CN105375998B

CN105375998B - The multiband cooperative frequency spectrum sensing method optimized based on sub-clustering

Info

Publication number: CN105375998B
Application number: CN201510830973.2A
Authority: CN
Inventors: 郑紫微; 张晓波; 秦闯
Original assignee: Ningbo University
Current assignee: Beijing Xuhui Xinrui Technology Co ltd
Priority date: 2015-11-25
Filing date: 2015-11-25
Publication date: 2017-11-07
Anticipated expiration: 2035-11-25
Also published as: CN105375998A

Abstract

The present invention relates to the multiband cooperative frequency spectrum sensing method optimized based on sub-clustering, the collaborative sensing model of frequency spectrum perception fusion center, N number of user and authorized user's composition is set up；Frequency spectrum perception fusion center according to each user itself noise when default M sub-clustering snr threshold to secondary user's sub-clustering, and in each sub-clustering containing secondary user, choose the cluster head time user that the secondary user with maximum signal to noise ratio is correspondence sub-clustering, the fusion center of correspondence cluster is used as using the cluster head time user, frequency spectrum perception result fusion to other user in this cluster, to obtain the cooperative detection result of this cluster；Global detection probability and global false-alarm probability carry out fusion detection in the corresponding cluster that last frequency spectrum perception fusion center is sent according to each cluster head time user, and using the fusion detection result as final multiband collaboration frequency spectrum testing result, so as to adapt to from user's received signal energy variation, time user's detection performance is improved, reduces frequency spectrum perception fusion center amount of calculation, improve cooperative detection efficiency.

Description

The multiband cooperative frequency spectrum sensing method optimized based on sub-clustering

Technical field

The present invention relates to wireless communication field, more particularly to a kind of multiband collaborative spectrum sensing side optimized based on sub-clustering Method.

Background technology

As the emerging technology with LTE, Wi-Fi, satellite communication and collaboration communication etc. for mark is emerged in large numbers in succession, these communications Technology proposes higher demand to radio spectrum resources, and make frequency spectrum resource change tends to be nervous, cognitive radio technology (Cognitive Radio, CR) arises at the historic moment in this context.The basic ideas of cognitive radio are that user secondary first uses Frequency spectrum perception is to having authorized frequency spectrum resource persistently to be detected in surrounding environment；Then can preferentially it be taken in guarantee authorized user Under conditions of the mandate frequency range and transmission performance are barely affected, secondary user is adaptively adjusted transceiver to idle frequency spectrum It is upper to be communicated.When secondary user, which perceives authorization user signal, to be occurred, secondary user then will quickly vacate channel and be used for authorizing Family is used, and then avoids disturbing the proper communication of authorized user, so as to improve frequency spectrum resource utilization rate.

In order to reduce the factors such as multipath fading in actual environment, shadow effect and incorrect noise to detection performance Adverse effect, the frequency spectrum sensing method based on multiple user collaborations constantly proposed.By by the perception of each user As a result frequency spectrum perception fusion center is sent to, fusion is made according to certain criterion by frequency spectrum perception fusion center, to reach standard The purpose of true perceived spectral., existing cooperative frequency spectrum sensing method majority perceived just for one-segment.

In order to improve the availability of frequency spectrum, new study hotspot is turned into for the cooperative frequency spectrum sensing method of multiband.Existing Have in the collaborative sensing method for multiband, when secondary user is using multiple frequency ranges of the energy detection method to multiple authorized users , it is necessary to the judging threshold for signal energy accurately be set, to be made when authorization user signal occurs when being perceived Accurate judgement, and testing result is sent to by frequency spectrum perception fusion center progress fusion treatment by each user respectively.

But, in actual multiband collaborative spectrum sensing, however it remains some problems：On the one hand, each user institute The signal energy of reception is not changeless, therefore causes the decision threshold of fixation set in existing energy detection method Value will not ensure that time user makes accurate perception, and then severely impact the overall collaborative sensing of multiple users Energy；On the other hand, frequency spectrum perception fusion center needs to carry out fusion calculation to the testing result of all users, and this undoubtedly increases The computation complexity of frequency spectrum perception fusion center, reduces cooperative detection efficiency.

The content of the invention

The technical problems to be solved by the invention are to provide one kind for above-mentioned prior art both to adapt to be connect from user Collection of letters energy variation, improves the detection performance of time user, can reduce frequency spectrum perception fusion center computation complexity again, improve association Make the multiband cooperative frequency spectrum sensing method optimized based on sub-clustering of detection efficiency.

The present invention solve the technical scheme that is used of above-mentioned technical problem for：The multiband collaboration frequency spectrum optimized based on sub-clustering Cognitive method, frequency spectrum detection, its feature are carried out for frequency spectrum perception fusion center and N number of secondary user with frequency spectrum perception function It is, in turn includes the following steps：

(1) the collaborative sensing model being made up of frequency spectrum perception fusion center, N number of user and authorized user is set up；Its In, frequency spectrum perception fusion center is designated as FC, and N number of time user is respectively labeled as CR_i(i=1,2 ..., N, N >=3), authorized user's note For PU；

(2) N number of user CR_iSeparately obtain itself signal to noise ratio snr_i, and respectively by the signal to noise ratio each obtained SNR_iSend to frequency spectrum perception fusion center FC and make sub-clustering processing；

(3) according to the ascending order order of snr threshold, the snr threshold SNR of M sub-clustering is preset_Wall,m(m=1,2 ..., M and 0.5N≤M<N), frequency spectrum perception fusion center FC is by each user CR_iItself signal to noise ratio snr sent_iRespectively with M letter Make an uproar than threshold value SNR_Wall,mJudgement is compared, and gets M₁The individual sub-clustering containing secondary user, gained sub-clustering is designated as C_l, l=1,2 ..., M₁, 1<M₁≤ M, SNR_Wall,1<SNR_Wall,2<…<SNR_Wall,M；Frequency spectrum perception fusion center FC is to each user CR_iSignal to noise ratio SNR_iWith each snr threshold SNR_Wall,mJudgement comparison procedure following steps (3-1) to step (3-2)：

(3-1) is according to the snr threshold SNR of M sub-clustering_Wall,m, M+1 sub-clustering signal to noise ratio segment is set, is respectively [-∞,SNR_Wall,1)、[SNR_Wall,1,SNR_Wall,2)、…、[SNR_Wall,M-1,SNR_Wall,M) and [SNR_Wall,M, ∞), wherein, it is located at The signal to noise ratio of secondary user in first sub-clustering is in [- ∞, SNR_Wall,1) in sub-clustering signal to noise ratio segment, in the second sub-clustering Secondary user signal to noise ratio be in [SNR_Wall,1,SNR_Wall,2) in sub-clustering signal to noise ratio segment, the like, positioned at M sub-clusterings The signal to noise ratio of interior secondary user is in [SNR_Wall,M-1,SNR_Wall,M) in sub-clustering signal to noise ratio segment, in M+1 sub-clusterings The signal to noise ratio of secondary user is in [SNR_Wall,M, ∞) and in sub-clustering signal to noise ratio segment；

