Anti-interference phase estimation method suitable for MSK modulation

Abstract

The invention provides an anti-interference phase estimation method suitable for MSK modulation, which belongs to the technical field of anti-interference phase estimation and comprises the following steps: S1, an interference identification and marking step which comprises a signal capturing and hopping link, an interference detection algorithm link and an interference mask generation link; s2, an interference range judgment and processing step, wherein the step comprises a whole-hop interfered processing link, a partial interference processing link, a pilot frequency sequence reconstruction link and a phase estimation and compensation link; and S3, a data integration and post-processing step, wherein the step comprises a demodulation link, a data splicing link, a de-interleaving processing link, a channel decoding link and a performance feedback link. In order to solve the problems that the coding gain of a decoder is reduced and the communication performance is influenced by a traditional method when short-time sudden interference occurs in communication, the phase can still be effectively estimated by using data which are not interfered through the characteristics of MSK modulation, so that the data which are not interfered can participate in subsequent demodulation and decoding, and the communication performance is improved. And the anti-interference capability of the system is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-interference phase estimation methods, and in particular to an anti-interference phase estimation method suitable for MSK modulation. Background Art

[0002] MSK, a type of continuous phase modulation, is a nonlinear modulation method with a constant envelope and continuously varying phase. It has small spectral sidelobes, resulting in high bandwidth utilization. Furthermore, due to its constant envelope, it is insensitive to the nonlinear characteristics of the power amplifier, resulting in high power efficiency. It is a key modulation mode in various new mobile communications and wireless radio systems.

[0003] Frequency hopping communication systems are susceptible to various short-term burst interferences for the following reasons: (1) Sudden pulse interference: For example, transient interference from industrial equipment (such as transient electromagnetic pulses generated by motor startup and high-voltage switch operation); (2) Intermodulation burst interference: Intermodulation products caused by nonlinear devices (such as amplifiers and mixers) may cause short-term burst interference under certain conditions. (3) Frequency collision interference during multi-channel reception: When receiving multiple signals, there is a certain probability that frequency points will collide in a short period of time. Due to the existence of the near-far effect, the target channel will experience short-term power surge interference.

[0004] When short-term burst interference occurs in some data hops, the traditional processing method is: if the short-term burst interference occurs only in the data portion, the phase can still be calculated using the pilot signal and the uninterrupted data can be retained; if the short-term burst interference occurs in the pilot signal portion, the pilot signal cannot be used to effectively estimate the phase. To avoid the influence of phase noise, the data hop is considered an invalid hop and does not participate in subsequent demodulation and decoding, which reduces the coding gain of the decoder and affects communication performance. Summary of the Invention

[0005] In frequency-hopping communication systems, which are susceptible to various short-duration burst interference, the present invention prevents phase estimation when the pilot portion of certain data hops is interfered with, rendering these data hops unusable and severely impacting communication quality. Without imposing any waveform constraints, the present invention leverages the characteristics of MSK modulation to address the issue of data hops being unusable when the pilot portion is interfered with, effectively improving the system's anti-interference capabilities and overcoming the aforementioned problems in the background art.

[0006] Based on the above technical ideas, the technical solution adopted by the present invention is:

[0007] An anti-interference phase estimation method suitable for MSK modulation includes the following steps:

[0008] S1 interference identification and marking step, which includes signal capture and hopping, interference detection algorithm and interference mask generation;

[0009] S2 interference range judgment and processing step, which includes the whole hop interference processing link, partial interference processing link, pilot sequence reconstruction link and phase estimation and compensation link;

[0010] S3 data integration and post-processing step, which includes demodulation, data splicing, deinterleaving, channel decoding and performance feedback.

[0011] To further limit the above technical solution, the S1 interference identification and marking step, in which the signal capture and hopping link includes the receiving end capturing the down-converted signal and then dividing it into independent data hops according to the frequency hopping pattern; the interference detection algorithm link includes an energy detection method to calculate the instantaneous power of each symbol. If it exceeds a dynamic threshold (such as 3 times the historical average power), it is marked as interference; the interference mask generation link includes generating a binary mask for each hop (0 indicates no interference, 1 indicates interference) and recording the starting and ending positions of the interfered symbol.

[0012] To further limit the above technical solution, the S2 interference range judgment and processing step includes an interference processing method for the entire hop being interfered with, and the interference processing method is to discard all data of the hop (set to zero) to avoid noise contamination of subsequent decoding.

