Deep space laser communication encoding and decoding methods, devices, equipment and readable storage media

Abstract

This application discloses a method, apparatus, device, and readable storage medium for encoding and decoding deep space laser communication. The method includes the following steps: acquiring information symbols to be encoded and acquiring a laser communication channel to be used; determining the encoding parameters corresponding to the laser communication channel, and performing LDPC ladder code encoding on the information symbols according to the encoding parameters to obtain encoded symbols; modulating the encoded symbols to obtain a symbol sequence; transmitting the symbol sequence to a decoder through the laser communication channel, so that the decoder can determine the decoding parameters corresponding to the laser communication channel, and demodulate and perform sliding window iterative decoding on the symbols according to the decoding parameters to obtain decoded symbols. The decoding parameters include at least the encoding parameters. This application achieves the selection of different encoding parameters and correspondingly different decoding parameters for different laser communication channels, thereby improving the encoding and decoding effect.

Description

Technical Field

[0001] This application relates to the field of deep space laser communication technology, and in particular to a deep space laser communication encoding and decoding method, apparatus, device and readable storage medium. Background Technology

[0002] Deep space laser end-to-end communication systems (Earth-to-planet probes) typically only consider the impact of coronal turbulence on the channel, and thus select a suitable ladder code decoding strategy for high-speed laser communication. The decoding strategies mainly include iterative bounded distance decoding and soft-decision sliding window decoding.

[0003] However, as the Earth and planets revolve around the Sun, the link of the laser communication channel between the Earth and planetary probes will change due to the revolution, resulting in changes in the link's position and length. Consequently, the influence of coronal turbulence on the link of the laser communication channel will also change.

[0004] If only the effects of coronal turbulence are considered without taking into account changes in the link, the changes in coronal turbulence caused by the link conditions will be ignored, thus affecting the establishment and use of the channel, resulting in poor performance during encoding and decoding, and consequently affecting the communication effect. Summary of the Invention

[0005] In view of this, this application provides a deep space laser communication encoding and decoding method, apparatus, device and readable storage medium, aiming to improve the encoding and decoding effect of deep space laser end-to-end communication.

[0006] To achieve the above objectives, this application provides a deep space laser communication encoding and decoding method, which includes the following steps:

[0007] Obtain the information symbols to be encoded, and obtain the laser communication channel to be used;

[0008] Determine the encoding parameters corresponding to the laser communication channel, and perform LDPC ladder code encoding on the information symbols according to the encoding parameters to obtain the encoded symbols;

[0009] The encoded symbols are modulated to obtain a symbol sequence;

[0010] The symbol sequence is transmitted to the receiving end through the laser communication channel, so that the receiving end can determine the decoding parameters corresponding to the laser communication channel, and demodulate and perform sliding window iterative decoding on the symbol according to the decoding parameters to obtain the decoded symbol, wherein the decoding parameters include at least the encoding parameters.

[0011] For example, the step of obtaining the laser communication channel to be used includes:

[0012] Based on the preset revolution model, determine the current diametrical distance from the Sun to the wireless link consisting of the Earth's location and the planet's location;

[0013] The preset revolution model is a model constructed based on the Earth's revolution period, the planet's revolution period, the Earth-Sun distance between the Sun and the Earth, the Sun-Star distance between the Sun and the planet, and the Star-Earth distance between the planet and the Earth, which shows that the wireless link changes periodically as the planet and the Earth revolve.

[0014] Based on the solar ray distance and a preset calculation formula, a scintillation index is calculated to assess the intensity of the coronal turbulence effect of the sun on the wireless link.

[0015] The preset calculation formula is designed based on the definition of the scintillation index and the influence parameters affecting the intensity of coronal turbulence. Specifically, the definition of the scintillation index is the ratio of the root mean square value of the laser signal intensity fluctuation to the average value of the laser signal intensity. The influence parameters include at least the solar radius distance.

[0016] The laser communication channel to be used is determined based on the flicker index.

[0017] For example, the step of determining the laser communication channel to be used based on the scintillation index includes:

[0018] If the flicker index is less than or equal to the first preset flicker threshold, then the AWGN channel is selected as the laser communication channel to be used.

[0019] If the flicker index is greater than the first preset flicker threshold and less than or equal to the second preset flicker threshold, then according to the preset channel model based on GG distribution, the channel characteristic parameters corresponding to the flicker index are determined, and according to the channel characteristic parameters, the laser communication channel to be used is determined.

[0020] The preset channel model based on the GG distribution is a channel model constructed based on the second-order Bessel function, the standard gamma function, the number of large-scale scatterers, and the number of small-scale scatterers to describe the light intensity fluctuation distribution at the signal receiver.

[0021] For example, the step of determining the channel characteristic parameters corresponding to the scintillation index based on a preset channel model based on the GG distribution includes:

[0022] Determine multiple threshold intervals between the first preset flicker threshold and the second preset flicker threshold;

[0023] Determine the threshold range to which the flicker index belongs, and take the middle value in the threshold range as the channel feature parameter corresponding to the threshold range.

[0024] For example, the step of performing LDPC ladder code encoding on the information symbol according to the encoding parameters to obtain the encoded symbol includes:

[0025] According to the encoding parameters, the information symbols are divided into LDPC codes with a codeword length of N and a parity bit length of r;

[0026] Based on the repeating coding subarray and the information bit subarray in the LDPC code, the signal symbol is encoded row by row in a ladder manner, and the corresponding check bit subarray is obtained; wherein, the repeating coding subarray is an Nm row × m column matrix;

[0027] The repeated coding subarray, the information bit subarray, and the check bit subarray are combined to form a ladder LDPC code block to obtain the encoded symbol.

[0028] For example, the step of sending the symbol sequence to the receiving end through the laser communication channel, so that the receiving end can determine the decoding parameters corresponding to the laser communication channel, and demodulate and perform sliding window iterative decoding on the symbols according to the decoding parameters to obtain the decoded symbols, includes:

[0029] The symbol sequence is transmitted to the receiving end through the laser communication channel, and the symbol sequence is demodulated;

[0030] After demodulation, the decoding parameters corresponding to the laser communication channel are determined according to the decoder, and each step LDPC code block within a preset-sized sliding window is determined according to the decoding parameters. The step LDPC code blocks are then decoded line by line for a preset number of iterations to obtain the extrinsic information value.

[0031] Based on the aforementioned extrinsic information values, the prior values ​​of each step LDPC code block are determined;

[0032] Based on the prior value, each group of code blocks is recoded to obtain the output soft information value corresponding to each group of code blocks.

[0033] Based on the output soft information value, an external information value corresponding to each group of code blocks is determined, and based on the external information value, each group of code blocks is iteratively decoded for a preset number of external iterations; wherein, the iterative decoding for the preset number of external iterations is a decoding process that iteratively updates the output soft information value corresponding to each group of code blocks.

[0034] After the outer iteration is completed, the output soft information value obtained in the last outer iteration is determined, and the decoded symbol is obtained based on the output soft information value obtained in the last outer iteration.

[0035] According to the preset number of steps, the position of the sliding window is adjusted, and the process returns to the step of decoding the ladder LDPC code block line by line for a preset number of iterations until the entire symbol sequence is decoded. In this process, after adjusting the position of the sliding window, the prior value of the code block in the current sliding window is determined by the extrinsic information value of the code block in the previous sliding window.

[0036] For example, the step of recoding each group of code blocks according to the prior value to obtain the output soft information value corresponding to each group of code blocks includes:

[0037] Based on the fixed information value of the ladder LDPC code block and the prior value, determine the decision sequence obtained by combining the fixed information value of each row and the prior value of each row for each ladder LDPC code block.

