WO2023065374A1 - Radar-communication integration signal generating and receiving method based on random step frequency ofdm - Google Patents

Abstract

Disclosed in the present invention is a radar-communication integration signal generating and receiving method based on random step frequency OFDM, comprising: generating a radar-communication integration signal; modulating the step frequency of each pulse in each symbol of a first pulse; modulating, in a corresponding symbol of a second pulse, user information to be communicated; modulating the communication information in the third to last pulses; performing up-conversion on a baseband signal of each pulse according to the step frequency and sending a signal; and receiving the radar-communication integration signal: performing down-conversion on the first pulse and demodulating to obtain the step frequency of each pulse, performing down-conversion on the second pulse according to the step frequency and demodulating to obtain the user information, and performing down-conversion on the third to last pulses according to the step frequency and demodulating to obtain the communication information. According to the present invention, one-point-to-multipoint communication in a radar-communication integration system can be realized, and confidential communication in a special system is realized by using the random step frequency of each pulse.

Description

Radar communication integrated signal generation and reception method based on random step frequency OFDM technical field

The invention belongs to the technical field of radar communication integration, and in particular relates to a radar communication integration signal generation and communication receiving method based on random step frequency OFDM.

Background technique

The Integration of Radar and Communications (IRC) system realizes radar detection and wireless communication functions at the transmitter and receiver, and has great advantages, such as improving spectrum utilization and spectrum resource utilization, and has become a research hotspot in recent years. The radar communication integrated system is widely used in wireless radar sensor network, indoor positioning and activity recognition, drone monitoring and vehicle networking and other systems. The integrated radar communication system usually uses pulsed communication signals to simultaneously realize detection and communication functions.

Orthogonal Frequency Division Modulation (OFDM) signals have many excellent characteristics, so they are used in radar and communication systems. The communication characteristics mainly include high frequency band utilization and anti-multipath effect, and the radar characteristics mainly include high range resolution and non-range Doppler coupling. The pulsed OFDM communication signal is an integrated signal often used in radar communication integrated systems. The random step frequency signal can synthesize the real-time narrow-bandwidth signal into an effective large-bandwidth signal to improve the distance resolution. In the integrated system of airborne radar communication, a signal transmission technology is needed to realize one-to-multipoint and confidential communication, and the existing technology cannot realize these requirements.

Contents of the invention

Purpose of the invention: In order to overcome the deficiencies in the prior art, provide a radar communication integrated signal generation and communication receiving method based on random step frequency OFDM, which can ensure multi-user and confidential communication of the radar communication integrated system.

Technical solution: In order to achieve the above object, the present invention provides a radar communication integrated signal generation and reception method based on random step frequency OFDM, including the following steps:

Generate radar communication integrated signal, the specific generation method is as follows:

A1: Modulate the step frequency of the random step frequency OFDM radar communication integrated baseband signal in each pulse in each symbol of the first pulse;

A2: Modulate the user information to be communicated in the corresponding symbol of the second pulse;

A3: Modulate the communication information in the third to last pulse;

A4: Up-convert the baseband signal of each pulse according to the step frequency and send the signal;

Receive radar communication integrated signal, the specific receiving method is:

B1: Down-convert and demodulate the first pulse to obtain the step frequency of each pulse;

B2: Down-convert and demodulate the second pulse according to the step frequency to obtain user information;

B3: Down-convert and demodulate the third to last pulses according to the step frequency to obtain communication information.

Further, the expression of the random step frequency OFDM radar communication integrated baseband signal in the step A1 is:

Among them, N _p is the number of pulses, p=0,1,...,N _p -1; N _s is the number of symbols, m=0,1,...,N _s -1; N _c is the number of subcarriers, n=0 ,1,...,N _c -1; c(n,m,p) is the communication modulation information of the pth pulse, the mth symbol, and the nth subcarrier, Δf is the subcarrier frequency interval, T=1/Δf is the time width of the OFDM symbol; T _cp is the time width of the cyclic prefix, T _s =T _cp +T is the time bandwidth of the complete OFDM symbol; T _p is the pulse repetition period; rect(t) is the window function, only when t ∈[0,1] its value is 1, otherwise its value is 0.

Further, for c(n,m,p) in the step A1, different ZC (Zadoff-Chu) sequences are used as modulation information of subcarriers in different symbols.

