CN103746756A - Primary user emulation attack-based interference estimation method for cognitive radio network - Google Patents

Abstract

The invention relates to the technical field of cognitive radio spectrum management and safety, in particular to a primary user emulation attack-based interference estimation method for a cognitive radio network. The method comprises the steps that a secondary user receives channel power, the channel power is utilized to detect whether any channel in the cognitive radio network is occupied, and the channel occupation state and the channel power are sent to a cluster head; the cluster head is used for judging whether the occupied channel is attacked; the interference energy distribution of the attacked channel is estimated. According to the method disclosed by the invention, the secondary user detects whether a malicious user exists in a channel and estimates the interference energy distribution of the malicious user by perceiving the surrounding radio environment, an interference situation graph is built further, the energy of the primary user and the energy of the malicious user is separated, the interference energy distribution of the malicious user can be obtained, and also an accurate spectrum situation graph can be obtained by combining with a spectrum hole detection means.

Description

The interference estimation method of cognitive radio networks based on simulated main customer attack

Technical field

The present invention relates to cognitive radio frequency spectrum management and safe practice field, the particularly interference estimation method of cognitive radio networks based on simulated main customer attack, by the estimation of the identification to information source identity and interfering energy, builds the interference situation of malicious user.

Background technology

Along with scientific and technical development, frequency spectrum resource growing tension, even (also claim primary user but current spectrum management mode is authorized user, Primary User, be called for short PU) not during use authority frequency range, unauthorized user (also claims to trust time user, Secondary User, be called for short SU) can not use this frequency range, this situation has greatly reduced again the utilance of frequency spectrum.In order to solve this contradiction, people have proposed cognitive radio (Cognitive Radio, being called for short CR) technology-unauthorized user perceives idle frequency range by frequency spectrum perception algorithm, under the prerequisite that does not affect authorized user communication, makes full use of frequency spectrum resource.The trust mentioned in this method time user is trusted user, and to send to all data of bunch head are all True Datas or calculate gained according to True Data to trust time user, do not pass through any malicious modification.

But, in frequency spectrum access procedure, also introduced some new safety problems.Such as: counterfeit main customer attack (Primary User Emulation Attack, be called for short PUEA), be malicious user (Malicious User, be called for short MU) send the signal of simulated main customer signal, mislead trust time user and think it is that primary user is in transmitted signal, thereby judge that channel is taken by primary user, and can not use this channel.

For the research of PUEA, mainly concentrate on single trust time user and how to detect attack at present, and the impact of not attacking from large-scale angle analysis, and formulate corresponding counte-rplan.For example, for counterfeit main customer attack, the anti-Attack Research that existing document proposes is all in sending and receiving end, to add some matching algorithms, as HASH function, primary user's energy fingerprint etc., avoids bogus attack impact to trust time user and correctly judges that whether channel is idle.These methods have guaranteed the right of eminent domain to all idle channels substantially, but for the channel that has malicious user, if disturbing situation to distribute to without distinction to it, channel allocation center trusts time user, even if time user of the trust in interference range has obtained this channel so, still can not use safely channel because of disturbing excessive, thereby reduce the fail safe of cognition network communication.

On the one hand, when how whether research detect attack and exist, it is significant to frequency spectrum perception safety equally that the distribution situation of energy is attacked in research.On the other hand, how systematically, excavate reliably usable spectrum cavity in network, it is one of key realizing cognitive radio technology, frequency spectrum situation map refers to image in cognitive radio, presents intuitively " the frequency spectrum map " of frequency spectrum cavity-pocket, more existing literature research are without the frequency spectrum situation map of attacking, when there is simulated main customer attack so, this situation map is because can not distinguish the energy of primary user and malicious user, and make system lose the right of eminent domain of the channel to bogus attack, reduced power system capacity.

Summary of the invention

For solving above technical problem, the present invention proposes the interference estimation method of cognitive radio networks based on simulated main customer attack.

The interference estimation method of cognitive radio networks of the present invention based on simulated main customer attack, comprise: trust time user's receive channel power, utilize any one channel in channel power detection cognitive radio networks whether occupied, channel occupancy state and channel power are sent to a bunch head; Bunch head judges whether occupied channel is attacked; Estimation is distributed by the interfering energy of attack channel.

Preferably, whether described to utilize channel power to detect any one channel in cognitive radio networks occupied, comprising: if there is P on this channel _rk-T _m< σ, determines that this channel is that doubtful primary user takies, wherein T _mfor interference threshold, P _rkbe k channel power of trusting the channel r that time user receives.