[0038] The sequence to be decided is subjected to permutation processing, and the processed sequence is then re-encoded.

[0039] Based on the codeword estimate with the lowest weighted Hamming distance generated by the OSD decoding algorithm, the results of the recoding process are weighted and accumulated to obtain the output soft information value.

[0040] For example, the step of performing iterative decoding on each group of code blocks for a preset number of external iterations based on the external information value includes:

[0041] Determine the extrinsic information value of the previous group of adjacent step LDPC code blocks within the current window;

[0042] Based on the extrinsic information value, determine the prior value of the previous group of adjacent step LDPC code blocks;

[0043] Based on the prior value, iteratively decode the previous group of adjacent step LDPC code blocks and update the extrinsic information value of the previous group of adjacent step LDPC code blocks.

[0044] Based on the updated extrinsic information value, iteratively decode the next group of adjacent step LDPC code blocks in the current window, and sequentially decode each group of adjacent step LDPC code blocks in the current window according to the order of each group of code blocks.

[0045] After each group of adjacent step LDPC code blocks has completed iterative decoding, the current number of iterations is determined. If the number is less than the preset number of external iterations, the process returns to the step of determining the external information value of the previous group of adjacent step LDPC code blocks in the current window, until the number equals the preset number of external iterations.

[0046] For example, to achieve the above objectives, this application also provides a deep space laser communication encoding and decoding device, the device comprising:

[0047] The acquisition module is used to acquire the information symbols to be encoded and the laser communication channel to be used.

[0048] The encoding module is used to determine the encoding parameters corresponding to the laser communication channel, and to perform LDPC ladder code encoding on the information symbols according to the encoding parameters to obtain encoded symbols;

[0049] A modulation module is used to modulate the coded symbols to obtain a symbol sequence;

[0050] A decoding module is used to transmit the symbol sequence to a receiving end through the laser communication channel, so that the receiving end can determine the decoding parameters corresponding to the laser communication channel, and demodulate and perform sliding window iterative decoding on the symbols according to the decoding parameters to obtain decoded symbols, wherein the decoding parameters include at least the encoding parameters.

[0051] For example, to achieve the above objectives, this application also provides a deep space laser communication encoding and decoding device, the device comprising: a memory, a processor, and a deep space laser communication encoding and decoding program stored in the memory and executable on the processor, the deep space laser communication encoding and decoding program being configured to implement the steps of the deep space laser communication encoding and decoding method as described above.

[0052] For example, to achieve the above objectives, this application also provides a computer-readable storage medium storing a deep space laser communication codec program, which, when executed by a processor, implements the steps of the deep space laser communication codec method as described above.

[0053] In contrast to related technologies that only consider the effects of coronal turbulence without comprehensively considering changes in the communication link, thus ignoring the variations in coronal turbulence caused by the link conditions and affecting channel establishment and usage, leading to poor encoding and decoding performance and consequently impacting communication effectiveness, this application obtains the information symbol to be encoded and the laser communication channel to be used; determines the encoding parameters corresponding to the laser communication channel; and performs LDPC ladder code encoding on the information symbol according to the encoding parameters to obtain the encoded symbol; modulates the encoded symbol to obtain a symbol sequence; and transmits the symbol sequence to the receiving end through the laser communication channel so that the receiving end can determine the signal relative to the laser communication channel. The decoding parameters corresponding to the optical communication channel are used to demodulate and perform sliding window iterative decoding on the symbols to obtain decoded symbols. The decoding parameters include at least the encoding parameters. That is, before establishing communication data transmission, the laser communication channel to be used is first obtained, and corresponding encoding and decoding parameters are selected based on the characteristics of the laser communication channel. Simultaneously, the decoding parameters also include the encoding parameters, thus unifying the encoding and decoding processes when selecting corresponding encoding and decoding parameters according to different laser communication channel conditions, ensuring their corresponding application. This guarantees the use of corresponding encoding and decoding parameters under different communication channel conditions, thereby improving the efficiency of encoding and decoding. Attached Figure Description

[0054] Figure 1 This is a flowchart illustrating the first embodiment of the deep space laser communication encoding and decoding method of this application;

[0055] Figure 2 This is a schematic diagram of the revolution model of the deep space laser communication encoding and decoding method of this application;

[0056] Figure 3 The changes in the SEP angle and SPE angle, as well as the corresponding scintillation index, during the orbital period of the deep space laser communication encoding and decoding method of this application are shown.

[0057] Figure 4 This is a flowchart illustrating the second embodiment of the deep space laser communication encoding and decoding method of this application;

[0058] Figure 5 This is a schematic diagram of the ladder code encoding process of the deep space laser communication encoding and decoding method of this application;

[0059] Figure 6 This is a flowchart illustrating the third embodiment of the deep space laser communication encoding and decoding method of this application;

[0060] Figure 7 This is a schematic diagram of the sliding window decoding structure of the ladder code in the deep space laser communication encoding and decoding method of this application;

[0061] Figure 8 This is a decoding diagram of the ladder SOSD algorithm used in the deep space laser communication encoding and decoding method of this application;

[0062] Figure 9 This is a schematic diagram of the hardware operating environment involved in the embodiments of this application.

[0063] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0064] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0065] This application provides a deep space laser communication encoding and decoding method, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the deep space laser communication encoding and decoding method of this application.

[0066] This application provides an embodiment of a deep-space laser communication encoding and decoding method. It should be noted that although the logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order. For ease of description, the following description of the execution entity and its various steps in the deep-space laser communication encoding and decoding method is omitted. The deep-space laser communication encoding and decoding method includes:

[0067] Step S110: Obtain the information symbol to be encoded and the laser communication channel to be used;

[0068] A laser communication channel will be established between Earth and planetary probes to transmit relevant data. Once a communication connection is established, the relevant information symbols of the communication content need to be encoded and modulated. The encoded data will then be sent from the encoding end to the decoding end that decodes the encoded data.

[0069] The laser communication channel between Earth and the planetary probe changes as the relative positions of Earth and the planet revolve around the Sun, resulting in variations in the communication channel and its minimum distance from the Sun. If the channel is too close to the Sun, it will be affected by coronal turbulence. Therefore, different laser communication channels need to be selected based on the different relative positions of the planet and Earth, and different encoding and decoding parameters need to be selected based on the different conditions of the laser communication channel (such as the influence of coronal turbulence) to improve the encoding and decoding performance.

[0070] The information symbols to be encoded are the symbol data corresponding to the information content that needs to be encoded and the encoded data will be sent to the corresponding receiving end through the laser communication channel.

[0071] The laser communication channel to be used is the channel with different configuration parameters required to address the degree of influence of coronal turbulence.

[0072] For example, the step of obtaining the laser communication channel to be used includes:

[0073] Step a: Based on the preset revolution model, determine the current diametrical distance from the Sun to the wireless link consisting of the Earth's location and the planet's location;

[0074] The preset revolution model is a model constructed based on the Earth's revolution period, the planet's revolution period, the Earth-Sun distance between the Sun and the Earth, the Sun-Star distance between the Sun and the planet, and the Star-Earth distance between the planet and the Earth, which shows that the wireless link changes periodically as the planet and the Earth revolve.

[0075] As can be seen from the above, when determining the degree of influence of coronal turbulence on laser communication channels, in addition to the distance between the coronal turbulence and the channel, it is also necessary to consider the planetary and Earth's revolution around the sun, so as to comprehensively determine the influence of coronal turbulence on communication channels.