且zc＝0,1,…,N _zc-1； N _s =N _p is specified in the step A1, and the number of ZC sequences is specified as N _zc , the number of sequences and the number of pulses need to satisfy N _zc >N _p ; the length of the ZC sequence is specified N _k =N _c - 1. Change the parameter μ to generate N _zc ZC sequences, expand its length to N _c by padding zeros and use it as the modulation information of different subcarriers in one symbol; number the N _zc ZC sequences to obtain

And zc=0,1,...,N _zc -1;

The step frequency d _p of each pulse is a random number between 0 and N _p -1, and the ZC sequence whose number is equal to the step frequency d _p of the pth pulse is used as the mth symbol in the first pulse The modulation information of N _c subcarriers, and p=m=zc, so far, the step frequency of each pulse is modulated in each symbol of the first pulse. In order to obtain the step frequency of different pulses at the communication receiving end, it is required that d ₀ =0.

且u＝0,1,…,N _u-1，将编号与待通信用户的编号相等的ZC序列作为第二个脉冲中第m个符号的N _c个子载波的调制信息，且u＝m＝zc，至此，待通信的用户信息调制在了第二个脉冲的对应符号中。 The step A2 specifically includes: in order to realize point-to-multipoint communication in the integrated radar communication system, user information needs to be carried in the integrated signal. It is stipulated that the number of users in the system is N _u , the number of users and the number of symbols need to satisfy N _u ≤ N _s , it is stipulated that N _u = N _s , and numbering _Nu users is obtained

And u=0,1,...,N _u -1, the ZC sequence whose number is equal to the number of the user to be communicated is used as the modulation information of the N _c subcarriers of the m-th symbol in the second pulse, and u=m= zc, so far, the user information to be communicated is modulated in the corresponding symbol of the second pulse.

因此，序列的个数和用户的个数需要满足N _zc>N _u，由于N _u＝N _s，N _s＝N _p，N _zc>N _p，因此该条件容易满足。在实际中，存在多个用户不需要通信的情况，因此存在第二个脉冲中的多个符号的N _c个子载波的调制信息为替补序列。 User information that does not need to be communicated does not need to be modulated in the corresponding symbol of the second pulse, and a substitute sequence is required as the modulation information of the _Nc subcarriers of the symbol. The number of this sequence is

Therefore, the number of sequences and the number of users need to _satisfy N _zc >N _u , since Nu =N _s , N _s =N _p , and N _zc >N _p , this condition is easy to satisfy. In practice, there are situations where multiple users do not need to communicate, so the modulation information of N _c subcarriers of multiple symbols in the second burst is a substitute sequence.

Further, the step B1 is specifically as follows: Since the carrier frequency of the first pulse is known to be f _c +d ₀ B, and d ₀ =0, the first pulse is down-converted at the communication receiving end to obtain the baseband received signal , the baseband received signal is demodulated to obtain the ZC sequence in each symbol, and the number of the ZC sequence in each symbol is obtained by looking up the table, which is the step frequency of each pulse.

Further, the step B2 is specifically:

In step B1, the step frequency d ₁ of the second pulse is obtained, and its carrier frequency is f _c +d ₁ B. The second pulse is down-converted at the communication receiving end to obtain the baseband receiving signal, and the baseband receiving signal is deciphered The ZC sequence in each symbol is tuned; the user numbered U _u uses the sequence numbered ZC _zc to perform correlation operations with the demodulation sequence in the mth symbol, and u=zc=m, and judges whether For the communicated user.

Further, the judging method of the communicated user in the step B2 is:

Judging the 2N _k -1 amplitudes of the normalized correlation sequence obtained, if only one amplitude is greater than 0.5, it means that the obtained sequence is an autocorrelation sequence, and the sequence carried by the mth symbol is the same as the ZC sequence with the same user number Sequence, the user is the communicated user and needs to continue to receive integrated signals; if there are two or more amplitudes greater than 0.5, it means that the obtained sequence is a cross-correlation sequence, and the sequence carried by the mth symbol is a substitute sequence, and the user is not The communicated user does not need to continue to receive integrated signals.

Beneficial effects: Compared with the prior art, the present invention uses the ZC sequence as the modulation information to ensure the low peak-to-average power ratio of the OFDM radar communication integrated signal and the high peak sidelobe ratio characteristic of its ambiguity function; by carrying user information , to realize the one-to-multipoint communication in the integrated radar communication system; through the randomness of each pulse carrier frequency, the confidential communication in the special environment is realized.

Description of drawings

Fig. 1 is the flowchart of the inventive method;

Fig. 2 is a schematic diagram of a random step frequency OFDM radar communication integrated signal model;

Fig. 3 is the ZC sequence autocorrelation function figure of length 31;

Fig. 4 is a ZC sequence cross-correlation function graph of length 31.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, further illustrate the present invention, should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention, after having read the present invention, those skilled in the art will understand various aspects of the present invention Modifications in equivalent forms all fall within the scope defined by the appended claims of this application.

