Method for reliably transmitting inter-satellite network data of small satellites

Abstract

The invention relates to a reliable transmission method for inter-satellite network data of small satellites, which comprises the following steps of: determining an error-correctable bit t of each packet of data during inter-satellite transmission, and determining a generator polynomial g (x) according to the length of a data packet needing to be protected and the t; the sender calculates a sending data code polynomial A (x) according to the information code polynomials c (x) and g (x) corresponding to the data packet and sends code elements to the receiver after coding is completed; the receiver generates a domain element according to the binary form of the g (x) and the order m of the minimum polynomial in the g (x); and a receiver calculates a syndrome according to the coefficient of the received code polynomial R (x) and the domain element, further calculates an error position polynomial sigma (x), solves the root of the error position polynomial by adopting a Chien search method, corrects the error position and completes inter-satellite data transmission, and the negative value of the exponent of the root is the error position of the received code element. According to the invention, reliable transmission of inter-satellite network data is realized, and inter-satellite broadcast network transmission of one-transmitting and multi-receiving is satisfied.

Description

Technical Field

[0001] The present invention belongs to the technical field of inter-satellite information transmission, and relates to a method for reliable transmission of small satellite inter-satellite network data. Background Art

[0002] Reliable intersatellite information transmission is fundamental to the formation or networking of small satellite constellations. Currently, intersatellite communications for small satellites utilize a reliable transmission mechanism based on error detection and retransmission to support applications such as network management, onboard processing, and intersatellite collaboration. The source and destination nodes collaborate to achieve end-to-end reliable transmission. Intersatellite messages sent by the source node contain check bits, such as CRC or cumulative sums. Upon receipt, the destination node verifies the received message and, if correct, sends a response packet to the source node. If the checksum is incorrect, no response packet is sent. After transmitting the message, the source node waits for feedback from the destination node regarding the message reception status. If the source node does not receive feedback from the destination node within a specified timeframe, it assumes that the message did not reach the destination node correctly. At this point, the source satellite retransmits the message. After reaching the maximum number of retransmissions (typically three), the transmission is considered abnormal and no further retransmissions are made. This status information is also communicated to the ground via telemetry data.

[0003] As the number of satellites in a constellation increases, the drawbacks of this error-detection and retransmission communication mechanism become increasingly apparent. First, this communication mechanism cannot be used over unidirectional channels; it requires a bidirectional channel to support retransmissions. Retransmitting erroneous packets not only requires a sufficiently large buffer, but also introduces system latency during retransmission, reducing the transmission efficiency of the communication system. In the event of severe channel interference, repeated retransmissions can effectively lead to communication interruption. Therefore, error-detection and retransmission communication systems cannot be used when real-time communication is required. Furthermore, error-detection and retransmission methods cannot be used in point-to-multipoint communication systems, such as intersatellite broadcast networks, because retransmission control is difficult to implement. Summary of the Invention

[0004] The technical problem solved by the present invention is to overcome the shortcomings of the existing technology and propose a method for reliable transmission of small satellite inter-satellite network data. BCH error correction coding and decoding are performed according to data length and reliability requirements to achieve reliable transmission of inter-satellite network data and meet the requirements of inter-satellite broadcast network transmission with one send and multiple receive.

[0005] The present invention solves the technical problem by providing a method for reliable transmission of data in a small satellite intersatellite network, comprising the following steps:

[0006] For both the sender and receiver of data transmission, the number of error-correctable bits t per packet of data during inter-satellite transmission is determined. The generating polynomial g(x) is determined based on the length of the data packet to be protected and the number of error-correctable bits t, where x is the symbol position.