[0076] Therefore, to address the above issues, a revolution model is constructed centered on the Sun, combining data such as the orbits of planets and Earth (Sun-Earth distance, Sun-Star distance), the revolution periods of planets and Earth (Earth's revolution period and the planet's revolution period), and the relative position changes between planets and Earth (Star-Earth distance). This revolution model will undergo corresponding periodic changes as the relative positions of planets and Earth change, i.e., the synodic period of planets and Earth.

[0077] Reference Figure 2 , Figure 2 This is a schematic diagram of the revolution model of an Earth and a planetary probe (taking a Mars probe as an example; all examples below use a Mars probe as an example, and the implementation process of other planetary probes is the same as that of the Mars probe, so it will not be repeated). It is assumed that the revolutions of both the Earth and Mars probes are circular motions. L se L is the average distance from the Earth to the Sun. sp Let α be the average distance from Mars to the Sun, β be the SEP (Sun-Earth-Mars probe) angle, β be the SPE (Sun-Mars probe-Earth) angle, and h be the solar radius distance (the shortest distance from the Sun to the wireless link). L is the laser link distance, which, according to geometric relationships, is L = L se cosα+L sp cosβ.

[0078] When Earth and planetary probes are within the lower conjunction range of the Sun, the laser communication channel is less affected by coronal turbulence. However, when Earth and planetary probes are within the upper conjunction range of the Sun, the laser communication channel is more significantly affected by coronal turbulence, causing fluctuations in the amplitude, phase, and even the angle of arrival of the received signal. Furthermore, the distance from the Sun to the laser communication channel further decreases, and the laser communication channel will inevitably enter the corona, causing communication interruption.

[0079] Step b: Based on the solar ray distance and a preset calculation formula, calculate the scintillation index used to assess the intensity of the coronal turbulence effect of the sun on the wireless link;

[0080] The preset calculation formula is designed based on the definition of the scintillation index and the influence parameters affecting the intensity of coronal turbulence. Specifically, the definition of the scintillation index is the ratio of the root mean square value of the laser signal intensity fluctuation to the average value of the laser signal intensity. The influence parameters include at least the solar radius distance.

[0081] After constructing the revolution model, it is necessary to design a calculation method that combines the current revolution model to calculate the intensity of the influence of coronal turbulence on the laser communication channel. Here, a scintillation index can be defined. It is used to characterize solar scintillation intensity, and its expression is the ratio of the root mean square value of the signal intensity fluctuation to the average value of the signal intensity. The specific formula is as follows:

[0082] Where I is the intensity of the laser.

[0083] The higher the scintillation index, the greater the impact of coronal turbulence on the laser communication channel. The scintillation index is used to model the laser communication channel from Earth to planetary probes. The laser communication channel link is greatly affected by coronal turbulence, in which case the laser link is considered to be interrupted; while when Laser communication channels are almost unaffected by coronal turbulence, so deep space channels can be replaced by additive white Gaussian noise.

[0084] Finally, for those in In cases where the corona channel model can well describe weak and moderate flicker, a gamma-gamma (GG) channel can be used for modeling.

[0085] The specific calculation formula that can be designed by combining the revolution model and the definition of the scintillation index is as follows:

[0086]

[0087] Where φ and These refer to the effective number of large-scale and small-scale scatterers, respectively.

[0088]

[0089]

[0090] in, D represents the diameter of the receiver aperture, λ is the wavelength, and D < <L,d≈0,χ 2 This represents the variance of amplitude fluctuations;

[0091]

[0092] Where p is the spectral index, r e L is the classical electron radius. o Let ζ be the outer scale of coronal turbulence, ζ be the relative solar wind density fluctuation rate, and N be the outer scale of coronal turbulence. e (h) represents the solar wind density. Except for the solar wind density, all other parameters mentioned above are known fixed values.

[0093]

[0094] Among them, R sun Where is the solar radius, and h is the solar axial distance;

[0095] In summary, by determining the distance to the sun using the revolution model and combining it with the corresponding formulas and functions, the current scintillation index can be calculated.

[0096] Step c: Determine the laser communication channel to be used based on the flicker index.

[0097] The scintillation index reflects the intensity of coronal turbulence; therefore, the laser communication channel to be used needs to be determined based on the magnitude of the scintillation index.

[0098] For example, the step of determining the laser communication channel to be used based on the scintillation index includes:

[0099] Step d: If the flicker index is less than or equal to the first preset flicker threshold, then the AWGN channel is selected as the laser communication channel to be used;

[0100] Step e: If the flicker index is greater than the first preset flicker threshold and less than or equal to the second preset flicker threshold, then according to the preset channel model based on GG distribution, determine the channel characteristic parameters corresponding to the flicker index, and according to the channel characteristic parameters, determine the laser communication channel to be used.

[0101] The preset channel model based on the GG distribution is a channel model constructed based on the second-order Bessel function, the standard gamma function, the number of large-scale scatterers, and the number of small-scale scatterers to describe the light intensity fluctuation distribution at the signal receiver.

[0102] In summary, based on the revolution model and calculation formula, the periodic changes in the scintillation index during a synodic period between Mars and Earth can be calculated accordingly.

[0103] Assuming Earth's orbital period is 365 days and Mars' orbital period is 687 days, calculations show that... Figure 3 The SEP and SPE angles and corresponding scintillation indices during the Mars-Earth orbital period are shown. The changes in the Earth-Mars communication channel are shown in Table 1, which corresponds to the changes in the channel during one orbital period (approximately 782 days).

[0104] Table 1. Statistics on the changes in the Mars-Earth laser channel

[0105]

[0106] As shown in Table 1 above, the communication link between Earth and Mars is interrupted for about 38 days within a rendezvous period of about 782 days. The Earth-Mars channel can be regarded as an AWGN (Additive White Gaussian Noise) channel for about 678 days, followed by a weak flicker GG channel for 54 days, while the duration of medium flicker and strong flicker is 6 days each.

[0107] In summary, At that time, directly select the AWGN channel. At that time, the GG channel was selected, while At that time, communication between Earth and the planetary probe was interrupted.

[0108] For example, the step of determining the channel characteristic parameters corresponding to the scintillation index based on a preset channel model based on the GG distribution includes:

[0109] Step f: Determine multiple threshold intervals between the first preset blink threshold and the second preset blink threshold;

[0110] According to Table 1, in Within the range, the flicker index will still fluctuate accordingly; therefore, it can continue to be... The range is divided into smaller threshold ranges, thereby adjusting the channel parameters accordingly, so that the channel can be more suitable for the communication environment corresponding to the current scintillation index.

[0111] The threshold range is shown in Table 1. The three threshold intervals within the interval.

[0112] Step g: Determine the threshold interval to which the flicker index belongs, and take the middle value in the threshold interval as the channel feature parameter corresponding to the threshold interval.

[0113] After determining the threshold range to which the flicker index belongs, each parameter in the threshold range corresponds to an h, and different h will calculate a channel characteristic parameter corresponding to the GG channel. Therefore, the middle value or an approximate middle value can be taken from multiple channel characteristic parameters. Taking the channel characteristic parameter range of 0.01 to 0.3 as an example, 0.15 or 0.2 can be taken.

[0114] The GG channel characteristic parameters need to be calculated based on the probability density function of the GG distribution, and the formula for calculating the probability density function is as follows:

[0115]

[0116] Where K is a second-order Bessel function, Γ is a standard gamma function, and φ and These are the effective numbers of large-scale and small-scale scatterers, respectively. Their specific sizes can be derived from the corresponding calculation formula when calculating the scintillation index, and will not be elaborated here.

