CN109274444A - A kind of three-dimensional frequency spectrum sensing method of Space-Time-frequency - Google Patents

A kind of three-dimensional frequency spectrum sensing method of Space-Time-frequency Download PDF

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CN109274444A
CN109274444A CN201811124363.0A CN201811124363A CN109274444A CN 109274444 A CN109274444 A CN 109274444A CN 201811124363 A CN201811124363 A CN 201811124363A CN 109274444 A CN109274444 A CN 109274444A
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frequency
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CN109274444B (en
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杜利平
薛慧
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University of Science and Technology Beijing USTB
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Abstract

The present invention provides a kind of three-dimensional frequency spectrum sensing method of Space-Time-frequency, can obtain time, frequency and the angle information of primary user's signal.The described method includes: carrying out whitening pretreatment to primary user's signal that multiple cognitive users receive;The pretreated signal of whitening carries out spacial time-frequency distribution and converts to obtain four-matrix, wherein the information in four-matrix includes: time, frequency and two-dimensional space information;The time-frequency two-dimensional information of four-matrix is filtered, is extracted single from reference point;Reference point progress Joint diagonalization is originated to obtained list to obtain estimating for the steering vector of angle estimation;According to obtained steering vector, the angle of arrival of each primary user's signal is determined.The present invention relates to radio spectrum sensing technical fields.

Description

A kind of three-dimensional frequency spectrum sensing method of Space-Time-frequency
Technical field
The present invention relates to radio spectrum sensing technical fields, particularly relate to a kind of three-dimensional frequency spectrum perception side of Space-Time-frequency Method.
Background technique
In recent years, as the global radio communication technology develops with rapid changepl. never-ending changes and improvementsly, the novel radio electric system phase of different function After appearance.For wireless communication system using static spectral allocation strategy, frequency spectrum resource is also more and more in short supply at present.Cognition wireless Electric energy reaches the variation of sensing external environment, improves the availability of frequency spectrum and power system capacity, solves the problems, such as spectrum shortage.It is common at present Frequency spectrum sensing method be mainly divided into single cognitive user frequency spectrum perception and more cognitive user frequency spectrum perception technologies.
Existing frequency spectrum perception technology can only obtain the presence or absence of primary user's signal mostly, when can not obtain detailed Between, frequency and angle information.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of three-dimensional frequency spectrum sensing methods of Space-Time-frequency, to solve existing skill Frequency spectrum perception technology present in art cannot obtain the problem of detailed time, frequency and angle information.
In order to solve the above technical problems, the embodiment of the present invention provides a kind of three-dimensional frequency spectrum sensing method of Space-Time-frequency, comprising:
Whitening pretreatment is carried out to primary user's signal that multiple cognitive users receive, wherein between each primary user's signal It is irrelevant;
The pretreated signal of whitening carries out spacial time-frequency distribution and converts to obtain four-matrix, wherein in four-matrix Information includes: time, frequency and two-dimensional space information;
The time-frequency two-dimensional information of four-matrix is filtered, is extracted single from reference point, wherein single source refers to each independence Primary user's signal source;
Reference point progress Joint diagonalization is originated to obtained list to obtain estimating for the steering vector of angle estimation;
According to obtained steering vector, the angle of arrival of each primary user's signal is determined.
Further, the primary user's signal progress whitening pretreatment received to multiple cognitive users includes:
Primary user's signal that multiple cognitive users are received forms receipt signal matrix;
Whitening pretreatment is carried out to receipt signal matrix.
Further, primary user's signal composition receipt signal matrix that multiple cognitive users are received include:
N number of primary user emits signal from different directions, reaches M cognitive user end, wherein M > N;
The signal that M cognitive user is received forms receipt signal matrix Y=[Y1,Y2,...,YM]T, wherein subscript T The transposition of representing matrix.
Further, described to include: to receipt signal matrix progress whitening pretreatment
Eigenvalues Decomposition is carried out to the covariance matrix of receipt signal matrix Y;
According to Eigenvalues Decomposition as a result, building whitening matrix W;
Whitening matrix W dot product receipt signal matrix Y, obtains whitened signal Z=WY, wherein Z=[Z1,Z2,...,ZN]T
Further, it is described according to Eigenvalues Decomposition as a result, building whitening matrix W include:
Descending arrangement is carried out to obtained characteristic value, the characteristic value [λ after obtaining descending arrangement1,...,λM], and its it is corresponding Feature vector [h1,...,hM];
From M characteristic value after descending arrangement, take preceding 1~N number of characteristic value and its feature vector be used to construct albefaction square Battle array W, wherein whitening matrix W is indicated are as follows:
Wherein, σ2For the average value of rear M-N lesser characteristic values after descending arrangement, the conjugation of subscript H representing matrix Transposition.