[0007] The sender refers to the cyclic code encoding method, calculates the sending data code polynomial A(x) based on the information code polynomial c(x) and the generator polynomial g(x) corresponding to the data packet, completes the encoding, and sends the code element to the receiver;

[0008] The receiver generates GF(2 m ) domain element α i ,0≤i≤2 m -1;

[0009] During the transmission process, the receiver receives the code polynomial R(x) corresponding to the transmitted data code polynomial A(x). According to the coefficients of the received code polynomial R(x) and the generated GF(2 m ) domain element α i , calculate the syndrome;

[0010] The receiver calculates the error position polynomial σ(x) based on the value of the companion equation and uses the Qian search method to find the root of the error position polynomial. The exponent of the root is the position where the error occurs in the code element received by the receiver. The error position is corrected to complete the inter-satellite data transmission.

[0011] Furthermore, the method for determining the number of error-correctable bits t is as follows:

[0012] Assuming that the bit error rate of inter-satellite transmission data packets is p, the length of the inter-satellite transmission data packet is n, the probability of i-bit error in each data packet is:

[0013]

[0014] When no error correction measures are taken, the packet error rate of each data packet is:

[0015]

[0016] After adopting error correction measures, if each packet of data can correct t random errors, the packet error rate after decoding becomes:

[0017]

[0018] For the error detection and retransmission method, a reliable transmission is completed with a maximum of three handshakes, ignoring the error of the acknowledgment packet. The packet error rate P of the error detection and retransmission method is f3 The probability of failure in sending data packets three times is:

[0019] p f3 =p f 3

[0020] The packet error rate after selecting the error correction measure cannot be higher than the packet error rate of the error detection and retransmission method, so Pt ≤P f3 ,Right now:

[0021]

[0022] Calculate the above formula to get the value of t.

[0023] Furthermore, the method for determining the generating polynomial g(x) is as follows:

[0024] For BCH codes, the number of correctable errors is t bits, the check bit length is mt bits, and assuming the length of the information bits to be protected is L bits, we have:

[0025] 2 m -1≥L+mt

[0026] Calculate the above formula to get the value of m, where m is the order of the minimum polynomial in g(x);

[0027] For error correction codes with a capability of correcting tbit errors, the primitive BCH code is selected, and the generating polynomial satisfies the following form:

[0028] g(x)=m1(x)·m3(x)…m 2t-1 (x)

[0029] According to the calculated minimum polynomial order m, look up the reduced polynomial table and get each minimum polynomial m in g(x) i (x) form of expression.

[0030] Furthermore, the calculation method of the transmission data code polynomial A(x) is as follows:

[0031] x mt Multiply by the information code polynomial c(x) corresponding to the data packet code element, and then divide x by g(x) mt c(x), we get the quotient Q(x) and the remainder p(x), namely:

[0032] x mt c(x) / g(x)=Q(x)+p(x) / g(x)

[0033] Wherein, the remainder p(x) represents the check digit polynomial;

[0034] Then the transmitted data code polynomial A(x) is:

[0035] A(x)=x mt c(x)+p(x).

[0036] Furthermore, GF(2 m ) domain element α i The method is as follows:

[0037] α 0 The binary form is 0000 0000 0001. If α i-1 The highest bit of the binary form is 0, then α i-1 The binary form is shifted left by one bit, and the lowest bit is filled with 0 to get α i If α i-1 If the highest bit of α is 1, i-1 The binary form of is shifted left by one bit, the lowest bit is filled with 0, and then bitwise XORed with the binary form of the generating polynomial g(x), the result is α i The binary form of .

[0038] Furthermore, the received code polynomial R(x), if no error occurs during data transmission, the received code polynomial R(x)=A(x); if an error occurs during data transmission, then R(x)=A(x)+e(x), where e(x) is the error polynomial.

[0039] Furthermore, the method for calculating the syndrome is as follows:

[0040]

[0041] where j = 1, 3, ..., 2t-1; r i are the coefficients of the received code polynomial R(x).

[0042] Furthermore, the root of the error position polynomial is obtained by using the Qian search method, specifically: Substitute the error position polynomial σ(x) one by one to see if it is a root of σ(x).

[0043] Furthermore, if α i ,0≤i≤2 m -1 is the root of σ(x), indicating that α -i The code element position is wrong, so it is corrected by inverting it.

