes include training symbols and pilot symbols;

[0939] In each subframe, in one polarization direction, there are N pilot symbols. PSThe value is one of -A2-A2j, -A2+A2j, A2-A2j, A2+A2j, where A2 is a real number, N PS is an even number; N PS pilot symbols to achieve DC balance; training symbols and N PS The combination of pilot symbols achieves DC balance;

[0940] The pilot symbol is generated by determining the target polynomial and the seed. The target polynomial is a primitive polynomial with no more than 5 non-zero terms. The target polynomial is one of the following Table Y-1.

[0941] Table Y-1

[0942] Sequence target polynomial 1x 10 +x 9 +x 7 +x 6 +12x 10 +x 9 +x 7 +x 3 +13x 10 +x 8 +x 4 +x 3 +1

[0943] 4x 10 +x 7 +x 6 +x 2 +15x 10 +x 9 +x 6 +x+16x 10 +x 9 +x 4 +x+17x 10 +x 7 +x 3 +x+18x 10 +x 4 +x 3 +x+1

[0944] 3302. The transmission device sends out a superframe, and correspondingly, the receiving device receives the superframe containing multiple subframes.

[0945] 3303. The receiving device decodes the received superframe.

[0946] In the embodiment of the present application, the pilot symbol is generated by a target polynomial and a seed. The target polynomial is any one of the items in Table Y-1 above. The target polynomial and the corresponding seed can satisfy the generated N PS pilot symbols to achieve DC balance, and the training symbols and N PSThe combination of pilot symbols achieves DC balance, which is beneficial for the receiving end to better recover the signal and improve the quality of the signal at the receiving end.

[0947] The structure of the superframe provided in the embodiment of the present application can be understood by referring to the corresponding contents of parts (a) to (c) in Figure 33 above, and will not be repeated here.

[0948] In the embodiment of the present application, the following specific superframe format is considered. The number of symbols before framing is 172032, which are encoded symbols. The encoding method can be obtained by using an open code (Open FEC, OFEC) or multiple encodings of a Hamming code with a code length of 128 bits, or other encoding methods; the corresponding N SF 、N TS 、N PS 、N FAW 、N RES 、N S 、N F , OH and other parameters are shown in the following table:

[0949]

[0950] The superframe includes 24 subframes, each of which includes 7296 symbols, as shown in (a) of FIG33 . The first subframe, as shown in (b) of FIG33 , has 11 training symbols, N FAW frame synchronization symbols, N RES reserved symbols, where N FAW +N RES =96; in subframes 2 to 24, there are also 11 training symbols, as shown in (c) of Figure 33; and in each subframe, the first symbol among every 64 symbols is a pilot symbol. Each subframe contains 114 pilot symbols.

[0951] Here, the number of frame synchronization symbols N FAW =22, the number of reserved symbols N RES =74 as an example, as shown in (b) in Figure 33.

[0952] The frame synchronization sequence of length 22 is shown in Table Y-2 below, where the real number A FAW The value of is not limited. It can be selected according to the actual application scenario to achieve a good compromise between the peak-to-average power ratio, noise and sensitivity of the FAW symbol. Taking 16QAM as an example, the 16 symbols on the 16QAM constellation are {±1±1j, ±1±3j, ±3±1j, ±3±3j}, and the real number A FAW The value of satisfies 1≤A≤3. For example, the real number The value of the pilot symbol is

[0953] Table Y-2

[0954]

[0955]

[0956] The 114 pilot symbols are determined based on the target polynomial and the corresponding seed. In the embodiment of the present application, the target polynomial adopts a 10th-order polynomial, which can be expressed as:

[0957] x 10 +a9×x 9 +a8×x 8 +a7×x 7 +a6×x 6 +a5×x 5 +a4×x 4 +a3×x 3 +a2×x 2 +a1×x+1

[0958] Among them, a9...a1 can take the value of 0 or 1.

[0959] The pilot symbol generation structure can be understood by referring to the previous Figure 34. As shown in Figure 34, the seed can be expressed in binary form as m9, m8, m7, m6, m5, m4, m3, m2, m1, and m0. Of course, the seed can also be expressed in hexadecimal or decimal. When operating with the target polynomial, it needs to be converted to binary form, such as: 0110111000 is expressed as 0x1B8 in hexadecimal and 440 in decimal.

[0960] In the embodiment of the present application, the same target generating polynomial may be used for the pilot symbols in two orthogonal polarization directions. However, due to different seeds, the pilot symbols output in the two polarization directions are not exactly the same.

[0961] As shown in FIG34 , for a scenario where 114 pilot symbols need to be generated, a bit sequence b0, b1, b2, ... b with a continuous length of 228 is obtained according to the target polynomial and the seed. 227 The bit sequence b0, b1, b2, ...b 227 Every two consecutive bits are mapped into a symbol, and b 2t and b 2t+1 Mapped to a symbol (2b 2t -1)A2+(2b 2t+1 -1)A2j,0≤t<114.

[0962] It should be understood that when the pilot symbols use the outermost 4 symbols of the constellation diagram, the sensitivity of the pilot symbols is higher, but the peak to average power ratio is larger; when the pilot symbol values ​​use the innermost 4 symbols of the constellation diagram, the noise of training and pilot is smaller, but its sensitivity is lower.

[0963] It should be noted that the pilot symbol may not be a symbol on the constellation diagram of the modulation format used, but may be a certain 4 symbols in the middle area between the 4 outermost symbols and the 4 innermost symbols of the constellation diagram of the modulation format used. At this time, the noise and sensitivity of the pilot symbol are average, but the peak-to-average power ratio is relatively low. Taking 16QAM as an example, the 16 symbols on 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 can be selected according to the actual application scenario so that the peak-to-average power ratio, noise and sensitivity of the training or pilot symbol have a good compromise. For example, the real number The values ​​of pilot symbols and training symbols are In addition, when the 16 symbols on the 16QAM constellation are power normalized and the value is The value of real number A2 satisfies For example, real numbers The value of the pilot symbol is

[0964] Taking into account that the sequence generated when the target polynomial is a primitive polynomial generally has better randomness, and taking into account that the more non-zero terms the target polynomial has, the more complex the implementation is, when the target polynomial adopts a primitive polynomial and its non-zero terms are not greater than 5, when the target polynomial and the seeds expressed in hexadecimal in the two polarization directions are a row in Table Y-3 below, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbol in the same polarization direction is not greater than 0.25, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.25.