Preferably, described bunch of head judges that whether occupied channel is attacked, and comprising:

The channel occupancy situation of each user's judgement that bunch head sends according to each user judges whether this channel takies;

Bunch head obtains the number of the information source of occupied channel, according to the number of described information source, judges whether this channel is attacked.

Preferably, the channel occupancy situation that each user that described bunch of head sends according to each user judges judges whether this channel takies and comprises: if there is user to think that channel is that doubtful primary user takies, think that this channel is occupied, if all users think that channel is unoccupied, channel is idle condition.

Preferably, the number that described bunch of head obtains the information source of occupied channel adopts Gerschgorin radii method.

Preferably, the described number according to described information source judges whether this channel is to be comprised by attacking: if number n >=2 of information source, this channel is in counterfeit main customer attack.

Preferably, the described number according to described information source judges whether this channel is to be comprised by attacking: if the number n=1 of information source:

(1) first judge that whether this channel is in occupied state, if Δ P _r'≤ε, this channel is occupied state;

In this formula, ${{\mathrm{\&Delta;P}}_r}^{\&prime;}=P_r^{T1}-P_r^{T2}=26.16\left[\log (f_1/f_2)\right]-[a_1\left(h_{\mathrm{re}}\right)-a_2\left(h_{\mathrm{re}}\right)],$ ε=26.16[log (f ₁/ f ₂)]-[a ₁(h _re)-a ₂(h _re)]+x _n, wherein:

for period T ₁at certain location point, to centre frequency, be f ₁channel received power,

for period T ₂at same position point, to centre frequency, be f ₂channel received power, a ₁(h _re), a ₂(h _re) be portable antenna modifying factor, x _nfor average system noise;

(2) judge whether this channel exists malicious interference user, if Δ P< is ε, there is malicious interference user in this channel again;

In this formula,

$\mathrm{\&Delta;P}=\left(\right|P_{1,T_1}^{f_{D1}}-P_{1,T_1-1}^{f_i}|+|P_{2,T_1}^{f_{D1}}-P_{2,T_1-1}^{f_i}|+...+|P_{k,T_1}^{f_{D1}}-P_{k,T_1-1}^{f_i}|+...+|P_{M,T_1}^{f_{D1}}-P_{M,T_1-1}^{f_i}\left|\right)/M,$ F _i∈ D-f _d1, D is the set of all channels in working frequency range,

be k and trust time user at T ₁individual sense cycle is interior to channel f _d1energy sensing value, M refers to and trusts time user's number.

Preferably, described estimation is distributed and comprises coordinate and the transmitting power of estimating this channel malicious user by the interfering energy of attack channel, specifically comprises:

303-1A, estimate the Bo Dajiao of each information source at array antenna 1 place

bo Dajiao with array antenna 2 places

303-1B, according to information source i, at the ripple at array antenna 1 and 2 places, reach angle θ _iand θ ' _iand the coordinate (a of array antenna 1,2 ₁, b ₁), (a ₂, b ₂), obtain the equation y of this malice information source place straight line _i=tan θ _i(x _i-a ₁)+b ₁and y _i=tan θ ' _i(x _i-a ₁)+b ₁;

303-1C, according to the equation of malice information source place straight line, obtain s the intersection point that comprises malice information source coordinate, the coordinate of definite malicious user from s intersection point, determines the transmitting power of malicious user.

Preferably, interfering energy is distributed and revised, comprise: in investigation region, be uniformly distributed some transducers, the received power error amount of calculating sensor position, error amount is adopted to interpolation method, calculate the error correction values between adjacent sensors position, the transmitting power at described channel malicious user coordinate place is revised.

Cognitive user of the present invention is by perception radio environment around, whether detect in channel has the interfering energy of malicious user and estimation malicious user to distribute, further set up and disturb situation map, by primary user's energy and malicious user energy separation, both can show that only embodying malicious user interfering energy distributes, and can combine with frequency spectrum cavity-pocket detection means and draw frequency spectrum situation map accurately again.

Accompanying drawing explanation

Fig. 1 is the network model figure of prior art;

Fig. 2 is the interference estimation method first preferred embodiment schematic flow sheet of cognitive radio networks of the present invention based on simulated main customer attack;

Fig. 3 is the step 301 preferred embodiment specific implementation schematic flow sheet of the interference estimation method of cognitive radio networks of the present invention based on simulated main customer attack;

Fig. 4 is the step 302 preferred embodiment specific implementation schematic flow sheet of the interference estimation method of cognitive radio networks of the present invention based on simulated main customer attack;

Fig. 5 is the step 303 preferred embodiment specific implementation schematic flow sheet of the interference estimation method of cognitive radio networks of the present invention based on simulated main customer attack;

Fig. 6 is the interference estimation method second preferred embodiment schematic flow sheet of cognitive radio networks of the present invention based on simulated main customer attack;

Fig. 7 is the interference situation map that adopts the interference estimation method of cognitive radio networks of the present invention based on simulated main customer attack to obtain;

Fig. 8 is the interference situation map that adopts prior art to obtain;

Fig. 9 adopts the interference estimation method of cognitive radio networks of the present invention based on simulated main customer attack and the relatively analogous diagram of power system capacity that adopts prior art.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Based on the embodiment in the present invention, those of ordinary skills, not making the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.

