CN104378169B - Collaborative spectrum sensing system and collaborative spectrum sensing method based on power set confidence coefficients - Google Patents

Abstract

The invention discloses a collaborative spectrum sensing system and a collaborative spectrum sensing method based on power set confidence coefficients. According to the technical scheme, the collaborative spectrum sensing method comprises the following steps of performing spectrum sensing from a user by using a plurality of perceive user terminals; judging whether a main user spectrum using state is in a spectrum idle state or in a spectrum occupation state according to respective sensing results; reporting judgment confidence coefficients of corresponding judgment results to a fusion center; and respectively calculating the judgment confidence coefficients of the reported spectrum idle state and judgment confidence coefficients of the reported spectrum occupation state by using the fusion center according to all data reported from the user so as to obtain an overall spectrum sensing judgment result. By the collaborative spectrum sensing system and the collaborative spectrum sensing method based on the power set confidence coefficients, influences of low confidence coefficients from the user on overall judgment are reduced effectively, the adaptive ability of a multi-user spectrum detecting system is greatly improved in a time-varying wireless communication environment, and the detectability of the spectrum detecting system is greatly improved.

Description

Joint spectrum sensory perceptual system and method based on power set confidence level

Technical field

The present invention relates to wireless communication field, more particularly to a kind of joint spectrum sensory perceptual system based on power set confidence level and Method.

Background technology

With developing rapidly for wireless communication technology and network, the quantity of wireless user is sharply increased, by wireless network The form of service of access becomes more diverse, and higher and higher bandwidth requirement is proposed to system so that frequency spectrum resource becomes non- It is often nervous.In addition, as wireless network is broadband and data, business, network IPization and integrated progressively evolution, people are to band The utilization rate of wide and frequency spectrum proposes higher and higher requirement.And cognitive radio, exactly use not for solving this frequency spectrum Equilibrium, the potential technological means of very tool the problems such as the availability of frequency spectrum is not high.At present, a typical case of cognitive radio should With being exactly that opportunistic spectrum is accessed.Its core concept is the cognition by Wireless Telecom Equipment to communication environment, and then according to certain The mode of " waiting for an opportunity ", goes in real time to find to authorize the frequency spectrum that can be utilized occurred in frequency range in spatial domain, time domain and frequency domain Chance, i.e. " spectrum interposition ", and reasonably utilize.When unauthorized user (SU, also referred to as from user, cognitive user) is by this When the mode of " borrow " is using the frequency spectrum resource of authorized user (PU, also referred to as primary user), it is necessary to assure its communication process will not Have influence on the communication of PU, or the interference of PU is controlled in certain it is specific within the scope of.

In order to find out " spectrum interposition " that be adapted to communication so that cognitive radio system can not affect existing communication system Effectively it is operated on the premise of system, generally this purpose is completed using frequency spectrum detection technology at present, frequency spectrum detection is referred to Cognitive radios perceive and analyze the frequency range service condition in wireless communications environment on specific time, specific region Ability.Existing frequency spectrum detecting method has energy detection method (H.Urkowitz, " Energy detection of unknown deterministic signals,”Proceedings of IEEE,vol.55,pp.523-531,April 1967；F.F.Digham,M.-S.Alouini and M.K.Simon,“On the energy detection of unknow signals over fading channels,”IEEE Trans.Commun,vol.55,no.1,pp.3575-3579, Jan.2007), matched filter and related detecting method (S.M.Kay, Fundamental of Statistical Signal Processing:Dection Theory.New Jersey:Prentice Hall, 1998) with cycle specificity detection method (S.Enserink and D.Cochran,“A cycolstationary feature detector,”in Proc.28^thAsilomar Conference on Signals,Systems,and Computers,Monterey,CA, Oct.1994, pp.806-810) etc..Existing method detection needs to know the priori of current frequency range PU, its implementation complexity And it is relatively costly, detection time is also longer.Therefore, for reduces cost and implementation complexity, existing frequency spectrum detection usually exists The transmitting terminal of SU by energy measuring with judgement completing, by measuring to the wireless signal in observed frequency range and energy Amount is calculated, and is compared with specific threshold value, so as to decide whether to occur in that " spectrum interposition " that meet communicating requirement.Frequently Can the performance of spectrum detection determines that SU cans catch spectrum opportunities to realize efficient data transfer, and than calibrated Really judge radiofrequency signal collision accident, SU is actively kept out of the way as early as possible in the case of PU appearance, it is to avoid to affect too much The communication of PU.

In actual wireless channel, the frequency spectrum detecting result of sole user is frequently subjected to the shadow of decline, shade and multipath Ring, it is impossible to reach a detection performance well.By the way that the testing result of multiple users is in addition comprehensive, just can be opened with a small amount of Pin transmission user's discriminative information, is greatly enhanced the performance of detection.

And in multi-user cognitive radio network, there is a primary user and N number of from user.Mutually do not do between user Disturb, each independently carries out frequency spectrum perception from user, then by control channel coherent detection data is activation to fusion center FC, is concentrated according to ad hoc rule by FC and is adjudicated, and generally using K/N rule judgements, the classic applications of K/N rules are exactly that minority is obeyed Majority principle, if referring to the judgement having in N number of user more than or equal to K based on the joint spectrum detection method of K/N rules It is true, then total judgement is true, and otherwise total judgement is false.