[0044] The beneficial effects of the present invention compared with the prior art are:

[0045] (1) The method proposed in the embodiment of the present invention replaces the original error control CRC or cumulative error detection code with BCH error correction code. For inter-satellite network data with a packet length of 512 bytes (the data to be protected is 506 bytes), the BCH code that can correct double-bit errors is selected based on comprehensive considerations of reliability and computational complexity. After the destination node of the inter-satellite network data receives the data, error detection and correction are performed to achieve reliable transmission of the inter-satellite network data and meet the requirements of point-to-multipoint inter-satellite broadcast network transmission. The method of the present invention can be used in an inter-satellite broadcast network with multiple receivers, while the existing detection and retransmission method cannot be used in an inter-satellite broadcast network.

[0046] (2) Since the present invention does not require a two-way handshake, it saves the response waiting time and the retransmission time, and its real-time performance is better than the existing error detection and retransmission method;

[0047] (3) When the bit error rate is 10 -4 ~10 -7 When the packet error rate of the present invention is lower than that of the error detection and retransmission method, the reliability is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a flow chart of a method for reliable transmission of data in a small satellite intersatellite network according to the present invention;

[0049] Figure 2 This is a flow chart of the data error detection and correction task according to an embodiment of the present invention;

[0050] Figure 3 The following are the error correction simulation test results of the embodiment of the present invention. DETAILED DESCRIPTION

[0051] like Figure 1 As shown, the present invention proposes a method for reliable transmission of small satellite intersatellite network data, comprising the following steps:

[0052] S1. For both the sender and receiver of data transmission, determine the number of error-correctable bits t per packet of data during inter-satellite transmission. Determine the generating polynomial g(x) based on the length of the data packet to be protected and the number of error-correctable bits t, where x is the symbol position.

[0053] S2. The sender refers to the cyclic code encoding method, calculates the sending data code polynomial A(x) based on the information code polynomial c(x) and the generator polynomial g(x) corresponding to the data packet, completes the encoding, and sends the code element to the receiver;

[0054] S3. The receiver generates GF(2 m ) domain element α i ,0≤i≤2 m -1;

[0055] S4. During the transmission process, the receiver receives the code polynomial R(x) corresponding to the transmitted data code polynomial A(x). According to the coefficients of the received code polynomial R(x) and the generated GF(2 m ) domain element α i , calculate the syndrome;

[0056] S5. The receiver calculates the error position polynomial σ(x) based on the value of the companion equation and uses the Qian search method to find the root of the error position polynomial. The exponent of the root is the position where the error occurs in the code element received by the receiver. The error position is corrected to complete the inter-satellite data transmission.

[0057] The method for determining the number of error-correctable bits t in step S1 is as follows:

[0058] Assuming that the bit error rate of inter-satellite transmission data packets is p, the length of the inter-satellite transmission data packet is n, the probability of i-bit error in each data packet is:

[0059]

[0060] When no error correction measures are taken, the packet error rate of each data packet is:

[0061]

[0062] After adopting error correction measures, if each packet of data can correct t random errors, the packet error rate after decoding becomes:

[0063]

[0064] If an error correction measure with an error correction capability of t=1 is used, the packet error rate is:

[0065]

[0066] If an error correction measure with an error correction capability of t=2 is used, the packet error rate is:

[0067]

[0068] For the error detection and retransmission method, a reliable transmission is completed, usually up to three handshakes are required, ignoring the error of the response packet. The packet error rate P of the error detection and retransmission method is f3 The probability of failure in sending data packets three times is:

[0069] p f3 =p f 3

[0070] The packet error rate after selecting the error correction measure cannot be higher than the packet error rate of the error detection and retransmission method, so P t ≤P f3 ,Right now:

[0071]

[0072] Calculate the above formula to get the value of t.

