阅读说明：本技术 一种抗强干扰的定时同步方法 (Timing synchronization method for resisting strong interference ) 是由 易志强 陈豪俊 张福洪 曾嵘 于 2020-05-12 设计创作，主要内容包括：本发明公开了一种抗强干扰的定时同步方法,针对现有基于训练序列的定时同步算法抗强干扰能力的不足。本发明的设计如下：首先构造发射端通信帧结构和同步序列的跳频图案,其次设计接收端本地载波的切换方式,接着构造接收端的本地同步序列,然后在接收端通过对零中频信号进行处理来捕捉相关峰,而后根据相关峰的特性及其频点信息确定接收到的数据信息的起始位置,最终完成信号同步。本发明可在强干扰环境下,可靠的完成通信信号的捕获同步,具备克服连续或突发大噪声、固定频点强干扰的特点,针对跳频干扰也具有较好的效果。(The invention discloses a timing synchronization method for resisting strong interference, which aims at the defect of strong interference resistance of the existing timing synchronization algorithm based on a training sequence. The design of the invention is as follows: firstly, constructing a communication frame structure of a transmitting terminal and a frequency hopping pattern of a synchronous sequence, secondly, designing a switching mode of a local carrier of a receiving terminal, secondly, constructing a local synchronous sequence of the receiving terminal, secondly, capturing a related peak at the receiving terminal by processing a zero intermediate frequency signal, and secondly, determining the initial position of received data information according to the characteristics of the related peak and frequency point information thereof, and finally completing signal synchronization. The invention can reliably complete the capture synchronization of communication signals in a strong interference environment, has the characteristics of overcoming continuous or burst large noise and fixed frequency point strong interference, and has better effect on frequency hopping interference.)

1. A timing synchronization method for resisting strong interference is characterized by comprising the following steps:

step one, designing a communication frame structure sequence S which consists of a leader sequence, a synchronous sequence and a data frame and is provided with a communication unitThe total length of the signal frame structure is L_S(ii) a The length of the synchronization sequence designed by the communication system is L_synIt is composed of 3M sub-sequence blocks with same structure, M is the number of frequency points needed for sending synchronous sequence, each sub-sequence block is composed of L length_switchOf length L_phaseHas an initial phase sequence of length L_PNTraining sequence of length L_guardThe guard interval sequences are sequentially formed; the training sequence of the 1 st to M blocks of the synchronous sequence adopts PN_a1The training sequence of the (M +1) -2M blocks adopts PN_a2The training sequence of the (2M +1) -3M blocks of the synchronization sequence adopts PN_a3；PN_a1，PN_a2And PN_a3Are all m₁(k)、m₂(k) Two groups of baseband m sequences with equal length and different lengths; PN (pseudo-noise)_a1，PN_a2And PN_a3Are respectively shown as formula (1), formula (2) and formula (3);

PN_a1(k)＝m₁(k)+j×m₂(k) k＝1,2,...,L_PNformula (1)

PN_a2(k)＝j×m₁(k)-m₂(k) k＝1,2,...,L_PNFormula (2)

PN_a3(k)＝-m₁(k)-j×m₂(k) k＝1,2,...,L_PNFormula (3)

In the formulae (1), (2) and (3),L_PNis the period of the m-sequence;

step two, setting the frequency point set of emission as phi: { f₁,f₂,…,f_MTotaling M frequency points; the switching between the sending frequency points needs to be controlled by a frequency switching signal; a hopping pattern (4) of the synchronization sequence;

in the formula (4), w represents the sequence number of the subsequence block in the synchronous sequence, the value range is 1-3M, and f_wShowing and connectingAfter receiving the frequency switching control signal, synchronizing the carrier frequency of the w-th block of the sequence when transmitting;

step three, before the communication receiving end works, the local carrier frequency f_rIs as shown in formula (5); the frequency point set of the local carrier wave of the receiving end is consistent with the carrier frequency set of the transmitting end and is phi: { f₁,f₂,…,f_MTotaling M frequency points;

in the formula (5), t is the working time of the receiver; n is the cycle number, and the complete cycle is ended by sequentially using all the frequency points in the frequency point set phi in the time period M tau; tau is the duration of each carrier frequency point, and the calculation method is shown as the formula (6);

in the formula (6), F_SInputting a symbol rate for the system;

step four, constructing a local training sequence PN_IAnd PN_Q(ii) a Are respectively shown as formula (7) and formula (8);

