阅读说明：本技术 一种含前导随机突发信号的存在性检测方法 (Presence detection method for random burst signal containing preamble ) 是由 贺俊文 于 2021-09-17 设计创作，主要内容包括：一种含前导随机突发信号的存在性检测方法,包括步骤：计算前导符号序列s的共轭差分符号序列计算信号样本序列y的共轭差分样本序列分别以共轭差分信号样本y-(d)[M],y-(d)[M+1],…,y-(d)[2M-1]为起点,以M为采样周期,从共轭差分样本序列y-(d)中抽取样本,将y-(d)分成样本数量相等的M组子样本序列针对每一组子样本序列m＝0,1,2,…,M-1,分别计算两个子检测统计量和的估计值；检测随机突发信号的存在性和进行随机突发信号的帧头位置估计。本方法能够同时实现随机突发信号的存在性检测功能和帧头定位功能,且具有较强的抗频偏能力。(A method for detecting the presence of a random burst signal containing a preamble, comprising the steps of: calculating a conjugate differential symbol sequence of a preamble symbol sequence s Calculating a conjugate differential sample sequence of a signal sample sequence y Respectively with conjugate differential signal samples y d [M],y d [M+1],…,y d [2M‑1]Starting from a conjugate differential sample sequence y with M as the sampling period d Extracting a sample of (A) and (B) from (A) and (B) d Dividing into M groups of sub-sample sequences with equal number of samples For each group of subsample sequences M is 0,1,2, …, M-1, and two sub-detection statistics are calculated respectively And an estimated value of (d); detecting the existence of the random burst signal and performing frame header position estimation of the random burst signal. The method can simultaneously realize the existence detection function and the frame head positioning function of the random burst signal, and has stronger anti-frequency deviation capability.)

1. A method for detecting the existence of random burst signals containing preamble, characterized by using symbolsA sequence of preamble symbols representing a random burst signal frame, wherein s [ l ]]Are known preamble symbols, the number of preamble symbols is L + 1; the symbol M represents the oversampling multiple of the digital modulation symbol in the signal sample sequence output by the receiver digital down converter; by symbolsRepresenting a sequence of signal samples taken from the output of a receiver digital down-converter, where y k]Is a signal sample, the number of signal samples is K ═ L +1) M;

the presence detection method comprises the steps of:

s1, calculating conjugate differential symbol sequence of leading symbol sequence SWherein the symbol interval of the differential operation is 1, conjugate differential leading symbol s_d[l]The calculation method of (2) is as follows:

s_d[l]＝s^*[l]s[l-1],l＝1,2,…,L；

wherein, represents a conjugate, conjugate differential symbol sequence s_dThe total number of symbols of (a) is L;

s2, calculating conjugate difference sample sequence of signal sample sequence yWhere the sample interval of the difference operation is M, conjugate difference samples y_d[k]The calculation method of (2) is as follows:

y_d[k]＝y^*[k]y[k-M],k＝M,M+1,…,K-1；

conjugate differential sample sequence y_dThe total number of samples of (a) is LM;

s3, respectively using the conjugate differential signal samples y_d[M],y_d[M+1],…,y_d[2M-1]Starting from a conjugate differential sample sequence y with M as the sampling period_dMiddle drawerTaking a sample, mixing y_dDividing into M groups of sub-sample sequences with equal number of samplesWherein the content of the first and second substances,representing a sequence of samples y from conjugate differences_dThe m-th group of subsample sequences extracted from

Sequence of subsamplesThe total number of samples of (a) is L;

s4, aiming at each group of sub-sample sequencesCalculating two sub-detection statistics separatelyAndestimated value of (a):

wherein, gamma is the detection threshold (·)^HRepresenting a conjugate transpose, | · non-conducting phosphor²Representing the square of the complex modulus, | · | non-woven phosphor²Expressing a squared euclidean norm;

s5, detecting the existence of the random burst signal, wherein the specific method is as follows:

if for each group of subsample sequencesAre all provided with

Then a determination is made as to the received signal sample sequenceThere is no preamble symbol sequence of the random burst signal, so the random burst signal does not exist;

if for a certain set of sub-sample sequencesIs provided with

Then a determination is made as to the received signal sample sequenceThe preamble symbol sequence of the random burst signal is contained in the random burst signal, so that the random burst signal is already present;

s6, estimating the frame header position of the random burst signal, specifically, the method comprises the following steps:

if M is more than or equal to 0 and less than or equal to M-1 for a certain value, the subsample sequenceSatisfies the detection conditionThen, the sample corresponding to the frame head position of the random burst signal is ym]。