Supposing to investigate region is a cognitive radio networks being comprised of L primary user (each primary user takies 1 channel), a M trust time user, a N malicious user and a pair of array antenna, as shown in Figure 1.Cognition network adopts collaborative spectrum sensing model, and the trust of certain area time user is combined into bunch automatically, and elects a bunch of head by election algorithm.Each SU is sent to a bunch head by detected energy value, by a bunch head, is unified to process.In general, the primary user in this network is mobile, trusts time user and can freely add or leave this cognition network, but can not move in testing process.

The interference estimation method of cognitive radio networks of the present invention based on simulated main customer attack, as shown in Figure 2, comprising:

Whether step 301, trust time user's receive channel power, utilize any one channel in channel power detection cognitive radio networks occupied, and channel occupancy state and channel power are sent to a bunch head;

Step 302, a bunch head judge whether occupied channel is attacked;

Step 303, estimation are distributed by the interfering energy in attack channel.

Below the execution mode of each step of the present invention is introduced.

Whether described step 301, trust time user's receive channel power, utilize any one channel in channel power detection cognitive radio networks occupied, and channel occupancy state and channel power are sent to a bunch head, specifically as shown in Figure 3, comprising:

301-1, for i channel in network, (be designated as f _i), each trust time user SU _kreceive this channel power P _rk, judge whether this channel is that doubtful primary user takies;

Suppose that k is trusted time user SU _kreceived power be designated as P _rkif, channel f _ion there is P _rk>=T _m, determine that this channel is that doubtful primary user takies, and is labeled as f _di, otherwise determine that this channel is vacant.Wherein, T _mfor interference threshold, its value is accepted modulating system and difference according to different cognitive users, its detailed establishing method is preferably referring to Li Yanlin, healthy and free from worry, Diao Yinliang, high formal guiding principle, Shi Dan. the expansion discussion of cognitive radio system intermediate-frequeney point thresholding. electric wave science journal, 2010,25 (9): 169-171

301-2, by received power P _rkand the channel occupancy situation of this user's judgement sends to a bunch head.

No matter SU _kwhether detect doubtful primary user and take, all need received power P _rksend to a bunch head.

Described step 302, a bunch head judge that whether occupied channel is attacked, and specifically comprises the following steps:

Described bunch is the set being formed by the user's independent assortment in certain territorial scope, and described bunch of head is an optional user from this bunch; Described bunch and a bunch head are this area Common Concepts, repeat no more.As shown in Figure 4, specifically comprise:

The channel occupancy situation of each user's judgement that 302-1, bunch head send according to each user judges whether this channel takies;

According to the principle of the preferential use authority channel of primary user in cognitive radio, after bunch head obtains the channel occupancy situation of each user's judgement that in this bunch, each user sends, judge that whether this channel is occupied;

If there is user to think that channel is that doubtful primary user takies, think that this channel is occupied, if all users think that channel is unoccupied, channel is idle condition.If channel is idle condition, returns to step 301 and detect other channel.

302-2, bunch head obtain the number of the information source of occupied channel, according to the number of described information source, judge whether this channel is attacked;

302-2A, bunch head obtain the number of the information source of occupied channel

As a kind of execution mode, described bunch of head determined the channel f that doubtful primary user takies _dithe number n of middle information source, judges the information source number of certain channel by each trust time user's the situation that reports.

As another kind of preferred implementation, described bunch of head determined the channel f that doubtful primary user takies _dithe number n of middle information source, adopts Gerschgorin radii method to estimate the channel f that doubtful primary user takies _dithe number n of middle information source

Described Gerschgorin radii method is referring to Cheng Zhiyou, Zuo Jingkun, and Liang Dong, etc. the Measurement of Harmonics in Power System [J] based on Gai Shi circle with TAM. East China University of Science's journal: natural science edition, 2012,38 (005): 612-616.

302-2B, according to the number of described information source, judge whether this channel is attacked

If number n >=2 of information source, this channel, in counterfeit main customer attack, because can not there are two primary users in a channel simultaneously, directly enters step 303.

If the number n=1 of information source, only has a user in channel, still can not determine primary user or malicious user, enter 302-2C.

