Space-air anti-interference method and system based on TH code packet bit interleaving coding modulation

Abstract

The application discloses a space anti-interference method and system based on TH code packet bit interleaving coding modulation, and belongs to the field of anti-interference digital signal processing.The application comprises a low code rate TH code coding unit, a bit level interleaver unit, an M-QAM mapping unit, a frequency hopping unit, an interference detection unit, a frequency hopping resolution unit, an M-QAM demapping unit, a deinterleaver unit and a low code rate TH code decoding unit.The application utilizes the error correction ability of Turbo code approaching Shannon limit and the low code rate structure of Hadamard code, and realizes extremely low code rate and extremely high coding gain in a strong interference environment through parallel concatenated convolution Hadamard code.Adopting high order modulation improves the communication efficiency of the system, and adopting bit level coding modulation method combines low code rate coding and decoding and high order modulation and demodulation, disperses continuous bit errors caused by interference, reduces the risk of error aggregation, and further enhances the stability and reliability of the system in a changeable electromagnetic environment.The application is especially suitable for a communication system which needs anti-interference and has high demand for communication rate.

Description

TECHNICAL FIELD

[0001] The application relates to a Turbo-Hadamard (TH) code-based anti-jamming method and system for air-ground Bit-Interleaved Coded Modulation (BICM), in particular to a low-code-rate TH code coding and decoding method, a high-order QAM modulation method, and a method for improving the anti-jamming performance of a system by using bit interleaved coded modulation, and belongs to the field of anti-jamming digital signal processing. BACKGROUND

[0002] In modern communication systems, the anti-jamming capability is a crucial factor to ensure the stability and reliability of information transmission. With the rapid development of communication technology and the diversification of application scenarios, communication systems not only face various challenges from environmental and malicious interference sources, but also must meet the demand for high-speed transmission. In the air-ground cooperative scenario, these challenges are more complex and severe. Air-ground cooperative communication involves efficient communication between ground devices and air devices, and the ground devices may be affected by various interference sources, including electromagnetic interference, spectrum congestion, weather influence, etc. These interference sources may cause signal quality degradation, communication interruption or data loss, thereby threatening the reliability of the entire communication system. In this context, it is crucial to design a system that can have strong anti-jamming capability while maintaining high-speed communication.

[0003] Traditional frequency hopping anti-jamming systems usually use spectrum spreading technology to spread the signal to a wider frequency band in the frequency domain to improve the anti-jamming performance. However, this method has serious problems in communication efficiency because spectrum spreading causes the signal power to be dispersed within the frequency band, reducing the energy efficiency of transmission. Therefore, finding a new type of anti-jamming communication system that can effectively resist various interferences while maintaining high communication efficiency has become an important research direction in the current communication field. The design of a new generation of anti-jamming system needs to consider multiple aspects of signal processing, modulation and demodulation, coding and decoding, etc., to achieve high-speed communication in a highly interfered environment. The integration of these technologies will help improve the anti-jamming performance of the system while maintaining high communication efficiency. SUMMARY

[0004] To solve the problem that traditional frequency hopping anti-jamming systems cannot have both high information efficiency and anti-jamming capability, the purpose of the present application is to provide a Turbo-Hadamard (TH) code-based anti-jamming method and system for air-ground Bit-Interleaved Coded Modulation (BICM), which uses a low-code-rate coding and decoding method to improve the anti-jamming capability of the communication system, uses high-order modulation to improve the communication efficiency of the low-code-rate coding anti-jamming system, and further improves the anti-jamming capability of the system by introducing a bit interleaved coded modulation method, thereby obtaining stronger anti-jamming capability than existing systems with the same information efficiency.

[0005] The application aims at the following technical scheme.

[0006] The application discloses an air-ground anti-interference method and system based on TH code grouping bit interleaved coded modulation, which utilizes the error correction ability of Turbo code approaching Shannon limit and the low code rate structure of Hadamard code, realizes extremely low code rate and extremely high coding gain in a strong interference environment through parallel concatenated convolution Hadamard code, adopts high-order modulation to improve the communication efficiency of the system, and adopts bit interleaved coded modulation method to combine low code rate coding and decoding and high-order modulation and demodulation, effectively disperses continuous bit errors caused by interference, reduces the risk of error aggregation, and further enhances the stability and reliability of the system in a variable electromagnetic environment.