(3-2) frequency spectrum perception fusion center FC is respectively by each user CR_iSignal to noise ratio snr_iWith M snr threshold SNR_Wall,mIt is compared, to judge the signal to noise ratio snr_iResiding sub-clustering signal to noise ratio segment；Wherein：

When the signal to noise ratio snr_iResiding sub-clustering signal to noise ratio segment is [- ∞, SNR_Wall,1) when, then the noise is not granted Compare SNR_iCorresponding time user participates in collaborative sensing；If the signal to noise ratio snr_iResiding sub-clustering signal to noise ratio segment is [SNR_Wall,M, When ∞), then by the signal to noise ratio snr_iCorresponding time user is positioned in M sub-clusterings；

(4) in M₁In the individual sub-clustering containing secondary user, according to the order of secondary user's signal to noise ratio from big to small, selection wherein has It is the cluster head time user in this sub-clustering to have the secondary user of maximum signal to noise ratio, so as to obtain M₁Individual cluster head time user；

(5) in the second sub-clustering containing secondary user, using the cluster head time user as the fusion center of this cluster, receive, simultaneously Frequency spectrum perception result to other user in this cluster is merged, to obtain the cooperative detection result of this cluster；Wherein, in the cluster Cooperative detection process comprise the following steps (5-1) to step (5-3)：

(5-1), which is set in the second sub-clustering, has K user CR_k(k=1,2 ..., K), K user CR_kCarry out respectively Frequency spectrum perception based on energy, independently obtain itself signal to noise ratio snr_k, and respectively by the signal to noise ratio snr of acquisition_kAnd frequency spectrum perception As a result send to cluster head time user CR₁；Wherein, frequency spectrum perception result includes time user CR_kDetection probability P_d,kAnd false-alarm is general Rate P_f,k；

(5-2) cluster head time user CR₁Receive other K-1 user CR_kThe signal to noise ratio snr of transmission_kWith frequency spectrum perception knot Really, and signal to noise ratio snr is judged_kMore than default signal to noise ratio screening value SNR_choseWhen, then select corresponding user of this signal to noise ratio To participate in the cognitive group membership of cooperative detection, and perform step (5-3)；Otherwise, secondary user institute of the selection with highest signal to noise ratio Corresponding frequency spectrum perception result is cluster head time user CR₁Final detection result；

(5-3) cluster head time user CR₁Carried out certainly according to the frequency spectrum perception result of the cognitive group membership of selected participation cooperation Adapt to perceive fusion；Wherein, the adaptive fusion process that perceives comprises the following steps (5-31) to step (5-33)：

(5-31) cluster head time user CR₁The frequency spectrum perception result sent according to K-1 time users, K-1 time users of statistics In perceive the secondary number of users that authorized user's PU frequency spectrums are seizure condition be m (1≤m≤K-1), perceive authorized user PU frequency Spectrum is that the secondary number of users of idle condition is K-1-m；Wherein, authorized user PU frequency spectrums are that seizure condition is designated as H₁, authorized user PU₁Frequency spectrum is that idle condition is designated as H₀；

(5-32) cluster head time user CR₁The signal to noise ratio sent according to K-1 time users, calculates m and perceives authorized user PU frequency spectrums are seizure condition H₁The sincere coefficient κ of secondary user_1,jAnd it is idle shape that K-1-m, which perceive authorized user PU frequency spectrums, State H₀The sincere coefficient κ of secondary user_2,t；Wherein, sincere coefficient κ_1,jAnd κ_2,tCalculation formula it is as follows：

(5-33) cluster head time user CR₁According to the respective sensing results and sincere coefficient κ of individual user of m_1,j, count respectively It is seizure condition H to calculate authorized user PU frequency spectrums₁Average detected probabilityGlobal detection probabilityWith this seizure condition H₁Corresponding global false dismissal probability D_undet,H1, and authorized user PU frequency spectrum is idle condition H₀Average detected probabilityGlobal detection probabilityThis idle condition H₀Corresponding global false dismissal probabilityWith global false-alarm probabilityWherein, the process comprises the following steps (a) to step (g)：

(a) the global error detection probability P that m time user collaborations are perceived is set up_e, obtain and examined on the energy of decision-making thresholding Survey majorized function γ^*And the optimal threshold value γ of energy measuring_opt, and authorized user PU frequency spectrums are calculated for seizure condition H₁It is flat Equal detection probabilityWherein,

The global error detection probability P that m time user collaborations are perceived_eCalculation formula is as follows：

Wherein,Idle condition H is in for authorized user PU frequency spectrums₀Probability,It is in for authorized user's PU frequency spectrums Seizure condition H₁Probability；P_fFor global false-alarm probability, P_dFor global detection probability, P_mFor global false dismissal probability；For correspondence Seizure condition H is in authorized user PU frequency spectrums₁M users average signal-to-noise ratio, wherein, snr_iFor secondary user CR_iThe signal to noise ratio of itself, Q (z) represents the complementary integral function of normal Gaussian；

Energy measuring majorized function γ on decision-making thresholding^*It is defined as：

The optimal threshold value γ of energy measuring_optFor：

Authorized user PU frequency spectrums are seizure condition H₁Average detected probabilityCalculation formula is as follows：

(b) it is seizure condition H according to gained authorized user PU frequency spectrums₁Average detected probabilityAnd m time users Sincere coefficient κ_1,j, it is seizure condition H to calculate authorized user PU frequency spectrums₁Global detection probabilityWith this seizure condition H₁ Corresponding global false dismissal probabilityWherein, global detection probabilityWith global false dismissal probabilityCalculation formula is such as Under：

(c) it is idle condition H according to gained authorized user PU frequency spectrums₀Average detected probabilityAnd K-1-m times The sincere coefficient κ of user_2,t, it is idle condition H to calculate authorized user PU frequency spectrums₀Global detection probabilityWith this idle shape State H₀Corresponding global false dismissal probabilityGlobal false-alarm probabilityWherein, average detected probabilityOverall situation inspection Survey probabilityGlobal false dismissal probabilityWith global false-alarm probabilityCalculation formula difference it is as follows：

(d) cluster head time user CR₁It is seizure condition H according to authorized user PU frequency spectrums₁Corresponding global false dismissal probability And authorized user PU frequency spectrums are idle condition H₀Corresponding global false-alarm probabilitySet up the frequency based on secondary number of users Compose perceptual error function Fun (m)；Wherein, frequency spectrum perception error function Fun (m) calculation formula are as follows：