For judging whether this channel is that malicious user takies, and the embodiment of the present invention provides two kinds of modes, described in following 302-2C and 302-2D, both can realize and judge whether this channel is that malicious user takies respectively.

As a kind of implementation, describedly judge that whether this channel is that malicious user takies, and comprising:

302-2C, judge whether this channel is that malicious user takies

(1) first judge that whether this channel is in occupied state

Because the position of malicious user and transmitting power are generally fixed, so in any two period T ₁and T ₂, the difference of the received power two different channels being transmitted at same position o'clock is only relevant with frequency,

${{\mathrm{\&Delta;P}}_r}^{\&prime;}=P_r^{T1}-P_r^{T2}=26.16\left[\log (f_1/f_2)\right]-[a_1\left(h_{\mathrm{re}}\right)-a_2\left(h_{\mathrm{re}}\right)]---\left(1\right)$

Wherein, a ₁(h _re), a ₂(h _re) be portable antenna modifying factor, f ₁, f ₂it is the centre frequency of these two channels.

So, by formula (1), if can obtain, detected that each SU is at T ₁cycle is to channel f _d1received power

with at T ₁-1 cycle is to channel f _d2received power

difference DELTA P _r'≤ε, illustrates channel f _d1in occupied state.Wherein, ε=26.16[log (f ₁/ f ₂)]-[a ₁(h _re)-a ₂(h _re)]+x _n, x _nfor average system noise.

(2) if this channel, in occupied state, then judges whether this channel exists malicious interference user.

Concrete detection algorithm is as follows:

Calculate current detection period T ₁middle f _d1on received power and last period T ₁-1 this test point is at the mean value of the difference of the received power of other all channels:

$\mathrm{\&Delta;P}=\left(\right|P_{1,T_1}^{f_{D1}}-P_{1,T_1-1}^{f_i}|+|P_{2,T_1}^{f_{D1}}-P_{2,T_1-1}^{f_i}|+...+|P_{k,T_1}^{f_{D1}}-P_{k,T_1-1}^{f_i}|+...+|P_{M,T_1}^{f_{D1}}-P_{M,T_1-1}^{f_i}\left|\right)/M---\left(2\right)$

In formula (2), f _i∈ D-f _d1, D is the set of all channels in working frequency range,

be k and trust time user at T ₁individual sense cycle is interior to channel f _d1energy sensing value, M refers to and trusts time user's number.

If Δ P>=ε, f _d1from in other channels, be different primary user, there is not the counterfeit user of malice in this channel, proceeds the detection of next channel; If Δ P< is ε, f is described _d1coincide with the energy fingerprint of certain channel, now f is described _d1in channel, exist malicious user to take, wherein, ε=26.16[log (f ₁/ f ₂)]-[a ₁(h _re)-a ₂(h _re)]+x _n, x _nfor average system noise.

As another kind of implementation, describedly judge that whether this channel is that malicious user takies, and comprising:

The receiver of 302-2D, cognitive user receives the signal that similar authorized master user is sent, start detection PUE attacking system.In the time window of observing, physical layer time domain samples is first carried out to power spectral density calculating and try to achieve domain samples, then carry out wavelet decomposition.Because the variation of fading channel feature generally concentrates on low-frequency range, therefore, when particular dimensions reconstruct original signal, select low frequency part (approaching part), strengthen its correlation.Then extract the individual features of separation signal, use the support vector machine testing of the training of training vector.If testing result is f _d1in channel, exist malicious user to take, specifically referring to Rong Hong. in a kind of cognitive radio, imitate authorized user and inveigle the detection method [J] of attacking. China switches from manufacturing military products to goods for civilian use, 2012,6:015.

When detecting that malicious user takies, determine that this channel is for to be attacked.

Can implementation as one, described step 303, estimate to be distributed by the interfering energy in attack channel, specifically as shown in Figure 5, comprise the following steps:

303-1, the coordinate of estimating this channel malicious user and transmitting power

303-1A, estimate the Bo Dajiao of each information source at array antenna 1 place bo Dajiao with array antenna 2 places

Estimate that ripple reaches angle and can adopt MUSIC algorithm, described MUSIC algorithm is shown in following list of references: Wang Yongliang, Chen Hui, Peng Yingning, ten thousand groups. Estimation of Spatial Spectrum theory and algorithm [M]. and Beijing: publishing house of Tsing-Hua University, 2013.Described ripple reaches angle and estimates also can adopt another kind of method, as follows described in list of references: Yan Fenggang, gold inscription, Qiao Xiaolin. and the transform domain two dimension ripple that is suitable for any array reaches angle Fast Estimation Algorithm [J]. electronic letters, vol, 2013.