[0007] The air-ground anti-interference method based on TH code grouping bit interleaved coded modulation disclosed by the application comprises the following steps:

[0008] Step one: determining the original information sequence length N, Hadamard order r and component code number H, performing low code rate TH code coding on the original information sequence to obtain a low code rate TH code word.

[0009] The low code rate TH code coding in step one is composed of parallel concatenated convolution Hadamard code. When coding, the information bit stream with a length of N is first divided into r-bit blocks for parity check, the check bits are subjected to convolution coding with a code rate of 1, the original information bits and the output of the convolution coder are combined, and Hadamard coding is performed to obtain convolution Hadamard code.

[0010] The H-path component code outputs are subjected to puncturing and merging to obtain the final low code rate TH code coding result, and the code rate calculation formula is as follows:

[0011]

[0012] Wherein, H represents the number of component codes, and r is the order of Hadamard code.

[0013] Step two: using a bit interleaved coded modulation method to perform bit interleaving on the low code rate TH code word to obtain sufficient time domain diversity effect under the low code rate characteristics of the TH code word.

[0014] The specific implementation mode of the bit interleaved coded modulation in step two is: performing serial-parallel conversion on the coding result to obtain log2 M parallel coding results, using log2 M interleavers to perform bit-level interleaving on the coding results to obtain a to-be-mapped code word.

[0015] The bit interleaved coded modulation disperses the continuous bit errors caused by the partial band interference. The bit interleaved coded modulation ensures that even in the case of partial band jamming, the interference is evenly distributed in the whole data stream, avoiding the generation of piece errors due to the aggregation of interference at the receiver, thereby improving the anti-interference performance of the communication system.

[0016] Step three: M-QAM mapping is performed on the log2 M parallel to-be-mapped code words.

[0017] The M-QAM mapping in step three adopts Gray mapping, which maps the data that has been encoded and subjected to diversity processing to M-QAM symbols. The mapping process is shown in formula (2):

[0018] S = f(B) (2)

[0019] Wherein, S is the M-QAM symbol, B is the bit group to be mapped, and f is the mapping function.

[0020] The bit group is converted into the corresponding M-QAM symbol through formula (2).

[0021] Step four: the signal subjected to low code rate TH channel coding, bit interleaved coded modulation, and frequency hopping processing is sent to the partial band interference channel.

[0022] Step five: the signal sent in step four is received, and the received signal at the disturbed frequency point is subjected to zero processing according to the interference detection result.

[0023] The interference detection in step five determines whether there is interference and the interference position according to the characteristics of the interference signal. From the frequency domain analysis of the received signal, for partial band interference, the received signal amplitude exceeds the preset interference judgment threshold value in the frequency domain in the partial band. The interference position is determined according to the above judgment criterion, and the disturbed bit is subjected to zero processing.

[0024] Step six: the signal subjected to interference detection and zero processing is subjected to de-hopping and demapping processing.

[0025] Step seven: a de-interleaver corresponding to the sending end is used to perform de-interleaving operation on the soft information output of the demapping, and a to-be-coded sequence is obtained through parallel-to-serial conversion.

[0026] Step eight: the to-be-coded sequence in step seven is subjected to iterative decoding of the low code rate TH code, and the judgment result of the information sequence is obtained after the iteration is completed.

[0027] The decoding of the TH code in step eight adopts the Max-Log-MAP algorithm to simplify the soft information L k (i) of the decoding output, and adopts the first layer fast Hadamard transform FHT to simplify the branch metric The forward metrics in the soft information are recursively calculated by using the BCJR algorithm and the backward metrics The forward metrics in the soft information are recursively calculated by using the BCJR algorithm The sum of the forward metrics and the backward metrics is δ k The FHT with the second layer of simplification is used to calculate δ k The maximum value is obtained by sorting and subtraction operation The final output is the decision result. The decoding of the low-rate TH code is realized with low complexity by combining various simplification algorithms.

[0028] The basic decoding criterion is:

[0029]

[0030] The soft information L is simplified by using the Max-Log-MAP algorithm k (i):

[0031]

[0032] The Max-log-MAP algorithm converts the metric value involved in the decoding of the TH code into the logarithmic domain, and converts the multiplication operation into addition operation, thereby simplifying the decoding process.