When SU ends energy detector works, signal filters out-of-band noise by a band filter first, then passes through Squarer and integrator calculate gross energy T, and last energy decision device is compared gross energy T with an energy judging threshold ξ Compared with to judge two possible situations：H₀And H₁, wherein H₀Represent the vacant frequency spectrums of PU, and H₁Represent PU and be currently in use frequency spectrum. If T is ＜ ξ, the result of energy measuring is H₀；Conversely, being H₁.Under spectrum intertexture pattern (SU only works in the idle periods of PU), SU Can only be H in court verdict₀When could transmission data.Gross energy T is in H₀And H₁Chi square distribution is obeyed under two hypothesis, Because the energy that SU is received is a random chi square distribution, when PU is actually when using frequency spectrum, the energy that SU is detected T ＜ ξ are possible to, and mistakenly draw H₀Court verdict, then, SU begins to use frequency spectrum, and the communication to PU to interfere. That is, the decision reliability from user SU is poor, especially to frequency spectrum perception ability (i.e. confidence level is low) from user's The reliability of judgement is worse, total decision reliability is affected, so as to reduce the performance of frequency spectrum detection.

The content of the invention

It is an object of the invention to overcome the above-mentioned deficiency in the presence of prior art, there is provided one kind is based on power set confidence level Joint spectrum sensory perceptual system and method, it can greatly strengthen multi-user's frequency spectrum detection under the wireless communications environment of time-varying Adaptive ability, reduce interference of the low confidence user to total judgement, improve the performance of frequency spectrum detection.

In order to realize foregoing invention purpose, the technical solution used in the present invention is：A kind of joint based on power set confidence level Frequency spectrum perception system, including at least two cognitive user terminals, for separately detecting the wireless communication loop around itself The appearance of authorized user's terminal in border, to its frequency range service condition frequency spectrum perception is carried out, and judges the frequency of authorized user's terminal Whether spectrum use state is idle, and corresponding judgement confidence level is reported respectively to fusion center according to judged result；And in fusion The heart, for receiving the judgement confidence level that at least two cognitive users terminal is reported respectively, by all of judgement Confidence level is divided into two set, and to two set power set confidence calculations process is carried out, and is judged to obtain institute according to result State total court verdict of the frequency spectrum use state of authorized user's terminal；Wherein, it is described in a set in described two set Judgement confidence level is to judge that the frequency spectrum use state is idle cognitive user end at least two cognitive users terminal The judgement confidence level that end reports, the judgement confidence level in another set is at least two cognitive users terminal It is middle to judge that the frequency spectrum use state is the judgement confidence level of occupied cognitive user terminal to report.

Preferably, all of judgement confidence level is divided into described two set and is specially by the fusion center：

The all of judgement confidence level is divided into by described two set according to the identification information of the judgement confidence level；

Wherein, the identification information is used to indicate that the judgement confidence level is to sentence at least two cognitive users terminal The frequency spectrum use state of breaking is the judgement confidence level of idle cognitive user terminal to report；Or, for indicating described to sentence Certainly confidence level is to judge that the frequency spectrum use state is occupied cognitive user end at least two cognitive users terminal The judgement confidence level that end reports.

Preferably, at least two cognitive users terminal, judging the frequency spectrum use state of authorized user's terminal is The no free time, corresponding judgement confidence level is reported respectively to fusion center according to judged result, specially：

At least two cognitive users terminal each independently carries out frequency spectrum perception, will detect calculated spectrum energy T compares with detection threshold ξ, and according to following formula judgement confidence level P is reported_i；

Wherein H₀The frequency spectrum use state for representing authorized user's terminal is idle, H₁Represent the frequency of authorized user's terminal Spectrum use state is occupied, and sign is the identification information；The i is positive integer, represents described at least two cognitive use The respective numbering of family terminal.

Preferably, the fusion center carries out power set confidence calculations process to described two set, according to result Judgement obtains total court verdict of the frequency spectrum use state of authorized user's terminal, specially；

The all of judgement confidence level is divided into according to the identification information of the judgement confidence level described two Set calculates respectively two set U according to following formula₀And U₁Power set confidence level,

Result is normalized respectively：

M (H are contrasted again₀) and m (H₁) size, make last total court verdict；

Wherein：Set U₀It is interior to judge that authorized user's terminal spectrum is used at least two cognitive users terminal State is H₀The judgement confidence level for reporting, set U₁It is interior for judge at least two cognitive users terminal it is described authorize use Family terminal spectrum use state is H₁The judgement confidence level for reporting, P_FC(H₀) it is set U₀Power set confidence level；P_FC(H₁) it is collection Close U₁Power set confidence level, m (H₀) it is set U₀Normalization power set confidence level；m(H₁) it is set U₁Normalization power set confidence Degree.

The present invention also provides a kind of joint spectrum cognitive method based on power set confidence level, comprises the following steps：

Authorize in the wireless communications environment that step one, at least two cognitive user terminals separately detect around itself The appearance of user terminal, to its frequency range service condition frequency spectrum perception is carried out, and the frequency spectrum for judging authorized user's terminal uses shape Whether state is idle, and corresponding judgement confidence level is reported respectively to fusion center according to judged result；

Step 2, the fusion center receive the judgement confidence that at least two cognitive users terminal is reported respectively Degree, by all of judgement confidence level two set are divided into, and to two set power set confidence calculations process is carried out, according to Result judges total court verdict of the frequency spectrum use state for obtaining authorized user's terminal；Wherein, described two set In one set in the judgement confidence level be at least two cognitive users terminal in judge the frequency spectrum use state For the judgement confidence level of idle cognitive user terminal to report, the judgement confidence level in another set for it is described extremely Judge that the frequency spectrum use state is the judgement of occupied cognitive user terminal to report in few two cognitive user terminals Confidence level.

