Two-stage frequency hopping method based on message driving

Abstract

The invention discloses a two-stage frequency hopping method based on message driving, and relates to the technical field of communication. Comprising the following steps: processing a transmitting end physical layer: channel coding and data segmentation, modulation and serial-to-parallel conversion, subcarrier frequency hopping position sequence generation, subcarrier mapping and OFDM modulation, radio frequency hopping sequence generation, frequency shifting and signal transmission; and the receiving end physical layer executes reverse transformation of the corresponding steps of the transmitting end physical layer to recover the data. According to the method, all data are not transmitted through a wireless channel, part of data are hidden in the frequency hopping sequence, random frequency hopping in the true sense is achieved at the subcarrier level and the radio frequency level through the unpredictability of message sending, and compared with a traditional frequency hopping scheme based on a pseudo-random sequence, an attacker cannot predict the communication frequency, and the communication efficiency is improved. And all data cannot be acquired from a wireless channel, so that malicious interference can be effectively avoided, and user data privacy is protected.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a two-stage frequency hopping method based on message driving. Background Art

[0002] Frequency hopping technology has outstanding performance in anti-interference, privacy protection, and extended transmission distance, and plays an important role in electronic countermeasures, the Internet of Things, mobile communications and other fields. OFDM uses the orthogonality between subchannels to prevent inter-carrier interference (ICI) from occurring when the frequency bands overlap, which can improve the utilization of the frequency band and reduce the transmission delay. Frequency hopping OFDM technology uses OFDM modulation in the process of frequency hopping transmission, retaining the characteristics of strong concealment and strong anti-interference of frequency hopping, and reducing the transmission delay. The concealment and anti-interference performance of traditional frequency hopping OFDM depend on the privacy of the frequency set and pseudo-random sequence. The cyclic prefix causes the OFDM signal to have correlation peaks at fixed intervals when performing autocorrelation operations. Attackers can easily analyze the frequency set based on this feature. Pseudo-random sequences have periodic characteristics. If attackers receive and analyze continuously for a long time, they can obtain pseudo-random sequences. The privacy and communication reliability of legitimate users are difficult to be effectively protected.

[0003] Therefore, it is an urgent problem for those skilled in the art to propose a two-stage frequency hopping method based on message driving to solve the difficulties existing in the prior art. Summary of the invention

[0004] In view of this, the present invention provides a message-driven two-stage frequency hopping method. Compared with the traditional pseudo-random sequence-based frequency hopping scheme, it makes it impossible for attackers to predict the communication frequency or obtain all data from the wireless channel, which can effectively avoid malicious interference and protect user data privacy.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A two-stage frequency hopping method based on message driving comprises the following steps:

[0007] S1. Input the data D to be sent, perform RS-CC channel coding on the data D to be sent, and obtain the coded data D C ;

[0008] S2. for D C Perform data segmentation to obtain the modulated data D M , subcarrier frequency hopping data D SC and RF frequency hopping data D RF ;

[0009] S3. Modulate the data D MThe serial input modulation module performs QAM modulation, and the parallel output obtains the modulation symbol S M ;

[0010] S4. The pseudo-random sequence PN1 and the subcarrier frequency hopping data D SC Input scrambling module, output scrambled subcarrier frequency hopping data Will Input subcarrier frequency hopping position calculation module, output subcarrier position sequence A SC ;

[0011] S5. Each modulation symbol S M According to the subcarrier position sequence A SC Placed at the corresponding subcarrier position, all unplaced modulation symbols S M Data 0 is placed on all subcarriers, and then OFDM modulation is implemented using IFFT operation, and a cyclic prefix CP is added;

[0012] S6. The pseudo-random sequence PN2 and the RF frequency hopping data D RF Input scrambling module, output scrambled RF frequency hopping data

[0013] S7. The transmitter transmits the scrambled RF frequency hopping data Move the DC subcarrier of the OFDM symbol to the final center frequency f c and send it to the receiver;

[0014] S8. The receiver simultaneously monitors the frequency set The signal energy in each frequency band in the frequency set is assumed to be The serial number in is k, and the estimated value of the scrambled RF frequency hopping data is obtained from k

[0015] S9. After descrambling, the final RF frequency hopping data estimate is obtained

[0016] S10. Remove the cyclic prefix CP from the received signal, and then perform FFT operation to achieve OFDM demodulation;