[0033] The branch metrics are simplified by using the first layer of fast Hadamard transform (FHT) The FHT converts the matrix multiplication operation into addition operation, and has the efficiency similar to the FFT, thereby significantly reducing the decoding complexity.

[0034] The forward metrics are recursively calculated by using the BCJR algorithm and the backward metrics

[0035]

[0036]

[0037] The branch metrics are recursively calculated by using the BCJR algorithm k (±h j ):

[0038]

[0039] The FHT with the second layer of simplification is used to calculate δ k The maximum value is obtained by sorting and subtraction operation The final output is the decision result:

[0040]

[0041] Step nine: the interference is evenly distributed in the whole data stream by using the bit interleaving coding modulation method in step two, so that the receiver is prevented from generating a piece error due to the gathered interference, thereby improving the anti-interference performance of the communication system; step five: the interference is detected and zeroed, so as to delete the interference as much as possible before processing the received signal; and step eight: the iterative decoding of the low code rate TH code is performed, and the uninterfered bits assist the interfered bits to converge to the correct judgment result in the iterative process, so as to reduce the bit error rate of the communication system and improve the anti-interference performance of the system.

[0042] The application discloses a TH code-based grouping bit interleaving coding modulation space-ground anti-interference system, which is used for realizing the TH code-based grouping bit interleaving coding modulation space-ground anti-interference method.

[0043] The low code rate TH code coding unit is used for coding original information bits by using a low code rate TH code, and transmitting the low code rate TH code word obtained after coding to the bit-level interleaver unit.

[0044] The bit-level interleaver unit is used for interleaving the low code rate TH code word, obtaining the to-be-mapped code word after the order is disturbed, and transmitting the to-be-mapped code word to the M-QAM mapping unit.

[0045] The M-QAM mapping unit is used for performing M-QAM mapping on the to-be-mapped code word, obtaining a QAM mapping symbol, and transmitting the QAM mapping symbol to the frequency hopping unit.

[0046] The frequency hopping unit is used for performing frequency hopping processing on the mapping symbol, obtaining a sending sequence, and sending the sending sequence to an interference channel.

[0047] The interference detection unit is used for performing interference detection and zeroing processing on the signal received from the channel, and transmitting the signal after the interference position is zeroed to the frequency hopping unit.

[0048] The frequency hopping unit is used for performing frequency hopping processing on the mapping symbol, obtaining a sending sequence, and sending the sending sequence to an interference channel.

[0049] The M-QAM demapping unit is used for performing demapping on the signal after frequency hopping, and transmitting the soft information output after demapping to the deinterleaver unit.

[0050] The deinterleaver unit is used for performing deinterleaving processing on the soft information output after demapping, and transmitting the signal after deinterleaving to the low code rate TH code decoding unit.

[0051] The low code rate TH code decoding unit is used for iterative decoding processing on the deinterleaved signal, and outputs a final decoding result after multiple iterations.

[0052] Advantages:

[0053] 1. The TH code-based grouping bit interleaving coding modulation space-ground anti-interference method and system disclosed in the application can fully disperse interference by using a bit interleaving coding modulation method, improve the reliability of the system in a strong interference environment, and is suitable for a communication system in a strong noise or strong interference electromagnetic environment.

[0054] 2. Compared with traditional Turbo code, LDPC code and Polar code, the TH code is selected as the channel coding in the TH code-based grouping bit interleaving coding modulation space-ground anti-interference method and system, the number of orders or component codes is increased to realize low code rate, max approximation and double fast Hadamard transform are used to simplify the decoding algorithm, the method has the advantages of low code rate, simple realization structure, low decoding complexity, low resource consumption and easy hardware implementation.

[0055] 3. Compared with a traditional frequency hopping anti-interference system, the TH code-based grouping bit interleaving coding modulation space-ground anti-interference method and system realizes anti-interference by using low code rate combined with high-order modulation, realizes anti-interference by using the gain of a low code rate coding scheme, and compensates for the reduction in the rate of the communication system by using high-order modulation, so that the method has a higher communication rate compared with a traditional anti-interference system and is suitable for a communication system that needs anti-interference and has a high demand for communication rate. BRIEF DESCRIPTION OF DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings needed to be used by the application. The drawings described in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0057] Figure 1 TH code-based grouping bit interleaving coding modulation anti-interference method block diagram.