Preferably, all of judgement confidence level is divided into described two set and is specially by the fusion center：

The all of judgement confidence level is divided into by described two set according to the identification information of the judgement confidence level； Wherein, the identification information is used to indicate that the judgement confidence level is to judge the frequency at least two cognitive users terminal Spectrum use state is the judgement confidence level of idle cognitive user terminal to report；Or, for indicating the judgement confidence level To judge that the frequency spectrum use state is occupied cognitive user terminal to report at least two cognitive users terminal Judgement confidence level.

Preferably, at least two cognitive users terminal, judging the frequency spectrum use state of authorized user's terminal is The no free time, corresponding judgement confidence level is reported respectively to fusion center according to judged result, specially：

At least two cognitive users terminal each independently carries out frequency spectrum perception, will detect calculated spectrum energy T compares with detection threshold ξ, and according to following formula judgement confidence level P is reported_i；

Wherein H₀The frequency spectrum use state for representing authorized user's terminal is idle, H₁Represent the frequency of authorized user's terminal Spectrum use state is occupied, and sign is the identification information；The i is positive integer, represents described at least two cognitive use The respective numbering of family terminal.

Preferably, the fusion center carries out power set confidence calculations process to described two set, according to result Judgement obtains total court verdict of the frequency spectrum use state of authorized user's terminal, specially；

The all of judgement confidence level is divided into according to the identification information of the judgement confidence level described two Set calculates respectively two set U according to following formula₀And U₁Power set confidence level,

Result is normalized respectively：

M (H are contrasted again₀) and m (H₁) size, make last total court verdict；

Wherein：Set U₀It is interior to judge that authorized user's terminal spectrum is used at least two cognitive users terminal State is H₀The judgement confidence level for reporting, set U₁It is interior for judge at least two cognitive users terminal it is described authorize use Family terminal spectrum use state is H₁The judgement confidence level for reporting, P_FC(H₀) it is set U₀Power set confidence level；P_FC(H₁) it is collection Close U₁Power set confidence level, m (H₀) it is set U₀Normalization power set confidence level；m(H₁) it is set U₁Normalization power set confidence Degree.

Compared with prior art, beneficial effects of the present invention：

Present system and method effectively reduce interference of the low confidence user to total judgement, can be greatly enhanced The detection performance of frequency spectrum detection system, enhances the self adaptation of multi-user's frequency spectrum detection system under the wireless communications environment of time-varying Ability.Meanwhile, in a preferred approach fusion center can quickly be merged by power set confidence level formula, be calculated very simple It is single, it is fully able to the power dissipation overhead for realizing being wanted needed for the quick response to environmental change and greatly reduction running.

Description of the drawings：

Fig. 1 is cognitive radio system illustraton of model；

Fig. 2 is based on the joint spectrum sensory perceptual system model of power set confidence level；

Fig. 3 is SU energy detector block diagrams.

Specific embodiment

With reference to specific embodiment, the present invention is described in further detail.But this should not be interpreted as the present invention The scope of above-mentioned theme is only limitted to below example, and all technologies realized based on present invention belong to the model of the present invention Enclose.

A kind of joint spectrum sensory perceptual system based on power set confidence level of the present invention, including at least two cognitive user ends End, for separately detecting the wireless communications environment around itself in authorized user's terminal appearance, its frequency range is used Situation carries out frequency spectrum perception, judges whether the frequency spectrum use state of authorized user's terminal is idle, is distinguished according to judged result Corresponding judgement confidence level is reported to fusion center；And fusion center, for receiving at least two cognitive users terminal The judgement confidence level for reporting respectively, by all of judgement confidence level two set are divided into, and two set are carried out The process of power set confidence calculations, total judgement of the frequency spectrum use state of authorized user's terminal is obtained according to result judgement As a result；Wherein, the judgement confidence level in described two set in a set is at least two cognitive users terminal The middle judgement confidence level for judging that the frequency spectrum use state is idle cognitive user terminal to report, in another set The judgement confidence level is to judge that the frequency spectrum use state is occupied cognition at least two cognitive users terminal The judgement confidence level that user terminal is reported.

The present invention is, to carrying out the estimation of confidence level from the judgement of user, i.e. cognitive user terminal, and to reduce low putting with this The interference from user to total judgement of reliability, effectively reduces interference of the low confidence user to total judgement, is greatly enhanced The detection performance of frequency spectrum detection system, enhances the self adaptation of multi-user's frequency spectrum detection system under the wireless communications environment of time-varying Ability.

Specifically, all of judgement confidence level is divided into described two set and is specially by the fusion center：Root The all of judgement confidence level is divided into into described two set according to the identification information of the judgement confidence level；Wherein, it is described Identification information is used to indicate that the judgement confidence level is to judge that the frequency spectrum uses shape at least two cognitive users terminal State is the judgement confidence level of idle cognitive user terminal to report；Or, for indicating the judgement confidence level for described in extremely The judgement confidence that the frequency spectrum use state is occupied cognitive user terminal to report is judged in few two cognitive user terminals Degree.

Preferably, at least two cognitive users terminal, judging the frequency spectrum use state of authorized user's terminal is The no free time, corresponding judgement confidence level is reported respectively to fusion center according to judged result, specially：

At least two cognitive users terminal each independently carries out frequency spectrum perception, will detect calculated spectrum energy T compares with detection threshold ξ, and according to following formula judgement confidence level P is reported_i；

Wherein H₀The frequency spectrum use state for representing authorized user's terminal is idle, H₁Represent the frequency of authorized user's terminal Spectrum use state is occupied, and sign is the identification information；The i is positive integer, represents described at least two cognitive use The respective numbering of family terminal.