[0017] S11. Perform subcarrier monitoring. During each monitoring process, select the subcarrier with the highest signal power among the four subcarriers. The symbols carried by the four subcarriers with the highest signal power are modulation symbols. The subcarrier mapping data is hidden in the subcarrier sequence number. The modulation symbols and the corresponding subcarrier sequence numbers are recorded in the monitoring order. After N / 4 monitorings are completed, two sequences with a length of N / 4 are obtained, which are the modulation symbol sequence and the subcarrier position sequence

[0018] S12. By Get the decimal representation of the estimated value of the scrambled subcarrier frequency hopping data use Calculate the estimated value of the scrambled subcarrier frequency hopping data

[0019] S13. After descrambling, the final RF frequency hopping data estimate is obtained

[0020] S14. Modulate the symbol Demodulate and obtain the estimated value of the modulated data

[0021] S15. Combine them in order to get an estimate of the coded data

[0022] S16.Yes Perform channel decoding to obtain the final output data

[0023] Optionally, the amount of data D to be sent input in S1 is as shown in formula (1):

[0024]

[0025] Among them, R is the coding efficiency of channel coding, N is the number of subcarriers of OFDM, L is the modulation order, and M is the number of frequencies in the frequency set.

[0026] Optionally, in S4, the pseudo-random sequence PN1 and the subcarrier frequency hopping data D SC Input scrambling module, output scrambled subcarrier frequency hopping data The calculation method of is shown in formula (2):

[0027]

[0028] in, Represents a bitwise exclusive OR operation;

[0029] Will Input subcarrier frequency hopping position calculation module, output subcarrier position sequence A SC The calculation method of is shown in formula (3):

[0030]

[0031] Wherein, bin2dec(a, b)=2×a+b, and both a and b are binary data.

[0032] Optionally, each modulation symbol S in S5M According to the subcarrier position sequence A SC Placed at the corresponding subcarrier position, the corresponding relationship is shown in equation (4) and equation (5):

[0033]

[0034]

[0035] Here, dec modk represents the remainder when dec is divided by k.

[0036] Optionally, in S6, the pseudo-random sequence PN2 and the radio frequency hopping data D RF Input scrambling module, output scrambled RF frequency hopping data The calculation method is shown in formula (6):

[0037]

[0038] Optionally, the transmitter in S7 can be configured to receive the scrambled RF frequency hopping data. Move the DC subcarrier of the OFDM symbol to the final center frequency f c Up, f c and The relationship between is shown in formula (7):

[0039]

[0040] in, Indicates the current frequency set The i-th frequency in

[0041] Optionally, the receiver in S8 monitors the frequency set The signal energy in each frequency band in the frequency set is assumed to be The serial number in is k, and the estimated value of the scrambled RF frequency hopping data is obtained from k As shown in formula (8):

[0042]

[0043] Here, dec2bin(·) indicates that a decimal number will be converted into a binary sequence.

[0044] Optionally, the final RF frequency hopping data estimate obtained after descrambling in S9 As shown in formula (10):

[0045]

[0046] Optionally, subcarrier monitoring is performed in S11. During each monitoring process, the subcarrier with the highest signal power among the four subcarriers is selected. The symbols carried by the four subcarriers with the highest signal power are modulation symbols, and the subcarrier mapping data is hidden in the subcarrier sequence number; the modulation symbols and the corresponding subcarrier sequence numbers are recorded in the monitoring order. After N / 4 monitorings are completed, two sequences with a length of N / 4 are obtained, which are the modulation symbol sequence and the subcarrier position sequence Then the subcarrier number set S monitored for the i-th time i As shown in formula (11):

[0047]

[0048] Optional, S12 by Get the decimal representation of the estimated value of the scrambled subcarrier frequency hopping data The calculation method is shown in formula (12) and (13):

[0049]

[0050] use Calculate the estimated value of the scrambled subcarrier frequency hopping data The calculation method is as shown in formula (14) and (15):

[0051]

[0052] It can be seen from the above technical solution that, compared with the prior art, the present invention provides a message-driven two-stage frequency hopping method, which has the following beneficial effects: the present invention does not transmit all data through the wireless channel, but hides part of the data in the frequency hopping sequence, and uses the unpredictability of the sent message at the subcarrier level and the radio frequency level to achieve true random frequency hopping. Compared with the traditional pseudo-random sequence-based frequency hopping scheme, it makes it impossible for attackers to predict the communication frequency or obtain all data from the wireless channel, which can effectively avoid malicious interference and protect user data privacy. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0054] Figure 1 A flow chart of a message-driven two-stage frequency hopping method provided by the present invention. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] Reference Figure 1 As shown, the present invention discloses a two-stage frequency hopping method based on message driving, comprising the following steps:

[0057] S1. Input the data D to be sent, perform RS-CC channel coding on the data D to be sent, and obtain the coded data D C ;

[0058] S2. for D C Perform data segmentation to obtain the modulated data D M , subcarrier frequency hopping data D SC and RF frequency hopping data D RF ;

[0059] S3. Modulate the data D M The serial input modulation module performs QAM modulation, and the parallel output obtains the modulation symbol S M ;

[0060] S4. The pseudo-random sequence PN1 and the subcarrier frequency hopping data D SC Input scrambling module, output scrambled subcarrier frequency hopping data Will Input subcarrier frequency hopping position calculation module, output subcarrier position sequence A SC ;

[0061] S5. Each modulation symbol S M According to the subcarrier position sequence A SC Placed at the corresponding subcarrier position, all unplaced modulation symbols S M Data 0 is placed on all subcarriers, and then OFDM modulation is implemented using IFFT operation, and a cyclic prefix CP is added;

[0062] S6. The pseudo-random sequence PN2 and the RF frequency hopping data D RF Input scrambling module, output scrambled RF frequency hopping data

[0063] S7. The transmitter transmits the scrambled RF frequency hopping data Move the DC subcarrier of the OFDM symbol to the final center frequency f c and send it to the receiver;

[0064] S8. The receiver simultaneously monitors the frequency set The signal energy in each frequency band in the frequency set is assumed to be The serial number in is k, and the estimated value of the scrambled RF frequency hopping data is obtained from k

[0065] S9. After descrambling, the final RF frequency hopping data estimate is obtained

[0066] S10. Remove the cyclic prefix CP from the received signal, and then perform FFT operation to achieve OFDM demodulation;

[0067] S11. Perform subcarrier monitoring. During each monitoring process, select the subcarrier with the highest signal power among the four subcarriers. The symbols carried by the four subcarriers with the highest signal power are modulation symbols. The subcarrier mapping data is hidden in the subcarrier sequence number. The modulation symbols and the corresponding subcarrier sequence numbers are recorded in the monitoring order. After N / 4 monitorings are completed, two sequences with a length of N / 4 are obtained, which are the modulation symbol sequence and the subcarrier position sequence

[0068] S12. By Get the decimal representation of the estimated value of the scrambled subcarrier frequency hopping data use Calculate the estimated value of the scrambled subcarrier frequency hopping data

[0069] S13. After descrambling, the final RF frequency hopping data estimate is obtained

[0070] S14. Modulate the symbol Demodulate and obtain the estimated value of the modulated data

[0071] S15. Combine them in order to get an estimate of the coded data

[0072] S16.Yes Perform channel decoding to obtain the final output data

[0073] Furthermore, the amount of data D to be sent in S1 is as shown in formula (1):

[0074]

[0075] Among them, R is the coding efficiency of channel coding, N is the number of subcarriers of OFDM, L is the modulation order, and M is the number of frequencies in the frequency set.

[0076] Further, in S4, the pseudo-random sequence PN1 and the subcarrier frequency hopping data D SC Input scrambling module, output scrambled subcarrier frequency hopping data The calculation method of is shown in formula (2):

[0077]

[0078] in, Represents a bitwise exclusive OR operation;

[0079] Will Input subcarrier frequency hopping position calculation module, output subcarrier position sequence A SC The calculation method of is shown in formula (3):

[0080]

[0081] Wherein, bin2dec(a, b)=2×a+b, and both a and b are binary data.

[0082] Furthermore, each modulation symbol S in S5 M According to the subcarrier position sequence A SC Placed at the corresponding subcarrier position, the corresponding relationship is shown in equation (4) and equation (5):

[0083]

[0084] Here, dec modk represents the remainder when dec is divided by k.