[0117] Step S120: Determine the encoding parameters corresponding to the laser communication channel, and perform LDPC ladder code encoding on the information symbols according to the encoding parameters to obtain encoded symbols;

[0118] Different channel characteristic parameters are calculated for different flicker indices, which leads to the selection of different channels and different channel parameters. Therefore, different coding parameters need to be selected to suit different channels.

[0119] That is, different coding parameters are selected based on the signal-to-noise ratio of different channel environments. Similarly, different decoding parameters need to be selected accordingly. At the same time, the coding parameters and decoding parameters for the same channel need to correspond one-to-one.

[0120] For example, when the current channel is greatly affected by coronal turbulence, the signal-to-noise ratio is low. In order to ensure the signal transmission effect, it is necessary to increase the signal-to-noise ratio. Therefore, it is necessary to select appropriate coding parameters to improve the signal transmission effect after coding.

[0121] Once the encoding parameters are determined, the information symbols can be encoded using LDPC (Low-density Parity-check) ladder code based on the encoding parameters to obtain the encoded symbols.

[0122] Step S130: Modulate the encoded symbols to obtain a symbol sequence;

[0123] After obtaining the encoded symbols, the encoded symbols need to be modulated to obtain a symbol sequence. This symbol sequence is then sent to the decoder, which performs the decoding process based on the symbol sequence.

[0124] The modulation process can use methods such as BPSK (Binary Phase Shift Keying, a method of converting analog signals into data values) and 4PPM (pulse position modulation, a modulation in which the occurrence time of the carrier pulse varies with the modulating signal).

[0125] Step S140: The symbol sequence is transmitted to the receiving end through the laser communication channel so that the receiving end can determine the decoding parameters corresponding to the laser communication channel, and demodulate and perform sliding window iterative decoding on the symbol according to the decoding parameters to obtain the decoded symbol, wherein the decoding parameters include at least the encoding parameters.

[0126] When a symbol sequence is transmitted to the receiver via a laser communication channel, the receiver will assess the overall condition of the symbol sequence and select decoding parameters corresponding to the current laser communication channel. Based on these decoding parameters, the receiver can adjust the relevant decoding parameters of the decoder, enabling the decoder to effectively and accurately demodulate and decode the current symbol sequence to obtain the decoded symbol.

[0127] In the decoding process, the symbol sequence is mainly decoded by setting a sliding window iterative decoding method. The SOSD (soft-output Ordered Statistics Decoder) can be used to input the code blocks in the sliding window into the SOSD in sequence, and the final decoding result is obtained by decoding in batches by the SOSD.

[0128] In addition, both the receiving and transmitting ends store the corresponding encoding and decoding parameter data. This data is established based on the mapping relationship between different laser communication channels, corresponding encoding parameters, and corresponding decoding parameters. This data is used as a reference to directly call the corresponding encoding and decoding parameters according to the laser communication channel used.

[0129] In contrast to related technologies that only consider the effects of coronal turbulence without comprehensively considering changes in the communication link, thus ignoring the variations in coronal turbulence caused by the link conditions and affecting channel establishment and usage, leading to poor encoding and decoding performance and consequently impacting communication effectiveness, this application obtains the information symbol to be encoded and the laser communication channel to be used; determines the encoding parameters corresponding to the laser communication channel; and performs LDPC ladder code encoding on the information symbol according to the encoding parameters to obtain the encoded symbol; modulates the encoded symbol to obtain a symbol sequence; and transmits the symbol sequence to the receiving end through the laser communication channel so that the receiving end can determine the signal relative to the laser communication channel. The decoding parameters corresponding to the optical communication channel are used to demodulate and perform sliding window iterative decoding on the symbols to obtain decoded symbols. The decoding parameters include at least the encoding parameters. That is, before establishing communication data transmission, the laser communication channel to be used is determined, and corresponding encoding and decoding parameters are selected based on the characteristics of the laser communication channel. Furthermore, the decoding parameters also include the encoding parameters, thus unifying the encoding and decoding processes when selecting corresponding encoding and decoding parameters according to different laser communication channel conditions. This ensures that the corresponding encoding and decoding parameters are used under different communication channel conditions, thereby improving the encoding and decoding efficiency.

[0130] For example, refer to Figure 4 , Figure 4 This is a flowchart illustrating the second embodiment of the deep space laser communication encoding and decoding method of this application. Based on the first embodiment of the deep space laser communication encoding and decoding method of this application described above, a second embodiment is proposed, wherein the method further includes:

[0131] Step S210: According to the encoding parameters, divide the information symbol into LDPC codes with a codeword length of N and a parity bit length of r;

[0132] Table 2. Encoding parameters of ladder LDPC coding

[0133] Code word length N 128 Check bit length r 64 Repeated encoding length m 32 Ladder code rate R 0.33

[0134] Referring to Table 2, the parameters in Table 2 are the encoding parameters. Table 2 is only an implementation example for simulation and does not imply that the encoding parameters in this application do not include other parameters. Therefore, before encoding, the information symbols need to be divided according to the corresponding encoding parameters to obtain an LDCP code whose codeword length and parity bit length are adjusted according to the encoding parameters. That is, an LDPC code with a codeword length of N and a parity bit length of r is selected. As a component of the ladder code.

[0135] The formula for calculating the actual code rate of the ladder code is as follows:

[0136]

[0137] Step S220: Based on the repeating coding subarray and the information bit subarray in the LDPC code, perform row-by-row ladder coding on the signal symbol and obtain the corresponding check bit subarray; wherein, the repeating coding subarray is an Nm row × m column matrix;

[0138] For details on the ladder code encoding method, please refer to [link / reference]. Figure 5 Where m is the number of repeated codes, T represents the matrix transpose, and B i This represents the i-th block of the ladder code.

[0139] The encoding process proceeds sequentially from B1, B2, B3, and so on. The m×(Nm) matrix B0 is initialized to a zero matrix known to the decoder and is not transmitted through the channel. B1, B2, B3, and so on are all matrices of size (Nm)×(Nm).

[0140] Definition B i，S T For B i T The rightmost m column.

[0141] Follow-up Similarly, respectively The rightmost m column.

[0142] Among them, the parity subarray can be obtained by retrieving and using a suitable parity subarray from the existing parity subarray database.

[0143] Step S230: Combine the repeating coding subarray, the information bit subarray, and the check bit subarray into a ladder LDPC code block to obtain the coded symbol.

[0144] With the Vth block B V =[B V,message B V,parity Taking the encoding process of ] as an example, where B V,message It is an information bit subarray of size (Nmr) × (Nm), and B V,parity It is a check subarray of size r×(Nm);

[0145] B V-1, T It is the previous code block B V-1 T The rightmost m column is used for B. V Repeated encoded portions of block encoding;

[0146] Then, input the (Nr)×(Nm) ladder LDPC code into the subarray [B]V-1,S T B V,message Encode line by line to obtain the check part B. V,parity .

[0147] Finally, the system structure's ladder LDPC code block B is obtained. V =[B V,message B V,parity ].

[0148] In this embodiment, based on the laser communication channel used, i.e., the signal-to-noise ratio during the current laser communication channel transmission is determined, the coding parameters that need to be adjusted in the current coding process are determined, and based on the coding parameters, the information symbols are encoded line by line in a stepwise manner to obtain coded symbols that can resist the influence of coronal turbulence, thereby improving the communication effect.