Preferably, the fusion center carries out power set confidence calculations process to described two set, according to result Judgement obtains total court verdict of the frequency spectrum use state of authorized user's terminal, specially；

The all of judgement confidence level is divided into according to the identification information of the judgement confidence level described two Set calculates respectively two set U according to following formula₀And U₁Power set confidence level,

Can see from formula, when the judgement confidence level of user is relatively low, the user is to P_FC(H₀) and P_FC(H₁) impact Will reduce, so can further reduce impact of the low confidence user to total judgement.

Result is normalized respectively：

M (H are contrasted again₀) and m (H₁) size, make last total court verdict；

H₀:m(H₀) ＞ m (H₁)；

H₁:m(H₀)≤m(H₁)

Wherein：Set U₀It is interior to judge that authorized user's terminal spectrum is used at least two cognitive users terminal State is H₀The judgement confidence level for reporting, set U₁It is interior for judge at least two cognitive users terminal it is described authorize use Family terminal spectrum use state is H₁The judgement confidence level for reporting, P_FC(H₀) it is set U₀Power set confidence level；P_FC(H₁) it is collection Close U₁Power set confidence level, m (H₀) it is set U₀Normalization power set confidence level；m(H₁) it is set U₁Normalization power set confidence Degree.

With reference to a specific embodiment explanation present invention.Fig. 1 be cognitive radio system illustraton of model, wherein γ_psTable Show primary user to the signal to noise ratio from user's transmitting terminal, γ_prRepresent primary user to the signal to noise ratio from user's receiving terminal, γ_srRepresent from User's transmitting terminal is to the signal to noise ratio from user's receiving terminal.

Fig. 2 is represented based on the joint spectrum sensory perceptual system model of power set confidence level.It is assumed that in cognitive radio networks, depositing In a primary user PU (i.e. authorized user's terminal) and N number of from user SU (i.e. cognitive user terminal).From between user SU mutually not Interference, each is independently carried out frequency spectrum perception, then related data is sent to fusion center by control channel from user SU FC, is concentrated by FC and is adjudicated.

Fig. 3 show the energy detector from user SU ends, and each part is followed successively by：Band filter (BPF), square Device, integrator and energy decision device.

The present invention improves cognitive radio users mainly to carrying out the estimation of confidence level from the judgement of user SU with this Detection performance, reduce interference of the low confidence user to total judgement.

First frequency spectrum perception is independently carried out from user SU by multiple, reported respectively accordingly according to respective sensing results Judgement confidence level gives fusion center FC.Fusion center has been collected after the data for reporting respectively to reporting H₀With report H₁Two collection Conjunction carries out the calculating of power set confidence level, is contrasted after normalization, finally draws total judgement.

Specifically, step 1：Respectively frequency spectrum perception is each independently carried out from user, by the spectrum energy T for detecting and detection door Limit ξ compares, and obtains court verdict；If court verdict is H₀Then calculated from user according to formula (1) and adjudicate H₀Judgement confidence level

If court verdict is H₁Then calculated from user according to formula (2) and adjudicate H₁Judgement confidence level

Wherein P_i{H₀| T ＜ ζ } it is to detect spectrum energy T less than thresholding ζ thus judgement for H from user i₀When, primary user Really the probability mourned in silence；P_i{H₁| T >=ζ } it is to detect spectrum energy T not less than thresholding ζ thus judgement for H from user i₁When, it is main The probability of user's busy channel really；P_r{H₀It is probability that primary user mourns in silence；P_r{H₁Be primary user's busy channel probability.P_i { T ＜ ζ } is to detect probability of the spectrum energy T less than thresholding ζ from user i, and it includes two kinds of scenes, one P_iT ＜ ζ | H₀Be When primary user mourns in silence, from user i probability of the spectrum energy T less than thresholding ζ is detected；Its two P_iT ＜ ζ | H₁It is primary user's occupancy During channel, from user i probability of the spectrum energy T less than thresholding ζ, i.e. false dismissal probability are detected.P_i{ T >=ζ } is from user i detections To probability of the spectrum energy T not less than thresholding ζ, it includes two kinds of scenes, one P_i{T≥ζ|H₁When being primary user's busy channel, Probability of the spectrum energy T not less than thresholding ζ is detected from user i；Its two P_i{T≥ζ|H₀When being that primary user mourns in silence, from user i Detect probability of the spectrum energy T not less than thresholding ζ, i.e. false-alarm probability.

Step 2：Judgement confidence level P is reported according to below equation (3) from user i_i；

Wherein negative sign shows that court verdict is H₀, positive sign shows that court verdict is H₁。

Step 3：Fusion center FC divides two set according to the sign for collecting data：Adjudicate as H₀From user set U₀And judgement is H₁From user set U₁, the power set confidence level of two set is calculated respectively, set is calculated respectively according to following formula U₀, set U₁Power set confidence level：

P_FC(H₀) it is set U₀Power set confidence level；P_FC(H₁) it is set U₁Power set confidence level.

Step 4：It is normalized：

m(H₀) it is set U₀Normalization power set confidence level；m(H₁) it is set U₁Normalization power set confidence level.

Step 5：Contrast m (H₀) and m (H₁) size, make last total judgement：

H₀:m(H₀) ＞ m (H₁)

H₁:m(H₀)≤m(H₁)

In further example the bright present invention, false so that one is pressed the cognition wireless network that time slot divides transmission channel as an example If having a PU, 10 SU in network.PU can be by counting in advance known to the statistical value of spectrum occupancy time, it is assumed that statistics It is P to obtain the actual probability for itself taking frequency spectrum of PU_r{H₁}=0.42, the probability for being not take up frequency spectrum (i.e. idle condition) is P_r {H₀}=0.58.

