CN104618886A - Early-warning method with wireless sensor network invading into danger zone - Google Patents

Early-warning method with wireless sensor network invading into danger zone Download PDF

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CN104618886A
CN104618886A CN201510106058.9A CN201510106058A CN104618886A CN 104618886 A CN104618886 A CN 104618886A CN 201510106058 A CN201510106058 A CN 201510106058A CN 104618886 A CN104618886 A CN 104618886A
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node
abc
destination node
step
test
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CN104618886B (en
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杨光友
马志艳
郑拓
全睿
陈学海
谢真良
李坤明
陈昊
李�浩
李达
明鑫朗
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湖北工业大学
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Abstract

The invention discloses an early-warning method with a wireless sensor network invading into a danger zone. According to the technical scheme, the wireless sensor network is composed of three sensor nodes, namely a goal node, an anchor node and a neighbor node. A judging algorithm with the goal node entering the danger zone synthetically takes the condition of edge effect into consideration, improves the rules of interior point judgment, and effectively reduces the error rate of Out-To-In. By reasonably selecting a restriction threshold, the Out-To-In error is eliminated. Through the comprehensive judgment adopting a counting way to count the interior and exterior judgment times, the purpose that the misjudgment of the total error rate is further reduced is realized, and the wireless sensor application for early-warning the danger zone has important application value.

Description

A kind of wireless sensor network method for early warning invading deathtrap

Technical field

The invention belongs to position field of locating technology, relate to a kind of localization method of mobile node of wireless sensor network position, be specifically related to a kind of wireless sensor network method for early warning invading deathtrap.

Background technology

At present, have a lot of location technology can position object, but be applicable to that general fit calculation requires, to mobile object effective location, technology that system electronic complexity is low few.Wherein, the APIT algorithm that [document 1] proposes is a kind of location technology required without the need to range finding, applicable WSN general fit calculation, its theoretical foundation is some test (perfect Point-In-Triangulation test, PIT) algorithm in best triangle.Because PIT algorithm is in the network of fixed structure, can obtain more rational positioning precision, performance is relatively stable, and network cost is low, realizes also than being easier to, so be useful in the location determination of mobile node.But, also easily In-To-Out Error and Out-To-In Error two class frequent fault is produced in PIT algorithm, have a significant impact final result of determination, it is necessary for therefore reducing Type Ⅰ Ⅱ error, then requires to stop In-To-Out Error mistake in the judgement of deathtrap.At present, main two classes of having improved one's methods a: class optimizes node screening process, reduces node locating region; Another kind of is improve decision method, reduces the error rate of result of determination.First kind method is adopted to have several as follows, the PB-APIT algorithm of improvement is proposed in [document 2], the perpendicular bisector on three limits is utilized the triangle in APIT algorithm to be divided into 4 or territory, 6 available cell, and the position of unknown node is judged further with the power of detection signal, namely judge which zonule is unknown node be in, thus reduce the locating area of former APIT algorithm, improve positioning precision; It is also proposed the APIT algorithm of improvement in [document 3], by the serious forgiveness and the adaptability that adopt the mode increasing neighbor node validity checking to improve algorithm, but still the probability of happening of Type Ⅰ Ⅱ error can not be reduced; For reducing the error that in APIT algorithm, subtriangular interior some method of testing brings, [document 4] introduces RSSI ranging technology in traditional APIT algorithm, RAPIT algorithm is proposed, by introducing the concept limiting distance, be limited to the position of the node causing error with anchor node is the center of circle, to limit in the overlapping region of the circle that distance is radius, finally reduce error, improve Signal Coverage Percentage.Adopt Equations of The Second Kind method to have several as follows, [document 5] improves APIT algorithm in conjunction with the cosine law, and the rule that in optimizing, point judges, can decrease the incidence of Type Ⅰ Ⅱ error; [document 6] proposes the IAPIT+ algorithm improved, and by analyzing the position distribution situation that Type Ⅰ Ⅱ error occurs, being improved respectively, can reduce total error rate in conjunction with triangle theorem.Generally speaking, these improvement can have certain optimization function to final result, but the algorithm that these schemes propose all cannot meet the requirement of practical application all the time, namely when ensureing that Out-To-In Error is very low, eliminate In-To-Out Error, so guarantee is not judged by accident the destination node entering deathtrap.