[0965] Table Y-3

[0966] Serial number Target polynomial Seed in polarization direction 1 Seed in polarization direction 2 1x 10 +x 9 +x 7 +x 6 +10x0020x3C62x 10 +x 9 +x 7 +x 6+10x0020x38D3x 10 +x 9 +x 7 +x 3 +10x0940x11F4x 10 +x 9 +x 7 +x 3 +10x1290x11F5x 10 +x 8 +x 4 +x 3 +10x07A0x1676x 10 +x 8 +x 4 +x 3 +10x07A0x2CF7x 10 +x 7 +x 6 +x 2 +10x1B80x22F8x 10 +x 7 +x 6 +x 2 +10x1B80x05F9x 10 +x 9 +x 6 +x+10x0400x21010x 10 +x 9 +x 6 +x+10x0400x30811x 10 +x 9 +x 6 +x+10x0400x18412x 10 +x 9 +x 6 +x+10x0400x0C213x 10 +x 9 +x 6 +x+10x0400x0E114x 10 +x 9 +x 6 +x+10x0400x0D715x 10 +x 9 +x 6 +x+10x0400x1AF16x 10 +x 9 +x 6 +x+10x2100x20117x 10 +x 9 +x 6 +x+10x3080x201

[0967] 18x 10 +x 9 +x 6 +x+10x1840x20119x 10 +x 9 +x 6 +x+10x0C20x20120x 10 +x 9 +x 6 +x+10x2010x0E121x 10 +x 9 +x 6 +x+10x2010x0D722x 10 +x 9 +x 6 +x+10x2010x1AF23x 10 +x 9 +x 4 +x+10x1A00x2D924x 10 +x 9 +x 4 +x+10x1A00x3DB25x 10 +x 9 +x 4 +x+10x0D00x2D926x 10 +x 9 +x 4 +x+10x0D00x3DB27x 10 +x 9 +x 4 +x+10x0580x2D928x 10 +x 9 +x 4 +x+10x0580x3DB29x 10 +x 9 +x 4 +x+10x22C0x2D930x 10 +x 9 +x 4 +x+10x22C0x3DB31x 10 +x 9 +x 4 +x+10x2D20x2D932x 10 +x 9 +x 4 +x+10x2D20x3DB33x 10 +x 9 +x 4 +x+10x2D90x1A534x 10 +x 9+x 4 +x+10x2D90x3DD35x 10 +x 9 +x 4 +x+10x1A50x3DB36x 10 +x 9 +x 4 +x+10x3DD0x3DB37x 10 +x 7 +x 3 +x+10x0840x1A738x 10 +x 7 +x 3 +x+10x1090x1A739x 10 +x 4 +x 3 +x+10x3650x3EB40x 10 +x 4 +x 3 +x+10x2CB0x3EB

[0968] In the table Y-3, in the row numbered 1, the target polynomial uses the primitive polynomial x 10 +x 9 +x 7 +x 6 +1, and the corresponding seeds expressed in hexadecimal in the two polarization directions are 0x002 and 0x3C6, the generation process of 114 pilot symbols can be understood by referring to Figure 43 below.

[0969] As shown in Figure 43, in the X-polarization direction, the input polarization seed is 0x002, which, after conversion to the binary sequence, is 0000000010, which is the value from m9 to m0. If the two bits 1 and 0 are output sequentially, the pilot symbol in the X-polarization direction is A2-A2j. If the two bits 0 and 0 are output sequentially, the pilot symbol in the X-polarization direction is -A2-A2j. If the two bits 1 and 1 are output sequentially, the pilot symbol in the X-polarization direction is A2+A2j. If the two bits 0 and 1 are output sequentially, the pilot symbol in the X-polarization direction is -A2+A2j. Similarly, 114 pilot symbols in the X-polarization direction are obtained.

[0970] As shown in Figure 43, in the Y polarization direction, the input polarization seed is 0x3C6, which, after conversion to the binary sequence, is 0010000100, which is the value from m9 to m0. If the two bits 1 and 0 are output sequentially, the pilot symbol in the Y polarization direction is A2-A2j. If the two bits 0 and 0 are output sequentially, the pilot symbol in the Y polarization direction is -A2-A2j. If the two bits 1 and 1 are output sequentially, the pilot symbol in the Y polarization direction is A2+A2j. If the two bits 0 and 1 are output sequentially, the pilot symbol in the Y polarization direction is -A2+A2j. Similarly, 114 pilot symbols in the Y polarization direction are obtained.

[0971] The polarization seeds in the X polarization direction and the polarization seeds in the Y polarization direction can be interchanged, so 114 pilot symbols as shown in the following Table Y-4 can be obtained.

[0972] Table Y-4

[0973]

[0974]

[0975] In Table Y-4, among the 114 pilot symbols in one polarization direction, the numbers of -A2-A2j, -A2+A2j, A2-A2j, and A2+A2j in the one polarization direction are 28, 29, 29, and 28, respectively. In one polarization direction, the numbers of -A2-A2j, -A2+A2j, A2-A2j, and A2+A2j in the pilot symbols included in a subframe are close to each other. Furthermore, in one polarization direction, the sum of the 114 pilot symbols in a subframe is 0, which achieves DC balance and facilitates signal quality recovery at the receiving end.

[0976] In an embodiment of the present application, the first symbol in each subframe serves as a pilot symbol and also as a training symbol. The first symbol of the 11 training symbols considered is the same as the first symbol of the 114 pilot symbols. In one polarization direction, each subframe includes 10 training symbols in addition to the first symbol, and the values ​​of these 10 training symbols are 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 or pilot symbol have a good compromise. A1 may not be equal to A2; taking 16QAM as an example, the 16 symbols on the 16QAM constellation diagram have the values ​​of {±1±1j, ±1±3j, ±3±1j, ±3±3j}, and the value of the real number A1 satisfies 1≤A2≤3. For example, the real number The values ​​of the 10 training symbols after the first symbol in each subframe are In addition, when the 16 symbols on the 16QAM constellation are power normalized and the value is The value of real number A2 satisfies For example, real numbers The value of the pilot symbol is

[0977] In (b) of Figure 33 , the training sequence length of 11 can use the entry in Table 40 where both polarization first symbols are -A+Aj. The real number A used in the first symbol in each polarization direction is set to A2, and the real number A used in the remaining 10 symbols excluding the first symbol is set to A1. Using entry number 15 in Table 40, the following Table Y-5 is obtained.

[0978] Table Y-5

[0979]

[0980]

[0981] With the above 114 pilot symbols and 11 training symbols, in one polarization direction, the combination of pilot symbols and training symbols included in one subframe satisfies DC balance.

[0982] It should be noted that when the values ​​of real numbers A1 and A2 are unequal, the first symbol in the 11 training sequences in Table Y-5 is -A2+A2j, which is unequal to the values ​​-A1-A1j, -A1+A1j, A1-A1j, and A1+A1j in the following 10 training sequences. In some practical applications, for ease of implementation, the first symbol in each subframe in one polarization direction is used only as a pilot symbol and no longer as a training symbol. In this case, the number of training symbols in the subframe is reduced to 10, and their values ​​are one of -A1-A1j, -A1+A1j, A1-A1j, and A1+A1j, facilitating equalization. In this case, a training sequence of length 10 can use one of the items in Table 33, with the real number A set to A1.