Wherein, P_puRepresent the probability that authorized user PU signals authorize frequency spectrum to occur at it；

(e) frequency spectrum perception error function Fun (m) frequency spectrum perception error minimum value Fun (m are calculated₀), and with the frequency spectrum sense Know error function minimum value Fun (m₀) corresponding numerical value m₀(m₀≤ m) it is used as the optimal cooperation time number of users for participating in collaborative sensing Mesh, and to m time users according to its corresponding snr value snr_iDescending arrangement is carried out, the descending arrangement of m time users is obtained Group；

(f) the preceding m in time user's descending arrangement group is chosen₀Individual user uses as the optimal cooperation time for participating in collaborative sensing Family；Wherein, the optimal cooperation time user that selection is marked respectively is CR'_r, wherein, r=1,2 ..., m₀；

(g) cluster head time user CR₁According to m in step (f)₀The frequency spectrum perception result of individual optimal cooperation time user is based on The collaborative sensing of OR criterions, and using the testing result of collaborative sensing as K in this cluster time user final detection result；Its In, OR criterions are as follows：

Wherein, P_d,rFor optimal cooperation time user CR " in this cluster_rDetection probability, P_fa,jUsed for optimal cooperation time in this cluster Family CR "_rFalse-alarm probability；Q_{D, 1}For the global detection probability after this cluster cooperative detection, Q_fa,1For the overall situation after this cluster cooperative detection False-alarm probability；ω_rRepresent signal to noise ratio snr "_rWeight coefficient, SNR "_maxRepresent m in this cluster₀The noise of individual optimal cooperation time user Than maximum, SNR "_minRepresent m in this cluster₀The signal to noise ratio minimum value of individual optimal cooperation time user；

(6) according to the process of step (5), the 3rd cluster is obtained respectively to M₁Global detection probability Q in cluster in cluster_{D, 3}ExtremelyAnd global false-alarm probability Q_fa,2Extremely

(7) frequency spectrum perception fusion center FC is according to M₁The global detection probability in corresponding cluster that individual cluster head time user sends Q_d,sWith global false-alarm probability Q_fa,sCarry out the fusion detection based on AND criterions, and using the fusion detection result as final many Frequency range collaboration frequency spectrum testing result；Wherein, AND criterions are as follows：

Wherein, Q_dFor the global detection probability after cooperation, Q_faFor the global false-alarm probability after cooperation.

Compared with prior art, the advantage of the invention is that：Frequency spectrum perception fusion center is according to each user itself noise Than and default sub-clustering snr threshold make sub-clustering to secondary user, and in each sub-clustering containing secondary user, choosing has maximum The secondary user of signal to noise ratio is the cluster head time user of correspondence sub-clustering, using the cluster head time user as the fusion center of correspondence cluster, by secondary The adaptive adjustment of user, the optimal threshold value for obtaining energy measuring, are changed with adapting to time user's received signal energy dynamics The need for, improve the energy measuring probability of time user；Then frequency spectrum perception knot of the cluster head time user to other user in this cluster Fruit is merged, by reduce traditional collaborative sensing method intermediate frequency spectrum perceive fusion center need to be to all user's testing results fusions in terms of Calculation amount, the memory space for saving frequency spectrum perception fusion center；Then frequency spectrum perception fusion center is sent according to each cluster head time user Corresponding cluster in global detection probability and global false-alarm probability carry out fusion detection, and using the fusion detection result for finally many Frequency range collaboration frequency spectrum testing result.Both adapted to receive letter from user using the multiband cooperative frequency spectrum sensing method of the sub-clustering Number energy variation, improves the detection performance of time user, can reduce frequency spectrum perception fusion center computation complexity again, improve cooperation inspection Survey efficiency.

Brief description of the drawings

Fig. 1 is the schematic flow sheet of the multiband cooperative frequency spectrum sensing method based on sub-clustering optimization in the embodiment of the present invention.

Embodiment

The present invention is described in further detail below in conjunction with accompanying drawing embodiment.

In order to realize the frequency spectrum of frequency spectrum perception fusion center FC and N number of secondary user with frequency spectrum perception function to multiband Situation is detected, as shown in figure 1, the multiband cooperative frequency spectrum sensing method optimized in the present embodiment based on sub-clustering, is wrapped successively Include following steps：

(1) the collaborative sensing model being made up of frequency spectrum perception fusion center FC, N number of user and authorized user is set up； Wherein, N number of user is respectively labeled as CR_i(i=1,2 ..., N, N >=3), authorized user is designated as PU；

(2) N number of user CR_iSeparately obtain itself signal to noise ratio snr_i, and respectively by the signal to noise ratio each obtained SNR_iSend to frequency spectrum perception fusion center FC and make sub-clustering processing；For example, secondary user CR₁Independently itself signal to noise ratio of acquisition is SNR₁, secondary user CR₂Independent itself signal to noise ratio obtained is SNR₃；

(3) according to the ascending order order of snr threshold, the snr threshold SNR of M sub-clustering is preset_Wall,m(m=1,2 ..., M and 0.5N≤M<N), i.e. snr threshold in M default clusters is respectively SNR_Wall,1、SNR_Wall,2... and SNR_Wall,M, frequency spectrum Fusion center FC is perceived by each user CR_iItself signal to noise ratio snr sent_iRespectively with M snr threshold SNR_Wall,mSentence It is disconnected to compare, get M₁The individual sub-clustering containing secondary user, gained sub-clustering is designated as C_l, l=1,2 ..., M₁, 1<M₁≤ M, SNR_Wall,1< SNR_Wall,2<…<SNR_Wall,M；

For example, by secondary user CR₁Itself signal to noise ratio be SNR₁Respectively with snr threshold SNR_Wall,1To SNR_Wall,MDo big Small judgement is compared, then again by secondary user CR₂Itself signal to noise ratio be SNR₁Respectively with snr threshold SNR_Wall,1To SNR_Wall,M Size is done to judge to compare, the like, finally by secondary user CR_NItself signal to noise ratio be SNR_NRespectively with snr threshold SNR_Wall,1To SNR_Wall,MSize is done to judge to compare；

Wherein, frequency spectrum perception fusion center FC is to each user CR_iSignal to noise ratio snr_iWith each snr threshold SNR_Wall,m's Judge comparison procedure following steps (3-1) to step (3-2)：