Further, it is indicated by the four-matrix that spacial time-frequency distribution converts are as follows:
Wherein, DZZ(t, f) is two-dimensional covariance matrix, representation space information;Each elementIt is one two The time-frequency matrix of dimension,Indicate i-th of signal ZiWith j-th of signal ZjMutual time-frequency distributions;T indicates the time;F is indicated Frequency.
Further, the time-frequency two-dimensional information to four-matrix is filtered, and is extracted list from reference point and is included:
Pass through relational expressionExtract the auto-correlation point comprising all primary user's signals, wherein ε2 To extract threshold value, the mark of trace () representing matrix;
By cluster, the auto-correlation point of all primary user's signals extracted is divided into N class, certain one kind represents a certain signal Auto-correlation point, obtain the K of N class list source signaliA auto-correlation pointWherein, i=1,2 ..., N, ki=1,2 ..., Ki
Further, described pair of obtained list is originated from reference point progress Joint diagonalization and obtains the guiding for angle estimation Vector is estimated
To obtained N class auto-correlation pointThe two-dimensional space information of four-matrix is extracted, constitutes signal when corresponding Correlation matrix on frequency point
To obtained correlation matrixJoint diagonalization processing is carried out, acquiring makesMost Small N × N-dimensional unitary matrice U, wherein I is unit matrix, and off () is the quadratic sum of matrix off-diagonal element;
Steering vector estimation is carried out using the unitary matrice U that Joint diagonalization obtains:
Wherein, W#For the pseudoinverse of whitening matrix,For steering vector.
Further, the steering vector that the basis obtains determines that the angle of arrival of each primary user's signal includes:
According to obtained steering vector, the angle of arrival of each primary user's signal is determined using multiple signal classification.
Further, the steering vector that the basis obtains determines each primary user's signal using multiple signal classification Angle of arrival includes:
It is rightSeek its covariance matrix:
Wherein, RAAFor the covariance matrix of M × M dimension;
By RAAFeature vector be divided into two parts by the size of characteristic value: UsAnd Un, wherein Us·Us H+Un·Un H=I, Us =[U1,U2,...,UN] it is the unitary space that the corresponding feature vector of top n maximum eigenvalue is constituted, it opens into signal subspace;Un =[UN+1,...,UM] it is the unitary matrice that the corresponding feature vector of rear M-N minimal eigenvalue is constituted, it opens into noise subspace;
Pass throughTo the angle of primary user's signal Estimated, obtains the angle of arrival of each primary user's signal.
The advantageous effects of the above technical solutions of the present invention are as follows:
In above scheme, whitening pretreatment is carried out to primary user's signal that multiple cognitive users receive;Whitening is located in advance Signal after reason carries out spacial time-frequency distribution and converts to obtain four-matrix, wherein the information in four-matrix includes: time, frequency With two-dimensional space information;The time-frequency two-dimensional information of four-matrix is filtered, list is extracted and is originated from reference point, to obtain each The accurate time-frequency distributions of primary user's signal;Reference point progress Joint diagonalization is originated to obtained list to obtain for angle estimation Steering vector estimation;According to obtained steering vector, the angle of arrival of each primary user's signal is determined.In this way, based on empty time-frequency Distribution transformation extracts the auto-correlation point of signal to obtain the accurate time frequency distribution map of signal, and so as to improve primary user's angle Estimate accuracy and resolution ratio.
Detailed description of the invention
Fig. 1 is the flow diagram of the three-dimensional frequency spectrum sensing method of Space-Time provided in an embodiment of the present invention-frequency;
Fig. 2 is more primary users, cognitive user schematic diagram in cognitive radio networks provided in an embodiment of the present invention;
Fig. 3 is the time-frequency energy signal of the three-dimensional frequency spectrum sensing method of Space-Time-frequency of signal 1 provided in an embodiment of the present invention Figure;
Fig. 4 is the time-frequency energy signal of the three-dimensional frequency spectrum sensing method of Space-Time-frequency of signal 2 provided in an embodiment of the present invention Figure;
Fig. 5 is the angle estimation signal of the three-dimensional frequency spectrum sensing method of Space-Time-frequency of signal 1 provided in an embodiment of the present invention Figure;
Fig. 6 is the angle estimation signal of the three-dimensional frequency spectrum sensing method of Space-Time-frequency of signal 2 provided in an embodiment of the present invention Figure.