[0983] In the above scheme, the correlation characteristics corresponding to the pilot symbols are shown in Figure 44 below. (a) in Figure 44 shows the periodic autocorrelation result of the sequence of pilot symbols in the X polarization direction, (b) in Figure 44 shows the periodic autocorrelation result of the sequence of pilot symbols in the Y polarization direction, and (c) in Figure 44 shows the periodic cross-correlation result of the sequence of pilot symbols in the X and Y polarization directions. The normalized amplitude of the sidelobe value of the periodic autocorrelation function of the symbol sequence in the two polarization directions is not greater than 0.167, and the normalized amplitude of the sidelobe value of the periodic cross-correlation function of the symbol sequence in the two polarization directions is not greater than 0.176. The frame redundancy of the superframe architecture provided in the embodiment of the present application is also low, at 1.79%, and the sequence autocorrelation and cross-correlation characteristics of the pilot symbols are good. The combination of training symbols and pilot symbols can also meet DC balance, which is beneficial to improving the signal recovery at the receiving end and improving the quality of the recovered signal.

[0984] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0985] The above description is only a preferred embodiment of the technical solution of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included in the scope of protection of this application.

Claims

1. A transmission method for optical communication, characterized in that, the method comprises: generating a superframe comprising a plurality of subframes, the subframes comprising training symbols and pilot symbols, wherein, in one polarization direction, the sum of the number of the training symbols and the number of the pilot symbols comprised in the subframe is not less than 5, and there is one symbol that is both a training symbol and a pilot symbol; and each of the training symbols and each of the pilot symbols is respectively one of -A - Aj, -A + Aj, A - Aj, A + Aj, where A is a real number; Among the training symbols and the pilot symbols included in each subframe, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively and the numbers in another polarization direction are respectively where N TS is the number of the training symbols in one polarization direction in each subframe, and N PS is the number of the pilot symbols in one polarization direction in each subframe, and N TS + N PS is odd, and the two polarization directions are orthogonal to each other; transmitting the superframe.

2. The transmission method according to claim 1, characterized in that, in one subframe, the sequence formed by the training symbols in one polarization direction is different from the sequence formed by the training symbols in the other polarization direction, and the sequence formed by the pilot symbols in one polarization direction is different from the sequence formed by the pilot symbols in the other polarization direction.

3. The transmission method according to claim 1 or 2, characterized in that, the training symbols are arranged continuously in the subframe, wherein, in one polarization direction, among the training symbols comprised in the subframe, the number of consecutive identical real - part elements is not greater than 5, and the number of consecutive identical imaginary - part elements is not greater than 5.

4. The transmission method according to claim 3, characterized in that, in one polarization direction, the number of consecutive identical training symbols in one subframe does not exceed 4.

5. The transmission method according to any one of claims 1 - 4, characterized in that, the plurality of subframes further comprises a first subframe, the first subframe comprising continuously arranged frame - synchronization symbols, and each frame - synchronization symbol is respectively one of -A - Aj, -A + Aj, A - Aj, A + Aj; in one polarization direction, among the frame - synchronization symbols comprised in the subframe, the number of consecutive identical real - part elements is not greater than 5, and the number of consecutive identical imaginary - part elements is not greater than 5.

6. The transmission method according to claim 5, characterized in that, in one polarization direction, the number of consecutive identical frame - synchronization symbols in the first subframe does not exceed 4.

7. The transmission method according to claim 5, characterized in that, Among the frame synchronization symbols included in the first sub-frame, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively where N FAW is the number of the frame synchronization symbols in the first sub-frame in one polarization direction, and N FAW is an even number.

8. The transmission method according to any one of claims 1 - 7, characterized in that, N TS is an even number, and among 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 9. The transmission method according to any one of claims 1 - 7, characterized in that, N TS is odd. Among the training symbols included in each subframe, excluding the training symbol that also serves as the pilot symbol, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are respectively 10. The transmission method according to any one of claims 1 - 7, characterized in that, In each subframe, the remainder of the number of pilot symbols in one polarization direction divided by 4 is 0. Among the pilot symbols included in each subframe, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are N PS / 4 + 1, N PS / 4 - 1, N PS / 4 - 1, N PS / 4 + 1, respectively, and the numbers in the other polarization direction are N PS / 4 - 1, N PS / 4 + 1, N PS / 4 + 1, N PS / 4 - 1; or, the numbers in both polarization directions are N PS / 4.

11. The transmission method according to any one of claims 1 - 7, characterized in that, In each subframe, the remainder of the number of pilot symbols in one polarization direction divided by 4 is 2. Among the pilot symbols included in each subframe, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are respectively (N PS -2) / 4, (N PS -2) / 4 + 1, (N PS -2) / 4 + 1, (N PS -2) / 4, and the numbers in the other polarization direction are respectively (N PS -2) / 4 + 1, (N PS -2) / 4, (N PS -2) / 4, (N PS -2) / 4 + 1.

12. The transmission method according to any one of claims 1 - 7, characterized in that, In each subframe, the remainder of the number of pilot symbols in one polarization direction divided by 4 is 1. Among the pilot symbols included in each subframe, excluding the pilot symbol that also serves as a training symbol, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are respectively (N PS -1) / 4 + 1, (N PS -1) / 4 - 1, (N PS -1) / 4 - 1, (N PS -1) / 4 + 1, and the numbers in the other polarization direction are respectively (N PS -1) / 4 - 1, (N PS -1) / 4 + 1, (N PS -1) / 4 + 1, (N PS -1) / 4 - 1; or, the numbers in both polarization directions are (N PS -1) / 4.

13. The transmission method according to any one of claims 1 - 7, characterized in that, In each subframe, when the remainder of the number of pilot symbols in one polarization direction divided by 4 is 3, among the pilot symbols included in each subframe, excluding the pilot symbol that also serves as a training symbol, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are respectively (N PS - 3) / 4, (N PS - 3) / 4 + 1, (N PS - 3) / 4 + 1, (N PS - 3) / 4, and the numbers in the other polarization direction are respectively (N PS - 3) / 4 + 1, (N PS - 3) / 4, (N PS - 3) / 4, (N PS - 3) / 4 + 1.

14. The transmission method according to any one of claims 1 - 13, characterized in that, The modulation format of the symbols in the superframe is 16QAM, and the value of A is ±1 or ±3 or 15. The transmission method according to any one of claims 1 - 7, characterized in that, in each subframe, the pilot symbols are at fixed positions among every 64 symbols.

16. The transmission method according to claim 15, characterized in that, Each subframe includes 15 training symbols and 56 pilot symbols. The first symbol of the training sequence formed by the training symbols and the pilot sequence formed by the pilot symbols is the same in the same polarization direction. Among them, the training sequence is one of the following table: The pilot sequence is one of the following table:

17. The transmission method according to claim 15, characterized in that, Each subframe includes 6 training symbols and 57 pilot symbols. The first symbol of the training sequence formed by the training symbols and the pilot sequence formed by the pilot symbols is the same in the same polarization direction. Among them, the training sequence is one of the following table: The pilot sequence is one of the following table:

18. The transmission method according to claim 15, characterized in that, Each subframe includes 10 training symbols and 65 pilot symbols. The first symbol of the training sequence formed by the training symbols and the pilot sequence formed by the pilot symbols is the same in the same polarization direction. Among them, the training sequence is one of the following table: The pilot sequence is one of the following table:

19. The transmission method according to any one of claims 1-7, characterized in that, In each subframe, the fixed positions among every 48 symbols are the pilot symbols.