[0149] For example, refer to Figure 6 , Figure 6 This is a flowchart illustrating the third embodiment of the deep space laser communication encoding and decoding method of this application. Based on the first and second embodiments of the deep space laser communication encoding and decoding method of this application described above, a third embodiment is proposed, wherein the method further includes:

[0150] Step S310: The symbol sequence is transmitted to the receiving end through the laser communication channel, and the symbol sequence is demodulated;

[0151] When transmitting the charged symbol sequence to the receiver via a laser communication channel, the symbol sequence needs to be demodulated first, and then the demodulated symbol sequence needs to be decoded accordingly.

[0152] The received encoded symbols are demodulated according to the modulation scheme used.

[0153] Without loss of generality, we will take binary phase shift keying (BPSK) modulation as an example for analysis. Since one bit in BPSK modulation is -1 or 1, the information received by the receiver after passing through the channel can be directly regarded as the prior information of each bit after demodulation. The following decoding process will be described using BPSK demodulation as an example.

[0154] Step S320: After demodulation, according to the decoder, the decoding parameters corresponding to the laser communication channel are determined, and according to the decoding parameters, each step LDPC code block within a preset-sized sliding window is determined, and the step LDPC code block is decoded line by line for a preset number of iterations to obtain the external information value.

[0155] After demodulation, the demodulated data needs to be decoded. In order to match the current symbol encoding and adapt to the laser communication channel currently in use, corresponding decoding parameters are selected. Based on these decoding parameters, the corresponding symbol data is decoded. The specific decoding parameters can be determined according to decoding parameter 3. Table 3 is only an example that can be implemented during simulation and does not mean that the decoding parameters in this application do not include other parameters.

[0156] Table 3 shows the decoding parameters for ladder LDPC encoding.

[0157] <![CDATA[The number of inner iterations I of the sliding window BP decoding algorithm max > 10 <![CDATA[The number of inner iterations J of the sliding window BP decoding algorithm max > 20 <![CDATA[Inner iteration count I of the sliding window SOSD decoding algorithm max > 1 <![CDATA[The inner iteration count J of the sliding window SOSD decoding algorithm max > 2 SOSD order Δ 2

[0158] Referring to Table 3, the corresponding parameters can be selected to decode the symbol sequence based on the contents of Table 3.

[0159] The size of the sliding window can be determined according to the number of complete LDPC code blocks it covers. In this embodiment, a sliding window size of 4 is used as an example, but the sliding window size can be increased accordingly.

[0160] Based on the decoding parameters, each step LDPC code block within a preset-sized sliding window is determined, and the step LDPC code block is decoded line by line for a preset number of iterations to obtain the extrinsic information value. The specific process can be found in [reference needed]. Figure 7 .

[0161] For example, with window size w = 4, the dashed box represents the current window, and the bold solid box represents the target block at the current moment. The decoder initialization process is as follows:

[0162]

[0163] in, The received value of the t-th block obtained from the channel;

[0164] Let be the prior value of the t-th block at the j-th outer iteration, then It is the prior value of the t-th block when the decoder starts decoding;

[0165] M is a (Nm)×(Nm) matrix of all 1s, and 0 is a (Nm)×(Nm) matrix of all 0s.

[0166] Step S330: Determine the prior value of each step LDPC code block based on the external information value;

[0167] According to the above formula, the prior value of each LDPC code block can be determined based on the extrinsic information value. If it cannot be determined, the prior value of the corresponding LDPC code block can be treated as zero.

[0168] Step S340: Based on the prior value, re-encode each group of code blocks to obtain the output soft information value corresponding to each group of code blocks;

[0169] Based on the prior values, each group of code blocks can be recoded. This recoding process is the process of iteratively decoding each group of code blocks. In this process, based on the prior values ​​generated during the iteration, external iteration is performed on each group of code blocks, and internal iteration is also performed on each code block.

[0170] During the outer iteration, the order of the ladder-shaped LDPC codes within the selected window is determined based on the current window's range, and the code blocks are arranged according to this order and the ladder-shaped code block positions (see details in [reference]). Figure 7 The method divides multiple staircase LDPC blocks into multiple groups, each group including two adjacent staircase LDPC code blocks. During each external iteration, the two adjacent staircase LDPC code blocks are iterated simultaneously.

[0171] During the internal iteration, while the external iteration is in progress, each code block in each group of code blocks is recoded line by line to perform the internal iteration, and finally the output soft information value of each code block and each group of code blocks is obtained.

[0172] For example, the step of recoding each group of code blocks according to the prior value to obtain the output soft information value corresponding to each group of code blocks includes:

[0173] Step h: Based on the fixed information value of the ladder LDPC code block and the prior value, determine the decision sequence obtained by combining the fixed information value of each row and the prior value of each row of the corresponding ladder LDPC code block;

[0174] Step i: Perform permutation processing on the sequence to be decided, and then re-encode the processed sequence;

[0175] Step j: Based on the codeword estimate with the lowest weighted Hamming distance generated by the OSD decoding algorithm, the result after the recoding process is weighted and accumulated to obtain the output soft information value.

[0176] SOSD decoder, given input

[0177] in, yes The j-th position.

[0178] Output

[0179] in, yes The j-th position.

[0180]

[0181] Where c(j:0)=[c1(j:0),c2(j:0),...,c N (j:0)];

[0182] c(j:1)=[c1(j:1),c2(j:1),...,c N [j:1] are the codeword estimates with the lowest weighted Hamming distance (WHD) generated by the OSD decoding algorithm when the j-th bit is 0 and 1.

[0183] Step S350: Determine the external information value corresponding to each group of code blocks based on the output soft information value, and perform iterative decoding on each group of code blocks for a preset number of external iterations based on the external information value; wherein, the iterative decoding for the preset number of external iterations is a decoding process that iteratively updates the output soft information value corresponding to each group of code blocks.

[0184] Based on the output soft information value, the corresponding external information value of each code block can be determined. Then, based on the external information value, each group of code blocks can be iteratively decoded for a preset number of external iterations. The preset number of external iterations can be referred to in Table 3. The iterative decoding process with the preset number of external iterations is the decoding process of iteratively updating the output soft information value corresponding to each group of code blocks. That is, the purpose of the current iteration process is to improve the accuracy of the output soft information value.

[0185] For example, the step of performing iterative decoding on each group of code blocks for a preset number of external iterations based on the external information value includes:

[0186] Step k: Determine the extrinsic information value of the previous group of adjacent ladder LDPC code blocks within the current window;

[0187] Step 1: Determine the prior value of the previous group of adjacent step LDPC code blocks based on the extrinsic information value;

[0188] Step m: Based on the prior value, iteratively decode the previous group of adjacent eddy LDPC code blocks and update the extrinsic information value of the previous group of adjacent eddy LDPC code blocks.

[0189] During the iterative decoding process of each group of code blocks for a preset number of external iterations, it is necessary to first determine the external information value within the current window. This external information value can be obtained in two ways. First, during the initial external iteration process, since the current group of code blocks has not been iteratively decoded, the output soft information value of the current code block is not obtained. At this time, it is necessary to determine the external information value of the stepped LDPC code block through a preset method. Second, during multiple iterations, the specific external information value of the stepped LDPC code block will be determined based on the iteration data.

[0190] For example, when iterating through code blocks, it is necessary to first calculate the extrinsic information value of the corresponding code block. Each time the extrinsic information value is calculated according to the sliding window, it is calculated in batches, line by line, for each code block. Figure 5 When iterating through a row of code blocks, first calculate the row containing B1 and B2, then the next row is the row consisting of B2 and B3, and so on.