[document 1] Tian He, Chengdu Huang, Brian M.Blum,John A。Stankovic;Range-FreeLocalization Schemes for Large Scale Sensor Networks[C]。Proceedings of theAnnual International Conference on Mobile Computing and Networking,MOBICOM,2003:81-95。

[document 2] Yang Ji, Liu Feng; The improvement location algorithm [J] of the APIT that wireless sensor network is split based on perpendicular bisector.Sensing technology journal.2008,28(8):1453-1457。

[document 3] Zhou Yong etc.; Based on the self-align algorithm of the improvement APIT wireless sensor network [J] of triangle core scanning.Journal of Computer Research and Development, 2009,46 (4): 566-574.

[document 4] Cao Meili etc.; Wireless sensor network is based on the mixed positioning algorithm [J] of APIT.Microelectronics and computer, 2009,26 (06): 58-61.

[document 5] Zeng Fanzhen; Based on improvement APIT location algorithm research [D] of the cosine law in wireless sensor network.Jiangxi: Jiangxi Normal University, 2011.

[document 6] Zhao Jiangyun; Wireless sensor network is non-based on ranging localization algorithm research [D].Sichuan: Southwest Jiaotong University, 2014.

Summary of the invention

In order to solve the problems of the technologies described above, the invention provides a kind of wireless sensor network method for early warning eliminating the intrusion deathtrap of In-To-Out mistake.

The technical solution adopted in the present invention is: a kind of wireless sensor network method for early warning invading deathtrap; Described wireless sensor network (WSN) is made up of this three classes sensor node of destination node, anchor node and neighbor node; The node of locating is needed to be called destination node in wireless sensor network (WSN); Position is known and destination node can be assisted to locate node is called anchor node; In a communication radius of destination node, and the node of direct communication can be called neighbor node; It is characterized in that, comprise the following steps:

Step 1: reasonably dispose anchor node on border, deathtrap, namely requires that anchor node integral layout meets substantially " profile of convex polygon ", with satisfied test prerequisite particularly; Wherein the judgement of Convex Polygon Domain can be converted into delta-shaped region again;

Step 2: anchor node is broadcasted, makes all anchor nodes can upgrade to obtain all reference anchor nodes that can communicate with; Step 3: choose destination node P;

Step 4: find out the N number of neighbor node meeting destination node P test condition; Described neighbor node must have one group of same reference anchor node with destination node P; If there is such neighbor node, so just can " movement " of simulated target node P, carry out test of heuristics;

Step 5: destination node collects the information with reference to anchor node, and the signal strength signal intensity that described information comprises identification number, receives, exchanges the information of the reference anchor node received separately, for test judgement provides design conditions with neighbor node;

Step 6: setting identification variable IsOut, and judge, is neighbor node quantity NeighbeiCount >=1 & & with reference to anchor node amount R efCounf >=3?

If so, order performs following step 7;

If not, then this destination node P is can not location node, then this destination node P is external node, and marking variable IsOut assignment is IsOut=TURE, and this flow process terminates;

Step 7: take out N number of neighbor node successively, carries out PIT test; The number of times CountIn=0 of initialized target node P in region, initialized target node P at extra-regional number of times CountOut=0, and performs Alpha test;

Step 7.1:

Destination node P and neighbor node exchange message, and carry out PIT test, if there is a direction, along this direction destination node P can simultaneously away from or close to three anchor nodes A, B, C, then P is positioned at outside △ ABC; Otherwise P is positioned at △ ABC;

Step 7.2:

If destination node P meets the condition in △ ABC, 1. so continuation rule tests;

If still met, rule is 1. middle judges the condition in △ ABC, so just judges in △ ABC; If do not meet rule 1. judge the condition in △ ABC, then 2. test by rule again, if test result meets outside △ ABC, so just sentence outside △ ABC, otherwise just change the original sentence in △ ABC;

If destination node P meets the condition outside △ ABC, 2. so continuation rule tests;

If still met, rule is 2. middle judges the condition outside △ ABC, so just judges outside △ ABC; If do not meet rule 2. judge the condition outside △ ABC, then 1. test by rule again, if test result meets in △ ABC, so just sentence in △ ABC, if test result meets outside △ ABC, so just sentence outside △ ABC;

Step 7.3:

If destination node P meets the condition in △ ABC, then CountIn=CountIn+1;

If destination node P meets the condition outside △ ABC, then CountOut=CountOut+1;

Step 7.4:

Take out next neighbor node, and the step 7.1 described in revolution execution, until all neighbor nodes take; Step 8: perform second stage test;

Step 8.1:

Do you judge that CountIn is greater than CountOut?