[0073] The method for determining the generating polynomial g(x) in step S1 is as follows:

[0074] The generating polynomial is determined based on the length of the data packet to be protected and the number of error-correctable bits t. For BCH codes, the number of error-correctable bits is t bits, the check bit length is mt bits, and assuming the length of the information bits to be protected is L bits, based on the characteristics of BCH coding, we have:

[0075] 2 m -1≥L+mt

[0076] Calculate the above formula to get the value of m, where m is the order of the minimum polynomial in g(x).

[0077] For error correction codes with a capability of correcting tbit errors, the primitive BCH code is selected, and the generating polynomial satisfies the following form:

[0078] g(x)=m1(x)·m3(x)…m 2t-1 (x)

[0079] According to the calculated minimum polynomial order m, look up the reduced polynomial table and get each minimum polynomial m in g(x) i (x) form of expression.

[0080] The calculation method of the data code polynomial A(x) sent in step S2 is as follows:

[0081] Referring to the cyclic code encoding method, first x mt Multiply by the information code polynomial c(x) corresponding to the data packet code element, and then divide x by g(x) mt c(x), we get the quotient Q(x) and the remainder p(x), namely:

[0082] x mt c(x) / g(x)=Q(x)+p(x) / g(x)

[0083] Wherein, the remainder p(x) represents the check digit polynomial.

[0084] Finally, the transmitted data code polynomial is obtained:

[0085] A(x)=x mt c(x)+p(x)

[0086] Step S3 generates GF(2 m ) domain element as follows:

[0087] Each domain element has an exponential form and a binary form. During the decoding calculation process, the exponential form and the binary form of the domain element must be frequently converted to each other. Therefore, the corresponding relationship between the exponential form and the binary form of the domain element must be established.

[0088] α 0The binary form is 0000 0000 0001. If α i-1 The highest bit of the binary form is 0, then α i-1 The binary form is shifted left by one bit, and the lowest bit is filled with 0 to get α i If α i-1 If the highest bit of α is 1, i-1 The binary form of is shifted left by one bit, the lowest bit is filled with 0, and then bitwise XORed with the binary form of the generating polynomial g(x), the result is α i The binary form of .

[0089] GF(2 m ) The operations on the domain elements mainly include addition, multiplication, and inversion of domain elements. For addition, just add the binary form of the two domain elements bit by bit. For multiplication, add the exponential form of the two domain elements and then add them to the value of 2. m -1 modulo as the exponent of the exponential form of the product, that is For the inversion operation, negate the exponent of the field element exponential form and then press 2 m Just take -1 modulo as the exponent of the inverse element.

[0090] In step S4, if no error occurs during data transmission, the received code polynomial R(x)=A(x); if an error occurs during data transmission, then R(x)=A(x)+e(x), where e(x) is the error polynomial.

[0091] In step S4, for a BCH code with t error-correctable bits, according to the coefficient of R(x) and GF(2 m ) domain element α i , the method to calculate the syndrome is as follows:

[0092]

[0093] where j = 1, 3, ..., 2t-1; r i are the coefficients of the received code polynomial R(x).

[0094] In step S5, the error location polynomial satisfies the following form:

[0095] σ(x)=1+σ1x+σ2x 2 +…+σ t x t

[0096] Among them, σ1, σ2,…, σ t are the coefficients of the error location polynomial.

[0097] In step S5, the root of the error position polynomial is obtained by using the Qian search method. Substitute into σ(x) one by one to see if it is a root of σ(x). If α i ,0≤i≤2 m -1 is a root of σ(x), which means that α -i If the position of the code element is wrong, it can be corrected by inverting it. The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0098] Example 1

[0099] like Figure 1 As shown, this embodiment selects a double-bit error-correctable BCH code for inter-satellite network data with a packet length of 512 bytes (the data to be protected is 506 bytes) by comprehensively considering reliability and computational complexity. After the destination node of the inter-satellite network data receives the data, it performs error detection and correction to achieve reliable transmission of the inter-satellite network data and meet the requirements of point-to-multipoint inter-satellite broadcast network transmission.