20. The transmission method according to claim 19, characterized in that, Each subframe includes 12 training symbols and 75 pilot symbols. The first symbol of the training sequence formed by the training symbols and the pilot sequence formed by the pilot symbols is the same in the same polarization direction. Among them, the training sequence is one of the following table: The pilot sequence is one of the following table:

21. A receiving method for optical communication, characterized in that, The method includes: Receiving a superframe including a plurality of subframes, where the subframe includes training symbols and pilot symbols. Among them, in one polarization direction, the sum of the number of the training symbols and the pilot symbols included in the subframe is not less than 5, and there is one symbol that is both a training symbol and a pilot symbol; and each of the training symbols and each of the pilot symbols is respectively one of -A - Aj, -A + Aj, A - Aj, A + Aj, where A is a real number; Among the training symbols and the pilot symbols included in each subframe, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are respectively and the numbers in another polarization direction are respectively wherein, N TS is the number of the training symbols in one polarization direction in each subframe, N PS is the number of the pilot symbols in one polarization direction in each subframe, N TS +N PS is odd, and the two polarization directions are orthogonal to each other; Decoding the received superframe.

22. The receiving method according to claim 21, characterized in that, In a subframe, the sequence formed by the training symbols in one polarization direction is different from the sequence formed by the training symbols in the other polarization direction, and the sequence formed by the pilot symbols in one polarization direction is different from the sequence formed by the pilot symbols in the other polarization direction.

23. The receiving method according to claim 21 or 22, characterized in that, The training symbols are arranged continuously in the subframe. Among them, in one polarization direction, among the training symbols included in the subframe, the number of consecutive identical real part elements is not greater than 5, and the number of consecutive identical imaginary part elements is not greater than 5.

24. The receiving method according to claim 23, characterized in that, In one polarization direction, the number of consecutive identical training symbols in a subframe does not exceed 4.

25. The receiving method according to any one of claims 21 - 24, wherein, the multiple sub - frames further include a first sub - frame, and the first sub - frame includes successively arranged frame synchronization symbols, and each frame synchronization symbol is respectively one of -A - Aj, -A + Aj, A - Aj, A + Aj; in one polarization direction, among the frame synchronization symbols included in the sub - frame, the number of consecutive identical elements in the real part is not greater than 5, and the number of consecutive identical elements in the imaginary part is not greater than 5.

26. The receiving method according to claim 25, wherein, in one polarization direction, the number of consecutive identical frame synchronization symbols in the first sub - frame does not exceed 4.

27. The receiving method according to claim 25, wherein, Among the frame synchronization symbols included in the first sub-frame, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively where N FAW is the number of the frame synchronization symbols in the first sub-frame in one polarization direction, and N FAW is an even number.

28. The receiving method according to any one of claims 21 - 27, wherein, N TS is an even number. Among 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 29. The receiving method according to any one of claims 21 - 27, wherein, N TS is odd. Among the training symbols included in each subframe, excluding the training symbol that is simultaneously the pilot symbol, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are respectively 30. The receiving method according to any one of claims 21 - 27, wherein, In each subframe, the remainder of the number of pilot symbols in one polarization direction divided by 4 is 0. Among the pilot symbols included in each subframe, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are N PS / 4 + 1, N PS / 4 - 1, N PS / 4 - 1, N PS / 4 + 1, and the numbers in the other polarization direction are N PS / 4 - 1, N PS / 4 + 1, N PS / 4 + 1, N PS / 4 - 1; or, the numbers in both polarization directions are N PS / 4.

31. The receiving method according to any one of claims 21 - 27, wherein, In each subframe, the remainder of the number of pilot symbols in one polarization direction divided by 4 is 2. Among the pilot symbols included in each subframe, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are respectively (N PS -2) / 4, (N PS -2) / 4 + 1, (N PS -2) / 4 + 1, (N PS -2) / 4, and the numbers in the other polarization direction are respectively (N PS -2) / 4 + 1, (N PS -2) / 4, (N PS -2) / 4, (N PS -2) / 4 + 1.

32. The receiving method according to any one of claims 21 - 27, wherein, In each subframe, the remainder of the number of pilot symbols in one polarization direction divided by 4 is 1. Among the pilot symbols included in each subframe, excluding the pilot symbol that also serves as a training symbol, the numbers of -A-Aj, -A+Aj, A-Aj, and A+Aj in one polarization direction are respectively (N PS -1) / 4 + 1, (N PS -1) / 4 - 1, (N PS -1) / 4 - 1, (N PS -1) / 4 + 1, and the numbers in the other polarization direction are respectively (N PS -1) / 4 - 1, (N PS -1) / 4 + 1, (N PS -1) / 4 + 1, (N PS -1) / 4 - 1; or, the numbers in both polarization directions are (N PS -1) / 4.

33. The receiving method according to any one of claims 21 - 27, wherein, In each subframe, when the remainder of the number of pilot symbols in one polarization direction divided by 4 is 3, among the pilot symbols included in each subframe, excluding the pilot symbol that also serves as a training symbol, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in one polarization direction are respectively (N PS - 3) / 4, (N PS - 3) / 4 + 1, (N PS - 3) / 4 + 1, (N PS - 3) / 4, and the numbers in the other polarization direction are respectively (N PS - 3) / 4 + 1, (N PS - 3) / 4, (N PS - 3) / 4, (N PS - 3) / 4 + 1.

34. The receiving method according to any one of claims 21 - 33, wherein, The modulation format of the symbols in the superframe is 16QAM, and the value of A is ±1 or ±3 or 35. The receiving method according to any one of claims 21 - 34, wherein, in each sub - frame, the pilot symbol is at a fixed position among every 64 symbols; or in each sub - frame, the pilot symbol is at a fixed position among every 48 symbols.

36. A transmission device for optical communication, wherein, the transmission device includes a processor and a memory, the memory is used for storing instructions, and the processor is used for executing the instructions so that the transmission device executes the transmission method according to any one of claims 1 - 20.

37. A receiving device for optical communication, wherein, the transmission device includes a processor and a memory, the memory is used for storing instructions, and the processor is used for executing the instructions so that the receiving device executes the receiving method according to any one of claims 21 - 35.

38. An optical communication system, wherein, the system includes the transmission device according to claim 36 and the receiving device according to claim 37.