The present invention provides a radar communication integrated signal generation and reception method based on random step frequency OFDM, which includes two parts: radar communication integrated signal generation and radar communication integrated signal reception, as shown in Figure 1, which includes the following steps :

1. Generate radar communication integrated signal, the specific generation method is as follows:

A1: Modulate the step frequency of the random step frequency OFDM radar communication integrated baseband signal in each pulse in each symbol of the first pulse:

The expression of the integrated baseband signal of the random step frequency OFDM radar communication is:

Among them, N _p is the number of pulses, p=0,1,...,N _p -1; N _s is the number of symbols, m=0,1,...,N _s -1; N _c is the number of subcarriers, n=0 ,1,...,N _c -1; c(n,m,p) is the communication modulation information of the pth pulse, the mth symbol, and the nth subcarrier, Δf is the subcarrier frequency interval, T=1/Δf is the time width of the OFDM symbol; T _cp is the time width of the cyclic prefix, T _s =T _cp +T is the time bandwidth of the complete OFDM symbol; T _p is the pulse repetition period; rect(t) is the window function, only when t ∈[0,1] its value is 1, otherwise its value is 0.

The communication modulation information c(n,m,p) is determined by the information to be transmitted, so it is random, which will affect the peak side lobe ratio performance of the integrated signal ambiguity function, and then affect the distance and speed detection performance of the integrated signal. In order to ensure its peak side lobe ratio, different ZC sequences are used as the modulation information of subcarriers in different symbols, mainly using the Fourier invariance of ZC sequences, low peak-to-average power ratio characteristics, and OFDM signal ambiguity functions modulated by ZC sequences The range and velocity dimensions have high peak sidelobe ratios and good autocorrelation and cross-correlation properties of the ZC sequence.

The expression to generate the ZC sequence is:

Among them, N _k is the length of the sequence, k=0,1,...,N _k -1; μ needs to satisfy that the greatest common divisor of μ and N _k is 1, two ZC sequences with the same μ are orthogonal to each other, and those with different μ Two ZC sequences are not orthogonal; c _f is the remainder of N _k divided by 2; q∈Z is a parameter.

且zc＝0,1,…,N _zc-1。 Each symbol in the first pulse of the integrated signal carries the step frequency of each pulse, so the number of symbols and the number of pulses need to satisfy N _s ≥ N _p , and this embodiment stipulates that N _s =N _p . Furthermore, it is stipulated that the number of ZC sequences is N _zc , and the number of sequences and the number of pulses need to satisfy N _zc >N _p . We stipulate the length of ZC sequence N _k =N _c -1, change the parameter μ to generate N _zc ZC sequences, expand their length to N _c by padding zeros, and use it as the modulation information of different subcarriers in a symbol. Number the N _zc ZC sequences to get

And zc=0, 1, . . . , N _zc −1.

The stepping frequency d _p of each pulse is a random number between 0 and N _p -1. The ZC sequence whose number is equal to the stepping frequency _dp of the pth pulse is used as the modulation information of the _Nc subcarriers of the mth symbol in the first pulse, and p=m=zc, so far, the step of each pulse Into frequency modulation in each symbol of the first pulse. In order to obtain the step frequency of different pulses at the communication receiving end, it is required that d ₀ =0.

A2: Modulate the user information to be communicated in the corresponding symbol of the second pulse:

且u＝0,1,…,N _u-1，将编号与待通信用户的编号相等的ZC序列作为第二个脉冲中第m个符号的N _c个子载波的调制信息，且 u＝m＝zc，至此，待通信的用户信息调制在了第二个脉冲的对应符号中。 In order to realize one-to-multipoint communication in the integrated radar communication system, it is necessary to carry user information in the integrated signal. It is stipulated that the number of users in the system is N _u , the number of users and the number of symbols need to satisfy N _u ≤ N _s , it is stipulated that N _u = N _s , and numbering _Nu users is obtained

And u=0,1,...,N _u -1, the ZC sequence whose number is equal to the number of the user to be communicated is used as the modulation information of the N _c subcarriers of the m-th symbol in the second pulse, and u=m= zc, so far, the user information to be communicated is modulated in the corresponding symbol of the second pulse.