Technical Field

The invention belongs to the technical field of digital communication, relates to a burst signal detection technology, and particularly relates to a method for detecting existence of random burst signals containing preambles.

Background

The main task of a digital communication receiver is to recover the information sent by the sender as completely as possible from the received lossy signal. To achieve this goal, the receiver needs to capture the desired signal in noise, demodulate and decode the desired signal, and finally extract error-free information. Signal acquisition is therefore a primary function of digital communication receivers. The signal acquisition function consists of two parts: detecting the existence of the signal and positioning the frame header of the signal.

In random burst communication, since the transmission time of burst signals is unpredictable and there is no continuity between burst signal frames, in order to improve the acquisition success rate of random burst signals, a fixed preamble sequence is usually added to the head of each random burst signal frame. If the existence detection and frame head positioning of the random burst signal can be simultaneously realized by using the leader sequence, the capture time delay of the whole burst signal can be obviously shortened.

Disclosure of Invention

In order to solve the above related prior art problems, the present invention provides a method for detecting the existence of a random burst signal containing a preamble, which can simultaneously implement the existence detection function of the random burst signal and the frame header positioning function, and has a strong capability of resisting frequency offset.

In order to achieve the purpose of the invention, the invention is realized by the following technical scheme:

a method for detecting the presence of a random burst signal containing a preamble, comprising: by symbolsA sequence of preamble symbols representing a random burst signal frame, wherein s [ l ]]Are known preamble symbols, the number of preamble symbols is L + 1; the oversampling multiple of a digital modulation symbol in a sequence of signal samples output by a receiver digital down-converter (DDC) is denoted by the symbol M; by symbolsRepresents a sequence of signal samples taken from the DDC output of the receiver, where y k]Is a signal sample, the number of signal samples is K ═ L +1) M;

the presence detection method comprises the steps of:

s1, calculating conjugate differential symbol sequence of leading symbol sequence SWherein the symbol interval of the differential operation is 1, conjugate differential leading symbol s_d[l]The calculation method of (2) is as follows:

s_d[l]＝s^*[l]s[l-1],l＝1,2,…,L；

wherein, represents a conjugate, conjugate differential symbol sequence s_dThe total number of symbols of (a) is L;

s2, calculating conjugate difference sample sequence of signal sample sequence yWhere the sample interval of the difference operation is M, conjugate difference samples y_d[k]The calculation method of (2) is as follows:

y_d[k]＝y^*[k]y[k-M],k＝M,M+1,…,K-1；

conjugate differential sample sequence y_dThe total number of samples of (a) is LM;

s3, respectively using the conjugate differential signal samples y_d[M],y_d[M+1],…,y_d[2M-1]Starting from a conjugate differential sample sequence y with M as the sampling period_dExtracting a sample of (A) and (B) from (A) and (B)_dDividing into M groups of sub-sample sequences with equal number of samplesWherein the content of the first and second substances,representing a sequence of samples y from conjugate differences_dThe m-th group of subsample sequences extracted from

Sequence of subsamplesThe total number of samples of (a) is L;

s4, aiming at each group of sub-sample sequencesM is 0,1,2, …, M-1, and two sub-detection statistics are calculated respectivelyAndestimated value of (a):

wherein, gamma is the detection threshold (·)^HRepresenting a conjugate transpose, | · non-conducting phosphor²Representing the square of the complex modulus, | · | non-woven phosphor²Expressing a squared euclidean norm;

s5, detecting the existence of the random burst signal, wherein the specific method is as follows:

if for each group of subsample sequencesM is 0,1,2, …, M-1, all have

Then a determination is made as to the received signal sample sequenceThere is no preamble symbol sequence of the random burst signal, so the random burst signal does not exist;

if for a certain set of sub-sample sequencesM is more than or equal to 0 and less than or equal to M-1, having