[0100] The steps of the reliable data transmission method for small satellite intersatellite network are as follows:

[0101] S1. For both the sender and receiver of data transmission, determine the number of error-correctable bits t per data packet during inter-satellite transmission, and determine the generating polynomial g(x) based on the length of the data packet to be protected and the number of error-correctable bits t.

[0102] The method for determining the number of correctable error bits t is as follows:

[0103] Assuming that the bit error rate of inter-satellite transmission data packets is p, the length of the inter-satellite transmission data packet is n, the probability of i-bit error in each data packet is:

[0104]

[0105] When no error correction measures are taken, the packet error rate of each data packet is:

[0106]

[0107] After adopting error correction measures, if each packet of data can correct t random errors, the packet error rate after decoding becomes:

[0108]

[0109] If an error correction measure with an error correction capability of t=1 is used, the packet error rate is:

[0110]

[0111] If an error correction measure with an error correction capability of t=2 is used, the packet error rate is:

[0112]

[0113] For the error detection and retransmission method, a reliable transmission is completed, usually up to three handshakes are required, ignoring the error of the response packet. The packet error rate P of the error detection and retransmission method is f3 The probability of failure in sending data packets three times is:

[0114] p f3 =p f 3

[0115] The packet error rate after selecting the error correction measure cannot be higher than the packet error rate of the error detection and retransmission method, so P t ≤P f3 ,Right now:

[0116]

[0117] For an intersatellite network data packet with a packet length of 512 bytes (the data to be protected is 506 bytes), the above formula calculates that the number of error-correctable bits t=2.

[0118] The method for determining the generating polynomial g(x) is as follows:

[0119] For BCH code, the number of correctable errors is t bit, the check bit length is mt bit, and it is assumed that the length of the information bit to be protected is L bit. According to the characteristics of BCH coding,

[0120] 2 m -1≥L+mt

[0121] Since the length of an intersatellite network data packet is 512 bytes, after deducting the 4-byte packet synchronization word and the original 2-byte check bit, the data packet length that needs to be protected is L = 4048 bits (506 bytes). Since t = 2, substituting the minimum polynomial order m into the above formula yields 12.

[0122] This embodiment selects an error correction code that corrects 2-bit errors, so the generating polynomial satisfies the following form:

[0123] g(x)=m1(x)*m3(x)

[0124] In addition, the order m = 12, and by looking up the reduced polynomial table, we can get the 12th-order minimum polynomial:

[0125] m1(x)=(10123)8=x 12 x 6 +x 4 +x 1 +1

[0126] m3(x)=(12133)8=x 12 =x 10 +x 6 +x4 +x 3 +x 1 +1

[0127] Therefore, the generating polynomial g(x) is:

[0128] g(x)=x 24 +x 22 +x 16 +x 15 +x 14 +x 12 +x 11 +x 9 +x 8 +x 7 +x 3 +x 2 +1.

[0129] S2. The sender refers to the cyclic code encoding method, calculates the sending data code polynomial A(x) based on the information code polynomial c(x) and the generating polynomial g(x) corresponding to the data packet, completes the encoding, and then sends the code element to the receiver.

[0130] Referring to the cyclic code encoding method, first x mt Multiply by the information code polynomial c(x) corresponding to the data packet code element, and then divide x by g(x) mt c(x), we get the quotient Q(x) and the remainder p(x), namely:

[0131] x mt c(x) / g(x)=Q(x)+p(x) / g(x)

[0132] Finally, the transmitted data code polynomial is obtained:

[0133] A(x)=x mt c(x)+p(x)

[0134] S3. The receiver generates GF(2 m ) domain element α i ,0≤i≤2 m -1.

[0135] Each domain element has an exponential form and a binary form. During the decoding calculation process, the exponential form and the binary form of the domain element must be frequently converted to each other. Therefore, the corresponding relationship between the exponential form and the binary form of the domain element must be established.