39. A transmission method for optical communication, wherein, comprising: generating a super - frame including multiple sub - frames, the sub - frames include training symbols and pilot symbols, wherein, in one polarization direction, there is a symbol that is both a training symbol and a pilot symbol, and each of the training symbols and each of the pilot symbols is respectively one of -A - Aj, -A + Aj, A - Aj, A + Aj, and A is a real number; In each subframe, in the one polarization direction, the pilot symbols are generated by a target polynomial and a seed, and there are N PS of them, and the combination with N TS training symbols achieves DC balance. The N TS is the number of training symbols in one polarization direction in each subframe, and N TS + N PS is odd; the target polynomial is one of the following table; Serial number Target polynomial 1 x 10 + x 9 + x 8 + x 7 + x 6 + 12x 10 + x 9 + x 8 + x 6 + x 4 + 13x 10 + x 9 + x 7 + x 6 + x 4 + 14x 10 + x 9 + x 6 + x 3 + 15x 10 + x 8 + x 5 + x 3 + 16x 10 + x 8 + x 6 + x 5 + x 3 + 17x 10 + x 8 + x 7 + x 4 + x 3 + 18x 10 + x 6 + x 5 + x 4 + x 3 + 19x 10 + x 9 + x 6 + x 2 + 110x 10 + x 7 + x 6 + x 2 + 111x 10 + x 7 + x 5 + x 2 + 112x 10 + x 8 + x 7 + x 5 + x 2 + 113x 10 + x 9 + x 8 + x 7 + x 4 + x 2 + 114x 10 + x 7 + x 5 +x 4 +x 2 +115x 10 +x 9 +x 7 +x 5 +x 4 +x 2 +116x 10 +x 9 +x 8 +x 3 +x 2 +117x 10 +x 9 +x 8 +x 7 +x 3 +x 2 +118x 10 +x 7 +x 6 +x 3 +x 2 +119x 10 +x 8 +x 5 +x+120x 10 +x 8 +x 4 +x+121x 10 +x 9 +x 8 +x 7 +x 4 +x+122x 10 +x 8 +x 5 +x 4 +x+123x 10 +x 5 +x 3 +x+124x 10 +x 8 +x 6 +x 5 +x 3 +x+125x 10 +x 9 +x 8 +x 7 +x 4 +x 3 +x+126x 10 +x 6 +x 4 +x 3 +x+127x 10 +x 8 +x 7 +x 2 +x+128x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +x + 129x 10 +x 9 +x 6 +x 3 +x 2 +x + 130x 10 +x 8 +x 6 +x 3 +x 2 +x + 131x 10 +x 6 +x 5 +x 3 +x 2 +x + 1 32x 10 +x 4 +x 3 +x 2 +x + 133x 10 +x 9 +x 7 +x 3 +134x 10 +x 9 +x 6 +x + 135x 10 +x 9 +x 4 +x + 136x 10 +x 7 +x 3 +x + 1 transmitting the super - frame.

40. The transmission method according to claim 39, wherein, In a polarization direction, the total number of symbols N in the superframe F = 175104, the number of subframes N SF = 24, the number of symbols in each subframe N S = 7296, N TS = 11, N PS = 114, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW + N RES = 96, the number of symbols before framing of the superframe is 172032.

41. The transmission method according to claim 40, Characterized in that, when the target polynomial and the seeds represented in hexadecimal in two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is not greater than 0.2, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.2, 42. The transmission method according to claim 41, Characterized in that, when the target polynomial and the seeds represented in hexadecimal in two polarization directions are a row in the following table, in one polarization direction, among the 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; Serial number Target polynomial Polarization in one direction Seed polarization in one direction Seed polarization in two directions 1 x 10 + x 9 + x 8 + x 7 + x 6 + 10x0460x3842x 10 + x 9 + x 8 + x 7 + x 6 + 10x0460x3C43x 10 + x 9 + x 6 + x 3 + 10x0760x07C4x 10 + x 8 + x 7 + x 4 + x 3 + 10x1A20x3305x 10 + x 8 + x 7 + x 4 + x 3 + 10x2E60x3306x 10 + x 8 + x 7 + x 2 + x + 10x2260x3DC7x 10 + x 9 + x 6 + x 3 + x 2 + x + 10x13A0x3308x 10 + x 4 + x 3 + x 2 + x + 10x3220x3689x 10 + x 4 + x 3 + x 2 + x + 10x3220x0E410x 10 + x 4 + x 3 + x 2 + x + 10x0E20x36811x 10 + x 4 + x 3 + x 2 + x + 10x0E20x0E412x 10 + x 4 + x 3 + x 2 + x + 10x04E0x2F0。 43. The transmission method according to claim 40, Characterized in that, when the target polynomial is a primitive polynomial and the number of its non-zero terms is not greater than 5, and when the target polynomial and the seeds represented in hexadecimal in two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is not greater than 0.25, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.25, Serial numberTarget polynomialPolarization in one directionSeed polarization in one directionPolarization in the second directionSeed polarization in the second direction1x 10 +x 9 +x 7 +x 3 +10x23E0x0942x 10 +x 7 +x 6 +x 2 +10x0BE0x1B83x 10 +x 9 +x 6 +x+10x0020x2104x 10 +x 9 +x 6 +x+10x0020x3085x 10 +x 9 +x 6 +x+10x0020x184 6x 10 +x 9 +x 6 +x + 10x1C20x0407x 10 +x 8 +x 5 +x + 10x3FE0x0E08x 10 +x 8 +x 5 +x + 10x3FE0x2709x 10 +x 8 +x 5 +x + 10x3FE0x30410x 10 +x 9 +x 4 +x + 10x3B60x1A011x 10 +x 9 +x 4 +x + 10x3B60x0D012x 10 +x 9 +x 4 +x + 10x3B60x05813x 10 +x 9 +x 4 +x + 10x3B60x22C14x 10 +x 7 +x 3 +x + 10x34E0x084。 44. The transmission method according to claim 43, Characterized in that, When the target polynomial is x 10 + x 7 + x 3 + x + 1, when the seeds represented in hexadecimal on the two corresponding polarization directions are 0x34E and 0x084, in one polarization direction, among the 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, and the 114 pilot symbols on each of the two polarization directions are shown in the following table:

45. The transmission method according to claim 41, Characterized in that, When the target polynomial is x 10 +x 7 +x 6 +x 2 +1, when the seeds represented in hexadecimal on the two polarization directions are 0x0BE and 0x1B8 respectively, the 114 pilot symbols on each of the two polarization directions are shown in the following table:

46. The transmission method according to claim 39, Characterized in that, In a polarization direction, the total number of symbols N in the superframe F = 175104, the number of subframes N SF = 48, the number of symbols N in each subframe S = 3648, N TS = 6, N PS = 57, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW + N RES = 96, the number of symbols before framing of the superframe is 172032.