Specific embodiment
To keep the technical problem to be solved in the present invention, technical solution and advantage clearer, below in conjunction with attached drawing and tool Body embodiment is described in detail.
The present invention aiming at the problem that existing frequency spectrum perception technology cannot obtain detailed time, frequency and angle information, A kind of three-dimensional frequency spectrum sensing method of Space-Time-frequency is provided.
As shown in Figure 1, the three-dimensional frequency spectrum sensing method of Space-Time provided in an embodiment of the present invention-frequency, comprising:
S101 carries out whitening pretreatment to primary user's signal that multiple cognitive users receive, wherein each primary user's signal Between it is irrelevant;
S102, the pretreated signal of whitening carry out spacial time-frequency distribution (Spatial Time-frequency Distribution, STFD) transformation obtain four-matrix, wherein the information in four-matrix includes: time, frequency and bidimensional Spatial information;
S103 is filtered the time-frequency two-dimensional information of four-matrix, extracts single from reference point, wherein single source refers to often A independent primary user's signal source;
S104 is originated from reference point progress Joint diagonalization to obtained list and obtains estimating for the steering vector of angle estimation Meter;
S105 determines the angle of arrival of each primary user's signal according to obtained steering vector.
The three-dimensional frequency spectrum sensing method of Space-Time described in the embodiment of the present invention-frequency, receives multiple cognitive users primary Family signal carries out whitening pretreatment;The pretreated signal of whitening carries out spacial time-frequency distribution and converts to obtain four-matrix, wherein Information in four-matrix includes: time, frequency and two-dimensional space information;The time-frequency two-dimensional information of four-matrix was carried out Filter extracts list and is originated from reference point, to obtain the accurate time-frequency distributions of each primary user's signal;Reference point is originated to obtained list Joint diagonalization is carried out to obtain estimating for the steering vector of angle estimation;According to obtained steering vector, determine each primary The angle of arrival of family signal.In this way, based on spacial time-frequency distribution convert, extract the auto-correlation point of signal obtain signal it is accurate when Frequency division Butut, and so as to improve the estimation accuracy and resolution ratio of primary user's angle.
It is further, described to recognize multiple in the specific embodiment of the three-dimensional frequency spectrum sensing method of aforementioned Space-Time-frequency Know that primary user's signal that user receives carries out whitening pretreatment and includes:
Primary user's signal that multiple cognitive users are received forms receipt signal matrix;
Whitening pretreatment is carried out to receipt signal matrix.
It is further, described to recognize multiple in the specific embodiment of the three-dimensional frequency spectrum sensing method of aforementioned Space-Time-frequency Know that primary user's signal composition receipt signal matrix that user receives include:
N number of primary user emits signal from different directions, reaches M cognitive user end, wherein M > N;
The signal that M cognitive user is received forms receipt signal matrix Y=[Y1,Y2,...,YM]T, wherein subscript T The transposition of representing matrix.
In the present embodiment, it is assumed that N number of primary user emits signal from different directions, and reaches M (M > N) a cognitive user End, angle of arrival is respectively θ12,...,θN.Each primary user's signal source is mutually indepedent, irrelevant between each primary user's signal, And it is irrelevant between primary user's signal and noise.The signal received is sent to decision center by each cognitive user, by certainly Plan is centrally formed receipt signal matrix Y=[Y1,Y2,...,YM]T
In the specific embodiment of the three-dimensional frequency spectrum sensing method of aforementioned Space-Time-frequency, further, the docking is collected mail Number matrix carries out whitening pretreatment
Eigenvalues Decomposition is carried out to the covariance matrix of receipt signal matrix Y;
According to Eigenvalues Decomposition as a result, building whitening matrix W;
Whitening matrix W dot product receipt signal matrix Y, obtains whitened signal Z=WY, wherein Z=[Z1,Z2,...,ZN]T
In the present embodiment, it is described according to Eigenvalues Decomposition as a result, building whitening matrix W specific steps may include:
Eigenvalues Decomposition is carried out to the covariance matrix of receipt signal matrix Y;
Descending arrangement is carried out to obtained characteristic value, the characteristic value [λ after obtaining descending arrangement1,...,λM] and its it is corresponding Feature vector [h1,...,hM], from M characteristic value after descending arrangement, take preceding 1~N number of characteristic value and its feature vector be used for Constructing whitening matrix W, that is to say, that the formula of whitening matrix W only used 1~N number of characteristic value and its feature vector.