[0058] Figure 2 TH code-based grouping bit interleaving coding modulation anti-interference system module diagram.

[0059] Figure 3 The bit error rate curve diagram of information bit length 200, code rate 1 / 10 (r=4) or 17.2 (r=5) through an AWGN channel under different orders and different numbers of component codes by using different algorithms. Figure 3 (a) is a bit error rate curve diagram using a 4-order Hadamard matrix coding, Figure 3(b) is a bit error rate curve chart of using 5-order Hadamard matrix coding.

[0060] Figure 4 The information bit length is 256 (r=4) or 255 (r=5), the code rate is 1 / 8, the number of component codes is 3, and the bit error rate curves of different algorithms under different orders and different noise proportions are shown in the following figures. Figure 4 (a) is a bit error rate curve chart of using 4-order Hadamard matrix coding, Figure 4 (b) is a bit error rate curve chart of using 5-order Hadamard matrix coding.

[0061] Figure 5 The information bit length is 256, and the bit error rate curves of the method of the application and the traditional LDPC-BPSK method under different noise proportions are shown in the following figures. DETAILED DESCRIPTION

[0062] Embodiment 1

[0063] As shown in Figure 1 (a) and Figure 1 (b), the anti-jamming method for TH code-based group bit interleaved coded modulation space disclosed in the embodiment comprises the following steps:

[0064] Step 1: Determine the original information sequence length N, Hadamard order r and the number of component codes H, and perform low code rate TH code encoding on the original information sequence to obtain a low code rate TH code word.

[0065] The low code rate TH code encoding in step 1 is composed of parallel concatenated convolutional Hadamard codes. When encoding, the information bit stream with a length of N is first divided into blocks of r bits for parity check, the check bits are subjected to a convolutional encoder with a code rate of 1, the original information bits and the output of the convolutional encoder are combined, and Hadamard encoding is performed to obtain a convolutional Hadamard code.

[0066] The H-path component code outputs are combined by puncturing to obtain the final low code rate TH code encoding result, and the calculation formula of the code rate is as follows:

[0067]

[0068] Wherein, H represents the number of component codes, and r is the order of Hadamard code.

[0069] Step 2: Use the bit interleaved coded modulation method to perform bit interleaving on the low code rate TH code word, and obtain sufficient time domain diversity effect under the low code rate characteristics of the TH code word through interleaving.

[0070] The specific implementation of the bit interleaved coded modulation in step two is: converting the coded result into serial-parallel conversion to obtain log2M parallel coded results, and using log2M interleavers to perform bit-level interleaving on the coded results to obtain the to-be-mapped code word.

[0071] The bit interleaved coded modulation is used to disperse the continuous bit errors caused by the partial band interference. The bit interleaved coded modulation ensures that even in the case of partial band jamming interference, the interference is uniformly distributed in the entire data stream, avoids the generation of piece errors due to the aggregation of interference at the receiver, and thus improves the anti-interference performance of the communication system.

[0072] Step three: performing M-QAM mapping on the log2M parallel to-be-mapped code words.

[0073] The M-QAM mapping in step three uses Gray mapping to map the coded and diversity-processed data to M-QAM symbols. The mapping process is shown in formula (2):

[0074] S = f(B) (2)

[0075] Wherein, S is the M-QAM symbol, B is the to-be-mapped bit group, and f is the mapping function.

[0076] The bit group is converted into the corresponding M-QAM symbol through formula (2).

[0077] Step four: sending the signal processed by the low code rate TH channel coding, bit-level interleaved coded modulation, and frequency hopping to the partial band interference channel.

[0078] Step five: receiving the signal sent in step four, and performing zero processing on the received signal at the disturbed frequency point according to the interference detection result.

[0079] The interference detection in step five determines whether there is interference and the interference position according to the characteristics of the interference signal. From the frequency domain analysis of the received signal, for partial band interference, the received signal amplitude exceeds the preset interference judgment threshold value in the frequency domain. The interference position is determined according to the above judgment criterion, and the disturbed bit is zero processed.

[0080] Step six: performing de-hopping and de-mapping processing on the signal after interference detection and zero processing.

[0081] Step seven: using a corresponding de-interleaver group at the sending end to perform de-interleaving operation on the soft information output of the de-mapping, and obtaining the to-be-decoded sequence through serial-parallel conversion.