47. The transmission method according to claim 46, Characterized in that, when the target polynomial and the seeds represented in hexadecimal in two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is not greater than 0.23, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.23, Serial number Target polynomial Polarization in one direction Seed polarization in one direction Seed polarization in the second direction 1 x 10 +x 7 +x 3 +x + 10x2040x2792x 10 +x 7 +x 3 +x + 10x0B10x3E93x 10 +x 7 +x 3 +x + 10x0B10x279。 48. The transmission method according to claim 47, Characterized in that, When the target polynomial is x 10 + x 7 + x 3 + x + 1, when the seeds represented in hexadecimal on the two polarization directions are 0x0B1 and 0x3E9 respectively, the 57 pilot symbols on the two polarization directions are respectively shown in the following table:

49. A receiving method for optical communication, Characterized in that, Comprising: Receiving a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols, wherein, in one polarization direction, there is a symbol that is both a training symbol and a pilot symbol, and each of the training symbols and each of the pilot symbols is respectively one of -A - Aj, -A + Aj, A - Aj, A + Aj, and A is a real number; In each subframe, in the one polarization direction, the pilot symbols are generated by a target polynomial and a seed, and there are N PS of them. The combination of the N TS pilot symbols and N TS training symbols reaches DC balance, where N TS is the number of the training symbols in one polarization direction in each subframe, and N PS + N is odd. The target polynomial is one of the following tables; Serial number Target polynomial 1 x 10 + x 9 + x 8 + x 7 + x 6 + 12x 10 + x 9 + x 8 + x 6 + x 4 + 13x 10 + x 9 + x 7 + x 6 + x 4 + 1 4x 10 +x 9 +x 6 +x 3 +15x 10 +x 8 +x 5 +x 3 +16x 10 +x 8 +x 6 +x 5 +x 3 +17x 10 +x 8 +x 7 +x 4 +x 3 +18x 10 +x 6 +x 5 +x 4 +x 3 +19x 10 +x 9 +x 6 +x 2 +110x 10 +x 7 +x 6 +x 2 +111x 10 +x 7 +x 5 +x 2 +112x 10 +x 8 +x 7 +x 5 +x 2 +113x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +114x 10 +x 7 +x 5 +x 4 +x 2 +115x 10 +x 9 +x 7 +x 5 +x 4 +x 2 +116x 10 +x 9 +x 8 +x 3 +x 2 +117x 10 +x 9 +x 8 +x 7 +x 3 +x 2 +118x 10 +x 7 +x 6 +x 3 +x 2 +119x 10 +x 8 +x 5 +x + 120x 10 +x 8 +x 4 +x + 121x 10 +x 9 +x 8 +x 7 +x 4 +x + 122x 10 +x 8 +x 5 +x 4 +x + 123x 10 +x 5 +x 3 +x + 124x 10 +x 8 +x 6 +x 5 +x 3 +x + 125x 10 +x 9 +x 8 +x 7 +x 4 +x 3 +x + 126x 10 +x 6 +x 4 +x 3 +x + 127x 10 +x 8 +x 7 +x 2 +x + 128x 10 +x 9 +x 8 +x 7 +x 4 +x 2 +x + 129x 10 +x 9 +x 6 +x 3 +x 2 +x + 130x 10 +x 8 +x 6 +x 3 +x 2 +x + 131x 10 +x 6 +x 5 +x 3 +x 2 +x + 132x 10 +x 4 +x 3 +x 2 +x + 133x 10 +x 9 +x 7 +x 3 +134x 10 +x 9 +x 6 +x + 135x 10 +x 9 +x 4 +x + 136x 10 +x 7 +x 3 +x + 1 Decoding the received superframe.

50. The receiving method according to claim 49, Characterized in that, In a polarization direction, the total number of symbols N in the superframe F = 175104, the number of subframes N SF = 24, the number of symbols in each subframe N S = 7296, N TS = 11, N PS = 114, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW + N RES = 96, the number of symbols before framing of the superframe is 172032.

51. The receiving method according to claim 50, Characterized in that, when the target polynomial and the seeds represented in hexadecimal in two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is not greater than 0.2, and the normalized amplitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.2, 52. The receiving method according to claim 51, Characterized in that, When the target polynomial and the seeds represented in hexadecimal for two polarization directions are a row in the following table, among the combination of 114 pilot symbols and 11 training symbols in one polarization direction, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in the one polarization direction are all 31; Serial number Target polynomial Polarization in one direction Seed polarization in one direction Seed polarization in two directions 1 x 10 + x 9 + x 8 + x 7 + x 6 + 10x0460x3842x 10 + x 9 + x 8 + x 7 + x 6 + 10x0460x3C43x 10 + x 9 + x 6 + x 3 + 10x0760x07C4x 10 + x 8 + x 7 + x 4 + x 3 + 10x1A20x3305x 10 + x 8 + x 7 + x 4 + x 3 + 10x2E60x3306x 10 + x 8 + x 7 + x 2 + x + 10x2260x3DC7x 10 + x 9 + x 6 + x 3 + x 2 + x + 10x13A0x3308x 10 + x 4 + x 3 + x 2 + x + 10x3220x3689x 10 + x 4 + x 3 + x 2 + x + 10x3220x0E410x 10 + x 4 + x 3 + x 2 + x + 10x0E20x36811x 10 + x 4 + x 3 + x 2 + x + 10x0E20x0E412x 10 + x 4 + x 3 + x 2 + x + 10x04E0x2F0。 53. The receiving method according to claim 50, wherein, when the target polynomial is a primitive polynomial and the number of its non - zero terms is no more than 5, and when the target polynomial and the seeds represented in hexadecimal for two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is no more than 0.25, and the normalized amplitude of the periodic cross - correlation function value of the pilot symbols in different polarization directions is no more than 0.25, Serial numberTarget polynomialPolarization in one directionSeed polarization in one directionPolarization in the second directionSeed polarization in the second direction1x 10 +x 9 +x 7 +x 3 +10x23E0x0942x 10 +x 7 +x 6 +x 2 +10x0BE0x1B83x 10 +x 9 +x 6 +x+10x0020x2104x 10 +x 9 +x 6 +x+10x0020x3085x 10 +x 9 +x 6 +x+10x0020x1846x 10 +x 9 +x 6 +x+10x1C20x0407x 10 +x 8 +x 5 +x+10x3FE0x0E08x 10 +x 8 +x 5 +x+10x3FE0x2709x 10 +x 8 +x 5 +x+10x3FE0x30410x 10 +x 9 +x 4 +x+10x3B60x1A011x 10 +x 9 +x 4 +x+10x3B60x0D012x 10 +x 9 +x 4 +x+10x3B60x05813x 10 +x 9 +x 4 +x+10x3B60x22C14x 10 +x 7 +x 3 +x+10x34E0x084。 54. The receiving method according to claim 53, wherein, When the target polynomial is x 10 +x 7 +x 3 +x + 1, when the seeds represented in hexadecimal on the two corresponding polarization directions are 0x34E and 0x084, in one polarization direction, among the combination of 114 pilot symbols and 11 training symbols, the numbers of -A - Aj, -A + Aj, A - Aj, and A + Aj in the said one polarization direction are all 31, and the 114 pilot symbols on each of the two polarization directions are as shown in the following table:

55. The receiving method according to claim 51, wherein, When the target polynomial is x 10 +x 7 +x 6 +x 2 +1, when the seeds represented in hexadecimal on the two polarization directions are 0x0BE and 0x1B8 respectively, the 114 pilot symbols on each of the two polarization directions are shown in the following table:

56. The receiving method according to claim 49, wherein, In a polarization direction, the total number of symbols N in the superframe F = 175104, the number of subframes N SF = 48, the number of symbols in each subframe N S = 3648, N TS = 6, N PS = 57, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW + N RES = 96, the number of symbols before framing of the superframe is 172032.