In the present embodiment, whitening matrix W is indicated are as follows:
Wherein, σ2For the average value of rear M-N lesser characteristic values after descending arrangement, the conjugation of subscript H representing matrix Transposition.
In the specific embodiment of the three-dimensional frequency spectrum sensing method of aforementioned Space-Time-frequency, further, frequency division when passing through sky The four-matrix that cloth converts indicates are as follows:
Wherein, DZZ(t, f) is two-dimensional covariance matrix, representation space information;Each elementIt is one two The time-frequency matrix of dimension,Indicate i-th of signal ZiWith j-th of signal ZjMutual time-frequency distributions;T indicates the time;F is indicated Frequency.
In the present embodiment, the pretreated signal of whitening carries out spacial time-frequency distribution and converts to obtain four-matrix DZZ(t, f), Concrete form are as follows:
In the present embodiment, DZZ(t, f) is two-dimensional covariance matrix, wherein each elementIt is one two again The time-frequency matrix of dimension is eventually exhibited as a four-dimensional form.
In the present embodiment, according to obtained four-matrix DZZ(t, f) extracts from reference point, and to the auto-correlation of extraction point Eigenvalues Decomposition is carried out, realizes Signal parameter estimation using subspace method.
It is further, described to four-dimensional square in the specific embodiment of the three-dimensional frequency spectrum sensing method of aforementioned Space-Time-frequency The time-frequency two-dimensional information of battle array is filtered, and is extracted list from reference point and is included:
Pass through relational expressionExtract the auto-correlation point comprising all primary user's signals, wherein ε2 To extract threshold value, the mark of trace () representing matrix;
By cluster, the auto-correlation point of all primary user's signals extracted is divided into N class, certain one kind represents a certain signal Auto-correlation point, obtain the K of N class list source signaliA auto-correlation pointWherein, i=1,2 ..., N, ki=1,2 ..., Ki
In the present embodiment, ε2It is the close but positive real number less than 1, it is related with noise, come from phase it is possible thereby to extract Guan Dian.
In the present embodiment, KiValue be every one kind in the N class extracted by all of above extraction step time frequency point Number, be not a determining value, method each run can all generate different results.
In the specific embodiment of the three-dimensional frequency spectrum sensing method of aforementioned Space-Time-frequency, further, described pair is obtained List is obtained from reference point progress Joint diagonalization
To obtained N class auto-correlation pointThe two-dimensional space information of four-matrix is extracted, constitutes signal when corresponding Correlation matrix on frequency point
To obtained correlation matrixJoint diagonalization processing is carried out, acquiring makes The smallest N × N-dimensional unitary matrice U, wherein I is unit matrix, and off () is the quadratic sum of matrix off-diagonal element;
Steering vector estimation is carried out using the unitary matrice U that Joint diagonalization obtains:
Wherein, W#For the pseudoinverse of whitening matrix,For steering vector.
In the specific embodiment of the three-dimensional frequency spectrum sensing method of aforementioned Space-Time-frequency, further, the basis is obtained Steering vector, determine that the angle of arrival of each primary user's signal includes:
According to obtained steering vector, using multiple signal classification (Multiple Signal Classification, MUSIC the angle of arrival of each primary user's signal) is determined.
In the specific embodiment of the three-dimensional frequency spectrum sensing method of aforementioned Space-Time-frequency, further, the basis is obtained Steering vector, the angle of arrival for determining each primary user's signal using multiple signal classification includes:
It is rightSeek its covariance matrix:
Wherein, RAAFor the covariance matrix of M × M dimension;
By RAAFeature vector be divided into two parts by the size of characteristic value: UsAnd Un, wherein Us·Us H+Un·Un H=I, Us =[U1,U2,...,UN] it is the unitary space that the corresponding feature vector of top n maximum eigenvalue is constituted, it opens into signal subspace;Un =[UN+1,...,UM] it is the unitary matrice that the corresponding feature vector of rear M-N minimal eigenvalue is constituted, it opens into noise subspace;
Pass throughTo the angle of primary user's signal Estimated, obtains the angle of arrival of each primary user's signal.