PN_I(k)＝m₁(k) k＝1,2,...,L_PNformula (7)

PN_Q(k)＝-j×m₂(k) k＝1,2,...,L_PNFormula (8)

Step five, changing the local carrier frequency f according to the formula (5)_r(ii) a Suppose that within the duration tau of the current carrier frequency point, the zero intermediate frequency in-phase path and orthogonal path signal sequences obtained after the frequency spectrum down-conversion are respectively R^IAnd R^QAll being (M +1) L in length_syn/3M；

Step six, assuming that the sliding variable is as the initial value of 0;

step seven, intercepting the sequence R^IIn subscript + 1- + L_PNGet the sequence ofAnd a value of +1 is noted

Step eight, calculating a real part correlation peak value P_realImaginary correlation peak P_imAnd a total correlation peak value P, which are respectively expressed by the formula (9), the formula (10) and the formula (11);

P＝(P_real)²+(P_im)²formula (11)

In the formulas (9) and (10), ". is an inner product operation;

step nine, setting a threshold lambda; if the total correlation peak value P is more than or equal to lambda, t stops timing, and the carrier frequency f of the current receiving end is adjusted_rthe r value in the total correlation peak value is marked as α, and the real part value P corresponding to the current total correlation peak value P is recorded as α_realIs marked as

step ten, if + L_PN＞(M+1)L_synPerforming step five by the aid of the step 3M; otherwise, returning to the step seven;

eleventh, determining the starting position of the data frame and

in the formula (12), "|" is a modulo operation.

Technical Field

The invention belongs to the technical field of burst communication, and particularly relates to a timing synchronization method for resisting strong interference.

Background

In the development process of the communication technology, the anti-interference capability of the communication system is gradually improved, and in contrast, the interference technology of the enemy is correspondingly enhanced. How to guarantee the correctness and the high efficiency of data transmission in a strong interference environment is a key research in the technical field of secret communication.

The burst communication technology has the characteristics of burstiness of information transmission and extremely short transmission time, so that the burst communication technology becomes a research hotspot of the anti-strong interference technology. Currently, the timing synchronization method based on the training sequence is widely applied in the burst communication field. The method can accurately synchronize data by utilizing the sharp characteristic of the autocorrelation function of the training sequence, the training sequence is easy to realize, and the capability of resisting broadband interference is greatly improved by adding the good pseudorandom characteristic of the training sequence. However, the sequence is simple in structure, the whole training sequence is only transmitted in a single frequency point mode, and the detected correlation peak of the single frequency point is the only standard of synchronous judgment, so that the original autocorrelation characteristic of the training sequence is seriously damaged by interference in the environment of strong narrow-band aiming type interference, the success probability of synchronization at a receiving end is obviously reduced, and communication interruption is caused.

For the above-mentioned shortcomings of the conventional timing synchronization method based on training sequence, a synchronization method which is easy to implement, has good synchronization performance and can effectively combat strong interference in communication needs to be designed for the burst communication system.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a timing synchronization method for resisting strong interference.

The invention relates to a timing synchronization method for resisting strong interference, which comprises the following specific steps:

step one, a communication frame structure sequence S designed by the communication system consists of a leader sequence, a synchronization sequence and a data frame, and the total length of the communication frame structure is set to be L_S(ii) a The length of the synchronization sequence designed by the communication system is L_synIt is composed of 3M sub-sequence blocks with same structure, M is the number of frequency points needed for sending synchronous sequence, each sub-sequence block is composed of L length_switchOf length L_phaseHas an initial phase sequence of length L_PNTraining sequence of length L_guardThe guard interval sequences are sequentially formed; the training sequence of the 1 st to M blocks of the synchronous sequence adopts PN_a1The training sequence of the (M +1) -2M blocks adopts PN_a2The training sequence of the (2M +1) -3M blocks of the synchronization sequence adopts PN_a3。PN_a1，PN_a2And PN_a3Are all m₁(k)、m₂(k) Two groups of baseband m sequences with equal length and different lengths. PN (pseudo-noise)_a1，PN_a2And PN_a3Is represented by formula (1), formula (2) and formula (3), respectively.