303-1B, according to information source i, at the ripple at array antenna 1 and 2 places, reach angle θ _iand θ ' _iand the coordinate (a of array antenna 1,2 ₁, b ₁), (a ₂, b ₂), obtain the equation y of this malice information source place straight line _i=tan θ _i(x _i-a ₁)+b ₁and y _i=tan θ ' _i(x _i-a ₁)+b ₁.

303-1C, according to the equation of malice information source place straight line, obtain s the intersection point that comprises malice information source coordinate, the coordinate of definite malicious user from s intersection point, determines the transmitting power of malicious user;

In s the intersection point that comprises malice information source coordinate, having s-n individual is not the coordinate of information source, below we pick out the coordinate of malicious user according to Di Li Cray principle and hypothesis testing algorithm.

Di Li Cray principle: m part article are put into the individual drawer of n (n<m) by any means, must have at least and be placed with two or two above article in a drawer.Application is in the present invention: in correct intersection point combination, contain and be not more than n-n ₁+ 1 intersection point, on the direction finding line of array antenna l, or contains and is not more than n-n in this combination ₂+ 1 intersection point is on the direction finding line of array antenna 2.

The number that step 302 has been tried to achieve the malicious user in this channel is n, and we are divided into this s intersection point the combination of n a group, total

plant combination.The 1st group of intersection point combination done to following detection: by step (21) known array antenna 1, have n ₁bar direction finding line, n ₁≤ n; If the number of hits of conllinear is more than n-n in this combination ₁+ 1, do not meet Di Li Cray principle, so get rid of this combination.If the n of the 1st group of combination pair array antenna 1 ₁bar direction finding line meets Di Li Cray principle, then sees for array antenna 2 have n ₂(n in the situation of bar direction finding line ₂≤ n), in this combination, whether the number of hits of conllinear is greater than n-n ₂+ 1, if be greater than, do not meet Di Li Cray principle, get rid of this combination.If meet, retain this combination, wait pending hypothesis testing.

To what be left identical detection is done in group combination, supposes, through the remaining C kind combination of above detection, to suppose every group of position that intersection point is all MU in remaining combination, and this C kind combination is carried out to hypothesis testing:

(1), to the 1st kind of combination, choose the received power P of n the SU that bunch head receives _r1, P _r2..., P _rn, according to

calculate the transmitting power PT ' of n malicious user ₁, PT ' ₂..., PT ' _n, then according to PT ' ₁, PT ' ₂..., PT ' _ncalculate the received power P ' of an other L-n SU _r1, P ' _r2..., P ' _{r (L-n)}, and by P ' _rkthe power P receiving with k SU _rksubtract each other (i=1,2 ..., L-n), obtain the 1st Δ P ' _r, ${{\mathrm{\&Delta;P}}^{\&prime;}}_r=\underset{i=M+1}{\overset{L}{\mathrm{\&Sigma;}}}{P^{\&prime;}}_{\mathrm{rk}}-P_{\mathrm{rk}}.$

(2) remaining C-1 kind combination is done to same calculating and can obtain altogether afterwards multiple different Δ P ' _r, preferably 10.

(3) by Δ P ' _rthe coordinate of minimum that combination is defined as malicious user coordinate.

(4) by Δ P ' _rminimum that group PT ' ₁, PT ' ₂..., PT ' _nbe defined as the transmitting power of a required n malicious user.

Preferably, in order to reduce the error of calculation, n the malicious user SU of transmitting power PT ' that calculates malicious user will select the SU close to from calculative malicious user MU node.Because bunch head is known the position of each SU, also know the position of each group of MU node, so choose this n SU by bunch head according to result of calculation above.

The transmitting power that can be obtained malicious user by preceding step is PT ', preferably, can also revise the transmitting power of malicious user, to obtain the transmitting power of malicious user more accurately, further comprises:

Step 303-2: multiple transducers are evenly set, the received power error amount of calculating sensor position, error amount is adopted to interpolation method, calculate the error correction values between adjacent sensors position, transmitting power to channel malicious user coordinate place is revised, and the transmitting power that is about to relevant position is added.

If after free space decline and shadow fading, the theoretical received power of transducer is P _r', by P _r' actual value the P that receives with the transducer setting in advance _rsubtract each other its poor Δ P _rbe the error at this place, Δ P _r=P _r'-P _r.To between the error amount of two adjacent transducers, evenly insert X value again, can obtain the error correction values of each position coordinates between two sensors, then the transmitting power at channel malicious user coordinate place is revised.

For example, the error at transducer 1 place is Δ P _r1, the error at transducer 2 places is Δ P _r2, the air line distance between transducer 1 and 2 is d,, on the straight line forming at the position coordinates of transducer 1 and transducer 2, from transducer 1 apart from d ₁(d ₁<d) error correction values of locating is

adopt in this way can the whole investigation of calculating place region error correction values.