All SU_iThe detection of frequency spectrum is independently carried out, and respective P is reported according to testing result_iValue, wherein P_iExpression Method such as following formula：

Assume that wireless channel is the rayleigh fading channel with additive white Gaussian noise.T is from user SU_iThe frequency for detecting Spectrum energy；SU_iDetection threshold ξ can be fixed threshold, or dynamic threshold；It is typically different SU_iUsing different judgements Thresholding ξ.SU_iEnergy detector false-alarm probability and detection probability can be expressed as：

Wherein, Γ () is gamma function, and Γ () is incomplete gamma functions；Sampled signal points M=3；Noise ThanDifferent SU_iDifferent spectrum energies are detected, using different detection thresholds ξ, therefore is led Cause different false-alarm probabilities P_fWith detection probability P_d.Therefore difference SU_iTesting result have different confidence levels, be obtained：

P_i{H₀| T ＜ ξ } represent that when adjudicating from user i be H₀Under the conditions of, the probability that primary user does not occur, this probability is got over Height, shows the H that user is done₀Judgement is more reliable；P_i{H₁| T ＞ ξ } represent that when adjudicating from user i be H₁Under the conditions of, primary user goes out Existing probability, this probability is higher, shows the H that user is done₁Judgement is more reliable.As can be seen that being put based on power set from formula The joint detection algorithm of reliability is more sensitive to the decision threshold from user, if the detection for coordinating the dynamic threshold of single user is calculated Method, can obtain very good effect.Therefore single user adopts the energy detection algorithm of adaptive threshold in embodiment.On 10 SU The P of report_iCollection be combined into -0.3195, and -0.9980, -0.6740,0.9889,0.8778,0.8657, -0.3312,0.9670, - 0.4981,-0.4570}。

Fusion center is divided into two set U according to positive and negative values after the data for having collected all reporting of user data₀ And U₁, the data in set are carried out after absolute value process, two set are respectively according to following formula and calculate respective power set confidence Degree.

Can see from formula, when the judgement confidence level of user is relatively low, the user is to P_FC(H₀) and P_FC(H₁) impact will Can reduce.By this method, it is possible to reduce impact of the low confidence user to total judgement.P_FC(H₀)=11.8234, P_FC(H₁) =12.7059.

When having calculated P_FC(H₀) and P_FC(H₁) after, to be normalized, its objective is to ensure that both sums are 1.

m(H₀)=0.4820, m (H₁)=0.5180.

Finally, by comparing m (H₀) and m (H₁) size, draw last total judgement：

H₀:m(H₀) ＞ m (H₁)

H₁:m(H₀)≤m(H₁)

The data that fusion center is reported according to 10 SU, conclusive judgement conclusion is H₁。

So far, frequency spectrum perception just finishes, and thereafter data transfer can have different ways, such as fusion center will concentrate inspection Survey result and notify all from user, from user oneself H is determined₀When whether send data at random.Again for example, want to send number from user According to when to fusion center application, fusion center determined according to centralized detecting result allow/refusal send request.

Experiment shows, the detecting system of the joint spectrum cognition technology based on power set confidence level has been used, compared to tradition The detecting system of K/N rules be significantly improved in terms of false alarm probability, what the reduction of false alarm probability brought most directly ties Fruit can be just to cause that SU user more sends data, so as to increase handling capacity, raising power system capacity.In false dismissal probability side Face, due to having used associated detection technique, relative to the frequency spectrum detecting method of single user, false dismissal probability is reduced very significantly, is The reliability of system is improved.

It should be noted that frequency spectrum detection technology not only plays crucial work in the search and judgement of " spectrum interposition " With also in the aspect vital effect of performance such as monitoring and statistics of frequency spectrum use state.By the monitoring of wireless frequency spectrum, can It is high-rise spectrum management provided auxiliary to collect the statistics of wireless environment, and the communication for SU provides necessary parameter Support.

Based on same design, the present invention also provides a kind of joint spectrum cognitive method based on power set confidence level, including with Lower step：

Authorize in the wireless communications environment that step one, at least two cognitive user terminals separately detect around itself The appearance of user terminal, to its frequency range service condition frequency spectrum perception is carried out, and the frequency spectrum for judging authorized user's terminal uses shape Whether state is idle, and corresponding judgement confidence level is reported respectively to fusion center according to judged result；

Step 2, the fusion center receive the judgement confidence that at least two cognitive users terminal is reported respectively Degree, by all of judgement confidence level two set are divided into, and to two set power set confidence calculations process is carried out, according to Result judges total court verdict of the frequency spectrum use state for obtaining authorized user's terminal；Wherein, described two set In one set in the judgement confidence level be at least two cognitive users terminal in judge the frequency spectrum use state For the judgement confidence level of idle cognitive user terminal to report, the judgement confidence level in another set for it is described extremely Judge that the frequency spectrum use state is the judgement of occupied cognitive user terminal to report in few two cognitive user terminals Confidence level.

Preferably, all of judgement confidence level is divided into described two set and is specially by the fusion center：

The all of judgement confidence level is divided into by described two set according to the identification information of the judgement confidence level； Wherein, the identification information is used to indicate that the judgement confidence level is to judge the frequency at least two cognitive users terminal Spectrum use state is the judgement confidence level of idle cognitive user terminal to report；Or, for indicating the judgement confidence level To judge that the frequency spectrum use state is occupied cognitive user terminal to report at least two cognitive users terminal Judgement confidence level.