[0013] Further limiting the above technical solution, the S2 interference range judgment and processing step, in which part of the interference link includes data preprocessing, intercepting undisturbed continuous symbol segments (such as pilot segments or data segments) according to the interference mask, and selecting the following processing methods according to the characteristics of the undisturbed continuous symbol segments:

[0014] When the pilot is not interfered with or partially not interfered with, the remaining valid pilot symbols are extracted and correlated with the ideal pilot symbols at the corresponding local position to complete phase estimation and perform phase correction on the entire hop data.

[0015] When all pilots are interfered with, the longest continuous data symbols that are not interfered with are selected through continuous data segment extraction (such as the continuous M symbols in the intercepted data segment), and the original binary bit stream (such as 0→+1, 1→-1) is generated using the non-coherent differential detection algorithm.

[0016] A further limitation of the above technical solution is that the situation in which all pilots are interfered with in the partial interference processing link also includes reconstructing the pilot sequence and phase estimation and compensation. The reconstructing the pilot sequence includes MSK modulation, and the original binary bit stream generated by the non-coherent differential detection algorithm is re-MSK modulated to generate equivalent pilot symbols. The modulation rule is that each symbol corresponds to a phase change of ±π / 2 to ensure phase continuity and align the timing. According to the starting position of the intercepted data segment, it is aligned with the time of the received signal; the phase estimation and compensation includes calculating the correlation between the reconstructed pilot and the undisturbed data segment at the corresponding position in the received signal, completing the phase estimation, correcting the phase, and performing phase correction on the entire hop data.

[0017] A further limitation of the above technical solution is the S3 data integration and post-processing step, in which the demodulation link and the data splicing link include valid data retention and interference part processing. The valid data retention includes performing maximum likelihood sequence detection (MLSE) demodulation on the undisturbed symbols and retaining the demodulation soft information value; the interference part processing includes setting the demodulation soft information value corresponding to the interference position to zero to avoid error divergence in the decoder, while forming a complete data demodulation result for each hop.

[0018] Further limitation of the above technical solution is the S3 data integration and post-processing step, in which the deinterleaving processing link includes interleaving rule analysis and deinterleaving algorithm. The interleaving rule analysis includes that the frequency hopping system usually adopts block interleaving or convolution interleaving, and the data corresponding to the position of the interfered symbol is 0 during deinterleaving.

[0019] Further limitation of the above technical solution: the S3 data integration and post-processing step, in which the channel decoding link includes the decoder type, error detection and correction, the decoder type includes the 1 / 3 code rate Turbo code mentioned in the document, and is not limited to the decoder type and code rate. The deinterleaved LLR soft information is received as the decoder input, the LLR corresponding to the interfered symbol is 0, and the decoder relies on the redundancy of the error correction code to restore the missing bits. After a fixed number of iterations (such as 8 times), the final LLR is symbolically judged; error detection and correction includes verifying the data integrity after decoding if the data packet contains a CRC check field, and whether a retransmission request is triggered.

[0020] Further limitation of the above technical solution: the S3 data integration and post-processing step, the performance feedback link in this step includes interference statistics and feedback, dynamic adjustment mechanism and retransmission strategy triggering, interference statistics and feedback include statistics of the interference ratio of each packet of data, interference position distribution (pilot / data segment), and bit error rate (BER); the dynamic adjustment mechanism includes adaptive interference detection and decoder parameter optimization, adaptive interference detection includes increasing the energy detection threshold if the false alarm rate is high (misjudged interference), and lowering the energy detection threshold if the missed detection rate is high (unidentified interference); decoder parameter optimization includes increasing the number of decoder iterations according to the channel status (such as high interference scenarios) (such as increasing the number of Turbo code iterations from 8 to 20 times).

[0021] Further limitation of the above technical solution, the S3 data integration and post-processing step, in which the retransmission strategy triggering in the performance feedback link includes notifying the sender to retransmit the damaged data packet if the interference ratio or CRC failure rate exceeds a threshold.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. High robustness: When the pilot signal is completely lost, the pilot signal is regenerated through the data segment, breaking through the limitation of traditional reliance on fixed reference signals.

[0024] 2. Low complexity: the non-coherent differential detection algorithm has low computational complexity and is suitable for real-time processing.

[0025] 3. High compatibility, no need to modify the existing MSK modulation architecture, can be directly integrated into the frequency hopping receiver. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 The present invention adds a system simulation model diagram of group jump and sub-jump;

[0028] Figure 2 This is a performance simulation diagram of the present invention. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-Figure 2 The present invention is described in further detail.