[0085] Further, in S6, the pseudo-random sequence PN2 and the radio frequency hopping data D RF Input scrambling module, output scrambled RF frequency hopping data The calculation method is shown in formula (6):

[0086]

[0087] Furthermore, the transmitter in S7 uses the scrambled RF frequency hopping data Move the DC subcarrier of the OFDM symbol to the final center frequency f c Up, f c and The relationship between is shown in formula (7):

[0088]

[0089] in, represents the i-th frequency in the current frequency set F,

[0090] Furthermore, the receiver in S8 simultaneously monitors the frequency set The signal energy in each frequency band in the frequency set is assumed to be The serial number in is k, and the estimated value of the scrambled RF frequency hopping data is obtained from k As shown in formula (8):

[0091]

[0092] Here, dec2bin(·) indicates that a decimal number will be converted into a binary sequence.

[0093] Furthermore, the final RF frequency hopping data estimate obtained after descrambling in S9 is As shown in formula (10):

[0094]

[0095] Furthermore, subcarrier monitoring is performed in S11. During each monitoring process, the subcarrier with the highest signal power among the four subcarriers is selected. The symbols carried by the four subcarriers with the highest signal power are modulation symbols. The subcarrier mapping data is hidden in the subcarrier sequence number. The modulation symbols and the corresponding subcarrier sequence numbers are recorded in the monitoring order. After N / 4 monitorings are completed, two sequences with a length of N / 4 are obtained, which are the modulation symbol sequence and the subcarrier position sequence Then the subcarrier number set S monitored for the i-th time i As shown in formula (11):

[0096]

[0097] Furthermore, in S12 Get the decimal representation of the estimated value of the scrambled subcarrier frequency hopping data The calculation method is shown in formula (12) and (13):

[0098]

[0099] use Calculate the estimated value of the scrambled subcarrier frequency hopping data The calculation method is as shown in formula (14) and (15):

[0100]

[0101] Specifically, after descrambling in S13, the final RF frequency hopping data estimation value is obtained. As shown in formula (16):

[0102]

[0103] In a specific embodiment, the following contents are included:

[0104] The physical layer processing flow at the transmitter is as follows: first, the original data message of the sender is channel-coded; then the coded data is divided into three parts: modulation data, subcarrier frequency hopping data, and RF frequency hopping data; the modulation data is QAM modulated to generate modulation symbols; the subcarrier frequency hopping data is randomly scrambled, and then the subcarrier frequency hopping position is calculated using the scrambled data; the modulation symbol is mapped to the corresponding subcarrier position according to the subcarrier frequency hopping position, and the unmapped position is filled with 0, and then the OFDM modulation is implemented using the IFFT algorithm; the RF frequency hopping data is scrambled and the RF center frequency is calculated; the OFDM signal is moved to the corresponding center frequency and sent out. The signal reaches the receiving end after passing through the wireless channel.

[0105] The physical layer processing flow at the receiving end is as follows: monitor all frequency bands in the frequency set, calculate the RF frequency hopping sequence according to the channel where the received signal is located, and obtain the RF frequency hopping data after descrambling; then perform FFT transformation on the received data to realize OFDM demodulation; perform subcarrier monitoring according to the signal power on the subcarrier to obtain the modulation symbol and the scrambled subcarrier frequency hopping data; obtain the modulation data after demodulating the modulation symbol; descramble the scrambled subcarrier frequency hopping data to obtain the subcarrier frequency hopping data; combine the modulation data, subcarrier frequency hopping data and RF frequency hopping data, and then perform channel decoding to restore the original transmitted data. This method uses the unpredictability of the original message to realize secondary random frequency hopping, and hides part of the data in the secondary frequency hopping pattern, which can effectively resist malicious interference and protect user data privacy.