57. The receiving method according to claim 56, wherein, when the target polynomial and the seeds represented in hexadecimal for two polarization directions are a row in the following table, the normalized amplitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is no more than 0.23, and the normalized amplitude of the periodic cross - correlation function value of the pilot symbols in different polarization directions is no more than 0.23, Serial numberTarget polynomialPolarization in one directionSeed polarization in one directionPolarization in the second directionSeed polarization in the second direction1x 10 +x 7 +x 3 +x + 10x2040x2792x 10 +x 7 +x 3 +x + 10x0B10x3E93x 10 +x 7 +x 3 +x + 10x0B10x279。 58. The receiving method according to claim 57, wherein, When the target polynomial is x 10 +x 7 +x 3 +x + 1, and the seeds represented in hexadecimal on the two corresponding polarization directions are 0x0B1 and 0x3E9, the 57 pilot symbols on each of the two polarization directions are shown in the following table:

59. A transmission device for optical communication, wherein, the transmission device includes a processor and a memory, the memory is used for storing instructions, and the processor is used for executing the instructions so that the transmission device executes the transmission method according to any one of claims 39 - 48.

60. A receiving device for optical communication, wherein, the transmission device includes a processor and a memory, the memory is used for storing instructions, and the processor is used for executing the instructions so that the receiving device executes the receiving method according to any one of claims 49 - 58.

61. A system for optical communication, wherein, the system includes the transmission device according to claim 59 and the receiving device according to claim 60.

62. A transmission method for optical communication, wherein, comprising: generating a super - frame including a plurality of sub - frames, the sub - frames including training symbols and pilot symbols; In each subframe, in one polarization direction, there are N pilot symbols PS with values of -A 2 -A 2 -j, -A 2 +A 2 +j, A 2 -A 2 -j, A 2 +A 2 +j, where A 2 is a real number and N PS is an even number; N PS of the pilot symbols achieve DC balance; the combination of the training symbols and N PS of the pilot symbols achieves DC balance; the pilot symbols are generated by determining a target polynomial and seeds, the target polynomial is a primitive polynomial and the number of its non - zero terms is no more than 5; the target polynomial is one of the following table; Serial number Target polynomial 1 x 10 + x 9 + x 7 + x 6 + 12x 10 + x 9 + x 7 + x 3 + 13x 10 + x 8 + x 4 + x 3 + 14x 10 + x 7 + x 6 + x 2 + 15x 10 + x 9 + x 6 + x + 16x 10 + x 9 + x 4 + x + 17x 10 + x 7 + x 3 + x + 1 8x 10 +x 4 +x 3 +x + 1 transmitting the super - frame.

63. The transmission method according to claim 62, wherein, In a polarization direction, the total number of symbols N in the superframe F = 175104, the number of subframes N SF = 24, the number of symbols N in each subframe S = 7296, N PS = 114, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW + N RES = 96, the number of symbols before framing of the superframe is 172032; When the target polynomial for generating the pilot symbols and the seeds represented in hexadecimal in two polarization directions are a row in the following table, the normalized magnitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is not greater than 0.25, and the normalized magnitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.

25. Serial number Target polynomial Polarization in one direction Seed polarization in one direction Seed polarization in two directions 1 x 10 + x 9 + x 7 + x 6 + 10x0020x3C62x 10 + x 9 + x 7 + x 6 + 10x0020x38D3x 10 + x 9 + x 7 + x 3 + 10x0940x11F4x 10 + x 9 + x 7 + x 3 + 10x1290x11F5x 10 + x 8 + x 4 + x 3 + 10x07A0x1676x 10 + x 8 + x 4 + x 3 + 10x07A0x2CF7x 10 + x 7 + x 6 + x 2 + 10x1B80x22F8x 10 + x 7 + x 6 + x 2 + 10x1B80x05F9x 10 + x 9 + x 6 + x + 10x0400x21010x 10 + x 9 + x 6 + x + 10x0400x30811x 10 + x 9 + x 6 + x + 10x0400x18412x 10 + x 9 + x 6 + x + 10x0400x0C213x 10 + x 9 + x 6 + x + 10x0400x0E114x 10 + x 9 + x 6 + x + 10x0400x0D715x 10 + x 9 + x 6 +x+10x0400x1AF16x 10 +x 9 +x 6 +x+10x2100x20117x 10 +x 9 +x 6 +x+10x3080x20118x 10 +x 9 +x 6 +x+10x1840x20119x 10 +x 9 +x 6 +x+10x0C20x20120x 10 +x 9 +x 6 +x+10x2010x0E1 21x 10 +x 9 +x 6 +x + 10x2010x0D722x 10 +x 9 +x 6 +x + 10x2010x1AF23x 10 +x 9 +x 4 +x + 10x1A00x2D924x 10 +x 9 +x 4 +x + 10x1A00x3DB25x 10 +x 9 +x 4 +x + 10x0D00x2D926x 10 +x 9 +x 4 +x + 10x0D00x3DB27x 10 +x 9 +x 4 +x + 10x0580x2D928x 10 +x 9 +x 4 +x + 10x0580x3DB29x 10 +x 9 +x 4 +x + 10x22C0x2D930x 10 +x 9 +x 4 +x + 10x22C0x3DB31x 10 +x 9 +x 4 +x + 10x2D20x2D932x 10 +x 9 +x 4 +x + 10x2D20x3DB33x 10 +x 9 +x 4 +x + 10x2D90x1A534x 10 +x 9 +x 4 +x + 10x2D90x3DD35x 10 +x 9 +x 4 +x + 10x1A50x3DB36x 10 +x 9 +x 4 +x + 10x3DD0x3DB37x 10 +x 7 +x 3 +x+10x0840x1A738x 10 +x 7 +x 3 +x+10x1090x1A739x 10 +x 4 +x 3 +x+10x3650x3EB40x 10 +x 4 +x 3 +x+10x2CB0x3EB。 64. The transmission method according to claim 63, wherein, When the target polynomial is x 10 + x 9 + x 7 + x 6 + 1, when the seeds represented in hexadecimal on the two polarization directions are 0x002 and 0x3C6, the 114 pilot symbols on each of the two polarization directions are shown in the following table:

65. The transmission method according to claim 62, wherein, In each subframe, in one polarization direction, when the remainder of the number of the pilot symbols divided by 4 is 0, among the pilot symbols included in each subframe, -A 2 -A 2 the number of j is equal to A 2 +A 2 the number of j, -A 2 +A 2 the number of j is equal to A 2 -A 2 the number of j, and -A 2 -A 2 the difference between the number of j and the number of is 2; or, -A 2 -A 2 j, -A 2 +A 2 j, A 2 -A 2 j, A 2 +A 2 the number of j are equal; When the remainder of the number of the pilot symbols divided by 4 is 2, among the pilot symbols included in each subframe, -A 2 -A 2 the number of j is equal to A 2 +A 2 the number of j, -A 2 +A 2 the number of j is equal to A 2 -A 2 the number of j, and -A 2 -A 2 the difference between the number of j and the number of is 1.