If so, then this destination node P is internal node, and marking variable IsOut assignment is IsOut=FALSE;

If not, then this destination node P is external node, and marking variable IsOut assignment is IsOut=TURE;

Step 8.2:

Do you judge that IsOut is TURE?

If so, then judge that destination node P is outside △ ABC region;

If not, then judge that destination node P is in △ ABC region;

Step 8.3: this flow process terminates;

Wherein:

1. rule is: cosine value decision rule;

If be a bit positioned at triangle interior, so it has following characteristic: the distance sum on this point and three summits is less than three limit sums; In the angle that this point and three summits form, obtuse angle number is no less than 2; Suppose that the distance between three anchor nodes A, B, C is respectively d aB, d bC, d aC; Destination node P is d to the distance of each anchor node aP, d bP, d cP; Use the cosine law can obtain the cosine value of angle between destination node P and three anchor node:

cos ∠ APB = d AP 2 + d BP 2 - d AB 3 = 2 2 d AP × d BP cos ∠ APC = d AP 2 + d CP 2 - d AC 2 2 d AP × d CP cos ∠ BPC = d BP 2 + d CP 2 - d BC 2 2 d BP × d CP - - - ( 1 ) ;

When having 2 obtuse angles at least in three angles of destination node P and three anchor node, so judge that P is inner at △ ABC; Otherwise, judge that P is outside at △ ABC;

2. rule is: edge effect rule;

When destination node P ecto-entad is when the sideline of △ ABC, also easily there are 2 obtuse angles, when appearance 2 obtuse angles, introduce constraint threshold k, if there is PA+PB-AB<K, namely the distance sum of destination node P to two anchor node A, B and the difference of two anchor node A, B spacings are less than threshold k, then change into and judge that P is outside at △ ABC; Otherwise just still judge that P is inner at △ ABC.

As preferably, the computing formula of the distance d of three described in cosine value decision rule between anchor node A, B, C is: d = d 0 &times; 10 ( PL ( d 0 ) - PL ( dB ) - X &sigma; ) / 10 n - - - ( 2 ) ; Wherein PL (dB)=PL (d 0)+10nlog 10(d/d 0)+X σ; PL (dB) unit is dBm, PL (d 0) for node is at reference distance d 0the signal strength values that place receives, d is the distance between transmitting-receiving node, and n is the path loss index under varying environment, X σthe normal random variable of to be standard deviation be σ.

As preferably, the choosing method of the constraint threshold k described in edge effect rule is, according to the communication radius R of destination node P, test from 5%R, continuous increase, by testing different constraint threshold k to the impact of this method decision error rate, finally chooses suitable numerical value; Described suitable criterion is the variation tendency depending on error rate in test process, and when retraining threshold value and being increased gradually by 5%R, error rate is declining thereupon, and this is rational variation tendency; Continuing in the process increased, error rate starts to stop declining, and then increase, this is between limited proportionality, also suitable just interval, and constraint threshold value corresponding when selecting error rate minimum is as suitable numerical value.

As preferably, described K value is 15%R.

The present invention and other method comparison existing, its main improvement aspect:

(1) with reference to the cosine law and triangle theorem, the rule that in improving, point judges, and for because mobile node is in edges of regions, easy appearance 2 obtuse angles and the situation causing Out-To-In to judge by accident, propose constraint threshold k, by choose reasonable K value, thus eliminate In-To-Out mistake;

(2) method using combination to judge, first judges all neighbor node combinations, and to being judged to be that inner or outer number of times carries out differential counting, then judging final result according to inside and outside counting size, reducing False Rate further.