For example, five snr thresholds of setting are respectively SNR now_Wall,1=1dB, SNR_Wall,2=3dB, SNR_Wall,3= 5dB、SNR_Wall,4=8dB, SNR_Wall,5Secondary user's signal to noise ratio in=11dB, the first sub-clustering be in [- ∞, 1dB) sub-clustering noise Than in segment, secondary user's signal to noise ratio in the second sub-clustering be in [1dB, 3dB) in sub-clustering signal to noise ratio segment, in the 3rd sub-clustering Secondary user's signal to noise ratio be in [3dB, 5dB) in sub-clustering signal to noise ratio segment, secondary user's signal to noise ratio in the 4th sub-clustering is in [5dB, 8dB) in sub-clustering signal to noise ratio segment, secondary user's signal to noise ratio in the 5th sub-clustering be in [8dB, 11dB) sub-clustering signal to noise ratio In segment, secondary user's signal to noise ratio in the 6th sub-clustering be in [11dB, ∞) in sub-clustering signal to noise ratio segment；

When the signal to noise ratio snr_iResiding sub-clustering signal to noise ratio segment is [- ∞, SNR_Wall,1) when, then the noise is not granted Compare SNR_iCorresponding time user participates in collaborative sensing；If the signal to noise ratio snr_iResiding sub-clustering signal to noise ratio segment is [SNR_Wall,M, When ∞), represent that corresponding user of the signal to noise ratio has extraordinary detection performance, then by the signal to noise ratio snr_iCorresponding use Family is positioned in M sub-clusterings, can both reduce sub-clustering number, improves arithmetic speed, and the overall association in M sub-clusterings can be improved again Make perceptual performance；

For example, five snr thresholds of setting are respectively SNR now_Wall,1=1dB, SNR_Wall,2=3dB, SNR_Wall,3= 5dB、SNR_Wall,4=10dB, SNR_Wall,5=11dB, secondary user's number is six, six user CR₁To CR₆It is corresponding itself Signal to noise ratio is respectively SNR₁=-1dB, SNR₂=1.5dB, SNR₃=2dB, SNR₄=6dB, SNR₅=7dB, SNR₆=14dB；Through Knowable to multilevel iudge, SNR₁In [- ∞, 1dB) in sub-clustering signal to noise ratio segment, then time user CR is not granted₁Participate in cooperation sense Know；Due to SNR₆In [11dB, ∞) in sub-clustering signal to noise ratio segment, then by secondary user CR₆Be positioned over [10dB, 11dB) sub-clustering In the corresponding sub-clustering of signal to noise ratio segment；

(5) in the second sub-clustering containing secondary user, using the cluster head time user as the fusion center of this cluster, receive, simultaneously Frequency spectrum perception result to other user in this cluster is merged, to obtain the cooperative detection result of this cluster；

Wherein, the cluster head time user in each sub-clustering can not only be reduced frequency spectrum perception and melted as the fusion center of this cluster Conjunction center FC to the fusion calculation amounts of all user's testing results, save frequency spectrum perception fusion center FC memory space, and And collaborative sensing can also independently be done by every cluster, and it is effective to improve the cooperative detection time for completing all users, meet Switch the requirement of spectrum efficiency in cognitive radio to secondary user, it is to avoid secondary user takes the interference of frequency range to authorized user；Its In, the cooperative detection process in the cluster comprises the following steps (5-1) to step (5-3)：

Wherein, in this step (5-2), signal to noise ratio screening value SNR why is preset_choseIt is because participating in , should be " severe during if there is secondary user (also known as " rogue user ") with compared with low signal-to-noise ratio in the secondary user of collaborative sensing The Detection accuracy that user " makes is extremely low, once participating in collaborative sensing, frequency spectrum perception fusion center FC can be caused to make The detection probability of overall collaborative sensing is pulled low, and reduces perception efficiency.So, in collaborative sensing, it is necessary to pass through setting one Individual snr threshold, these " rogue users " are weeded out.

(5-32) cluster head time user CR₁The signal to noise ratio sent according to K-1 time users, calculates m and perceives authorized user PU frequency spectrums are seizure condition H₁The sincere coefficient κ of secondary user_1,jAnd it is idle shape that K-1-m, which perceive authorized user PU frequency spectrums, State H₀The sincere coefficient κ of secondary user_2,t；Wherein, sincere coefficient represents the credibility of the made detection of corresponding user, Characterize the detectability of time user；Sincere coefficient is higher, shows that the detection probability of corresponding user is higher；Wherein, it is sincere Coefficient κ_1,jAnd κ_2,tCalculation formula it is as follows：

(5-33) cluster head time user CR₁According to the respective sensing results and sincere coefficient κ of individual user of m_1,j, count respectively It is seizure condition H to calculate authorized user PU frequency spectrums₁Average detected probabilityGlobal detection probabilityWith this seizure condition H₁Corresponding global false dismissal probabilityAnd authorized user PU frequency spectrum is idle condition H₀Average detected probabilityGlobal detection probabilityThis idle condition H₀Corresponding global false dismissal probabilityWith global false-alarm probabilityWherein, the process comprises the following steps (a) to step (g)：

By to the energy measuring majorized function γ on decision-making thresholding^*Extreme value is sought, to obtain the optimum gate of energy measuring Limit value γ_optFor：

I.e. during each user utilizes energy measuring, when the judging threshold for signal energy takes γ_optWhen, it is secondary User can accurately detect the presence of received signal, adapt to time situation of change of user's received signal energy, so that Improve time accuracy of the user based on energy measuring；

(d) cluster head time user CR₁It is seizure condition H according to authorized user PU frequency spectrums₁Corresponding global false dismissal probability And authorized user PU frequency spectrums are idle condition H₀Corresponding global false-alarm probabilitySet up the frequency based on secondary number of users Compose perceptual error function Fun (m)；The frequency spectrum perception error function Fun (m) is characterize when time number of users is m time-frequency spectrum sense The error condition known；Wherein, frequency spectrum perception error function Fun (m) calculation formula are as follows：

Wherein, when the secondary number of users for participating in collaborative sensing is m₀When, the collaborative sensing of time user has minimum in cluster Frequency spectrum perception error, now correspond to collaborative spectrum sensing has stronger detection performance；Due to the signal to noise ratio of each user Be still influence its frequency spectrum detection performance key, therefore, descending arrangement is made according to snr value size order, can conveniently pair The performance of each user is made comparisons after sequence, to select the secondary user with high detection performance；

For example, the secondary user's descending arrangement group obtained after being arranged according to signal to noise ratio descending is { CR₁, CR₂、…、CR_m0、 CR_m0+1..., CR_mWhen, then m before selecting₀Individual user, i.e. { CR₁, CR₂、…、CR_m0It is used as the optimal association for participating in collaborative sensing Make time user, and correspondence markings CR respectively₁To CR_m0For optimal cooperation time user CR'₁To CR'_m0；