Then a determination is made as to the received signal sample sequenceThe preamble symbol sequence of the random burst signal is contained in the random burst signal, so that the random burst signal is already present;

s6, estimating the frame header position of the random burst signal, specifically, the method comprises the following steps:

if M is more than or equal to 0 and less than or equal to M-1 for a certain value, the subsample sequenceSatisfies the detection conditionThen, the sample corresponding to the frame head position of the random burst signal is ym]。

The invention has the beneficial effects that: the method can simultaneously realize the existence detection function and the frame header positioning function of the random burst signal, and has stronger anti-frequency deviation capability.

Drawings

Fig. 1 is a block diagram of a random burst detector in an embodiment of the present invention.

Fig. 2 is a block diagram of a conjugate differentiator according to an embodiment of the present invention.

FIG. 3 is a view of an embodiment of the present inventionThe calculator is a block diagram implemented by a type I FIR filter.

FIG. 4 is a view of an embodiment of the present inventionThe calculator is a block diagram implemented by a type II FIR filter.

FIG. 5 is a view of an embodiment of the present inventionThe calculator is a block diagram implemented by a type I FIR filter.

FIG. 6 is a view of an embodiment of the present inventionThe calculator is a block diagram implemented by a type II FIR filter.

Detailed Description

In order to make the purpose, technical scheme and specific implementation method of the application clearer, the application is further described in detail by combining with an example of the attached drawings.

The method for detecting the existence of the random burst signal adopted by the application comprises the following steps: if it is not

Judging that a random burst signal exists; otherwise, it is absent. Wherein the content of the first and second substances,is the detection statistic and gamma is the detection threshold.

In order to apply the method, the following detection statistics are designed in the application:

wherein s is_dIs a conjugate differential symbol sequence of a preamble symbol sequence s, having a length L;is a conjugate differential sample sequence y from a received signal sample sequence y_dThe sub-sample sequence with the length of L is extracted at intervals of oversampling multiple M; l. capillary²Representing the square of the complex modulus, | · | non-woven phosphor²Representing a squared euclidean norm.

The determination method of the detection threshold gamma comprises the following steps: first determining the false alarm rate P of the detector_FAThen, the approximate value of the detection threshold is estimated by the formula (3)Finally, the detection threshold gamma which meets the design requirements is obtained through simulation verification and proper adjustment.

In the formula (3), F_1,L-1Showing the F distribution with a numerator degree of freedom of 1 and a denominator degree of freedom of L-1,represents the F distribution F_1,L-1The inverse of the right-tailed probability function of (c).

For convenience of calculation, two sub-detection statistics are obtained according to the arrangement of the expressions (1) and (2):

therefore, the method of detecting the presence of a random burst signal can be restated as: if it is not

Judging that a random burst signal exists; otherwise, it is absent.

The embodiment of the application provides a method for detecting existence of random burst signals containing preambles.

First, the relevant parameter symbol in the present embodiment will be explained. SymbolA sequence of preamble symbols representing a random burst signal frame, wherein s [ l ]]Are known preamble symbols, the number of preamble symbols is L + 1; the symbol M represents the oversampling multiple of the digitally modulated symbols in the sequence of signal samples output by the receiver DDC; symbolRepresents a sequence of signal samples, containing (L +1) M samples, taken from the DDC output of the receiver, before time k.Represents a sequence of conjugate differential samples prior to time k, comprising LM samples.Representing a sequence of samples y from conjugate differences_d[k]Contains L samples.

In random burst communication, the transmission time of a random burst signal is unpredictable. In order to avoid missing detection, the random burst signal detector for detecting the existence of the random burst signal is in a continuous detection state, that is, every time a signal sample is received, it detects whether a preamble symbol sequence of the random burst signal exists in a received signal sample. Therefore, in the random burst signal detector described in this embodiment, a delay register is used to buffer a segment of recently received signal samples.