[0136] α 0 The binary form is 0000 0000 0001. If α i-1 The highest bit of the binary form is 0, then αi-1 The binary form is shifted left by one bit, and the lowest bit is filled with 0 to get α i If α i-1 If the highest bit of α is 1, i-1 The binary form of is shifted left by one bit, the lowest bit is filled with 0, and then bitwise XORed with the binary form of the generating polynomial g(x), the result is α i The binary form of .

[0137] GF(2 12 ) The domain elements are shown in Table 1.

[0138] Table 1

[0139] Primitive domain element representation α polynomial 12-fold vector <![CDATA[α 0 =1]]> <![CDATA[α 0 ]]> 0000 0000 0001 α α 0000 0000 0010 <![CDATA[α 2 ]]> <![CDATA[α 2 ]]> 0000 0000 0100 ┅ ┅ ┅ <![CDATA[α 11 ]]> <![CDATA[α 11 ]]> 1000 0000 0000 <![CDATA[α 12 ]]> <![CDATA[α 6 +a 4 +a+1]]> 0000 0101 0011 <![CDATA[α 13 ]]> <![CDATA[α 7 +a 5 +a 2 +a]]> 0000 1010 0110 --- --┅ --- <![CDATA[α 4095 =1]]> <![CDATA[α 0 ]]> 0000 0000 0001

[0140] S4. During the transmission process, the receiver receives the code polynomial R(x) corresponding to the transmitted data code polynomial A(x). According to the coefficients of the received code polynomial R(x) and the generated GF(2 m ) domain element α i , calculate the syndrome.

[0141] This embodiment selects a BCH code with a correctable error bit number t of 2, so the required syndromes are S1 and S3.

[0142] The received code group is represented by a polynomial, where each code element represents the coefficient of the polynomial R(x). The received code polynomial is R(x)=r n-1 x n-1 +r n-2 x n-2 +…+r0x 0 ,but:

[0143]

[0144] S5. The receiver calculates the error position polynomial σ(x) based on the value of the companion equation and uses the Qian search method to find the root of the error position polynomial. The exponent of the root is the position where the error occurs in the code element received by the receiver. The error position is corrected to complete the inter-satellite data transmission.

[0145] like Figure 2 As shown, the error position polynomial σ(x) is calculated by the syndromes S1 and S3:

[0146] The present invention focuses on correcting errors of 2 bits or less, so the error location polynomial satisfies the following form:

[0147] σ(x)=1+σ1x+σ2x 2

[0148] There are three specific situations:

[0149] If S1 = 0, the error location polynomial is σ(x) = 1, corresponding to the error-free case;

[0150] If S1≠0, For 1 error, the error location polynomial is σ(x)=1+S1x

[0151] If S1≠0, Corresponding to the 2-error case, the error location polynomial is

[0152]

[0153] The Qian search method is used to find the root of the error position polynomial. Substitute into σ(x) one by one to see if it is a root of σ(x). If α i ,0≤i≤2 m -1 is a root of σ(x), which means that α -i If the code element position is wrong, it can be corrected.

[0154] The simulation test results are as follows Figure 3 As shown, it can be seen that the packet error rate of the method of this embodiment (red line) is significantly lower than that of the unprocessed method and the error detection and retransmission method, and the reliability of small satellite inter-satellite transmission is higher.

[0155] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

[0156] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for reliable transmission of small satellite intersatellite network data, characterized in that: The following steps are involved: For both the sender and receiver of data transmission, the number of error-correctable bits t per packet of data during inter-satellite transmission is determined. The generating polynomial g(x) is determined based on the length of the data packet to be protected and the number of error-correctable bits t, where x is the symbol position. The sender refers to the cyclic code encoding method, calculates the sending data code polynomial A(x) based on the information code polynomial c(x) and the generator polynomial g(x) corresponding to the data packet, completes the encoding, and sends the code element to the receiver; The receiver generates GF(2 m ) domain element α i ,0≤i≤2 m -1; During the transmission process, the receiver receives the code polynomial R(x) corresponding to the transmitted data code polynomial A(x). According to the coefficients of the received code polynomial R(x) and the generated GF(2 m ) domain element α i , calculate the syndrome; The receiver calculates the error position polynomial σ(x) based on the value of the companion equation and uses the Qian search method to find the root of the error position polynomial. The exponent of the root is the position where the error occurs in the code element received by the receiver. The error position is corrected to complete the inter-satellite data transmission.