[0030] Example 1: This embodiment provides an anti-interference phase estimation method suitable for MSK modulation, such as Figure 1-Figure 2As shown, the following steps are included:

[0031] S1 interference identification and marking step, which includes signal capture and hopping, interference detection algorithm and interference mask generation;

[0032] S2 interference range judgment and processing step, which includes the whole hop interference processing link, partial interference processing link, pilot sequence reconstruction link and phase estimation and compensation link;

[0033] S3 data integration and post-processing step, which includes demodulation, data splicing, deinterleaving, channel decoding and performance feedback.

[0034] The S1 interference identification and marking step includes the signal capture and hopping process at the receiving end, which captures the down-converted signal and then divides it into independent data hops according to the frequency hopping pattern. The interference detection algorithm includes an energy detection method, which calculates the instantaneous power of each symbol. If it exceeds a dynamic threshold (such as 3 times the historical average power), it is marked as interference. The interference mask generation process includes generating a binary mask for each hop (0 indicates no interference, 1 indicates interference) and recording the starting and ending positions of the interfered symbol.

[0035] The S2 interference range judgment and processing step includes an interference processing method for the entire hop being interfered with, and the interference processing method is to discard all data of the hop (set to zero) to avoid noise contamination of subsequent decoding.

[0036] The S2 interference range determination and processing step includes data preprocessing, intercepting undisturbed continuous symbol segments (such as pilot segments or data segments) according to the interference mask, and selecting the following processing methods based on the characteristics of the undisturbed continuous symbol segments:

[0037] When the pilot is not interfered or partially not interfered, the remaining valid pilot symbols (such as the N undisturbed pilot symbols of the original 16 pilots) are extracted and correlated with the ideal pilot symbols at the corresponding local positions to complete phase estimation.

[0038] When all pilots are interfered with, the longest continuous data symbols that are not interfered with are selected through continuous data segment extraction (such as the continuous M symbols in the intercepted data segment), and the original binary bit stream (such as 0→+1, 1→-1) is generated using the non-coherent differential detection algorithm.

[0039] The situation where all pilots are interfered with in the partial interference processing link also includes reconstructing the pilot sequence and phase estimation and compensation. The reconstructing the pilot sequence includes MSK modulation, re-MSK modulating the original binary bit stream generated by the non-coherent differential detection algorithm to generate an equivalent pilot waveform. The modulation rule is that each symbol corresponds to a phase change of ±π / 2 to ensure phase continuity and align the timing. According to the starting position of the intercepted data segment, it is aligned with the time of the received signal; the phase estimation and compensation includes calculating the correlation between the reconstructed pilot and the non-interfered data segment at the corresponding position in the received signal to complete the phase estimation and perform phase correction on the entire hop data.

[0040] The S3 data integration and post-processing step includes the demodulation link and data splicing link, which include valid data retention and interference part processing. The valid data retention includes maximum likelihood sequence detection (MLSE) demodulation of non-interfered symbols and retaining the demodulation soft information value; the interference part processing includes setting the demodulation soft information value corresponding to the interference position to zero to avoid error divergence in the decoder and form a complete data demodulation result.

[0041] The S3 data integration and post-processing step includes a deinterleaving process including interleaving rule analysis and a deinterleaving algorithm. The interleaving rule analysis includes that the frequency hopping system usually adopts block interleaving or convolution interleaving, and the data corresponding to the position of the interfered symbol is 0 during deinterleaving.

[0042] The S3 data integration and post-processing step, in which the channel decoding link includes the decoder type, error detection and correction, the decoder type includes the 1 / 3 code rate Turbo code mentioned in the document, but is not limited to this decoder type and code rate, and the deinterleaved LLR soft information is received as the decoder input. The LLR corresponding to the interfered symbol is 0. The decoder relies on the redundancy of the error correction code to restore the missing bits. After a fixed number of iterations (such as 8 times), the final LLR is symbolically judged; error detection and correction includes verifying the data integrity after decoding if the data packet contains a CRC check field, and whether a retransmission request is triggered.

[0043] The S3 data integration and post-processing step, the performance feedback link in this step includes interference statistics and feedback, dynamic adjustment mechanism and retransmission strategy triggering, interference statistics and feedback include statistics of the interference ratio of each packet of data, interference location distribution (pilot / data segment), and bit error rate (BER); the dynamic adjustment mechanism includes adaptive interference detection and decoder parameter optimization, adaptive interference detection includes increasing the energy detection threshold if the false alarm rate is high (misjudged interference), and lowering the energy detection threshold if the missed detection rate is high (unidentified interference); decoder parameter optimization includes increasing the number of decoder iterations according to the channel status (such as high interference scenarios) (such as increasing the number of Turbo code iterations from 8 to 20 times).