Accompanying drawing explanation

Fig. 1: the positions of mobile nodes resolution principle figure of the embodiment of the present invention;

Fig. 2: the PIT principle schematic of the embodiment of the present invention, wherein (a) destination node P is outside △ ABC, and (b) destination node P is in △ ABC;

Fig. 3: the Type Ⅰ Ⅱ error of the PIT testing algorithm of the embodiment of the present invention judges schematic diagram, wherein (a) In-To-Out mistake schematic diagram, (b) Out-To-In mistake schematic diagram;

Fig. 4: the distance schematic diagram between the destination node of the embodiment of the present invention and anchor node;

Fig. 5: the position view at 2 obtuse angles appears in the external point of the embodiment of the present invention;

Fig. 6: the flow chart of the embodiment of the present invention;

Fig. 7: the test zone schematic diagram of the embodiment of the present invention.

Embodiment

Understand for the ease of those of ordinary skill in the art and implement the present invention, below in conjunction with drawings and Examples, the present invention is described in further detail, should be appreciated that exemplifying embodiment described herein is only for instruction and explanation of the present invention, is not intended to limit the present invention.

Ask for an interview Fig. 1, in practical implementation, the polygonal region in a deathtrap can be represented, the judgement of mobile node at polygonal region can be converted into the judgement of mobile node in deathtrap, and the judgement of polygonal region can be converted into delta-shaped region.The node of locating is needed to be called destination node in WSN; Position is known and destination node can be assisted to locate node is called anchor node; In a communication radius of destination node, and the node of direct communication can be called neighbor node, namely the sensor network that the present invention studies is made up of this three classes sensor node.This is made to following necessity hypothesis: the sensing range of each node is with itself coordinate for the center of circle, and communication distance R is the border circular areas of radius.In target area, anchor node communication radius is R s1, destination node and neighbor node communication radius be R s2, and R s1>R s2.Anchor node position fixes and self-position is known, and destination node has locomotivity.As shown in Figure 1, adopting hexagon to divide target area is comparatively rational dividing mode, and hypothetical target node is along track P → P ' → P " mobile, so the distance on itself and adjacent nearest leg-of-mutton each summit all can change thereupon.The change of distance is often also along with the change of signal strength signal intensity between node, and this characteristic can as one of important reference of positions of mobile nodes judgement.

Ask for an interview Fig. 2, PIT test philosophy is: if there is a direction, along this direction destination node P can simultaneously away from or close to leg-of-mutton 3 terminal A, B, C, then P is positioned at outside △ ABC; Otherwise P is positioned at △ ABC, as shown in Figure 2.In actual applications, usually can from all anchor nodes that mobile node can listen to, select 3 to test in the triangle himself whether formed at these three nodes.This algorithm is original PIT testing algorithm;

Ask for an interview Fig. 3, PIT algorithm errors: in the PIT test of reality, the node being positioned at triangle interior is mistaken at its outside (In-To-Out Error) by normal appearance, and being positioned at the node erroneous judgement of triangular exterior (Out-To-In Error) therein, Fig. 3 gives the scene that these two kinds mistakes judge to occur.

As shown in Fig. 3 (a), destination node P is originally at triangle interior, and near a leg-of-mutton limit, but after comparing with neighbor node 2, find that the signal strength signal intensity that node 2 receives from A, B, C tri-anchor nodes is all less than the signal strength values oneself received, according to the definition of PIT algorithm, judge that P is positioned at △ ABC outside, just In-To-Out mistake occurs.As shown in Fig. 3 (b), destination node P is in the outside near a triangle limit, P and neighbor node 1 find that the signal strength values that neighbor node 1 receives B, C point is less than P more afterwards, but the signal strength values receiving A point is greater than P, just judge that P is positioned at △ ABC inner, produce Out-To-In mistake.The basic reason causing this Type Ⅰ Ⅱ error to occur is because destination node is near edges of regions, abundant not to the position judgment rule of destination node, thus occurs erroneous judgement, and this is this algorithm so-called " edge effect ".

When carrying out algorithm simulating test, because general sensor node keeps static, as described, PIT test cannot be performed by mobile node above, but still by judging the distance with a certain anchor node with the information exchange of neighbor node, the node motion in PIT can be imitated with this.As shown in Fig. 3 (a), 4 neighbor nodes 1,2,3 and 4 are had around hypothetical target node P, by carrying out information exchange with neighbor node 1, analog node P moves towards the direction of neighbor node 1, utilize the nature of radio propagation of Received signal strength power to realize PIT test, similar according to this, analog node P moves towards other adjacent node directions, so just can judge whether P is in △ ABC according to PIT algorithm.But as described above, the mistake that PIT algorithm has two classes intrinsic, if can not more effectively reduce, will inevitably reduce the accuracy of final testing result.