Can implementation as another kind, described step 303, estimate to be distributed by the interfering energy in attack channel, adopt the interference temperature algorithm for estimating based on Kriging method.

In investigation region, a large amount of transducers is installed, due to each transducer present position difference, the interference temperature of its acquisition also can change according to the variation of locus, but due to the correlation of interference source transmitted signal, also there is certain spatial coherence in the interference temperature of each transducer present position.The interference temperature value that each transducer obtains, is the measured value of space variable model, according to measured value, uses Kriging method can estimate the interference temperature spatial distribution of investigating in region.Specifically referring to Publication about Document: Feng Wenjiang, Li Jun. the interference temperature spatial distribution based on Kriging method in cognitive radio is estimated [J]. the journal ISTIC EI of University Of Chongqing, 2011,34 (2).

Preferably, the interference estimation method of cognitive radio networks of the present invention based on simulated main customer attack, as shown in Figure 6, also comprise: step 304, build the interference situation map of this channel, this step is just for the interference exhibition method to channel is convenient to understand, be not to realize steps necessary of the present invention, it is specially:

1, the Distribution Value that calculates interfering energy, method is as follows:

P _r′=PT′-PL （3）

In formula (3),

p _r' the interfering energy that can receive for each coordinate points, P _tfor the transmitting power of interference source, PL _sthe loss causing for shadow effect,

for free space path loss, preferably, free space path loss adopts HATA model,

$\stackrel{\&OverBar;}{\mathrm{PL}(f,d)}\left(\mathrm{dB}\right)=69.55+26.16\log f_c-13.82\log h_{\mathrm{te}}-a\left(h_{\mathrm{re}}\right)+(44.9-6.55\log h_{\mathrm{te}})\log d$

From three formula above, received power P _r' with P _t, f _c, h _te, h _re, d is relevant.

At same launch point, same receiving station, transmitting power is identical but in situation that operating frequency is different, the difference of received power is:

${{\mathrm{\&Delta;P}}_r}^{\&prime;}=P_r^{f1}-P_r^{f2}=P_t^{f1}-{\mathrm{PL}}^{f1}-(P_t^{f2}-{\mathrm{PL}}^{f2})$

Because

so

${{\mathrm{\&Delta;P}}_r}^{\&prime;}=-{\mathrm{PL}}^{f1}-(-{\mathrm{PL}}^{f2})={\mathrm{PL}}^{f2}-{\mathrm{PL}}^{f1}=\stackrel{\&OverBar;}{{\mathrm{PL}}^{f2}(f,d)}+{\mathrm{PL}}_s^{f2}-(\stackrel{\&OverBar;}{{\mathrm{PL}}^{f1}(f,d)}+{\mathrm{PL}}_s^{f1})$

Due to for same MU and same SU,

h _te, h _re, d all equate, so

ΔP _r′=26.16[log(f ₁/f ₂)]-[a ₁(h _re)-a ₂(h _re)]

In HATA model, for the urban environment of different scales, a (h _re) difference.For big city, portable antenna modifying factor is:

a(h _re)=8.29(log1.54h _re) ²-1.1dB f _c≤300MHz

a(h _re)=3.2(log11.75h _re) ²-4.97dB f _c≥300MHz

For small and medium-sized cities, for:

a(h _re)=(1.1logf _c-0.7)h _re-(1.56logf _c-0.8)dB

As the above analysis, for same launch point, at the identical but operating frequency f of the power of twice emitting signal _cin different situations, the difference DELTA P of the received power of same SU _ronly with the centre frequency f of these two channels _crelevant.So ε is set as

ε=26.16[log(f ₁/f ₂)]-[a ₁(h _re)-a ₂(h _re)]+x _n

2, draw and disturb situation map

The calculated value being distributed by the interfering energy obtained, adds error correction values, can draw out investigate in region, embody that interfering energy distributes disturb comparatively really situation map.

Cognitive user of the present invention is by perception radio environment around, whether detect in channel has the interfering energy of malicious user and estimation malicious user to distribute, further set up and disturb situation map, by primary user's energy and malicious user energy separation, both can show that only embodying malicious user interfering energy distributes, and can combine with frequency spectrum cavity-pocket detection means and draw frequency spectrum situation map accurately again.