因此，序列的个数和用户的个数需要满足N _zc>N _u，由于N _u＝N _s，N _s＝N _p，N _zc>N _p，因此该条件容易满足。在实际中，存在多个用户不需要通信的情况，因此存在第二个脉冲中的多个符号的N _c个子载波的调制信息为替补序列。 User information that does not need to be communicated does not need to be modulated in the corresponding symbol of the second pulse, and a substitute sequence is required as the modulation information of the _Nc subcarriers of the symbol. The number of this sequence is

Therefore, the number of sequences and the number of users need to _satisfy N _zc >N _u , since Nu =N _s , N _s =N _p , and N _zc >N _p , this condition is easy to satisfy. In practice, there are situations where multiple users do not need to communicate, so the modulation information of N _c subcarriers of multiple symbols in the second burst is a substitute sequence.

A3: Modulate the communication information in the third to last pulse:

Take the maximum l value where 2 ^l <N _zc holds true, divide the binary communication information into each l and convert it into a 2 ^- ary number, and modulate the ZC sequence with the same number as the conversion value in the third to the last N _p In N _s (N _p -2) symbols of -2 pulses.

A4: Up-convert the baseband signal of each pulse according to the step frequency and send the signal:

The integrated transmission signal is obtained by up-converting the baseband signal, the expression is:

Wherein, f _p is the carrier frequency of the pth pulse, and f _p =f _c +d _p B, f _c is the basic carrier frequency, and B=N _c Δf is the signal bandwidth. The model of the random step frequency OFDM radar communication integrated transmission signal is shown in Figure 2.

2. Receive the radar communication integrated signal, the specific receiving method is:

B1: Down-convert and demodulate the first pulse to obtain the step frequency of each pulse:

Since the carrier frequency of the first pulse is known to be f _c +d ₀ B, and d ₀ =0, the first pulse is down-converted at the communication receiving end to obtain the baseband received signal, and the baseband received signal is demodulated to obtain each The ZC sequence in each symbol, the number of the ZC sequence in each symbol obtained by looking up the table is the step frequency of each pulse.

B2: Down-convert and demodulate the second pulse according to the step frequency to obtain user information:

In step B1, the step frequency d ₁ of the second pulse is obtained, and its carrier frequency is f _c +d ₁ B. The second pulse is down-converted at the communication receiving end to obtain the baseband receiving signal, and the baseband receiving signal is deciphered Tune in to get the ZC sequence in each symbol. The user numbered U _u uses the sequence numbered ZC _zc to perform a correlation operation with the demodulation sequence in the mth symbol, and u=zc=m, and judges whether it is the communicated user according to the operation result.

The expression for the correlation function of the two sequences is:

Wherein _, i=-N _k ⁺¹ , _. When the two sequences are identical, the expression is an autocorrelation function, otherwise, the expression is a cross-correlation function. The normalized autocorrelation and cross-correlation sequences are shown in Figures 3 and 4.

Judging the 2N _k -1 amplitudes of the normalized correlation sequence obtained, if only one amplitude is greater than 0.5, it means that the obtained sequence is an autocorrelation sequence, and the sequence carried by the mth symbol is the same as the ZC sequence with the same user number Sequence, the user is the communicated user and needs to continue to receive integrated signals; if there are two or more amplitudes greater than 0.5, it means that the obtained sequence is a cross-correlation sequence, and the sequence carried by the mth symbol is a substitute sequence, and the user is not The communicated user does not need to continue to receive integrated signals.

B3: Down-convert and demodulate the third to last pulses according to the step frequency to obtain communication information:

In step B1, the stepping frequency d _p of the third to the last pulse is obtained, and its carrier frequency is f _c +d _p B, and the communication user performs down-conversion on the third to the last pulse to obtain the baseband reception signal, and the baseband reception The signal is demodulated to obtain the ZC sequence in each symbol, and the number of the ZC sequence in each symbol is obtained by looking up the table. The 2 ^- ary number is converted into l binary numbers, and the binary numbers in the N _s (N _p -2) symbols of the N _p -2 pulses are combined to obtain communication information.