Ask for an interview Fig. 4, Fig. 5 and Fig. 6, a kind of wireless sensor network method for early warning invading deathtrap provided by the invention; Wireless sensor network (WSN) is made up of this three classes sensor node of destination node, anchor node and neighbor node; The node of locating is needed to be called destination node in wireless sensor network (WSN); Position is known and destination node can be assisted to locate node is called anchor node; In a communication radius of destination node, and the node of direct communication can be called neighbor node; It is characterized in that, comprise the following steps:

Step 1: reasonably dispose anchor node on border, deathtrap, namely requires that anchor node integral layout meets substantially " profile of convex polygon ", with satisfied test prerequisite particularly;

Step 2: anchor node is broadcasted, makes all anchor nodes can upgrade to obtain all reference anchor nodes that can communicate with; Step 3: choose destination node P;

Step 4: find out the N number of neighbor node meeting destination node P test condition; Neighbor node must have one group of same reference anchor node with destination node P; If there is such neighbor node, so just can " movement " of simulated target node P, carry out test of heuristics;

Step 5: destination node collects the information with reference to anchor node, and the signal strength signal intensity that information comprises identification number, receives, exchanges the information of the reference anchor node received separately, for test judgement provides design conditions with neighbor node;

Step 6: setting identification variable IsOut, and judge, is neighbor node quantity NeighbeiCount >=1 & & with reference to anchor node amount R efCounf >=3?

If so, order performs following step 7;

If not, then this destination node P is can not location node, then this destination node P is external node, and marking variable IsOut assignment is IsOut=TURE, and this flow process terminates;

Wherein, neighbor node quantity be at least 1 this be algorithm itself determine, lacked change in signal strength without neighbor node, cannot judge with algorithmic rule; Similarly, reference node quantity is at least 3, because form delta-shaped region at least need 3 summits, if less than 3, algorithm cannot carry out equally;

Step 7: take out N number of neighbor node successively, carries out PIT test; The number of times CountIn=0 of initialized target node P in region, initialized target node P at extra-regional number of times CountOut=0, and performs Alpha test;

Step 7.1:

Destination node P and neighbor node exchange message, and carry out PIT test, if there is a direction, along this direction destination node P can simultaneously away from or close to three anchor nodes A, B, C, then P is positioned at outside △ ABC; Otherwise P is positioned at △ ABC;

Step 7.2:

If destination node P meets the condition in △ ABC, 1. so continuation rule tests;

If still met, rule is 1. middle judges the condition in △ ABC, so just judges in △ ABC; If do not meet rule 1. judge the condition in △ ABC, then 2. test by rule again, if test result meets outside △ ABC, so just sentence outside △ ABC, otherwise just change the original sentence in △ ABC;

If destination node P meets the condition outside △ ABC, 2. so continuation rule tests;

If still met, rule is 2. middle judges the condition outside △ ABC, so just judges outside △ ABC; If do not meet rule 2. judge the condition outside △ ABC, then use regular testing again, if test result meets in △ ABC, so just sentence in △ ABC, if test result meets outside △ ABC, so just sentence outside △ ABC;

Step 7.3:

If destination node P meets the condition in △ ABC, then CountIn=CountIn+1;

If destination node P meets the condition outside △ ABC, then CountOut=CountOut+1;

Step 7.4:

Take out next neighbor node, and revolution performs step 7.1, until all neighbor nodes take;

Step 8: perform second stage test;

Step 8.1:

Do you judge that CountIn is greater than CountOut?

If so, then this destination node P is internal node, and marking variable IsOut assignment is IsOut=FALSE;

If not, then this destination node P is external node, and marking variable IsOut assignment is IsOut=TURE;

Step 8.2:

Do you judge that IsOut is TURE?