Wherein, P_d,rFor optimal cooperation time user CR " in this cluster_rDetection probability, P_fa,jUsed for optimal cooperation time in this cluster Family CR "_rFalse-alarm probability；Q_{D, 1}For the global detection probability after this cluster cooperative detection, Q_fa,1For the overall situation after this cluster cooperative detection False-alarm probability；ω_rRepresent signal to noise ratio snr "_rWeight coefficient, ω_rIt is bigger, represent that the corresponding optimal cooperation time of the weight coefficient is used The detection performance at family is stronger；SNR”_maxRepresent m in this cluster₀The signal to noise ratio maximum of individual optimal cooperation time user, SNR "_minRepresent M in this cluster₀The signal to noise ratio minimum value of individual optimal cooperation time user；

(6) according to the process of step (5), the 3rd cluster is obtained respectively to M₁Global detection probability Q in cluster in cluster_{D, 3}ExtremelyAnd global false-alarm probabilityExtremelyWherein, the step (6) is complete i.e. according to the cooperating process in the second sub-clustering Collaborative sensing in paired residue sub-clustering；

Wherein, Q_dFor the global detection probability after cooperation, Q_faFor the global false-alarm probability after cooperation.In step (7), frequency Spectrum perceives fusion center FC and only needed to M₁(1<M₁≤M<N) the global detection probability Q that individual cluster head time user sends_d,sAnd the overall situation False-alarm probability Q_fa,sFusion calculation is carried out, is merged without the testing result again to N number of user, so that in very great Cheng Fusion calculation amount is reduced on degree, fusion efficiencies are improved.

Claims

1. based on sub-clustering optimize multiband cooperative frequency spectrum sensing method, for frequency spectrum perception fusion center and it is N number of have frequency spectrum The secondary user of perceptional function carries out frequency spectrum detection, it is characterised in that in turn include the following steps：

(1) the collaborative sensing model being made up of frequency spectrum perception fusion center, N number of user and authorized user is set up；Wherein, frequency Spectrum perceives fusion center and is designated as FC, and N number of time user is respectively labeled as CR_i(i=1,2 ..., N, N >=3), authorized user is designated as PU；

(2) N number of user CR_iSeparately obtain itself signal to noise ratio snr_i, and respectively by the signal to noise ratio snr each obtained_iHair Deliver to frequency spectrum perception fusion center FC and make sub-clustering processing；

(3) according to the ascending order order of snr threshold, the snr threshold SNR of M sub-clustering is preset_Wall,m(m=1,2 ..., M and 0.5N≤M<N), frequency spectrum perception fusion center FC is by each user CR_iItself signal to noise ratio snr sent_iRespectively with M noise Than threshold value SNR_Wall,mJudgement is compared, and gets M₁The individual sub-clustering containing secondary user, gained sub-clustering is designated as C_l, l=1,2 ..., M₁, 1 <M₁≤ M, SNR_Wall,1<SNR_Wall,2<…<SNR_Wall,M；Frequency spectrum perception fusion center FC is to each user CR_iSignal to noise ratio snr_iWith Each snr threshold SNR_Wall,mJudgement comparison procedure following steps (3-1) to step (3-2)：

(3-1) is according to the snr threshold SNR of M sub-clustering_Wall,m, M+1 sub-clustering signal to noise ratio segment is set, be respectively [- ∞, SNR_Wall,1)、[SNR_Wall,1,SNR_Wall,2)、…、[SNR_Wall,M-1,SNR_Wall,M) and [SNR_Wall,M, ∞), wherein, positioned at first The signal to noise ratio of secondary user in sub-clustering is in [- ∞, SNR_Wall,1) in sub-clustering signal to noise ratio segment, time in the second sub-clustering The signal to noise ratio of user is in [SNR_Wall,1,SNR_Wall,2) in sub-clustering signal to noise ratio segment, the like, in M sub-clusterings The signal to noise ratio of secondary user is in [SNR_Wall,M-1,SNR_Wall,M) in sub-clustering signal to noise ratio segment, the secondary use in M+1 sub-clusterings The signal to noise ratio at family is in [SNR_Wall,M, ∞) and in sub-clustering signal to noise ratio segment；

(3-2) frequency spectrum perception fusion center FC is respectively by each user CR_iSignal to noise ratio snr_iWith M snr threshold SNR_Wall,mEnter Row compares, to judge the signal to noise ratio snr_iResiding sub-clustering signal to noise ratio segment；Wherein：

When the signal to noise ratio snr_iResiding sub-clustering signal to noise ratio segment is [- ∞, SNR_Wall,1) when, then the signal to noise ratio snr is not granted_i Corresponding time user participates in collaborative sensing；If the signal to noise ratio snr_iResiding sub-clustering signal to noise ratio segment is [SNR_Wall,M,∞) When, then by the signal to noise ratio snr_iCorresponding time user is positioned in M sub-clusterings；

(4) in M₁In the individual sub-clustering containing secondary user, according to the order of secondary user's signal to noise ratio from big to small, choosing wherein has most The secondary user of big signal to noise ratio is the cluster head time user in this sub-clustering, so as to obtain M₁Individual cluster head time user；

(5) in the second sub-clustering containing secondary user, using the cluster head time user as the fusion center of this cluster, receive and to this The frequency spectrum perception result of other user is merged in cluster, to obtain the cooperative detection result of this cluster；Wherein, the association in the cluster Comprise the following steps (5-1) to step (5-3) as detection process：

(5-1), which is set in the second sub-clustering, has K user CR_k(k=1,2 ..., K), K user CR_kIt is based on respectively The frequency spectrum perception of energy, independently obtain itself signal to noise ratio snr_k, and respectively by the signal to noise ratio snr of acquisition_kWith frequency spectrum perception result Send to cluster head time user CR₁；Wherein, frequency spectrum perception result includes time user CR_kDetection probability P_d,kAnd false-alarm probability P_f,k；

(5-2) cluster head time user CR₁Receive other K-1 user CR_kThe signal to noise ratio snr of transmission_kWith frequency spectrum perception result, and Judge signal to noise ratio snr_kMore than default signal to noise ratio screening value SNR_choseWhen, then it is participation to select corresponding user of this signal to noise ratio The cognitive group membership of cooperative detection, and perform step (5-3)；Otherwise, corresponding to secondary user of the selection with highest signal to noise ratio Frequency spectrum perception result is cluster head time user CR₁Final detection result；

(5-3) cluster head time user CR₁Adaptively felt according to the frequency spectrum perception result of the cognitive group membership of selected participation cooperation Know fusion；Wherein, the adaptive fusion process that perceives comprises the following steps (5-31) to step (5-33)：

(5-31) cluster head time user CR₁Perceived in the frequency spectrum perception result sent according to K-1 time users, K-1 time users of statistics It is m (1≤m≤K-1), perceives authorized user PU frequency spectrums for sky to the secondary number of users that authorized user's PU frequency spectrums are seizure condition The secondary number of users of not busy state is K-1-m；Wherein, authorized user PU frequency spectrums are that seizure condition is designated as H₁, authorized user PU₁Frequency spectrum H is designated as idle condition₀；