[0082] Step eight: performing iterative decoding on the to-be-decoded sequence in step seven using the low code rate TH code, and obtaining the judgment result of the information sequence after the iteration is completed.

[0083] Step eight, the decoding of TH code, uses Max-Log-MAP algorithm to simplify the output soft information L k (i) ; the first layer of FHT is used to simplify the branch metric in the above soft information Operation; the forward metric in the above soft information is recursively calculated by using BCJR algorithm and the backward metric By summing up to get δ k , the second layer of FHT is used to simplify the output of δ k classification to get the maximum value, and subtraction operation to get the final output decision result. By combining various simplification algorithms, the decoding of low code rate TH code is realized with low complexity.

[0084] The basic decoding criterion is:

[0085]

[0086] Max-Log-MAP algorithm is used to simplify the output soft information L k (i) :

[0087]

[0088] Max-log-MAP algorithm converts the metric value involved in the decoding of TH code to the logarithmic domain, and converts the multiplication operation to addition operation, thereby simplifying the decoding process.

[0089] The first layer of FHT is used to simplify the branch metric Operation, FHT converts the matrix multiplication operation to addition operation, and its efficiency is similar to FFT, which can significantly reduce the decoding complexity.

[0090] The forward metric is recursively calculated by using BCJR algorithm and the backward metric

[0091]

[0092]

[0093] Based on the branch merging of state transition graph, δ k (±h j ) is calculated:

[0094]

[0095] The second layer of FHT is used to simplify the output of δ k of the previous step Final output decision result:

[0096]

[0097] Step nine: the interference is evenly distributed in the whole data stream by using the bit interleaving coding modulation method in step two, so that the piece error is avoided due to the gathered interference, thereby improving the anti-interference performance of the communication system; step five detects and zeroes the interference, so as to delete the interference as much as possible before processing the received signal; and step eight performs the iterative decoding of the low code rate TH code, so that the disturbed bits converge to the correct decision result under the assistance of the undisturbed bits in the iterative process, thereby reducing the error rate of the communication system and improving the anti-interference performance of the system.

[0098] The application discloses a TH code-based grouping bit interleaving coding modulation space-ground anti-interference system, which is used for realizing the TH code-based grouping bit interleaving coding modulation space-ground anti-interference method. The TH code-based grouping bit interleaving coding modulation space-ground anti-interference system comprises a low code rate TH code coding unit, a bit-level interleaver unit, an M-QAM mapping unit, a frequency hopping unit, an interference detection unit, a de-hopping unit, an M-QAM demapping unit, a de-interleaver unit and a low code rate TH code decoding unit.

[0099] The low code rate TH code coding unit is used for coding original information bits by using a low code rate TH code, and transmitting the low code rate TH code word obtained after coding to the bit-level interleaver unit.

[0100] The bit-level interleaver unit is used for interleaving the low code rate TH code word to obtain a to-be-mapped code word with a disturbed order, and transmitting the to-be-mapped code word to the M-QAM mapping unit.

[0101] The M-QAM mapping unit is used for performing M-QAM mapping on the to-be-mapped code word to obtain a QAM mapping symbol, and transmitting the QAM mapping symbol to the frequency hopping unit.

[0102] The frequency hopping unit is used for performing frequency hopping processing on the mapping symbol to obtain a sending sequence, and sending the sending sequence to an interference channel.

[0103] The interference detection unit is used for performing interference detection and zero processing on a signal received from the channel, and transmitting the signal after zero processing on the interference position to the de-hopping unit.

[0104] The de-hopping unit is used for performing de-hopping processing on the signal after zero processing on the interference bit, and transmitting the processed signal to the M-QAM demapping unit.

[0105] The M-QAM demapping unit is used for performing demapping on the signal after de-hopping, and transmitting soft information output by demapping to the de-interleaver unit.

[0106] The deinterleaving unit is configured to perform deinterleaving processing on the soft information of the demapping output and transmit the deinterleaved signal to the low code rate TH code decoding unit.

[0107] The low code rate TH code decoding unit is configured to perform iterative decoding processing on the deinterleaved signal, and output a final decoding result after multiple iterations.