2. The method for reliable transmission of small satellite intersatellite network data according to claim 1, characterized in that: The method for determining the number of error-correctable bits t is as follows: Assuming that the bit error rate of inter-satellite transmission data packets is p, the length of the inter-satellite transmission data packet is n, the probability of i-bit error in each data packet is: When no error correction measures are taken, the packet error rate of each data packet is: After adopting error correction measures, if each packet of data can correct t random errors, the packet error rate after decoding becomes: For the error detection and retransmission method, a reliable transmission is completed with a maximum of three handshakes, ignoring the error of the acknowledgment packet. The packet error rate P of the error detection and retransmission method is f3 The probability of failure in sending data packets three times is: p f3 =p f 3 The packet error rate after selecting the error correction measure cannot be higher than the packet error rate of the error detection and retransmission method, so P t ≤P f3 ,Right now: Calculate the above formula to get the value of t.

3. The method for reliable transmission of small satellite intersatellite network data according to claim 1, characterized in that: The method for determining the generating polynomial g(x) is as follows: For BCH codes, the number of correctable errors is t bits, the check bit length is mt bits, and assuming the length of the information bits to be protected is L bits, we have: 2 m -1≥L+mt Calculate the above formula to get the value of m, where m is the order of the minimum polynomial in g(x); For error correction codes with a capability of correcting tbit errors, the primitive BCH code is selected, and the generating polynomial satisfies the following form: g(x)=m1(x)·m3(x)…m 2t-1 (x) According to the calculated minimum polynomial order m, look up the reduced polynomial table and get each minimum polynomial m in g(x) i (x) form of expression.

4. The method for reliable transmission of small satellite intersatellite network data according to claim 3, characterized in that: The calculation method of the transmission data code polynomial A(x) is as follows: x mt Multiply by the information code polynomial c(x) corresponding to the data packet code element, and then divide x by g(x) mt c(x), we get the quotient Q(x) and the remainder p(x), namely: x mt c(x) / g(x)=Q(x)+p(x) / g(x) Wherein, the remainder p(x) represents the check digit polynomial; Then the transmitted data code polynomial A(x) is: A(x)=x mt c(x)+p(x)。 5. The method for reliable transmission of small satellite intersatellite network data according to claim 1, characterized in that: Generate GF(2 m ) domain element α i The method is as follows: α 0 The binary form is 0000 0000 0001. If α i-1 The highest bit of the binary form is 0, then α i-1 The binary form is shifted left by one bit, and the lowest bit is filled with 0 to get α i If α i-1 If the highest bit of α is 1, i-1 The binary form of is shifted left by one bit, the lowest bit is filled with 0, and then bitwise XORed with the binary form of the generating polynomial g(x), the result is α i The binary form of .

6. The method for reliable transmission of small satellite intersatellite network data according to claim 1, characterized in that: The received code polynomial R(x), if no error occurs during data transmission, the received code polynomial R(x)=A(x); if an error occurs during data transmission, then R(x)=A(x)+e(x), where e(x) is the error polynomial.

7. The method for reliable transmission of small satellite intersatellite network data according to claim 1, characterized in that: The method to calculate the syndrome is as follows: where j = 1, 3, ..., 2t-1; r i are the coefficients of the received code polynomial R(x).

8. The method for reliable transmission of small satellite intersatellite network data according to claim 1, characterized in that: The root of the error position polynomial is obtained by using the Qian search method, specifically: Substitute the error position polynomial σ(x) one by one to see if it is a root of σ(x).

9. The method for reliable transmission of small satellite intersatellite network data according to claim 8, characterized in that: If α i ,0≤i≤2 m -1 is the root of σ(x), indicating that α -i The code element position is wrong, so it is corrected by inverting it.

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