As shown in fig. 1, the random burst detector described in this embodiment includes four parts: a conjugate differentiator,A calculator,A calculator and a decider. The conjugate differentiator is used for conjugate differentiating the received signal samples to eliminate the frequency offset in the signal samples. As shown in fig. 2, the conjugate differentiator has M delay registers D.Calculator for real-time operator detection statisticsThe value of (c). As shown in figures 3 and 4 of the drawings,the calculator can be implemented in two ways, wherein FIG. 3 isThe calculator is realized by a type I FIR filter structure diagram and comprises (L-1) M +1 delay registers. FIG. 4 isThe calculator is a structure diagram implemented by a type II FIR filter, and comprises (L-1) M delay registers.Calculator for real-time operator detection statisticsThe value of (c). As shown in figures 5 and 6 of the drawings,the calculator can also passTwo ways of implementation, wherein, FIG. 5 isThe calculator is realized by a type I FIR filter structure diagram and comprises (L-1) M +1 delay registers. FIG. 6 isThe calculator is a structure diagram implemented by a type II FIR filter, and comprises (L-1) M delay registers.

In the present embodiment, it is preferred that,calculator andthe calculators all adopt II type FIR filter structures.

In the present embodiment, the detection threshold γ is determined by the following method:

first, the false alarm rate P of the detector is determined_FA(ii) a Then by the following formula

Approximation of estimated detection thresholdFinally, the detection threshold gamma which meets the design requirements is obtained through simulation verification and proper adjustment. In the above formula, F_1,L-1Showing the F distribution with a numerator degree of freedom of 1 and a denominator degree of freedom of L-1,represents the F distribution F_1,L-1The inverse of the right-tailed probability function of (c).

The method for detecting the existence of the random burst signal containing the preamble, which is described in the embodiment of the application, has the following specific implementation mode:

1. initialization:

1.1, initializationThe coefficients of the FIR filter in the calculator.

First, a conjugate differential symbol sequence of a preamble symbol sequence s is calculatedWherein the symbol interval of the differential operation is 1, conjugate differential leading symbol s_d[l]The calculation method of (2) is as follows:

s_d[l]＝s^*[l]s[l-1],l＝1,2,…,L；

wherein denotes conjugation.

Then, calculateCoefficients of FIR filter in calculator

Finally, the coefficients of the filter are initialized in the order shown in fig. 4.

1.2, initializing a delay register of the random burst signal detector. The initial values of all delay registers are set to 0.

2. A continuous sensing operation is performed.

2.1 when the DDC of the receiver outputs one signal sample y k, the receiver performs the following two operations in parallel:

2.1.1, sending the signal sample y [ k ] into a buffer.

2.1.2, sending the signal sample y [ k ] to a random burst signal detector.

2.2 conjugate differentiator calculates the signal samples y [ k ]]Conjugate differential sample y of_d[k]The calculation method is as follows:

y_d[k]＝y^*[k]y[k-M]。

2.3, differentiating the conjugate of the samples y_d[k]Fed in parallel as shown in FIG. 4Calculator and as shown in figure 6A calculator for performing a filtering operation by the two filters respectively and calculating the resultsAndand the estimated values are output to the decision device as the estimated values of the two sub-detection statistics at the k moment.

2.4, judging whether the random burst signal exists or not, wherein the specific method comprises the following steps:

if it is not

Then the received signal sample sequence is determinedThe sequence of leading symbols containing random burst signals, wherein the random burst signals are already present; otherwise, judging that the received signal sample sequence has no preamble symbol sequence of the random burst signal, and the random burst signal does not exist.

If the random burst signal is detected to exist at the moment k, the sample corresponding to the frame head position of the random burst signal can be estimated to be y [ k-D ]₀]Wherein D is₀Is the processing delay of the random burst signal detector.

After the presence of the random burst signal is detected, the process returns to step 2.1, and the next signal sample is received and the detection is continued regardless of the result.