Preferably, at least two cognitive users terminal, judging the frequency spectrum use state of authorized user's terminal is The no free time, corresponding judgement confidence level is reported respectively to fusion center according to judged result, specially：

At least two cognitive users terminal each independently carries out frequency spectrum perception, will detect calculated spectrum energy T compares with detection threshold ξ, and according to following formula judgement confidence level P is reported_i；

Wherein H₀The frequency spectrum use state for representing authorized user's terminal is idle, H₁Represent the frequency of authorized user's terminal Spectrum use state is occupied, and sign is the identification information；The i is positive integer, represents described at least two cognitive use The respective numbering of family terminal.

Preferably, the fusion center carries out power set confidence calculations process to described two set, according to result Judgement obtains total court verdict of the frequency spectrum use state of authorized user's terminal, specially；

The all of judgement confidence level is divided into according to the identification information of the judgement confidence level described two Set calculates respectively two set U according to following formula₀And U₁Power set confidence level,

Result is normalized respectively：

M (H are contrasted again₀) and m (H₁) size, make last total court verdict；

H₀:m(H₀) ＞ m (H₁)；

H₁:m(H₀)≤m(H₁)

Wherein：Set U₀It is interior to judge that authorized user's terminal spectrum is used at least two cognitive users terminal State is H₀The judgement confidence level for reporting, set U₁It is interior for judge at least two cognitive users terminal it is described authorize use Family terminal spectrum use state is H₁The judgement confidence level for reporting, P_FC(H₀) it is set U₀Power set confidence level；P_FC(H₁) it is collection Close U₁Power set confidence level, m (H₀) it is set U₀Normalization power set confidence level；m(H₁) it is set U₁Normalization power set confidence Degree.

Each step and its specific descriptions of said method embodiment can be described referring to aforementioned system embodiment relevant portion, this Place is no longer described in detail.

Present system and method effectively reduce interference of the low confidence user to total judgement, can be greatly enhanced The detection performance of frequency spectrum detection system, enhances the self adaptation of multi-user's frequency spectrum detection system under the wireless communications environment of time-varying Ability.Meanwhile, in a preferred approach fusion center can quickly be merged by power set confidence level formula, be calculated very simple It is single, it is fully able to the power dissipation overhead for realizing being wanted needed for the quick response to environmental change and greatly reduction running.

The specific embodiment of the present invention has been described in detail above in conjunction with accompanying drawing, but the present invention is not restricted to Embodiment is stated, in the case of the spirit and scope without departing from claims hereof, those skilled in the art can make Go out various modifications or remodeling.

Claims (4)

1. a kind of joint spectrum sensory perceptual system based on power set confidence level, it is characterised in that include：

At least two cognitive user terminals, for separately detecting the wireless communications environment around itself in authorized user's end The appearance at end, to its frequency range service condition frequency spectrum perception is carried out, and whether judges the frequency spectrum use state of authorized user's terminal Free time, corresponding judgement confidence level is reported respectively to fusion center according to judged result；The cognitive user terminal passes through an energy Amount detector carries out frequency spectrum perception, and the energy detector includes band filter, squarer, integrator and the energy being sequentially connected Amount decision device；

Fusion center, for receiving the judgement confidence level that at least two cognitive users terminal is reported respectively, will be all The judgement confidence level be divided into two set, power set confidence calculations process is carried out to two set, according to result Judgement obtains total court verdict of the frequency spectrum use state of authorized user's terminal；

Wherein, the judgement confidence level in described two set in a set is at least two cognitive users terminal Judge the judgement confidence level that the frequency spectrum use state is idle cognitive user terminal to report, the institute in another set It is to judge that the frequency spectrum use state is occupied cognitive use at least two cognitive users terminal to state judgement confidence level The judgement confidence level of family terminal to report；

The all of judgement confidence level is divided into described two set and is specially by the fusion center：

The all of judgement confidence level is divided into by described two set according to the identification information of the judgement confidence level；

Wherein, the identification information is used to indicate the judgement confidence level to judge institute at least two cognitive users terminal State the judgement confidence level that frequency spectrum use state is idle cognitive user terminal to report；Or, for indicating that the judgement is put Reliability is to judge the frequency spectrum use state in occupied cognitive user terminal at least two cognitive users terminal The judgement confidence level of report；

At least two cognitive users terminal, judges whether the frequency spectrum use state of authorized user's terminal is idle, according to Judged result reports respectively corresponding judgement confidence level to fusion center, specially：

At least two cognitive users terminal each independently carries out frequency spectrum perception, will detect calculated spectrum energy T with Detection threshold ξ compares, and according to following formula judgement confidence level P is reported_i；

Wherein H₀The frequency spectrum use state for representing authorized user's terminal is idle, H₁Represent the frequency of authorized user's terminal Spectrum use state is occupied, and sign is the identification information；The i is positive integer, represents described at least two cognitive use The respective numbering of family terminal；

Wherein, it is detected as H₀When,

$P_i\left\{H_0\right|T<\mathrm{\&xi;}\}=\frac{P_i\{T<\mathrm{\&xi;}|H_0\left\}{P}_r\right\{H_0\}}{P_i\{T<\mathrm{\&xi;}\}}=\frac{P_i\{T<\mathrm{\&xi;}|H_0\left\}{P}_r\right\{H_0\}}{P_i\{T<\mathrm{\&xi;}|H_0\left\}{P}_r\right\{H_0\}+P_i\{T<\mathrm{\&xi;}\left|H_1\right\}{P}_r\left\{H_1\right\}};$