The three-dimensional frequency spectrum sensing method of Space-Time described in embodiment-frequency for a better understanding of the present invention, it is specific with one Embodiment is described, as shown in Fig. 2, N=2 is set, M=6:
Step 1: N number of primary user emit from different directions signal (assuming that: primary user 1 emit signal 1, primary user 2 send out Signal 2 is penetrated), and M cognitive user end is reached, angle of arrival is respectively -2 ° and 2 °, and the instantaneous frequency of two signals is respectively 1e9 and 2e9, signal-to-noise ratio are -5dB.
In the present embodiment, by 2 " statistically " independent signals, observe 6 include white noise mixed signals.
In the present embodiment, N number of primary user emits signal from different directions, and reaches a cognitive user end M (M > N), arrives It is respectively θ up to angle12,...,θN.It is irrelevant between each primary user's signal, and mutual not phase between primary user's signal and noise It closes.The signal received is sent to decision center by each cognitive user, forms receipt signal matrix Y=[Y by decision center1, Y2,...,YM]T
Step 2: carrying out whitening pretreatment to receipt signal matrix, the specific steps are as follows:
A21 carries out Eigenvalues Decomposition to the covariance matrix for receiving signal, if [λ1,...,λM] it is the feature that descending arranges Value, [h1,...,hM] it is corresponding feature vector, σ2For the average value of rear M-N lesser characteristic values of the covariance matrix. Define whitening matrix W are as follows:
Wherein, subscript H is the conjugate transposition of matrix.
A22, then signal after albefaction are as follows:
Z=WY
Wherein, Z=[Z1,Z2,...,ZN]T
It converts to obtain four-matrix D Step 3: the pretreated signal of whitening carries out spacial time-frequency distributionZZ(t, f), specifically Form are as follows:
Wherein, wherein DZZ(t, f) is two-dimensional covariance matrix, representation space information;Each elementIt is One two-dimensional time-frequency matrix,Indicate i-th of signal ZiWith j-th of signal ZjMutual time-frequency distributions;When t is indicated Between;F indicates frequency.
Step 4: the time-frequency two-dimensional information to four-matrix is filtered, extracts list and be originated from reference point, obtain each primary The accurate time-frequency distributions of family signal, the specific steps are as follows:
A41, extracting the auto-correlation point process comprising all primary user's signals can indicate to extract the time frequency point for meeting following formula:
Wherein, the mark of trace () representing matrix, ε2It is the close but positive real number less than 1, it is related with noise, by This can extract auto-correlation point.
The auto-correlation point of all primary user's signals is divided into N class by clustering method by A42, certain one kind represents a certain signal Auto-correlation point, obtain the K of N class list source signaliA auto-correlation pointWherein i=1,2 ..., N, ki=1,2 ..., Ki
Step 5: the four-matrix Jing Guo filtration treatment, which is carried out Joint diagonalization, obtains the guiding arrow for being used for angle estimation Amount estimation, the specific steps are as follows:
A51, to obtained N class auto-correlation pointExtract four-matrix DZZTwo-dimensional space information, constitute corresponding Correlation matrix in time frequency point
A52, to what is obtainedJoint diagonalization processing is carried out, that is, acquiring makes the smallest N of following formula × N-dimensional tenth of the twelve Earthly Branches square Battle array U:
Wherein, I is unit matrix, and off () is the quadratic sum of matrix off-diagonal element.
A53 carries out steering vector estimation using the unitary matrice U that Joint diagonalization obtains:
Wherein, W#For the pseudoinverse of whitening matrix,For steering vector.