[0044] The S3 data integration and post-processing step, in which the retransmission strategy triggering in the performance feedback link includes notifying the sending end to retransmit the damaged data packet if the interference ratio or CRC failure rate exceeds a threshold.

[0045] Example 2: This embodiment provides an anti-interference phase estimation method suitable for MSK modulation, such as Figure 1-Figure 2 As shown, the following steps are also included:

[0046] First, interference identification is performed, and the interference position of each data hop is marked. If the hop is interfered with as a whole, it is considered an invalid hop and all demodulation results are set to zero. If only part of the hop is interfered with, the uninterrupted part is cut out. If the pilot is not interfered with or partially not interfered with, the phase is estimated using the remaining valid pilot, and demodulation is completed after the phase is corrected. The demodulation result of the interference position is set to zero. If the pilot is completely interfered with, the remaining continuous uninterrupted data is used to use the incoherent differential detection algorithm to decode its corresponding original binary bit stream, and then MSK modulation is performed on it as a new pilot, the phase is estimated and demodulated, and the demodulation result of the interference position is set to zero.

[0047] The principle of incoherent differential detection is as follows:

[0048] MSK's phase path is continuous, and the phase variation within each symbol period is . The phase difference between adjacent symbols is determined solely by the current symbol data. When the current symbol data is 0 (+1), the phase increases; when the current symbol data is 1 (-1), the phase decreases. By detecting the phase difference between adjacent symbols, the original binary bit stream can be demodulated.

[0049] This technology is mainly explained from three aspects: system simulation model, algorithm process description, and simulation conclusion:

[0050] (1) System simulation model

[0051] System simulation model such as Figure 1 As shown in Figure 1, the transmitter consists of channel coding, interleaving, pilot group hopping, modulation, and up-conversion. The receiver corresponds to the transmitter and consists of down-conversion, acquisition, hopping, interference identification, phase estimation, demodulation, deinterleaving, and channel decoding.

[0052] (2) Algorithm flow description

[0053] First, interference identification is performed, marking the interference location of each data hop. If the entire hop is interfered with, the demodulation results are reset to zero. If only part of the hop is interfered with, the uninterrupted data is cut out. If the pilot is not interfered with or partially uninterrupted, the pilot is used to estimate the phase. If the pilot is completely interfered with, the remaining continuous uninterrupted data is used using a non-coherent differential detection algorithm to decode the corresponding original binary bit stream. MSK modulation is then performed and used as a pilot to estimate the phase. After removing the phase, the uninterrupted data portion is demodulated using Maximum Likelihood Sequence Detection (MLSE). The demodulation results of the interfered portion are reset to zero, completing the subsequent deinterleaving and decoding.

[0054] (3) Simulation conclusion

[0055] The simulation conditions are as follows: 32 hops per data packet, 112 valid symbols per hop, including 96 data symbols and 16 pilot symbols, 1024 bits of information length before encoding, 1 / 3 code rate Turbo code, MSK modulation, and 20%, 40%, and 60% random short-term burst interference for each data packet, respectively. The interference occurs in half a hop symbol including the pilot, i.e., 56 symbols. Figure 2 The performance comparison between the present invention and the prior art is shown in the simulation results. The simulation results show that as the interference ratio increases, the performance advantage of the present invention becomes more significant. When the interference ratio reaches 60%, the traditional method can no longer resist the interference, but the present invention can still work well.

[0056] The present invention will not render the entire data hop unusable due to short-term burst interference, thereby effectively improving the anti-interference capability of the communication system.

[0057] The present invention does not require any additional waveform constraints and does not require any additional hardware costs.

[0058] The above contents are further detailed descriptions of the present invention in conjunction with specific preferred embodiments, so as to facilitate those skilled in the art to understand and apply the present invention. It should not be considered that the specific implementation of the present invention is limited to these descriptions.

Claims

1. An anti-interference phase estimation method suitable for MSK modulation, characterized in that: The following steps are involved: S1 interference identification and marking step, which includes signal capture and hopping, interference detection algorithm and interference mask generation; S2 interference range judgment and processing step, which includes the whole hop interference processing link, partial interference processing link, pilot sequence reconstruction link and phase estimation and compensation link; S3 data integration and post-processing step, which includes demodulation, data splicing, deinterleaving, channel decoding and performance feedback.