66. A receiving method for optical communication, wherein, comprising: receiving a superframe including a plurality of subframes, the subframes including training symbols and pilot symbols; In each subframe, in one polarization direction, there are N pilot symbols PS with values of -A 2 -A 2 -j, -A 2 +A 2 +j, A 2 -A 2 -j, A 2 +A 2 +j, where A 2 is a real number and N PS is an even number; N PS pilot symbols achieve DC balance; the combination of the training symbols and N PS pilot symbols achieves DC balance; the pilot symbols are generated by determining a target polynomial and seeds, the target polynomial is a primitive polynomial, and the number of its non-zero terms is not greater than 5; the target polynomial is one of the following table; Serial number Target polynomial 1 x 10 + x 9 + x 7 + x 6 + 12x 10 + x 9 + x 7 + x 3 + 13x 10 + x 8 + x 4 + x 3 + 14x 10 + x 7 + x 6 + x 2 + 15x 10 + x 9 + x 6 + x + 16x 10 + x 9 + x 4 + x + 17x 10 + x 7 + x 3 + x + 18x 10 + x 4 + x 3 + x + 1 decoding the received superframe.

67. The receiving method according to claim 66, wherein, In a polarization direction, the total number of symbols N in the superframe F = 175104, the number of subframes N SF = 24, the number of symbols N in each subframe S = 7296, N PS = 114, the number of frame synchronization symbols N FAW and the number of reserved symbols N RES The sum N FAW + N RES = 96, the number of symbols before framing of the superframe is 172032; When the target polynomial for generating the pilot symbols and the seeds represented in hexadecimal in two polarization directions are a row in the following table, the normalized magnitude of the sidelobe value of the periodic autocorrelation function of the pilot symbols in the same polarization direction is not greater than 0.25, and the normalized magnitude of the periodic cross-correlation function value of the pilot symbols in different polarization directions is not greater than 0.

25. Serial number Target polynomial Polarization in one direction Seed polarization in one direction Seed polarization in two directions 1 x 10 +x 9 +x 7 +x 6 +10x0020x3C62x 10 +x 9 +x 7 +x 6 +10x0020x38D3x 10 +x 9 +x 7 +x 3 +10x0940x11F4x 10 +x 9 +x 7 +x 3 +10x1290x11F5x 10 +x 8 +x 4 +x 3 +10x07A0x1676x 10 +x 8 +x 4 +x 3 +10x07A0x2CF7x 10 +x 7 +x 6 +x 2 +10x1B80x22F8x 10 +x 7 +x 6 +x 2 +10x1B80x05F9x 10 +x 9 +x 6 +x+10x0400x21010x 10 +x 9 +x 6 +x+10x0400x308 11x 10 +x 9 +x 6 +x+10x0400x18412x 10 +x 9 +x 6 +x+10x0400x0C213x 10 +x 9 +x 6 +x+10x0400x0E114x 10 +x 9 +x 6 +x+10x0400x0D715x 10 +x 9 +x 6 +x+10x0400x1AF16x 10 +x 9 +x 6 +x+10x2100x20117x 10 +x 9 +x 6 +x+10x3080x20118x 10 +x 9 +x 6 +x+10x1840x20119x 10 +x 9 +x 6 +x+10x0C20x20120x 10 +x 9 +x 6 +x+10x2010x0E121x 10 +x 9 +x 6 +x+10x2010x0D722x 10 +x 9 +x 6 +x+10x2010x1AF23x 10 +x 9 +x 4 +x+10x1A00x2D924x 10 +x 9 +x 4 +x+10x1A00x3DB25x 10 +x 9 +x 4 +x+10x0D00x2D926x 10 +x 9 +x 4 +x+10x0D00x3DB27x 10 +x 9 +x 4 +x + 10x0580x2D928x 10 +x 9 +x 4 +x + 10x0580x3DB29x 10 +x 9 +x 4 +x + 10x22C0x2D930x 10 +x 9 +x 4 +x + 10x22C0x3DB31x 10 +x 9 +x 4 +x + 10x2D20x2D932x 10 +x 9 +x 4 +x + 10x2D20x3DB33x 10 +x 9 +x 4 +x + 10x2D90x1A534x 10 +x 9 +x 4 +x + 10x2D90x3DD35x 10 +x 9 +x 4 +x + 10x1A50x3DB36x 10 +x 9 +x 4 +x + 10x3DD0x3DB37x 10 +x 7 +x 3 +x + 10x0840x1A7 38x 10 +x 7 +x 3 +x + 10x1090x1A739x 10 +x 4 +x 3 +x + 10x3650x3EB40x 10 +x 4 +x 3 +x + 10x2CB0x3EB。 68. The receiving method according to claim 67, wherein, When the target polynomial is x 10 +x 9 +x 7 +x 6 +1, when the seeds represented in hexadecimal on the two polarization directions are 0x002 and 0x3C6, the 114 pilot symbols on each of the two polarization directions are shown in the following table:

69. The receiving method according to claim 66, wherein, In each subframe, in one polarization direction, when the remainder of the number of the pilot symbols divided by 4 is 0, among the pilot symbols included in each subframe, -A 2 -A 2 the number of j is equal to A 2 +A 2 the number of j, -A 2 +A 2 the number of j is equal to A 2 -A 2 the number of j, and -A 2 -A 2 the difference between the number of j and the number of... is 2; or, -A 2 -A 2 j, -A 2 +A 2 j, A 2 -A 2 j, A 2 +A 2 the number of j are equal; When the remainder of the number of the pilot symbols divided by 4 is 2, among the pilot symbols included in each subframe, -A 2 -A 2 the number of j is equal to A 2 +A 2 the number of j, -A 2 +A 2 the number of j is equal to A 2 -A 2 the number of j, and -A 2 -A 2 the difference between the number of j and the number of is 1.

70. A transmission device for optical communication, wherein, the transmission device includes a processor and a memory, the memory is used for storing instructions, and the processor is used for executing the instructions so that the transmission device executes the transmission method according to any one of claims 62-65.

71. A receiving device for optical communication, wherein, the transmission device includes a processor and a memory, the memory is used for storing instructions, and the processor is used for executing the instructions so that the receiving device executes the receiving method according to any one of claims 66-69.

72. An optical communication system, wherein, the system includes the transmission device according to claim 70 and the receiving device according to claim 71.

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