If so, then judge that destination node P is outside △ ABC region;

If not, then judge that destination node P is in △ ABC region;

Step 8.3: this flow process terminates;

Wherein:

1. rule is: cosine value decision rule;

Ask for an interview Fig. 4, if be a bit positioned at triangle interior, so it has following characteristic: the distance sum on this point and three summits is less than three limit sums; In the angle that this point and three summits form, obtuse angle number is no less than 2; Suppose that the distance between three anchor nodes A, B, C is respectively d aB, d bC, d aC; Destination node P is d to the distance of each anchor node aP, d bP, d cP; Use the cosine law can obtain the cosine value of angle between destination node P and three anchor node:

cos &angle; APB = d AP 2 + d BP 2 - d AB 3 = 2 2 d AP &times; d BP cos &angle; APC = d AP 2 + d CP 2 - d AC 2 2 d AP &times; d CP cos &angle; BPC = d BP 2 + d CP 2 - d BC 2 2 d BP &times; d CP - - - ( 1 ) ;

When having 2 obtuse angles at least in three angles of destination node P and three anchor node, so judge that P is inner at △ ABC; Otherwise, judge that P is outside at △ ABC;

Location algorithms a lot of in wireless sensor network all adopts and RSSI is become internodal actual range by classical propagation path loss model conversion.In the actual environment, radio transmission signal is by the impact of many environmental factors such as multipath, refraction, reflection, barrier, therefore select logarithmic decrement model, and consider the environmental factor causing signal propagation losses, increase path loss index PL (dB);

The computing formula of the distance d then between three anchor nodes A, B, C is: d = d 0 &times; 10 ( PL ( d 0 ) - PL ( dB ) - X &sigma; ) / 10 n - - - ( 2 ) ;

Wherein PL (dB)=PL (d 0)+10nlog 10(d/d 0)+X σ; PL (dB) unit is dBm, PL (d 0) for node is at reference distance d 0the signal strength values that place receives, d is the distance between transmitting-receiving node, and n is the path loss index under varying environment, X σthe normal random variable of to be standard deviation be σ.

2. rule is: edge effect rule;

Ask for an interview Fig. 5, when destination node ecto-entad is near leg-of-mutton sideline, also easily there are 2 obtuse angles, as shown in Fig. 5-(a), so according to above-mentioned cosine value decision rule, Out-To-In mistake will occur, this also just matches with " edge effect " before.Namely dash area as shown in Fig. 5-(b) is the perimeter that there will be 2 obtuse angles.For this reason, when appearance 2 obtuse angles, introduce constraint threshold k, increase one deck decision rule: if there is PA+PB-AB<K, namely destination node is less than threshold k to the distance sum of two anchor nodes and the difference of two anchor node spacings, so just changes into and judges that P is outside at △ ABC; Otherwise just still judge that P is inner at △ ABC.

Because the distribution situation of node is under various circumstances had nothing in common with each other, the value of constraint threshold k also needs respective change, need first repeatedly simulated field environment on emulation platform at the algorithm initial stage thus, substitute into algorithm to find out suitable constraint threshold k, ensure the performance of algorithm.

The choosing method of the constraint threshold k of the present embodiment is, according to the communication radius R of destination node P, tests, constantly increasing, by testing different constraint threshold k to the impact of this method decision error rate, finally choosing suitable numerical value from 5%R; Suitable criterion is the variation tendency depending on error rate in test process, and when retraining threshold value and being increased gradually by 5%R, error rate is declining thereupon, and this is rational variation tendency; Continuing in the process increased, error rate starts to stop declining, and then increase, this is between limited proportionality, also suitable just interval, and constraint threshold value corresponding when selecting error rate minimum is as suitable numerical value.The K value of the present embodiment is 15%R.

In order to verify the performance of the CT-IPIT localization method that the present embodiment proposes, the present invention is based on MFC and developing a dedicated emulated platform of test of heuristics.By the analysis to simulation result, to verify the validity of CT-IPIT localization method, and seek to improve in relevant details.The present embodiment emulation platform has carried out the emulation testing of several innovatory algorithm such as original PIT algorithm, CT-IPIT algorithm respectively.

In order to assessment algorithm performance, existing with reference to anchor node A, B, C for the center of circle, make circle A, B, C respectively with its communication radius, the overlapping region MPQ that three circles are intersected as test zone, as shown in Figure 7.100 differences in even chosen area, use several innovatory algorithm such as original PIT algorithm, CT-IPIT algorithm to test respectively, the relevant parameter of test environment is as shown in table 1.