Disturb situation map as shown in Figure 7, Figure 8, the color of figure coil is shallow by being deep to, and the interference power that expression trust time user receives from large to small.Black shows the interfering energy maximum that SU receives herein, as A, B, C tri-places (this three place also just the position at malicious user place); Along with color shoals gradually, the interfering energy that SU can receive also diminishes gradually, and the white space as shown in the lower left corner in figure shows to be disturbed hardly herein.Interference power in figure reaches as high as 20dB, minimum only have-15dB, if the interference power in somewhere is less than the signal-noise ratio threshold of receiver, in the situation that knowing this channel by bogus attack, we still can use this channel so; If but interference power is greater than the signal-noise ratio threshold of receiver herein, be just not suitable for using this channel.

Wherein, Fig. 7 is the interfering energy distribution situation of the malicious user of reality in T cycle, channel i, and Fig. 8 adopts this method to estimate the interfering energy distribution situation of the malicious user in T cycle, the channel i of gained.Comparison diagram 7 and Fig. 8 are known, and the coordinate in Fig. 7 and the region that in Fig. 8, lines shade is identical is also approximate identical, and this illustrates the identical interference power of size in two figure, and the position of its distribution is approximate identical, and this method can estimate more exactly interfering energy and distribute.Bunch malicious user interfering energy distribution map that head draws according to this programme carrys out the allocated channel to SU, and the probability of success that can make to communicate by letter improves greatly, has improved communications security.

To considering, disturb situation and do not consider to disturb the channel capacity of situation to analyze respectively below:

Definition 1: power system capacity is to investigate the summation of each channel average size in region.If being each trust time user, the average size of each channel accesses the mean value of the channel capacity that this primary user's channel can obtain.According to shannon formula, if the maximum channel capacity that the inferior user's access of each trust primary user channel can obtain is:

$C\left(N_i\right)=B\log (1+\frac{S}{N_0+N_i})---\left(4\right)$

Wherein, B is channel width, and S is for trusting time user emission power, N _ifor trusting time user, to the received power of malicious user, be interference power, N ₀for other noise jamming on channel.

From formula (4), the capacity of i the cognitive user based on disturbing situation map is

$C\left(N_i\right)=\left\{\begin{array}{c}B\log (1+S/N_0),\\ B\log [1+S/(N_i+N_0)],\end{array}\right.---\left(5\right)$

And the capacity of not considering i cognitive user disturbing situation is

$C\left(N_i\right)=\left\{\begin{array}{c}B\log (1+S/N_0),\\ 0,\end{array}\right.---\left(6\right)$

From formula (5) and formula (6), contrasted the capacity difference when channel capacity difference in two kinds of situations is bogus attack.Because the latter does not consider the situation of attacking, when having bogus attack, the latter can think it is that primary user uses and abandons the right of eminent domain to this channel by mistake, so its channel capacity is 0.

Define the capacity C of 2: the i channels _iaverage for the capacity of time user of each trust in system to this channel.Power system capacity C _sthe capacity sum of each channel, for

$C_S=\underset{i=1}{\overset{L}{\mathrm{\&Sigma;}}}{C}_i=\underset{i=1}{\overset{L}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}C\left(N_j\right)---\left(7\right)$

For whole system, the channel capacity while considering to disturb the frequency spectrum situation map of situation will obtain much attacking, and then improved the capacity of system.When the malicious user in system only has one, the power system capacity difference under two kinds of methods is Δ C _s=Blog[1+S/(N _i+ N ₀)], when having m malicious user, the capacity difference Δ C of system _s=mBlog[1+S/(N _i+ N ₀)], so when malicious user is more, power system capacity difference is larger.But this trend is along with malicious user number reduces more than the number of channel.Because when malicious user number equals after the number of channel, MU of every increase, N _icontinue to become large, by the C (N of formula (5) gained _i) continue to reduce, its power system capacity also continues to reduce, and that is to say, and 1 MU attacks a channel or the capacity of 2 attack same channel formula (5) gained are different; Concerning formula (6), do not have this difference, so equal after the number of channel when MU number, its capacity loss trend obviously slows down.

Figure 9 shows that the power system capacity of the present invention under many malicious users of multichannel environment, its power system capacity is higher than the power system capacity of cognition network in the method for ZHANG.

The present invention has carried out further detailed description for execution mode or embodiment to the object, technical solutions and advantages of the present invention; institute is understood that; above lifted execution mode or embodiment are only the preferred embodiment of the present invention; not in order to limit the present invention; all any modifications made for the present invention within the spirit and principles in the present invention, be equal to replacement, improvement etc., within protection scope of the present invention all should be included in.

Claims (9)

1. the interference estimation method of cognitive radio networks based on simulated main customer attack, it is characterized in that: comprising: trust time user's receive channel power, utilize any one channel in channel power detection cognitive radio networks whether occupied, channel occupancy state and channel power are sent to a bunch head; Bunch head judges whether occupied channel is attacked; Estimation is distributed by the interfering energy of attack channel.