[0106] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0107] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A two-stage frequency hopping method based on message driving, characterized in that: The following steps are involved: S1. Input the data D to be sent, perform RS-CC channel coding on the data D to be sent, and obtain the coded data D C ; S2. for D C Perform data segmentation to obtain the modulated data D M , subcarrier frequency hopping data D SC and RF frequency hopping data D RF ; S3. Modulate the data D M The serial input modulation module performs QAM modulation, and the parallel output obtains the modulation symbol S M ; S4. The pseudo-random sequence PN1 and the subcarrier frequency hopping data D SC Input scrambling module, output scrambled subcarrier frequency hopping data Will Input subcarrier frequency hopping position calculation module, output subcarrier position sequence A SC ; S5. Each modulation symbol S M According to the subcarrier position sequence A SC Placed at the corresponding subcarrier position, all unplaced modulation symbols S M Data 0 is placed on all subcarriers, and then OFDM modulation is implemented using IFFT operation, and a cyclic prefix CP is added; S6. The pseudo-random sequence PN2 and the RF frequency hopping data D RF Input scrambling module, output scrambled RF frequency hopping data S7. The transmitter transmits the scrambled RF frequency hopping data Move the DC subcarrier of the OFDM symbol to the final center frequency f c and send it to the receiver; S8. The receiver simultaneously monitors the frequency set The signal energy in each frequency band in the frequency set is assumed to be The serial number in is k, and the estimated value of the scrambled RF frequency hopping data is obtained from k S9. After descrambling, the final RF frequency hopping data estimate is obtained S10. Remove the cyclic prefix CP from the received signal, and then perform FFT operation to achieve OFDM demodulation; S11. Perform subcarrier monitoring. During each monitoring process, select the subcarrier with the highest signal power among the four subcarriers. The symbols carried by the four subcarriers with the highest signal power are modulation symbols. The subcarrier mapping data is hidden in the subcarrier sequence number. The modulation symbols and the corresponding subcarrier sequence numbers are recorded in the monitoring order. After N / 4 monitorings are completed, two sequences with a length of N / 4 are obtained, which are the modulation symbol sequence and the subcarrier position sequence S12. By Get the decimal representation of the estimated value of the scrambled subcarrier frequency hopping data use Calculate the estimated value of the scrambled subcarrier frequency hopping data S13. After descrambling, the final RF frequency hopping data estimate is obtained S14. Modulate the symbol Demodulate and obtain the estimated value of the modulated data S15. Combine them in order to get an estimate of the coded data S16.Yes Perform channel decoding to obtain the final output data 2. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: The amount of data D to be sent in S1 is shown in formula (1): Among them, R is the coding efficiency of channel coding, N is the number of subcarriers of OFDM, L is the modulation order, and M is the number of frequencies in the frequency set.

3. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: In S4, the pseudo-random sequence PN1 and the subcarrier frequency hopping data D SC Input scrambling module, output scrambled subcarrier frequency hopping data The calculation method of is shown in formula (2): in, Represents a bitwise exclusive OR operation; Will Input subcarrier frequency hopping position calculation module, output subcarrier position sequence A SC The calculation method of is shown in formula (3): Wherein, bin2dec(a, b)=2×a+b, and both a and b are binary data.

4. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: Each modulation symbol S in S5 M According to the subcarrier position sequence A SC Placed at the corresponding subcarrier position, the corresponding relationship is shown in equation (4) and equation (5): Here, dec mod k represents the remainder when dec is divided by k.

5. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: In S6, the pseudo random sequence PN2 and the radio frequency hopping data D RF Input scrambling module, output scrambled RF frequency hopping data The calculation method is shown in formula (6):

6. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: The transmitter in S7 uses the scrambled RF frequency hopping data Move the DC subcarrier of the OFDM symbol to the final center frequency f c Up, f c and The relationship between is shown in formula (7): in, Indicates the current frequency set The i-th frequency in 7. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: The receiver in S8 simultaneously monitors the frequency set The signal energy in each frequency band in the frequency set is assumed to be The serial number in is k, and the estimated value of the scrambled RF frequency hopping data is obtained from k As shown in formula (8): Here, dec2bin(·) indicates that a decimal number will be converted into a binary sequence.

8. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: The final RF frequency hopping data estimate obtained after descrambling in S9 As shown in formula (10):

9. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: Subcarrier monitoring is performed in S11. During each monitoring process, the subcarrier with the highest signal power among the four subcarriers is selected. The symbols carried by the four subcarriers with the highest signal power are modulation symbols. The subcarrier mapping data is hidden in the subcarrier sequence number. The modulation symbols and the corresponding subcarrier sequence numbers are recorded in the monitoring order. After N / 4 monitorings are completed, two sequences with a length of N / 4 are obtained, which are modulation symbol sequences and the subcarrier position sequence Then the subcarrier number set S monitored for the i-th time i As shown in formula (11):

10. The message-driven two-stage frequency hopping method according to claim 1, characterized in that: S12 Get the decimal representation of the estimated value of the scrambled subcarrier frequency hopping data The calculation method is shown in formula (12) and (13): use Calculate the estimated value of the scrambled subcarrier frequency hopping data The calculation method is as shown in formula (14) and (15):

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