Step 6: gained steering vector to be estimated to the angle estimation for being acquired signal using MUSIC method, specific steps are such as Under:
A 61 is rightSeek its covariance matrix:
Wherein, RAAFor the covariance matrix of M × M dimension;
A 62, by RAAFeature vector be divided into two parts by the size of characteristic value: UsAnd Un, wherein Us·Us H+Un·Un H =I, Us=[U1,U2,...,UN] it is the unitary space that the corresponding feature vector of top n maximum eigenvalue is constituted, it opens into signal subspace sky Between;Un=[UN+1,...,UM] it is the unitary matrice that the corresponding feature vector of rear M-N minimal eigenvalue is constituted, it opens empty at noise Between;
A63 is estimated using angle of the following formula to primary user's signal:
In the embodiment of the present invention, Fig. 3 and Fig. 4 are described and are collected signal from phase to the time-frequency two dimensions of information of four-matrix The filtration treatments such as Guan Dian, cluster extract list and are originated from reference point, obtain the accurate time-frequency estimation of two primary user's signals.Fig. 3 and figure Abscissa in 4 is temporal operator (s), and ordinate is the instantaneous frequency of signal, should be the result is that being 2 in signal number, cognition is used Family end is 6, and snapshot number is 1000, time interval 1s, and the frequency of two signals is respectively that the conditions such as 1e9HZ and 2e9HZ repeat What experiment obtained.As Fig. 3 and Fig. 4 it is known that the time-frequency figure that the embodiment of the present invention obtains not only reduces present in system The problems such as noise, and obtained better performance.This illustrates that method proposed by the present invention is comprehensive and effective.Together When, the method for as a result also indicating that the three-dimensional frequency spectrum perception research of Space-Time provided in an embodiment of the present invention-frequency has excellent performance.
Fig. 5 and Fig. 6, which is described, passes through the side such as Joint diagonalization, MUSIC using single STFD matrix for being originated from reference point composition Method obtains the angle of each signal.Abscissa in Fig. 5 and Fig. 6 is azimuth, and ordinate is the peak value of signal, should the result is that Signal number is 2, and cognitive user end is 6, and snapshot number is 1000, time interval 1s, the angles of two signals be respectively -2 ° and The conditions such as 2 ° repeat what experiment obtained.By Fig. 5 and Fig. 6 it is known that the obtained angle figure of the present invention not only peak value is more sharp, And resolution ratio is greatly improved.This illustrates that method proposed by the present invention is comprehensive and effective.Meanwhile as a result also table The method of the three-dimensional frequency spectrum perception research of bright Space-Time provided in an embodiment of the present invention-frequency has excellent performance.
To sum up, greater concentration of auto-correlation point can be obtained during frequency spectrum perception using the method for the design, reduce The influence of noise, while the resolution ratio of signal is improved, mainly there is following advantage:
1) using STFD matrix can include simultaneously space, the time, three dimensions of frequency spectrum information;
2) filtration treatments such as signal autocorrelation point, cluster, Neng Gouti are collected to the time-frequency two dimensions of information of four-matrix The auto-correlation point for taking out each signal, reduces the operand of angle calculation;Can effectively it press down in white Gaussian noise simultaneously The interference of cross term processed and noise have higher time-frequency convergence property;
3) the steady of algorithm is enhanced come processing space time-frequency matrix using Joint diagonalization and classics MUSIC method Property, direction of arrival (Direction Of Arrival, the DOA) estimated capacity of algorithm under Low SNR is improved, together When improve the resolution ratio and accuracy of angle.
It should be noted that, in this document, relational terms such as first and second and the like are used merely to a reality Body or operation are distinguished with another entity or operation, are deposited without necessarily requiring or implying between these entities or operation In any actual relationship or order or sequence.
The above is a preferred embodiment of the present invention, it is noted that for those skilled in the art For, without departing from the principles of the present invention, several improvements and modifications can also be made, these improvements and modifications It should be regarded as protection scope of the present invention.

Claims (10)

1. a kind of three-dimensional frequency spectrum sensing method of Space-Time-frequency characterized by comprising
Whitening pretreatment is carried out to primary user's signal that multiple cognitive users receive, wherein between each primary user's signal mutually not It is related;
The pretreated signal of whitening carries out spacial time-frequency distribution and converts to obtain four-matrix, wherein the information in four-matrix It include: time, frequency and two-dimensional space information;
The time-frequency two-dimensional information of four-matrix is filtered, is extracted single from reference point, wherein single source refers to each independent master Subscriber signal source;
Reference point progress Joint diagonalization is originated to obtained list to obtain estimating for the steering vector of angle estimation;
According to obtained steering vector, the angle of arrival of each primary user's signal is determined.
2. the three-dimensional frequency spectrum sensing method of Space-Time according to claim 1-frequency, which is characterized in that described to use multiple cognitions Primary user's signal that family receives carries out whitening pretreatment
Primary user's signal that multiple cognitive users are received forms receipt signal matrix;
Whitening pretreatment is carried out to receipt signal matrix.