[0191] Reference Figure 5 The specific correspondence between extrinsic information values ​​and prior values ​​is that the extrinsic information value of B1 is equal to the prior value of B2, the extrinsic information value of B2 is equal to the prior value of B3, and so on.

[0192] For example, refer to Figure 7 When the decoder processes the Vth code block B V At that time, the indices of the w blocks contained in the decoding window are t∈[V,V+w-1];

[0193] The sliding window decoder is initialized as follows:

[0194]

[0195] Among them, the latest block B V+w-1 The prior value is zero. The prior values ​​of other blocks in the current window can be obtained from the previous window during the last iteration, as shown in the following formula:

[0196]

[0197] Among them, J max The maximum number of outer iterations. Let be the external information value obtained by the t-th block in the J-th outer iteration.

[0198] Among them, reference Figure 7Taking the current time as time V, when the ladder LDPC code blocks in the current window are the first external iterations, Bv and Bv+1 are grouped together, Bv+1 and Bv+2 are grouped together, and Bv+2 and Bv+3 are grouped together. First, each line of the target block Bv is recoded to obtain the output soft information value of the Bv block. At the same time, the iteration process decodes multiple ladder LDPC code blocks in groups. Based on the output soft information value of Bv, the external information value of Bv+1 is determined to obtain the prior value of Bv+1. Based on this prior value, Bv+1 can be recoded to obtain the output soft information value of Bv+1. Thus, when recoding Bv+1 and Bv+2 as a group, the output soft information value of Bv+1 can be directly used to determine the corresponding external information value and prior value, thereby realizing the recoding process of Bv+1 and Bv+2. This process is repeated to complete the first iteration within the window.

[0199] Step n: Based on the updated extrinsic information value, iteratively decode the next group of adjacent step LDPC code blocks in the current window, and sequentially iteratively decode each group of adjacent step LDPC code blocks in the current window according to the order of each group of code blocks.

[0200] Based on the above, when continuing the Nth (not the first) iteration of the ladder LDPC code blocks within the window, the Bv block, after the previous iteration, obtains the corresponding output soft information value. Based on the output soft information value from the previous iteration, the Bv block is recoded, thus updating its output soft information value. After the update, Bv+1 is recoded with the updated content. When recoding Bv+1 and Bv+2, Bv+2 has obtained the corresponding output soft information value in the previous iteration, while Bv+1 uses the updated output soft information value. That is, when iterating the ladder code blocks within the window according to the grouping order, adjacent ladder code blocks will use the most recently updated output soft information value. (When recoding Bv+1 and Bv+2, the most recently updated output soft information value of Bv+1 is obtained when recoding Bv and Bv+1, and the most recently updated output soft information value of Bv+2 is obtained during the previous iteration outside the window.) This process continues, updating and iterating all the ladder code blocks.

[0201] Step o: After each group of adjacent step LDPC code blocks has completed iterative decoding, determine the current number of iterations. If the number is less than the preset number of external iterations, return to the step of determining the external information value of the previous group of adjacent step LDPC code blocks in the current window, until the number equals the preset number of external iterations.

[0202] Since the window slides accordingly during decoding, the window position can be adjusted when the iterative decoding of each group of adjacent staircase LDPC code blocks is completed and the number of external iterations meets the preset number of external iterations. Therefore, when the window completes the decoding of all groups of staircase LDPC code blocks, the current number of external iterations is determined. If the current number of external iterations reaches the preset number of external iterations, the iteration process in the current window can be ended and the position of the current window needs to be moved. If the current number of external iterations does not reach the preset number of external iterations, the iteration of the staircase LDPC code blocks in the current window needs to continue.

[0203] Step S360: After the outer iteration is completed, determine the output soft information value obtained in the last outer iteration, and convert it into a decoded symbol based on the output soft information value obtained in the last outer iteration;

[0204] The sliding window decoder starts decoding at B. V and B V+1 The SOSD decoder is used to decode line by line. For detailed instructions, please refer to [link / reference needed]. Figure 7 and Figure 8 ;

[0205] In the Jth iteration, let...

[0206] in, For matrix The i-th row;

[0207] Similarly:

[0208]

[0209] and Divided into matrices The i-th row.

[0210] The input to the decoder corresponding to SOSD is... Where μ is the scaling factor, and its output is This yields the output soft information value.

[0211] In the process of using the SOSD algorithm, the corresponding symbol sequence needs to be re-encoded to obtain the output soft information value. Furthermore, the decoded symbol is obtained based on the output soft information value.

[0212] That is, when the outer iteration is completed, the decoded symbol can be obtained by converting the output soft information value obtained in the last outer iteration.

[0213] Step S370: Adjust the position of the sliding window according to the preset number of steps, and return to the step of decoding the ladder LDPC code block line by line for a preset number of iterations until all symbol sequences are decoded. In this step, after adjusting the position of the sliding window, the prior value of the code block in the current sliding window is determined by the extrinsic information value of the code block in the previous sliding window.

[0214] The preset number of steps can be the distance to slide one code block position; the specific sliding effect can be referenced. Figure 7 When adjusting the sliding window, the prior value of the code block in the current sliding window is determined by the extrinsic information value of the code block in the previous sliding window. Taking the current time as V+1 as an example, the prior values ​​of the first three step LDPC code blocks in the current window can be directly obtained from the output soft information value and extrinsic information value obtained at time V.

[0215] Furthermore, assuming SOSD is performed only once, then

[0216] Information exchange after the internal iteration process is completed

[0217] Information exchange after the external iteration process ends

[0218] Repeat the external iterative process until the maximum number of iterations J max When the condition is met, the decoder outputs an estimate of the target block. At time V+1, the decoder receives the new block B. V+w The decoding window slides the first block to the "right side," and the whole process is repeated.

[0219] Based on the different channel conditions at different time periods during the rendezvous cycle of the deep space laser communication system, the number of inner and outer iterations I of the sliding window decoding algorithm can be adjusted. max (Preset number of iterations) and J max (Preset number of external iterations) to balance complexity and reliability.

[0220] In this embodiment, the symbol sequence is transmitted to the receiving end through the laser communication channel, and the symbol sequence is demodulated. After demodulation, the decoding parameters corresponding to the laser communication channel are determined according to the decoder, and each step LDPC code block within a preset-sized sliding window is determined according to the decoding parameters. The step LDPC code blocks are then decoded line by line for a preset number of iterations to obtain extrinsic information values. The prior values ​​of each step LDPC code block are determined according to the extrinsic information values. Each group of code blocks is recoded according to the prior values ​​to obtain decoded symbols. The position of the sliding window is adjusted according to a preset number of steps, and the step of decoding the step LDPC code blocks line by line for a preset number of iterations is returned until all symbol sequences are decoded. After adjusting the position of the sliding window, the prior values ​​of the code blocks in the current sliding window are determined by the extrinsic information values ​​of the code blocks in the previous sliding window. That is, by providing a row-by-row iterative algorithm with a sliding window, combined with the SOSD decoding algorithm, and after adjusting the decoding parameters according to the laser communication channel, the process of efficiently decoding symbol sequences is achieved. The key is to adjust the decoding parameters so that the decoding effect approaches the performance limit.

[0221] Furthermore, this application also provides a deep space laser communication encoding and decoding device, which includes:

[0222] The acquisition module is used to acquire the information symbols to be encoded and the laser communication channel to be used.