It is detected as H₁When,

$P_i\left\{H_1\right|T\&GreaterEqual;\mathrm{\&xi;}\}=\frac{P_i\{T\&GreaterEqual;\mathrm{\&xi;}|H_1\left\}{P}_r\right\{H_1\}}{P_i\{T\&GreaterEqual;\mathrm{\&xi;}\}}=\frac{P_i\{T\&GreaterEqual;\mathrm{\&xi;}|H_1\left\}{P}_r\right\{H_1\}}{P_i\{T\&GreaterEqual;\mathrm{\&xi;}|H_0\left\}{P}_r\right\{H_0\}+P_i\{T\&GreaterEqual;\mathrm{\&xi;}\left|H_1\right\}{P}_r\left\{H_1\right\}};$

Wherein, P_i{H₀| T ＜ ξ } it is that cognitive user terminal i detects spectrum energy T less than thresholding ξ thus judgement for H₀When, authorize The probability that user terminal is mourned in silence really；P_i{H₁| T >=ξ } be cognitive user terminal i detect spectrum energy T not less than thresholding ξ because And it is H to adjudicate₁When, the probability of authorized user's terminal busy channel really；P_r{H₀It is probability that authorized user's terminal is mourned in silence；P_r {H₁Be authorized user's terminal busy channel probability；

P_i{ T ＜ ξ } is that cognitive user terminal i detects probability of the spectrum energy T less than thresholding ξ, and it includes two kinds of scenes, and one is P_iT ＜ ξ | H₀When being that authorized user's terminal is mourned in silence, cognitive user terminal i detects probability of the spectrum energy T less than thresholding ξ；Two It is P_iT ＜ ξ | H₁When being authorized user's terminal busy channel, cognitive user terminal i detects spectrum energy T less than thresholding ξ Probability；

P_i{ T >=ξ } is that cognitive user terminal i detects probability of the spectrum energy T not less than thresholding ξ, and it includes two kinds of scenes, one It is P_i{T≥ξ|H₁When being authorized user's terminal busy channel, cognitive user terminal i detects spectrum energy T not less than thresholding ξ Probability；Two is P_i{T≥ξ|H₀When being that authorized user's terminal is mourned in silence, cognitive user terminal i detects spectrum energy T and is not less than The probability of thresholding ξ.

2. the joint spectrum sensory perceptual system based on power set confidence level according to claim 1, it is characterised in that the fusion Center carries out power set confidence calculations process to described two set, is judged to obtain authorized user's terminal according to result Frequency spectrum use state total court verdict, specially；

The all of judgement confidence level is divided into by described two set according to the identification information of the judgement confidence level Two set U are calculated respectively according to following formula₀And U₁Power set confidence level,

$P_{FC}\left(H_0\right)=\underset{i\&Element;U_0}{\mathrm{\&Pi;}}\&lsqb;P_i\left(H_0\right)+1\&rsqb;-1;$

$P_{FC}\left(H_1\right)=\underset{i\&Element;U_1}{\mathrm{\&Pi;}}\&lsqb;P_i\left(H_1\right)+1\&rsqb;-1;$

Result is normalized respectively：

$m\left(H_0\right)=\frac{P_{FC}\left(H_0\right)}{P_{FC}\left(H_0\right)+P_{FC}\left(H_1\right)}$

$m\left(H_1\right)=\frac{P_{FC}\left(H_1\right)}{P_{FC}\left(H_0\right)+P_{FC}\left(H_1\right)};$

M (H are contrasted again₀) and m (H₁) size, make last total court verdict；

$\begin{array}{c}{H}_0:m\left(H_0\right)>M\left(H_1\right)\\ H_1:m\left(H_0\right)\&le;M\left(H_1\right)\end{array};$

Wherein：Set U₀It is interior to judge authorized user's terminal spectrum use state at least two cognitive users terminal For H₀The judgement confidence level for reporting, set U₁It is interior to judge authorized user's end at least two cognitive users terminal End frequency spectrum use state is H₁The judgement confidence level for reporting, P_FC(H₀) it is set U₀Power set confidence level；P_FC(H₁) it is set U₁ Power set confidence level, m (H₀) it is set U₀Normalization power set confidence level；m(H₁) it is set U₁Normalization power set confidence level.

3. a kind of joint spectrum cognitive method based on power set confidence level, it is characterised in that comprise the following steps：

Authorized user in the wireless communications environment that step one, at least two cognitive user terminals separately detect around itself The appearance of terminal, to its frequency range service condition frequency spectrum perception is carried out, and is judged the frequency spectrum use state of authorized user's terminal and is The no free time, corresponding judgement confidence level is reported respectively to fusion center according to judged result；The cognitive user terminal passes through one Energy detector carries out frequency spectrum perception, band filter that the energy detector includes being sequentially connected, squarer, integrator and Energy decision device；

Step 2, the fusion center receive the judgement confidence level that at least two cognitive users terminal is reported respectively, The all of judgement confidence level is divided into into two set, power set confidence calculations process is carried out to two set, according to place Reason result judges total court verdict of the frequency spectrum use state for obtaining authorized user's terminal；

Wherein, the judgement confidence level in described two set in a set is at least two cognitive users terminal Judge the judgement confidence level that the frequency spectrum use state is idle cognitive user terminal to report, the institute in another set It is to judge that the frequency spectrum use state is occupied cognitive use at least two cognitive users terminal to state judgement confidence level The judgement confidence level of family terminal to report；

The all of judgement confidence level is divided into described two set and is specially by the fusion center：

The all of judgement confidence level is divided into by described two set according to the identification information of the judgement confidence level；Its In, the identification information is used to indicate that the judgement confidence level is to judge the frequency spectrum at least two cognitive users terminal Use state is the judgement confidence level of idle cognitive user terminal to report；Or, being used to indicate that the judgement confidence level is Judge that the frequency spectrum use state is sentencing for occupied cognitive user terminal to report at least two cognitive users terminal Certainly confidence level；