Claims (10)

The radar communication integrated signal generation and receiving method based on random step frequency OFDM is characterized in that, comprising the following steps: Generate radar communication integrated signal, the specific generation method is as follows: A1: Modulate the step frequency of the random step frequency OFDM radar communication integrated baseband signal in each pulse in each symbol of the first pulse; A2: Modulate the user information to be communicated in the corresponding symbol of the second pulse; A3: Modulate the communication information in the third to last pulse; A4: Up-convert the baseband signal of each pulse according to the step frequency and send the signal; Receive radar communication integrated signal, the specific receiving method is: B1: Down-convert and demodulate the first pulse to obtain the step frequency of each pulse; B2: Down-convert and demodulate the second pulse according to the step frequency to obtain user information; B3: Down-convert and demodulate the third to last pulses according to the step frequency to obtain communication information. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 1, wherein the expression of the random step frequency OFDM radar communication integrated baseband signal in the step A1 is:

Among them, N _p is the number of pulses, p=0,1,...,N _p -1; N _s is the number of symbols, m=0,1,...,N _s -1; N _c is the number of subcarriers, n=0 ,1,...,N _c -1; c(n,m,p) is the communication modulation information of the pth pulse, the mth symbol, and the nth subcarrier, Δf is the subcarrier frequency interval, T=1/Δf is the time width of the OFDM symbol; T _cp is the time width of the cyclic prefix, T _s =T _cp +T is the time bandwidth of the complete OFDM symbol; T _p is the pulse repetition period; rect(t) is the window function, only when t ∈[0,1] its value is 1, otherwise its value is 0. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 2, wherein, in the step A1, for c (n, m, p), different ZC sequences are used as different Modulation information for subcarriers in a symbol. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 3, characterized in that N _s =N _p is specified in the step A1, and the number of ZC sequences is specified as N _zc , the number of sequences and the number of pulses need to satisfy N _zc >N _p ; stipulate the length of ZC sequence N _k =N _c -1, change the parameter μ to generate N _zc ZC sequences, and expand their length to N _c by padding zeros And as the modulation information of different subcarriers in a symbol; N _zc ZC sequences are numbered to obtain

And zc=0,1,...,N _zc -1; The step frequency d _p of each pulse is a random number between 0 and N _p -1, and the ZC sequence whose number is equal to the step frequency d _p of the pth pulse is used as the mth symbol in the first pulse The modulation information of N _c subcarriers, and p=m=zc, so far, the step frequency of each pulse is modulated in each symbol of the first pulse. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 2, wherein the step A2 is specifically: specifying that the number of users in the system is _Nu , the number of users The number of sum symbols needs to satisfy N _u ≤ N _s , stipulate that N _u = N _s , and number N _u users to get

And u=0,1,...,N _u -1, the ZC sequence whose number is equal to the number of the user to be communicated is used as the modulation information of the N _c subcarriers of the m-th symbol in the second pulse, and u=m= zc, so far, the user information to be communicated is modulated in the corresponding symbol of the second pulse. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 2, wherein the step A3 is specifically: Take the maximum l value where 2 ^l <N _zc holds true, divide the binary communication information into each l and convert it into a 2 ^- ary number, and modulate the ZC sequence with the same number as the conversion value in the third to the last N _p In N _s (N _p -2) symbols of -2 pulses. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 2, characterized in that, in the step A4, the baseband signal is up-converted to obtain an integrated transmission signal, and the expression is:

Wherein, f _p is the carrier frequency of the pth pulse, and f _p =f _c +d _p B, f _c is the basic carrier frequency, and B=N _c Δf is the signal bandwidth. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 1, wherein the step B1 is specifically: since the carrier frequency of the first pulse is known to be f _c +d ₀ B, and d ₀ =0, at the communication receiving end, down-convert the first pulse to obtain the baseband received signal, demodulate the baseband received signal to obtain the ZC sequence in each symbol, and obtain the ZC sequence in each symbol by looking up the table The number of the ZC sequence is the step frequency of each pulse. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 1, wherein the step B2 is specifically: In step B1, the step frequency d ₁ of the second pulse is obtained, and its carrier frequency is f _c +d ₁ B. The second pulse is down-converted at the communication receiving end to obtain the baseband receiving signal, and the baseband receiving signal is deciphered The ZC sequence in each symbol is tuned; the user numbered U _u uses the sequence numbered ZC _zc to perform correlation operations with the demodulation sequence in the mth symbol, and u=zc=m, and judges whether For the communicated user. The radar communication integrated signal generation and receiving method based on random step frequency OFDM according to claim 7, wherein the method for judging the communicated user in the step B2 is: Judging the 2N _k -1 amplitudes of the normalized correlation sequence obtained, if only one amplitude is greater than the set threshold, it means that the obtained sequence is an autocorrelation sequence, and the sequence carried by the mth symbol is the same ZC sequence as the user number is the same sequence, the user is the communicated user and needs to continue to receive the integrated signal; if there are two or more amplitudes greater than the set threshold, it means that the obtained sequence is a cross-correlation sequence, and the sequence carried by the mth symbol is Substitute sequence, the user is not the communicated user and does not need to continue to receive integrated signals.

Images