PN_a1(k)＝m₁(k)+j×m₂(k) k＝1,2,...,L_PNFormula (1)

PN_a2(k)＝j×m₁(k)-m₂(k) k＝1,2,...,L_PNFormula (2)

PN_a3(k)＝-m₁(k)-j×m₂(k) k＝1,2,...,L_PNFormula (3)

In the formulae (1), (2) and (3),

L_PNis the period of the m-sequence.

Step two, setting the frequency point set of emission as phi: { f₁,f₂,…,f_MAnd totaling M frequency points. Switching between the transmission frequency points needs to be controlled by a frequency switching signal. The hopping pattern (4) of the synchronization sequence is shown.

In the formula (4), w represents the sequence number of the subsequence block in the synchronous sequence, the value range is 1-3M, and f_wIndicating the carrier frequency at which the w-th block of the synchronization sequence is transmitted after receiving the frequency switching control signal.

Step three, before the communication receiving end works, the local carrier frequency f_rIs as shown in formula (5). The frequency point set of the local carrier wave of the receiving end is consistent with the carrier frequency set of the transmitting end and is phi: { f₁,f₂,…,f_MAnd totaling M frequency points.

In equation (5), t is the receiver on time. n is the number of cycles, and using all the frequency points in the frequency point set Φ in sequence in the time period M τ means the end of one complete cycle. τ is the duration of each carrier frequency point, and the calculation method is shown in formula (6).

In the formula (6), F_SThe symbol rate is input for the system.

Step four, constructing a local training sequence PN_IAnd PN_Q. Are respectively shown as formula (7) and formula (8).

PN_I(k)＝m₁(k) k＝1,2,...,L_PNFormula (7)

PN_Q(k)＝-j×m₂(k) k＝1,2,...,L_PNFormula (8)

Step five, changing the local carrier frequency f according to the formula (5)_r. Suppose that within the duration tau of the current carrier frequency point, the zero intermediate frequency in-phase path and orthogonal path signal sequences obtained after the frequency spectrum down-conversion are respectively R^IAnd R^QAll being (M +1) L in length_syn/3M。

And step six, assuming that the sliding variable is 0.

Step seven, intercepting the sequence R^IIn subscript + 1- + L_PNGet the sequence ofAnd a value of +1 is notedIs a sequence of

The starting position of (a). Truncation sequence R^QIn subscript + 1- + L_PNGet the sequence of

Step eight, calculating a real part correlation peak value P_realImaginary correlation peak P_imAnd a total correlation peak value P, as shown in formula (9), formula (10) and formula (11), respectively.

P＝(P_real)²+(P_im)²Formula (11)

In the formulae (9) and (10), "·" is an inner product operation.

Step nine, setting a threshold lambda. If the total correlation peak value P is more than or equal to lambda, t stops timing, and the carrier frequency f of the current receiving end is adjusted_rthe r value in the total correlation peak value is marked as α, and the real part value P corresponding to the current total correlation peak value P is recorded as α_realIs marked asThe imaginary part value P corresponding to the current total correlation peak value P_imIs marked as

Step eleven is executed. Otherwise, 1 is incremented and step ten is performed.

Step ten, if + L_PN＞(M+1)L_synand/3M, executing the step five. Otherwise, returning to the step seven.

Eleventh, determining the starting position of the data frame andthe distance y of (d) is as shown in equation (12).

In the formula (12), "|" is a modulo operation.

The invention has the following benefits:

the invention can reliably complete the capture synchronization of communication signals in a strong interference environment, has the characteristics of overcoming continuous or burst large noise and fixed frequency point strong interference, and has better effect on frequency hopping interference.

Drawings

Fig. 1 is a schematic diagram of a framing method of the burst communication system.

Fig. 2 is a schematic structural diagram of the 1 st block to the mth block of the synchronization sequence.

Fig. 3 is a schematic structural diagram of the 1+ M block to the 2M block of the synchronization sequence.