[0108] As Figure 3 shown in the simulation results, the parameters are set as follows: the original information bit length N is 200, Figure 3 (a) the Hadamard code order r is set to 4, and the code rate is 1 / 10; Figure 3 (b) the Hadamard code order r is set to 5, and the code rate is 17.2. The generating polynomial of the convolutional code is g(x) = 1 + x / 1 + x + x2, that is, the grid state number S is 4. It can be observed from the image that the error rate of the method of the present application is significantly lower than that of the modulation method of only using THC-QAM, which shows that compared with the combination of only TH code and QAM modulation, the present application has significant performance gain in AWGN channel communication. At the same time, the system error rate when r = 5 is also lower than that when r = 4, which shows that the higher the order of Hadamard code is, the better the performance is.

[0109] In the simulation of partial band interference, the parameters are set as follows: the original information bit is 256 (r = 4) or 255 (r = 5), the code rate is 1 / 8, and the number of component codes is 3. Figure 3 (a) shows the error rate curve of the 4-order Hadamard matrix coding, Figure 3 (b) shows the error rate curve of the 5-order Hadamard matrix coding. It can be concluded that compared with the combination of only TH code and QAM modulation, the present application also has significant performance gain in anti-interference communication

[0110] Figure 4 The error rates of the BITHCM system and the classic LDPC-BPSK scheme in Figure Four are compared. As Figure Five can be seen, compared with the LDPC-BPSK system, the BITHCM has significant performance gain in anti-interference communication. And when the interference ratio reaches 40%, the LDPC-BPSK loses the error correction ability, while the present application still has good error correction ability.

[0111] The above describes the main content of the TH code-based packet bit interleaved coded modulation anti-interference method and system. Through the above simulation experiment, the performance of the TH code-based packet bit interleaved coded modulation anti-interference method under different conditions can be evaluated and compared, especially the advantages in anti-interference. Such an experimental process not only verifies the effect of the scheme, but also provides a comparative analysis with other methods, thereby showing its effectiveness and superiority in specific application scenarios.

Claims

1. A space anti-jamming method based on TH code packet bit interleaving coding modulation, characterized in that: The method comprises the following steps: Step one: determining the original information sequence length N, Hadamard order r and component code number H, and performing low code rate TH code encoding on the original information sequence to obtain a low code rate TH code word; Step two: using a bit interleaving encoding modulation method to perform bit interleaving on the low code rate TH code word to obtain sufficient time domain diversity effect under the low code rate characteristic of the TH code word; Step three: performing M-QAM mapping on the log2M parallel to-be-mapped code words; Step four: sending the signal processed by the low code rate TH channel encoding, bit-level interleaving encoding modulation and frequency hopping to a partial band interference channel; Step five: receiving the signal sent in step four, and performing zero processing on the received signal at the disturbed frequency point according to the interference detection result; Step six: performing de-hopping and demapping processing on the interference detected and zeroed signal; Step seven: using a corresponding de-interleaver group to perform de-interleaving operation on the soft information output of the demapping, and obtaining a to-be-coded sequence through parallel-serial conversion; Step eight: performing iterative decoding on the to-be-coded sequence in step seven, and obtaining the judgment result of the information sequence after the iteration is completed; In step two, the interference is evenly distributed in the entire data stream, avoiding the generation of piece errors due to the aggregation of interference at the receiver; in step five, the interference is detected and zeroed, and the interference is deleted as much as possible before the received signal is processed; in step eight, the iterative decoding of the low code rate TH code is performed, and the disturbed bits converge to the correct judgment result with the aid of the undisturbed bits in the iteration process, so as to reduce the error rate of the communication system and improve the anti-interference performance of the system.

2. The TH code based packet bit interleaved coded modulation space anti-jamming method according to claim 1, characterized in that: In step one, The low code rate TH code encoding in step one is composed of parallel concatenated convolution Hadamard codes; during the encoding, the information bit stream with a length of N is first divided into r-bit blocks for parity check, the check bits are subjected to convolution encoding with a code rate of 1, the original information bits and the output of the convolution encoder are combined, and Hadamard encoding is performed to obtain the convolution Hadamard code; The H component code outputs are combined through puncturing to obtain the final low code rate TH code encoding result, and the calculation formula of the code rate is as follows: Wherein, H represents the number of component codes, and r is the order of the Hadamard code.