(5-32) cluster head time user CR₁The signal to noise ratio sent according to K-1 time users, calculates m and perceives authorized user's PU frequency spectrums For seizure condition H₁The sincere coefficient κ of secondary user_1,jAnd it is idle condition H that K-1-m, which perceive authorized user PU frequency spectrums,₀Time User's sincerity coefficient κ_2,t；Wherein, sincere coefficient κ_1,jAnd κ_2,tCalculation formula it is as follows：

<mrow> <msub> <mi>&kappa;</mi> <mrow> <mn>1</mn> <mo>,</mo> <mi>j</mi> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>snr</mi> <mi>j</mi> <mn>2</mn> </msubsup> </mrow> <mrow> <mfrac> <mn>1</mn> <mi>m</mi> </mfrac> <munderover> <mi>&Sigma;</mi> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>m</mi> </munderover> <msubsup> <mi>snr</mi> <mi>j</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>,</mo> <msub> <mi>&kappa;</mi> <mrow> <mn>2</mn> <mo>,</mo> <mi>t</mi> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msubsup> <mi>snr</mi> <mi>t</mi> <mn>2</mn> </msubsup> </mrow> <mrow> <mfrac> <mn>1</mn> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>m</mi> </mrow> </mfrac> <munderover> <mi>&Sigma;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>m</mi> </mrow> </munderover> <msubsup> <mi>snr</mi> <mi>t</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mo>;</mo> </mrow>

(5-33) cluster head time user CR₁According to the respective sensing results and sincere coefficient κ of individual user of m_1,j, calculate authorize respectively User PU frequency spectrums are seizure condition H₁Average detected probabilityGlobal detection probabilityWith this seizure condition H₁Correspondence Global false dismissal probabilityAnd authorized user PU frequency spectrum is idle condition H₀Average detected probabilityIt is global Detection probabilityThis idle condition H₀Corresponding global false dismissal probabilityWith global false-alarm probabilityWherein, The process comprises the following steps (a) to step (g)：

(a) the global error detection probability P that m time user collaborations are perceived is set up_e, obtain excellent on the energy measuring of decision-making thresholding Change function gamma^*And the optimal threshold value γ of energy measuring_opt, and authorized user PU frequency spectrums are calculated for seizure condition H₁Average inspection Survey probabilityWherein,

<mrow> <msub> <mi>P</mi> <mi>f</mi> </msub> <mo>=</mo> <mi>Q</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mi>&gamma;</mi> <mo>-</mo> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>2</mn> </msubsup> </mrow> <mrow> <mfrac> <mn>2</mn> <mi>m</mi> </mfrac> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>4</mn> </msubsup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>,</mo> <msub> <mi>P</mi> <mi>d</mi> </msub> <mo>=</mo> <mi>Q</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mi>&gamma;</mi> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mo>)</mo> </mrow> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>2</mn> </msubsup> </mrow> <mrow> <mfrac> <mn>2</mn> <mi>m</mi> </mfrac> <mrow> <mo>(</mo> <mn>2</mn> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mo>+</mo> <mn>1</mn> <mo>)</mo> </mrow> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>4</mn> </msubsup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>,</mo> <msub> <mi>P</mi> <mi>m</mi> </msub> <mo>=</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mi>d</mi> </msub> <mo>,</mo> <mi>Q</mi> <mrow> <mo>(</mo> <mi>z</mi> <mo>)</mo> </mrow> <mo>=</mo> <msubsup> <mo>&Integral;</mo> <mi>z</mi> <mi>&infin;</mi> </msubsup> <mfrac> <mn>1</mn> <msqrt> <mrow> <mn>2</mn> <mi>&pi;</mi> </mrow> </msqrt> </mfrac> <msup> <mi>e</mi> <mrow> <mo>-</mo> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> <msup> <mi>x</mi> <mn>2</mn> </msup> </mrow> </msup> <mi>d</mi> <mi>x</mi> <mo>;</mo> </mrow>

Wherein,Idle condition H is in for authorized user PU frequency spectrums₀Probability,It is in for authorized user PU frequency spectrums and takes shape State H₁Probability；P_fFor global false-alarm probability, P_dFor global detection probability, P_mFor global false dismissal probability；It is in and awards for correspondence Weigh user PU frequency spectrums and be in seizure condition H₁M users average signal-to-noise ratio, wherein,snr_iTo be secondary User CR_iThe signal to noise ratio of itself, Q (z) represents the complementary integral function of normal Gaussian, and γ is the threshold value of energy measuring,For height The variance of this white noise；

<mrow> <msup> <mi>&gamma;</mi> <mo>*</mo> </msup> <mo>=</mo> <munder> <mrow> <msub> <mi>argminP</mi> <mi>e</mi> </msub> </mrow> <mi>&gamma;</mi> </munder> <mo>=</mo> <msub> <mi>P</mi> <msub> <mi>H</mi> <mn>0</mn> </msub> </msub> <mo>&CenterDot;</mo> <mi>Q</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mi>&gamma;</mi> <mo>-</mo> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>2</mn> </msubsup> </mrow> <mrow> <mfrac> <mn>2</mn> <mi>m</mi> </mfrac> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>4</mn> </msubsup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>+</mo> <msub> <mi>P</mi> <msub> <mi>H</mi> <mn>1</mn> </msub> </msub> <mo>&CenterDot;</mo> <mi>Q</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <mi>&gamma;</mi> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mo>)</mo> </mrow> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>2</mn> </msubsup> </mrow> <mrow> <mfrac> <mn>2</mn> <mi>m</mi> </mfrac> <mrow> <mo>(</mo> <mn>2</mn> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mo>+</mo> <mn>1</mn> <mo>)</mo> </mrow> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>4</mn> </msubsup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>;</mo> </mrow>

Represent to work as function P_eCorresponding variable γ value when obtaining minimum value；

The optimal threshold value γ of energy measuring_optFor：

<mrow> <mtable> <mtr> <mtd> <mrow> <msub> <mi>&gamma;</mi> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> <mo>=</mo> <mi>&gamma;</mi> <msub> <mo>|</mo> <mrow> <mfrac> <mrow> <mo>&part;</mo> <mi>P</mi> <mi>e</mi> </mrow> <mrow> <mo>&part;</mo> <mi>&gamma;</mi> </mrow> </mfrac> <mo>=</mo> <mn>0</mn> </mrow> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mo>=</mo> <mfrac> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>2</mn> </msubsup> <mn>2</mn> </mfrac> <mo>+</mo> <msubsup> <mi>&sigma;</mi> <mi>n</mi> <mn>2</mn> </msubsup> <msqrt> <mrow> <mfrac> <mn>1</mn> <mn>4</mn> </mfrac> <mo>+</mo> <mfrac> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mn>2</mn> </mfrac> <mo>+</mo> <mfrac> <mrow> <mn>4</mn> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mo>+</mo> <mn>2</mn> </mrow> <mrow> <mi>m</mi> <mo>&CenterDot;</mo> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> </mrow> </mfrac> <mi>l</mi> <mi>n</mi> <mo>(</mo> <mfrac> <msub> <mi>P</mi> <msub> <mi>H</mi> <mn>0</mn> </msub> </msub> <msub> <mi>P</mi> <msub> <mi>H</mi> <mn>1</mn> </msub> </msub> </mfrac> <msqrt> <mrow> <mn>2</mn> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mo>+</mo> <mn>1</mn> </mrow> </msqrt> </mrow> </msqrt> <mo>)</mo> </mrow> </mtd> </mtr> </mtable> <mo>;</mo> </mrow>