Fig. 4 is a schematic structural diagram of the 1+2M block to the 3M block of the synchronization sequence.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Step one, a communication frame structure sequence S designed by the communication system consists of a leader sequence, a synchronization sequence and a data frame, and the total length of the communication frame structure is set to be L_SThe constitution is shown in FIG. 1. The length of the synchronization sequence designed by the communication system is L_synIt is composed of 3M sub-sequence blocks with same structure, M is the number of frequency points needed for sending synchronous sequence, each sub-sequence block is composed of L length_switchOf length L_phaseHas an initial phase sequence of length L_PNTraining sequence of length L_guardThe guard interval sequences are sequentially formed; as shown in FIG. 2, the training sequence of the 1 st to M th blocks of the synchronization sequence adopts PN_a1As shown in FIG. 3, PN is used as the training sequence for the (M +1) -2M blocks_a2As shown in FIG. 4, PN is used as the training sequence of the (2M +1) -3M blocks of the synchronization sequence_a3。PN_a1，PN_a2And PN_a3Are all m₁(k)、m₂(k) Two groups of baseband m sequences with equal length and different lengths. PN (pseudo-noise)_a1，PN_a2And PN_a3Is represented by formula (1), formula (2) and formula (3), respectively.

PN_a1(k)＝m₁(k)+j×m₂(k) k＝1,2,...,L_PNFormula (1)

PN_a2(k)＝j×m₁(k)-m₂(k) k＝1,2,...,L_PNFormula (2)

PN_a3(k)＝-m₁(k)-j×m₂(k) k＝1,2,...,L_PNFormula (3)

In the formulae (1), (2) and (3),

L_PNis the period of the m-sequence.

Step two, setting the frequency point set of emission as phi: { f₁,f₂,…,f_MAnd totaling M frequency points. Switching between the transmission frequency points needs to be controlled by a frequency switching signal. The hopping pattern (4) of the synchronization sequence is shown.

In the formula (4), w represents the sequence number of the subsequence block in the synchronous sequence, the value range is 1-3M, and f_wIndicating the carrier frequency at which the w-th block of the synchronization sequence is transmitted after receiving the frequency switching control signal.

Step three, before the communication receiving end works, the local carrier frequency f_rIs as shown in formula (5). The frequency point set of the local carrier wave of the receiving end is consistent with the carrier frequency set of the transmitting end and is phi: { f₁,f₂,…,f_MAnd totaling M frequency points.

In equation (5), t is the receiver on time. n is the number of cycles, and using all the frequency points in the frequency point set Φ in sequence in the time period M τ means the end of one complete cycle. τ is the duration of each carrier frequency point, and the calculation method is shown in formula (6).

In the formula (6), F_SThe symbol rate is input for the system.

Step four, constructing a local training sequence PN_IAnd PN_Q. Are respectively shown as formula (7) and formula (8).

PN_I(k)＝m₁(k) k＝1,2,...,L_PNFormula (7)

PN_Q(k)＝-j×m₂(k) k＝1,2,...,L_PNFormula (8)

Step five, changing the local carrier frequency f according to the formula (5)_r. Suppose that within the duration tau of the current carrier frequency point, the zero intermediate frequency in-phase path and orthogonal path signal sequences obtained after the frequency spectrum down-conversion are respectively R^IAnd R^QAll being (M +1) L in length_syn/3M。

And step six, assuming that the sliding variable is 0.

Step seven, intercepting the sequence R^IIn subscript + 1- + L_PNGet the sequence ofAnd a value of +1 is notedIs a sequence of

The starting position of (a). Truncation sequence R^QIn subscript + 1- + L_PNGet the sequence of

Step eight, calculating a real part correlation peak value P_realImaginary correlation peak P_imAnd a total correlation peak value P, as shown in formula (9), formula (10) and formula (11), respectively.

P＝(P_real)²+(P_im)²Formula (11)

In the formulae (9) and (10), "·" is an inner product operation.

Step nine, setting a threshold lambda. If the total correlation peak value P is more than or equal to lambda, t stops timing, and the carrier frequency f of the current receiving end is adjusted_rthe r value in the total correlation peak value is marked as α, and the real part value P corresponding to the current total correlation peak value P is recorded as α_realIs marked asThe imaginary part value P corresponding to the current total correlation peak value P_imIs marked asStep eleven is executed. Otherwise, 1 is incremented and step ten is performed.

Step ten, if + L_PN＞(M+1)L_synand/3M, executing the step five. Otherwise, returning to the step seven.

Eleventh, determining the starting position of the data frame andthe distance y of (d) is as shown in equation (12).

In the formula (12), "|" is a modulo operation.