[0223] The encoding module is used to determine the encoding parameters corresponding to the laser communication channel, and to perform LDPC ladder code encoding on the information symbols according to the encoding parameters to obtain encoded symbols;

[0224] A modulation module is used to modulate the coded symbols to obtain a symbol sequence;

[0225] A decoding module is used to transmit the symbol sequence to a receiving end through the laser communication channel, so that the receiving end can determine the decoding parameters corresponding to the laser communication channel, and demodulate and perform sliding window iterative decoding on the symbols according to the decoding parameters to obtain decoded symbols, wherein the decoding parameters include at least the encoding parameters.

[0226] For example, the acquisition module includes:

[0227] The first determining submodule is used to determine the current diametrical distance from the Sun to the wireless link consisting of the Earth's location and the planet's location, based on a preset revolution model; wherein, the preset revolution model is a model constructed based on the Earth's revolution period, the planet's revolution period, the Sun-Earth distance between the Sun and the Earth, the Sun-Star distance between the Sun and the planet, and the Star-Earth distance between the planet and the Earth, which shows that the wireless link changes periodically with the revolution of the planet and the Earth;

[0228] The calculation submodule is used to calculate the scintillation index, which is used to assess the intensity of the coronal turbulence influence of the sun on the wireless link, based on the solar ray distance and a preset calculation formula. The preset calculation formula is designed based on the definition of the scintillation index and the influence parameters affecting the intensity of coronal turbulence. Specifically, the definition of the scintillation index is the ratio of the root mean square value of the laser signal intensity fluctuation to the average value of the laser signal intensity, and the influence parameters include at least the solar ray distance.

[0229] The second determining submodule is used to determine the laser communication channel to be used based on the flicker index.

[0230] For example, the second determining submodule includes:

[0231] The selection unit is used to select the AWGN channel as the laser communication channel to be used if the scintillation index is less than or equal to a first preset scintillation threshold.

[0232] The first determining unit is configured to, if the scintillation index is greater than the first preset scintillation threshold and less than or equal to the second preset scintillation threshold, determine the channel characteristic parameters corresponding to the scintillation index according to a preset channel model based on the GG distribution, and determine the laser communication channel to be used according to the channel characteristic parameters; wherein, the preset channel model based on the GG distribution is a channel model constructed based on the second-order Bessel function, the standard gamma function, the number of large-scale scatterers, and the number of small-scale scatterers to describe the light intensity fluctuation distribution at the signal receiving end.

[0233] For example, the determining unit includes:

[0234] The first determining subunit is used to determine multiple threshold intervals between the first preset flashing threshold and the second preset flashing threshold;

[0235] The second determining subunit is used to determine the threshold interval to which the flicker index belongs, and to take the middle value in the threshold interval as the channel feature parameter corresponding to the threshold interval.

[0236] For example, the encoding module includes:

[0237] The partitioning submodule is used to partition the information symbols into LDPC codes with a codeword length of N and a parity bit length of r according to the encoding parameters.

[0238] The encoding submodule is used to perform row-by-row ladder encoding on the signal symbol according to the repeating encoding subarray and the information bit subarray in the LDPC code, and to obtain the corresponding check bit subarray; wherein, the repeating encoding subarray is an Nm row × m column matrix;

[0239] A generation submodule is used to combine the repeating coding subarray, the information bit subarray, and the check bit subarray into a ladder LDPC code block to obtain a coded symbol.

[0240] For example, the decoding module includes:

[0241] The demodulation submodule is used to transmit the symbol sequence to the receiving end through the laser communication channel and demodulate the symbol sequence;

[0242] The third determining submodule is used to determine the decoding parameters corresponding to the laser communication channel according to the decoder after demodulation, and to determine each step LDPC code block within a preset-sized sliding window according to the decoding parameters, and to perform line-by-line decoding of the step LDPC code block for a preset number of iterations to obtain the external information value.

[0243] The fourth determining submodule is used to determine the prior value of each step LDPC code block based on the external information value;

[0244] The recoding submodule is used to recode each group of code blocks according to the prior value to obtain the output soft information value corresponding to each group of code blocks.

[0245] The iterative submodule is used to determine the external information value corresponding to each group of code blocks based on the output soft information value, and to perform iterative decoding on each group of code blocks for a preset number of external iterations based on the external information value; wherein, the iterative decoding for the preset number of external iterations is a decoding process that iteratively updates the output soft information value corresponding to each group of code blocks.

[0246] The fifth determining submodule is used to determine the output soft information value obtained in the last outer iteration after the outer iteration is completed, and to convert the output soft information value obtained in the last outer iteration to obtain the decoding symbol.

[0247] The adjustment submodule is used to adjust the position of the sliding window according to a preset number of steps, and return to the step of decoding the ladder LDPC code block line by line for a preset number of iterations until the entire symbol sequence is decoded. After adjusting the position of the sliding window, the prior value of the code block in the current sliding window is determined by the extrinsic information value of the code block in the previous sliding window.

[0248] For example, the iterative submodule includes:

[0249] The second determining unit is used to determine the extrinsic information value of the previous group of adjacent ladder LDPC code blocks within the current window;

[0250] The third determining unit is used to determine the prior value of the previous group of adjacent step LDPC code blocks based on the external information value.

[0251] The update unit is used to iteratively decode the previous group of adjacent step LDPC code blocks according to the prior value, and update the extrinsic information value of the previous group of adjacent step LDPC code blocks.

[0252] The iterative unit is used to iteratively decode the next group of adjacent step LDPC code blocks in the current window according to the updated extrinsic information value, and to iteratively decode each group of adjacent step LDPC code blocks in the current window in the order of each group of code blocks.

[0253] The loop unit is used to determine the current number of iterations after each group of adjacent step LDPC code blocks has completed iterative decoding. If the number is less than the preset number of external iterations, the unit returns to the step of determining the external information value of the previous group of adjacent step LDPC code blocks in the current window, until the number is equal to the preset number of external iterations.

[0254] The specific implementation of the deep space laser communication encoding and decoding device in this application is basically the same as the embodiments of the deep space laser communication encoding and decoding method described above, and will not be repeated here.

[0255] Furthermore, this application also provides a deep-space laser communication encoding and decoding device. For example... Figure 9 As shown, Figure 9 This is a schematic diagram of the hardware operating environment involved in the embodiments of this application.

[0256] For example, Figure 9 This is a schematic diagram of the hardware operating environment for deep space laser communication encoding and decoding equipment.

[0257] like Figure 9As shown, the deep space laser communication encoding and decoding device may include a processor 901, a communication interface 902, a memory 903, and a communication bus 904. The processor 901, the communication interface 902, and the memory 903 communicate with each other through the communication bus 904. The memory 903 is used to store computer programs. When the processor 901 executes the program stored in the memory 903, it implements the steps of the deep space laser communication encoding and decoding method.

[0258] The communication bus 904 mentioned in the aforementioned deep-space laser communication encoding and decoding equipment can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus 904 can be divided into an address bus, a data bus, and a control bus, etc. For ease of illustration, it is represented by only one thick line in the figure, but this does not indicate that there is only one bus or one type of bus.

[0259] Communication interface 902 is used for communication between the aforementioned deep space laser communication encoding and decoding equipment and other devices.

[0260] The memory 903 may include random access memory (RMD) or non-volatile memory (NM), such as at least one disk storage device. Optionally, the memory 903 may also be at least one storage device located remotely from the aforementioned processor 901.

[0261] The processor 901 mentioned above can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0262] The specific implementation of the deep space laser communication encoding and decoding device in this application is basically the same as the embodiments of the deep space laser communication encoding and decoding method described above, and will not be repeated here.