2. The anti-interference phase estimation method suitable for MSK modulation according to claim 1, characterized in that: The S1 interference identification and marking step includes the signal capture and hopping process at the receiving end, which captures the down-converted signal and then divides it into independent data hops according to the frequency hopping pattern. The interference detection algorithm includes an energy detection method, which calculates the instantaneous power of each symbol and marks it as interference if it exceeds a dynamic threshold. The interference mask generation step includes generating a binary mask for each hop and recording the starting and ending positions of the interfered symbols.

3. The anti-interference phase estimation method suitable for MSK modulation according to claim 2, characterized in that: The S2 interference range judgment and processing step includes an interference processing method for the entire hop, which is to discard all data of the hop to avoid noise contamination of subsequent decoding to form error diffusion, and set all demodulation soft information values of the hop to zero.

4. The anti-interference phase estimation method suitable for MSK modulation according to claim 3, characterized in that: The S2 interference range determination and processing step includes data preprocessing, intercepting undisturbed continuous symbol segments according to the interference mask, and selecting the following processing methods based on the characteristics of the undisturbed continuous symbol segments: When the pilot is not interfered with or partially not interfered with, the remaining valid pilot symbols are extracted and correlated with the ideal pilot symbols at the corresponding local position to complete phase estimation and perform phase correction on the entire hop data. When all pilots are interfered, the longest continuous data symbols that are not interfered with are selected through continuous data segment extraction, and the original binary bit stream is generated using a non-coherent differential detection algorithm.

5. The anti-interference phase estimation method suitable for MSK modulation according to claim 4, characterized in that: The situation where all pilots are interfered with in the partial interference processing link also includes reconstructing the pilot sequence and phase estimation and compensation. The reconstructing the pilot sequence includes MSK modulation, re-MSK modulating the original binary bit stream generated by the non-coherent differential detection algorithm to generate equivalent pilot symbols. The modulation rule is that each symbol corresponds to a phase change of ±π / 2 to ensure phase continuity and align the timing. According to the starting position of the intercepted data segment, it is aligned with the time of the received signal; the phase estimation and compensation includes performing correlation calculation between the reconstructed pilot and the non-interfered data segment at the corresponding position in the received signal to complete phase estimation and perform phase correction on the entire hop data.

6. The anti-interference phase estimation method suitable for MSK modulation according to claim 5, characterized in that: The S3 data integration and post-processing step includes the demodulation link and data splicing link, which include valid data retention and interference part processing. The valid data retention includes performing maximum likelihood sequence detection (MLSE) demodulation on the non-interfered symbols and retaining the demodulation soft information value; the interference part processing includes setting the demodulation soft information value corresponding to the interference position to zero to avoid error divergence in the decoder and form a complete demodulation result for each hop.

7. The anti-interference phase estimation method suitable for MSK modulation according to claim 6, characterized in that: The S3 data integration and post-processing step includes a deinterleaving process including interleaving rule analysis and a deinterleaving algorithm. The interleaving rule analysis includes that the frequency hopping system usually adopts block interleaving or convolution interleaving, and the data corresponding to the position of the interfered symbol is 0 during deinterleaving.

8. The anti-interference phase estimation method suitable for MSK modulation according to claim 7, characterized in that: The S3 data integration and post-processing step includes the channel decoding link, which includes the decoder type, error detection and correction. The decoder type includes the 1 / 3 code rate Turbo code mentioned in the document, but is not limited to this decoder type and code rate. The deinterleaved LLR soft information is received as the decoder input. The LLR corresponding to the position of the interfered symbol is 0. The decoder relies on the redundancy of the error correction code to recover the missing bits. After a fixed number of iterations, the final LLR is used for symbol decision. Error detection and correction includes verifying the data integrity after decoding if the data packet contains a CRC check field, and whether to trigger a retransmission request.

9. The anti-interference phase estimation method suitable for MSK modulation according to claim 8, characterized in that: The S3 data integration and post-processing step, in which the performance feedback link includes interference statistics and feedback, dynamic adjustment mechanism and retransmission strategy triggering, the interference statistics and feedback include statistics of the interference ratio, interference location distribution and bit error rate of each packet of data; the dynamic adjustment mechanism includes adaptive interference detection and decoder parameter optimization, the adaptive interference detection includes increasing the energy detection threshold if the false alarm rate is high, and lowering the energy detection threshold if the missed detection rate is high, and the decoder parameter optimization includes increasing the number of decoder iterations according to the channel status.

10. The anti-interference phase estimation method suitable for MSK modulation according to claim 9, characterized in that: The S3 data integration and post-processing step, in which the retransmission strategy triggering in the performance feedback link includes notifying the sender to retransmit the damaged data packet if the interference ratio or CRC failure rate exceeds a threshold.

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