At least two cognitive users terminal, judges whether the frequency spectrum use state of authorized user's terminal is idle, according to Judged result reports respectively corresponding judgement confidence level to fusion center, specially：

At least two cognitive users terminal each independently carries out frequency spectrum perception, will detect calculated spectrum energy T with Detection threshold ξ compares, and according to following formula judgement confidence level P is reported_i；

Wherein H₀The frequency spectrum use state for representing authorized user's terminal is idle, H₁Represent the frequency of authorized user's terminal Spectrum use state is occupied, and sign is the identification information；The i is positive integer, represents described at least two cognitive use The respective numbering of family terminal；

Wherein, it is detected as H₀When,

$P_i\left\{H_0\right|T<\mathrm{\&xi;}\}=\frac{P_i\{T<\mathrm{\&xi;}|H_0\left\}{P}_r\right\{H_0\}}{P_i\{T<\mathrm{\&xi;}\}}=\frac{P_i\{T<\mathrm{\&xi;}|H_0\left\}{P}_r\right\{H_0\}}{P_i\{T<\mathrm{\&xi;}|H_0\left\}{P}_r\right\{H_0\}+P_i\{T<\mathrm{\&xi;}\left|H_1\right\}{P}_r\left\{H_1\right\}};$

It is detected as H₁When

$P_i\left\{H_1\right|T\&GreaterEqual;\mathrm{\&xi;}\}=\frac{P_i\{T\&GreaterEqual;\mathrm{\&xi;}|H_1\left\}{P}_r\right\{H_1\}}{P_i\{T\&GreaterEqual;\mathrm{\&xi;}\}}=\frac{P_i\{T\&GreaterEqual;\mathrm{\&xi;}|H_1\left\}{P}_r\right\{H_1\}}{P_i\{T\&GreaterEqual;\mathrm{\&xi;}|H_0\left\}{P}_r\right\{H_0\}+P_i\{T\&GreaterEqual;\mathrm{\&xi;}\left|H_1\right\}{P}_r\left\{H_1\right\}};$

Wherein, P_i{H₀| T ＜ ξ } it is that cognitive user terminal i detects spectrum energy T less than thresholding ξ thus judgement for H₀When, authorize The probability that user terminal is mourned in silence really；P_i{H₁| T >=ξ } be cognitive user terminal i detect spectrum energy T not less than thresholding ξ because And it is H to adjudicate₁When, the probability of authorized user's terminal busy channel really；P_r{H₀It is probability that authorized user's terminal is mourned in silence；P_r {H₁Be authorized user's terminal busy channel probability；

P_i{ T ＜ ξ } is that cognitive user terminal i detects probability of the spectrum energy T less than thresholding ξ, and it includes two kinds of scenes, and one is P_iT ＜ ξ | H₀When being that authorized user's terminal is mourned in silence, cognitive user terminal i detects probability of the spectrum energy T less than thresholding ξ；Two It is P_iT ＜ ξ | H₁When being authorized user's terminal busy channel, cognitive user terminal i detects spectrum energy T less than thresholding ξ Probability；

P_i{ T >=ξ } is that cognitive user terminal i detects probability of the spectrum energy T not less than thresholding ξ, and it includes two kinds of scenes, one It is P_i{T≥ξ|H₁When being authorized user's terminal busy channel, cognitive user terminal i detects spectrum energy T not less than thresholding ξ Probability；Two is P_i{T≥ξ|H₀When being that authorized user's terminal is mourned in silence, cognitive user terminal i detects spectrum energy T and is not less than The probability of thresholding ξ.

4. the joint spectrum cognitive method based on power set confidence level according to claim 3, it is characterised in that the fusion Center carries out power set confidence calculations process to described two set, is judged to obtain authorized user's terminal according to result Frequency spectrum use state total court verdict, specially；

The all of judgement confidence level is divided into by described two set according to the identification information of the judgement confidence level Two set U are calculated respectively according to following formula₀And U₁Power set confidence level,

$P_{FC}\left(H_0\right)=\underset{i\&Element;U_0}{\mathrm{\&Pi;}}\&lsqb;P_i\left(H_0\right)+1\&rsqb;-1;$

$P_{FC}\left(H_1\right)=\underset{i\&Element;U_1}{\mathrm{\&Pi;}}\&lsqb;P_i\left(H_1\right)+1\&rsqb;-1;$

Result is normalized respectively：

$m\left(H_0\right)=\frac{P_{FC}\left(H_0\right)}{P_{FC}\left(H_0\right)+P_{FC}\left(H_1\right)}$

$m\left(H_1\right)=\frac{P_{FC}\left(H_1\right)}{P_{FC}\left(H_0\right)+P_{FC}\left(H_1\right)};$

M (H are contrasted again₀) and m (H₁) size, make last total court verdict；

$\begin{array}{c}{H}_0:m\left(H_0\right)>M\left(H_1\right)\\ H_1:m\left(H_0\right)\&le;M\left(H_1\right)\end{array};$

Wherein：Set U₀It is interior to judge authorized user's terminal spectrum use state at least two cognitive users terminal For H₀The judgement confidence level for reporting, set U₁It is interior to judge authorized user's end at least two cognitive users terminal End frequency spectrum use state is H₁The judgement confidence level for reporting, P_FC(H₀) it is set U₀Power set confidence level；P_FC(H₁) it is set U₁ Power set confidence level, m (H₀) it is set U₀Normalization power set confidence level；m(H₁) it is set U₁Normalization power set confidence level.