[0263] Furthermore, this application also proposes a computer-readable storage medium storing a deep space laser communication encoding / decoding program, which, when executed by a processor, implements the steps of the deep space laser communication encoding / decoding method described above.

[0264] The specific implementation of the computer-readable storage medium in this application is basically the same as the embodiments of the deep space laser communication encoding and decoding method described above, and will not be repeated here.

[0265] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0266] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0267] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0268] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A deep-space laser communication encoding and decoding method, characterized in that, The deep space laser communication encoding and decoding method includes the following steps: Obtain the information symbols to be encoded, and obtain the laser communication channel to be used; Determine the encoding parameters corresponding to the laser communication channel, and perform LDPC ladder code encoding on the information symbols according to the encoding parameters to obtain the encoded symbols; The encoded symbols are modulated to obtain a symbol sequence; The symbol sequence is transmitted to the receiving end through the laser communication channel so that the receiving end can determine the decoding parameters corresponding to the laser communication channel, and demodulate and perform sliding window iterative decoding on the symbol according to the decoding parameters to obtain the decoded symbol, wherein the decoding parameters include at least the encoding parameters; The step of obtaining the laser communication channel to be used includes: Based on the preset revolution model, determine the current diametrical distance from the Sun to the wireless link consisting of the Earth's location and the planet's location; The preset revolution model is a model constructed based on the Earth's revolution period, the planet's revolution period, the Earth-Sun distance between the Sun and the Earth, the Sun-Star distance between the Sun and the planet, and the Star-Earth distance between the planet and the Earth, which shows that the wireless link changes periodically as the planet and the Earth revolve. Based on the solar ray distance and a preset calculation formula, a scintillation index is calculated to assess the intensity of the coronal turbulence effect of the sun on the wireless link. The preset calculation formula is designed based on the definition of the scintillation index and the influence parameters affecting the intensity of coronal turbulence. Specifically, the definition of the scintillation index is the ratio of the root mean square value of the laser signal intensity fluctuation to the average value of the laser signal intensity. The influence parameters include at least the solar radius distance. The laser communication channel to be used is determined based on the flicker index.

2. The deep space laser communication encoding and decoding method as described in claim 1, characterized in that, The step of determining the laser communication channel to be used based on the scintillation index includes: If the flicker index is less than or equal to the first preset flicker threshold, then the AWGN channel is selected as the laser communication channel to be used. If the flicker index is greater than the first preset flicker threshold and less than or equal to the second preset flicker threshold, then according to the preset channel model based on GG distribution, the channel characteristic parameters corresponding to the flicker index are determined, and according to the channel characteristic parameters, the laser communication channel to be used is determined. The preset channel model based on the GG distribution is a channel model constructed based on the second-order Bessel function, the standard gamma function, the number of large-scale scatterers, and the number of small-scale scatterers to describe the light intensity fluctuation distribution at the signal receiver.

3. The deep space laser communication encoding and decoding method as described in claim 2, characterized in that, The step of determining the channel characteristic parameters corresponding to the scintillation index based on a preset channel model based on the GG distribution includes: Determine multiple threshold intervals between the first preset flicker threshold and the second preset flicker threshold; Determine the threshold range to which the flicker index belongs, and take the middle value in the threshold range as the channel feature parameter corresponding to the threshold range.

4. The deep space laser communication encoding and decoding method as described in claim 1, characterized in that, The step of performing LDPC ladder code encoding on the information symbol according to the encoding parameters to obtain the encoded symbol includes: According to the encoding parameters, the information symbols are divided into LDPC codes with a codeword length of N and a parity bit length of r; Based on the repeating coding subarray and the information bit subarray in the LDPC code, the information symbol is encoded row by row in a ladder manner, and the corresponding check bit subarray is obtained; wherein, the repeating coding subarray is an Nm row × m column matrix; The repeated coding subarray, the information bit subarray, and the check bit subarray are combined to form a ladder LDPC code block to obtain the encoded symbol.

5. The deep space laser communication encoding and decoding method as described in claim 4, characterized in that, The step of transmitting the symbol sequence to the receiving end through the laser communication channel, so that the receiving end can determine the decoding parameters corresponding to the laser communication channel, and demodulate and perform sliding window iterative decoding on the symbols according to the decoding parameters to obtain the decoded symbols, includes: The symbol sequence is transmitted to the receiving end through the laser communication channel, and the symbol sequence is demodulated; After demodulation, the decoding parameters corresponding to the laser communication channel are determined according to the decoder, and each step LDPC code block within a preset-sized sliding window is determined according to the decoding parameters. The step LDPC code blocks are then decoded line by line for a preset number of iterations to obtain the external information value. Based on the aforementioned extrinsic information values, the prior values ​​of each step LDPC code block are determined; Based on the prior value, each group of code blocks is recoded to obtain the output soft information value corresponding to each group of code blocks. Based on the output soft information value, an external information value corresponding to each group of code blocks is determined, and based on the external information value, each group of code blocks is iteratively decoded for a preset number of external iterations; wherein, the iterative decoding for the preset number of external iterations is a decoding process that iteratively updates the output soft information value corresponding to each group of code blocks. After the outer iteration is completed, the output soft information value obtained in the last outer iteration is determined, and the decoded symbol is obtained based on the output soft information value obtained in the last outer iteration. According to the preset number of steps, the position of the sliding window is adjusted, and the process returns to the step of decoding the ladder LDPC code block line by line for a preset number of iterations until the entire symbol sequence is decoded. In this process, after adjusting the position of the sliding window, the prior value of the code block in the current sliding window is determined by the extrinsic information value of the code block in the previous sliding window.

6. The deep space laser communication encoding and decoding method as described in claim 5, characterized in that, The step of recoding each group of code blocks according to the prior value to obtain the output soft information value corresponding to each group of code blocks includes: Based on the fixed information value of the ladder LDPC code block and the prior value, determine the decision sequence obtained by combining the fixed information value of each row and the prior value of each row for each ladder LDPC code block. The sequence to be decided is subjected to permutation processing, and the processed sequence is then re-encoded. Based on the codeword estimate with the lowest weighted Hamming distance generated by the OSD decoding algorithm, the results of the recoding process are weighted and accumulated to obtain the output soft information value.

7. The deep space laser communication encoding and decoding method as described in claim 5, characterized in that, The step of performing iterative decoding on each group of code blocks for a preset number of external iterations based on the external information value includes: Determine the extrinsic information value of the previous group of adjacent step LDPC code blocks within the current window; Based on the extrinsic information value, determine the prior value of the previous group of adjacent step LDPC code blocks; Based on the prior value, iteratively decode the previous group of adjacent step LDPC code blocks and update the extrinsic information value of the previous group of adjacent step LDPC code blocks. Based on the updated extrinsic information value, iteratively decode the next group of adjacent step LDPC code blocks in the current window, and sequentially decode each group of adjacent step LDPC code blocks in the current window according to the order of each group of code blocks. After each group of adjacent step LDPC code blocks has completed iterative decoding, the current number of iterations is determined. If the number is less than the preset number of external iterations, the process returns to the step of determining the external information value of the previous group of adjacent step LDPC code blocks in the current window, until the number equals the preset number of external iterations.

8. A deep-space laser communication encoding and decoding device, characterized in that, The device includes: a memory, a processor, and a deep space laser communication codec program stored in the memory and executable on the processor, the deep space laser communication codec program being configured to implement the steps of the deep space laser communication codec method as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a deep space laser communication encoding and decoding program, which, when executed by a processor, implements the steps of the deep space laser communication encoding and decoding method as described in any one of claims 1 to 7.

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