3. The TH code based packet bit interleaved coded modulation space anti-jamming method according to claim 2, characterized in that: The specific implementation mode of the bit interleaving encoding modulation in step two is that the encoding result is subjected to serial-parallel conversion to obtain log2M parallel encoding results, log2M interleavers are used to perform bit-level interleaving on the encoding results to obtain to-be-mapped code words; The bit interleaving encoding modulation disperses the continuous bit errors caused by the band interference.

4. The TH code based packet bit interleaved coded modulation space anti-jamming method of claim 3, wherein: The M-QAM mapping in step three adopts Gray mapping mode to map the data that has been encoded and subjected to diversity processing to M-QAM symbols; the mapping process is shown in formula (2): S=f(B) (2) Wherein, S is an M-QAM symbol, B is a to-be-mapped bit group, and f is a mapping function; The bit group is converted into a corresponding M-QAM symbol through formula (2).

5. The TH code based packet bit interleaved coded modulation space anti-jamming method according to claim 4, characterized in that: The interference detection in step five determines whether there is interference and the interference position according to interference signal characteristics; the received signal is analyzed in the frequency domain, and for partial band interference, the received signal amplitude in the frequency domain exceeds a preset interference determination threshold value in some frequency bands; the interference position is determined according to the above determination criterion, and the disturbed bits are zeroed.

6. The TH code based packet bit interleaved coded modulation space anti-jamming method of claim 5, wherein: The decoding of the TH code described in step eight uses the Max-Log-MAP algorithm to simplify the decoding output of soft information L. k (i); First-level Fast Hadamard Transform (FHT) is used to simplify the branching metric in soft information. The forward metric in the aforementioned soft information is calculated recursively using the BCJR algorithm. and backward metric pass Summing gives δ k The FHT with simplified output from the second layer is used for δ k Find the maximum value by classifying and subtracting. The final output is the decision result, and the decoding of low-rate TH codes is achieved with low complexity. The basic decoding criterion is: Max-Log-MAP algorithm is used to simplify the decoding output soft information L k (i): The Max-log-MAP algorithm converts the metric value involved in TH code decoding into the logarithmic domain, and converts the multiplication operation into an addition operation; Simplifying branch metrics with a first layer of fast hadamard transform (FHT) Operations, FHT converts matrix multiplication operations into addition operations; BCJR algorithm to recursively compute forward metrics and backward metrics Branch merging based on state transition graph, computing delta k (±h j ): FHT with second level simplified output on the delta of the previous step k Classification maxima, subtraction operation Output decision result:

7. The TH code based packet bit interleaved coded modulation space-time anti-jamming system of claim 1, 2, 3, 4, 5 or 6, wherein: It includes a low-rate TH code encoding unit, a bit-level interleaver unit, an M-QAM mapping unit, a frequency hopping unit, an interference detection unit, a de-hopping unit, an M-QAM demapping unit, a de-interleaver unit, and a low-rate TH code decoding unit. ​ The low-rate TH code encoding unit is configured to encode the original information bits into low-rate TH code words, and transmit the encoded low-rate TH code words to the bit-level interleaver unit. The bit-level interleaver unit is configured to interleave the low-rate TH code words to obtain the reordered code words to be mapped, and transmit the reordered code words to the M-QAM mapping unit. The M-QAM mapping unit is configured to map the code words to be mapped into QAM mapping symbols, and transmit the QAM mapping symbols to the frequency hopping unit. The frequency hopping unit is configured to perform frequency hopping processing on the mapping symbols to obtain a transmission sequence, and transmit the transmission sequence to the interference channel. The interference detection unit is configured to perform interference detection and zero processing on the signal received from the channel, and transmit the signal after zeroing the interference position to the de-hopping unit. The de-hopping unit is configured to perform de-hopping processing on the signal after zeroing the interference bits, and transmit the processed signal to the M-QAM demapping unit. The M-QAM demapping unit is configured to demap the de-hopped signal, and transmit the soft information output by demapping to the de-interleaver unit. The de-interleaver unit is configured to perform de-interleaving processing on the soft information output by demapping, and transmit the de-interleaved signal to the low-rate TH code decoding unit. The low-rate TH code decoding unit is configured to perform iterative decoding processing on the de-interleaved signal, and output the final decoding result after multiple iterations.

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