Represent to work as function P_eWhen first derivative on variable γ is zero, corresponding variable γ value；

<mrow> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> <mo>=</mo> <mi>Q</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <msub> <mi>&gamma;</mi> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mo>)</mo> </mrow> </mrow> <msqrt> <mrow> <mo>(</mo> <mn>2</mn> <mo>/</mo> <mo>(</mo> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> <mo>)</mo> <mo>)</mo> <msup> <mrow> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mover> <mrow> <mi>s</mi> <mi>n</mi> <mi>r</mi> </mrow> <mo>&OverBar;</mo> </mover> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> </msqrt> </mfrac> <mo>)</mo> </mrow> <mo>;</mo> </mrow>

(b) it is seizure condition H according to gained authorized user PU frequency spectrums₁Average detected probabilityAnd individual user's of m is sincere Believe coefficient κ_1,j, it is seizure condition H to calculate authorized user PU frequency spectrums₁Global detection probabilityWith this seizure condition H₁Correspondence Global false dismissal probabilityWherein, global detection probabilityWith global false dismissal probabilityCalculation formula is as follows：

<mrow> <msub> <mi>D</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> <mo>=</mo> <mroot> <mrow> <munderover> <mi>&Pi;</mi> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>m</mi> </munderover> <msub> <mi>&kappa;</mi> <mrow> <mn>1</mn> <mo>,</mo> <mi>j</mi> </mrow> </msub> </mrow> <mi>m</mi> </mroot> <mo>&CenterDot;</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>l</mi> <mo>=</mo> <mi>m</mi> </mrow> <mi>N</mi> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> <mo>)</mo> </mrow> <mi>l</mi> </msup> <msup> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> <mo>)</mo> </mrow> <mrow> <mi>N</mi> <mo>-</mo> <mi>l</mi> </mrow> </msup> <mo>;</mo> <msub> <mi>D</mi> <mrow> <mi>u</mi> <mi>n</mi> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> <mo>=</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>D</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> </mrow>

(c) it is idle condition H according to gained authorized user PU frequency spectrums₀Average detected probabilityAnd K-1-m time users Sincere coefficient κ_2,t, it is idle condition H to calculate authorized user PU frequency spectrums₀Global detection probabilityWith this idle condition H₀ Corresponding global false dismissal probabilityGlobal false-alarm probabilityWherein, average detected probabilityGlobal detection is general RateGlobal false dismissal probabilityWith global false-alarm probabilityCalculation formula difference it is as follows：

<mrow> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow> </msub> <mo>=</mo> <mn>1</mn> <mo>-</mo> <mi>Q</mi> <mrow> <mo>(</mo> <mfrac> <mrow> <msub> <mi>&gamma;</mi> <mrow> <mi>o</mi> <mi>p</mi> <mi>t</mi> </mrow> </msub> <mo>-</mo> <mn>1</mn> </mrow> <msqrt> <mrow> <mo>(</mo> <mn>2</mn> <mo>/</mo> <mo>(</mo> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> <mo>)</mo> <mo>)</mo> </mrow> </msqrt> </mfrac> <mo>)</mo> </mrow> <mo>;</mo> </mrow>

<mrow> <msub> <mi>D</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow> </msub> <mo>=</mo> <mroot> <mrow> <munderover> <mi>&Pi;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>m</mi> </mrow> </munderover> <msub> <mi>&kappa;</mi> <mrow> <mn>2</mn> <mo>,</mo> <mi>t</mi> </mrow> </msub> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>m</mi> </mrow> </mroot> <mo>&CenterDot;</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>l</mi> <mo>=</mo> <mrow> <mo>(</mo> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>m</mi> <mo>)</mo> </mrow> <mo>+</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow> </msub> <mo>)</mo> </mrow> <mi>l</mi> </msup> <msup> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow> </msub> <mo>)</mo> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>l</mi> </mrow> </msup> <mo>;</mo> </mrow>

(d) cluster head time user CR₁It is seizure condition H according to authorized user PU frequency spectrums₁Corresponding global false dismissal probabilityAnd Authorized user PU frequency spectrums are idle condition H₀Corresponding global false-alarm probabilitySet up the frequency spectrum sense based on secondary number of users Know error function Fun (m)；Wherein, frequency spectrum perception error function Fun (m) calculation formula are as follows：

<mrow> <mtable> <mtr> <mtd> <mrow> <mi>F</mi> <mi>u</mi> <mi>n</mi> <mrow> <mo>(</mo> <mi>m</mi> <mo>)</mo> </mrow> <mo>=</mo> <msub> <mi>P</mi> <mrow> <mi>p</mi> <mi>u</mi> </mrow> </msub> <mo>&CenterDot;</mo> <msub> <mi>D</mi> <mrow> <mi>u</mi> <mi>n</mi> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> <mo>+</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>p</mi> <mi>u</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>&CenterDot;</mo> <msub> <mi>D</mi> <mrow> <mi>F</mi> <mi>a</mi> <mi>i</mi> <mi>l</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mo>=</mo> <msub> <mi>P</mi> <mrow> <mi>p</mi> <mi>u</mi> </mrow> </msub> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>D</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> <mo>)</mo> </mrow> <mo>+</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>p</mi> <mi>u</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>D</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow> </msub> <mo>)</mo> </mrow> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mo>=</mo> <msub> <mi>P</mi> <mrow> <mi>p</mi> <mi>u</mi> </mrow> </msub> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mroot> <mrow> <munderover> <mi>&Pi;</mi> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>m</mi> </munderover> <msub> <mi>&kappa;</mi> <mrow> <mn>1</mn> <mo>,</mo> <mi>j</mi> </mrow> </msub> </mrow> <mi>m</mi> </mroot> <mo>&CenterDot;</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>l</mi> <mo>=</mo> <mi>m</mi> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> <mo>)</mo> </mrow> <mi>l</mi> </msup> <msup> <mrow> <mo>(</mo> <mrow> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow> </msub> </mrow> <mo>)</mo> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>l</mi> </mrow> </msup> <mo>)</mo> </mrow> <mo>+</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>p</mi> <mi>u</mi> </mrow> </msub> <mo>)</mo> <mo>&CenterDot;</mo> <mo>(</mo> <mn>1</mn> <mo>-</mo> <mroot> <mrow> <munderover> <mi>&Pi;</mi> <mrow> <mi>t</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>m</mi> </mrow> </munderover> <msub> <mi>&kappa;</mi> <mrow> <mn>2</mn> <mo>,</mo> <mi>t</mi> </mrow> </msub> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>m</mi> </mrow> </mroot> <mo>&CenterDot;</mo> <munderover> <mi>&Sigma;</mi> <mrow> <mi>l</mi> <mo>=</mo> <mrow> <mo>(</mo> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>m</mi> <mo>)</mo> </mrow> <mo>+</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msup> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow> </msub> <mo>)</mo> </mrow> <mi>l</mi> </msup> <msup> <mrow> <mo>(</mo> <mrow> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>det</mi> <mo>,</mo> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow> </msub> </mrow> <mo>)</mo> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> <mo>-</mo> <mi>l</mi> </mrow> </msup> <mo>)</mo> </mrow> </mtd> </mtr> </mtable> <mo>;</mo> </mrow>