3. the three-dimensional frequency spectrum sensing method of Space-Time according to claim 2-frequency, which is characterized in that described to use multiple cognitions Primary user's signal that family receives forms receipt signal matrix
N number of primary user emits signal from different directions, reaches M cognitive user end, wherein M > N;
The signal that M cognitive user is received forms receipt signal matrix Y=[Y1,Y2,...,YM]T, wherein subscript T is indicated The transposition of matrix.
4. the three-dimensional frequency spectrum sensing method of Space-Time according to claim 3-frequency, which is characterized in that described pair of reception signal square Battle array carries out whitening pretreatment
Eigenvalues Decomposition is carried out to the covariance matrix of receipt signal matrix Y;
According to Eigenvalues Decomposition as a result, building whitening matrix W;
Whitening matrix W dot product receipt signal matrix Y, obtains whitened signal Z=WY, wherein Z=[Z1,Z2,...,ZN]T
5. the three-dimensional frequency spectrum sensing method of Space-Time according to claim 4-frequency, which is characterized in that described according to characteristic value point Solution is as a result, building whitening matrix W includes:
Descending arrangement is carried out to obtained characteristic value, the characteristic value [λ after obtaining descending arrangement1,...,λM] and its corresponding spy Levy vector [h1,...,hM];
From M characteristic value after descending arrangement, take preceding 1~N number of characteristic value and its feature vector be used to construct whitening matrix W, Wherein, whitening matrix W is indicated are as follows:
Wherein, σ2For the average value of rear M-N lesser characteristic values after descending arrangement, the conjugate transposition of subscript H representing matrix.
6. the three-dimensional frequency spectrum sensing method of Space-Time according to claim 5-frequency, which is characterized in that become by spacial time-frequency distribution The four-matrix got in return indicates are as follows:
Wherein, DZZ(t, f) is two-dimensional covariance matrix, representation space information;Each elementIt is one two-dimensional Time-frequency matrix,Indicate i-th of signal ZiWith j-th of signal ZjMutual time-frequency distributions;T indicates the time;F indicates frequency Rate.
7. Space-Time according to claim 6-the three-dimensional frequency spectrum sensing method of frequency, which is characterized in that it is described to four-matrix Time-frequency two-dimensional information is filtered, and is extracted list from reference point and is included:
Pass through relational expressionExtract the auto-correlation point comprising all primary user's signals, wherein ε2To extract Threshold value, the mark of trace () representing matrix;
By cluster, the auto-correlation point of all primary user's signals extracted is divided into N class, certain one kind represents oneself of a certain signal Reference point obtains Ki auto-correlation point of N class list source signalWherein, i=1,2 ..., N, ki=1,2 ..., Ki
8. the three-dimensional frequency spectrum sensing method of Space-Time according to claim 7-frequency, which is characterized in that described pair of obtained single source Auto-correlation point progress Joint diagonalization obtains
To obtained N class auto-correlation pointThe two-dimensional space information of four-matrix is extracted, constitutes signal in corresponding time frequency point On correlation matrix
To obtained correlation matrixJoint diagonalization processing is carried out, acquiring makes The smallest N × N-dimensional unitary matrice U, wherein I is unit matrix, and off () is the quadratic sum of matrix off-diagonal element;
Steering vector estimation is carried out using the unitary matrice U that Joint diagonalization obtains:
Wherein, W#For the pseudoinverse of whitening matrix,For steering vector.
9. the three-dimensional frequency spectrum sensing method of Space-Time according to claim 8-frequency, which is characterized in that the basis obtained leads To vector, determine that the angle of arrival of each primary user's signal includes:
According to obtained steering vector, the angle of arrival of each primary user's signal is determined using multiple signal classification.
10. the three-dimensional frequency spectrum sensing method of Space-Time according to claim 9-frequency, which is characterized in that the basis obtained Steering vector, the angle of arrival for determining each primary user's signal using multiple signal classification include:
It is rightSeek its covariance matrix:
Wherein, RAAFor the covariance matrix of M × M dimension;
By RAAFeature vector be divided into two parts by the size of characteristic value: UsAnd Un, wherein Us·Us H+Un·Un H=I, Us= [U1,U2,...,UN] it is the unitary space that the corresponding feature vector of top n maximum eigenvalue is constituted, it opens into signal subspace;Un= [UN+1,...,UM] it is the unitary matrice that the corresponding feature vector of rear M-N minimal eigenvalue is constituted, it opens into noise subspace;
Pass throughThe angle of primary user's signal is carried out Estimation, obtains the angle of arrival of each primary user's signal.
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