2. the interference estimation method of cognitive radio networks based on simulated main customer attack according to claim 1, it is characterized in that: whether described to utilize channel power to detect any one channel in cognitive radio networks occupied, comprising: if there is P on this channel _rk-T _m< σ, determines that this channel is that doubtful primary user takies, wherein T _mfor interference threshold, P _rkbe k channel power of trusting the channel r that time user receives.

3. the interference estimation method of cognitive radio networks based on simulated main customer attack according to claim 1, is characterized in that: described bunch of head judges that whether occupied channel is attacked, and comprising:

The channel occupancy situation of each user's judgement that bunch head sends according to each user judges whether this channel takies;

Bunch head obtains the number of the information source of occupied channel, according to the number of described information source, judges whether this channel is attacked.

4. the interference estimation method of cognitive radio networks based on simulated main customer attack according to claim 3, it is characterized in that: the channel occupancy situation that each user that described bunch of head sends according to each user judges judges whether this channel takies and comprises: if there is user to think that channel is that doubtful primary user takies, think that this channel is occupied, if all users think that channel is unoccupied, channel is idle condition.

5. the interference estimation method of cognitive radio networks based on simulated main customer attack according to claim 3, is characterized in that: the number that described bunch of head obtains the information source of occupied channel adopts Gerschgorin radii method.

6. the interference estimation method of cognitive radio networks based on simulated main customer attack according to claim 3, it is characterized in that: the described number according to described information source judges whether this channel is to be comprised by attacking: if number n >=2 of information source, this channel is in counterfeit main customer attack.

7. the interference estimation method of cognitive radio networks based on simulated main customer attack according to claim 3, is characterized in that: the described number according to described information source judges whether this channel is to be comprised by attacking: if the number n=1 of information source:

(1) first judge that whether this channel is in occupied state, if Δ P _r'≤ε, this channel is occupied state; Wherein,

${{\mathrm{\&Delta;P}}_r}^{\&prime;}=P_r^{T1}-P_r^{T2}=26.16\left[\log (f_1/f_2)\right]-[a_1\left(h_{\mathrm{re}}\right)-a_2\left(h_{\mathrm{re}}\right)],$ ε=26.16[log (f ₁/ f ₂)]-[a ₁(h _re)-a ₂(h _re)]+x _n, for period T ₁at certain location point, to centre frequency, be f ₁channel received power,

for period T ₂at same position point, to centre frequency, be f ₂channel received power, a ₁(h _re), a ₂(h _re) be portable antenna modifying factor, x _nfor average system noise;

(2) judge whether this channel exists malicious interference user, if Δ P< is ε, there is malicious interference user in this channel again; Wherein,

$\mathrm{\&Delta;P}=\left(\right|P_{1,T_1}^{f_{D1}}-P_{1,T_1-1}^{f_i}|+|P_{2,T_1}^{f_{D1}}-P_{2,T_1-1}^{f_i}|+...+|P_{k,T_1}^{f_{D1}}-P_{k,T_1-1}^{f_i}|+...+|P_{M,T_1}^{f_{D1}}-P_{M,T_1-1}^{f_i}\left|\right)/M,$ F _i∈ D-f _d1, D is the set of all channels in working frequency range,

be k and trust time user at T ₁individual sense cycle is interior to channel f _d1energy sensing value, M refers to and trusts time user's number.

8. the interference estimation method of cognitive radio networks based on simulated main customer attack according to claim 1, is characterized in that: described estimation is distributed and comprises coordinate and the transmitting power of estimating this channel malicious user by the interfering energy of attack channel, specifically comprises:

303-1A, estimate the Bo Dajiao of each information source at array antenna 1 place

bo Dajiao with array antenna 2 places

303-1B, according to information source i, at the ripple at array antenna 1 and 2 places, reach angle θ _iand θ ' _iand the coordinate (a of array antenna 1,2 ₁, b ₁), (a ₂, b ₂), obtain the equation y of this malice information source place straight line _i=tan θ _i(x _i-a ₁)+b ₁and y _i=tan θ ' _i(x _i-a ₁)+b ₁;

303-1C, according to the equation of malice information source place straight line, obtain s the intersection point that comprises malice information source coordinate, the coordinate of definite malicious user from s intersection point, determines the transmitting power of malicious user.

9. the interference estimation method of cognitive radio networks based on simulated main customer attack according to claim 8, it is characterized in that: interfering energy is distributed and revised, comprise: multiple transducers are evenly set, the received power error amount of calculating sensor position, error amount is adopted to interpolation method, calculate the error correction values between adjacent sensors position, the transmitting power of described channel malicious user coordinate is revised.

Images