(e) frequency spectrum perception error function Fun (m) frequency spectrum perception error minimum value Fun (m are calculated₀), and missed with the frequency spectrum perception Difference function minimum value Fun (m₀) corresponding numerical value m₀(m₀≤ m) as the optimal cooperation time number of users for participating in collaborative sensing, and To m time users according to its corresponding snr value snr_iDescending arrangement is carried out, the descending arrangement group of m time users is obtained；

(f) the preceding m in time user's descending arrangement group is chosen₀Individual user is used as the optimal cooperation time user for participating in collaborative sensing；Its In, the optimal cooperation time user that selection is marked respectively is CR'_r, wherein, r=1,2 ..., m₀；

(g) cluster head time user CR₁According to m in step (f)₀The frequency spectrum perception result of the individual final secondary user for participating in collaborative sensing is entered Collaborative sensing of the row based on OR criterions, and using the testing result of collaborative sensing as K in this cluster time user final detection knot Really；Wherein, OR criterions are as follows：

<mrow> <msub> <mi>Q</mi> <mrow> <mi>d</mi> <mo>,</mo> <mn>1</mn> </mrow> </msub> <mo>=</mo> <mn>1</mn> <mo>-</mo> <munderover> <mi>&Pi;</mi> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>m</mi> <mn>0</mn> </mrow> </munderover> <msub> <mi>&omega;</mi> <mi>r</mi> </msub> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>d</mi> <mo>,</mo> <mi>r</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>,</mo> <msub> <mi>Q</mi> <mrow> <mi>f</mi> <mi>a</mi> <mo>,</mo> <mn>1</mn> </mrow> </msub> <mo>=</mo> <mn>1</mn> <mo>-</mo> <munderover> <mi>&Pi;</mi> <mrow> <mi>r</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>m</mi> <mn>0</mn> </mrow> </munderover> <mrow> <mo>(</mo> <mn>1</mn> <mo>-</mo> <msub> <mi>P</mi> <mrow> <mi>f</mi> <mo>,</mo> <mi>r</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>;</mo> </mrow>

<mrow> <msub> <mi>&omega;</mi> <mi>r</mi> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <msup> <mi>SNR</mi> <mrow> <mo>&prime;</mo> <mo>&prime;</mo> </mrow> </msup> <mi>r</mi> </msub> </mrow> <mrow> <mn>0.5</mn> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <msub> <msup> <mi>SNR</mi> <mrow> <mo>&prime;</mo> <mo>&prime;</mo> </mrow> </msup> <mrow> <mi>m</mi> <mi>a</mi> <mi>x</mi> </mrow> </msub> <mo>+</mo> <msub> <msup> <mi>SNR</mi> <mrow> <mo>&prime;</mo> <mo>&prime;</mo> </mrow> </msup> <mrow> <mi>m</mi> <mi>i</mi> <mi>n</mi> </mrow> </msub> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>,</mo> <mi>r</mi> <mo>=</mo> <mn>1</mn> <mo>,</mo> <mn>2</mn> <mo>,</mo> <mo>...</mo> <mo>,</mo> <msub> <mi>m</mi> <mn>0</mn> </msub> <mo>;</mo> </mrow>

Wherein, P_d,rFor optimal cooperation time user CR " in this cluster_rDetection probability, P_fa,jFor optimal cooperation time user in this cluster CR”_rFalse-alarm probability；Q_{D, 1}For the global detection probability after this cluster cooperative detection, Q_fa,1It is empty for the overall situation after this cluster cooperative detection Alarm probability；w_rRepresent signal to noise ratio snr "_rWeight coefficient, SNR "_maxRepresent m in this cluster₀The signal to noise ratio of individual optimal cooperation time user Maximum, SNR "_minRepresent m in this cluster₀The signal to noise ratio minimum value of individual optimal cooperation time user；

(6) according to the process of step (5), the 3rd cluster is obtained respectively to M₁Global detection probability Q in cluster in cluster_{D, 3}ExtremelyWith And global false-alarm probabilityExtremely

(7) frequency spectrum perception fusion center FC is according to M₁The global detection probability Q in corresponding cluster that individual cluster head time user sends_d,sWith Global false-alarm probability Q_fa,sThe fusion detection based on AND criterions is carried out, and final multiband is used as using the fusion detection result Collaboration frequency spectrum testing result；Wherein, AND criterions are as follows：

<mrow> <msub> <mi>Q</mi> <mi>d</mi> </msub> <mo>=</mo> <munderover> <mi>&Pi;</mi> <mrow> <mi>s</mi> <mo>=</mo> <mn>2</mn> </mrow> <msub> <mi>M</mi> <mn>1</mn> </msub> </munderover> <msub> <mi>Q</mi> <mrow> <mi>d</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>,</mo> <msub> <mi>Q</mi> <mrow> <mi>f</mi> <mi>a</mi> </mrow> </msub> <mo>=</mo> <munderover> <mi>&Pi;</mi> <mrow> <mi>s</mi> <mo>=</mo> <mn>2</mn> </mrow> <msub> <mi>M</mi> <mn>1</mn> </msub> </munderover> <msub> <mi>Q</mi> <mrow> <mi>f</mi> <mi>a</mi> <mo>,</mo> <mi>s</mi> </mrow> </msub> <mo>,</mo> <mi>s</mi> <mo>=</mo> <mn>2</mn> <mo>,</mo> <mn>3</mn> <mo>,</mo> <mo>...</mo> <mo>,</mo> <msub> <mi>M</mi> <mn>1</mn> </msub> <mo>.</mo> </mrow> 4