Table 1 experiment parameter

The object that test zone is so chosen is to ensure that destination node that intra-zone is affixed one's name to has one group of identical reference anchor node, meeting the precondition of PIT test.

Emulation platform carries out the test of CT-IPIT method, when test zone disposes node, requires to accomplish to be uniformly distributed, and ensure there is neighbor node in the communication radius of destination node, be beneficial to test and carry out smoothly.

All methods test 20 groups respectively, and often organize test 50 points, its result is as shown in table 2.As shown in Table 2, the decision error rate of the CT-IPIT method that the present embodiment proposes can control 5.4%, compares original PIT method result of determination and obviously improves, and is also better than other simultaneously and severally improves one's methods, In-To-Out mistake is extremely low, and Out-To-In mistake significantly reduces.

Table 2 test result compares

The mistake not allowing to occur In-To-Out type to be considered, the Out-To-In mistake that tolerable is certain in the practical application that the present invention judges in deathtrap.The total false rate that even now may cause method to detect slightly increases, but for safety monitoring practical application particularly important.For this reason, thoroughly to limit In-To-Out mistake for target in CT-IPIT method, a part of Out-To-In mistake of suitably compromising.Its method CT-IPIT+ improved realizes by regulating threshold k, by reducing K value, thus when applying the rule of the edge effect in CT-IPIT algorithm, may be judged as at the mobile node that delta is overseas within it, but have rejected mobile node and be judged in triangle in its outer situation.The simulation result of CT-IPIT+ method when table 3 is K=10%R under test environment.

Table 3 CT-IPIT +test result

As can be seen from Table 3, the CT-IPIT+ algorithm of improvement has stopped In-To-Out mistake, and Out-To-In mistake slightly increases.

Simulation result shows, under identical experimental situation, reducing significantly with existing Measures compare decision error rate of CT-IPIT method proposed by the invention, especially can eliminate In-To-Out mistake after choosing suitable threshold value by emulation testing, this is significant to the safe early warning of deathtrap.The localization method that the present invention proposes, add certain traffic, node energy consumption increases to some extent, but the accuracy that the method that substantially increases judges, this is necessary to the application scenario that accuracy has higher requirements.

Should be understood that, the part that this specification does not elaborate all belongs to prior art.

Should be understood that; the above-mentioned description for preferred embodiment is comparatively detailed; therefore the restriction to scope of patent protection of the present invention can not be thought; those of ordinary skill in the art is under enlightenment of the present invention; do not departing under the ambit that the claims in the present invention protect; can also make and replacing or distortion, all fall within protection scope of the present invention, request protection range of the present invention should be as the criterion with claims.

Claims (4)

1. one kind invades the wireless sensor network method for early warning of deathtrap; Described wireless sensor network (WSN) is made up of this three classes sensor node of destination node, anchor node and neighbor node; The node of locating is needed to be called destination node in wireless sensor network (WSN); Position is known and destination node can be assisted to locate node is called anchor node; In a communication radius of destination node, and the node of direct communication can be called neighbor node; It is characterized in that, comprise the following steps:
Step 1: reasonably dispose anchor node on border, deathtrap, namely requires that anchor node integral layout meets substantially " profile of convex polygon ", with satisfied test prerequisite particularly;
Step 2: anchor node is broadcasted, makes all anchor nodes can upgrade to obtain all reference anchor nodes that can communicate with; Step 3: choose destination node P;
Step 4: find out the N number of neighbor node meeting destination node P test condition; Described neighbor node must have one group of same reference anchor node with destination node P; If there is such neighbor node, so just can " movement " of simulated target node P, carry out test of heuristics;
Step 5: destination node collects the information with reference to anchor node, and the signal strength signal intensity that described information comprises identification number, receives, exchanges the information of the reference anchor node received separately, for test judgement provides design conditions with neighbor node;
Step 6: setting identification variable IsOut, and judge, is neighbor node quantity NeighbeiCount >=1 & & with reference to anchor node amount R efCounf >=3?
If so, order performs following step 7;
If not, then this destination node P is can not location node, then this destination node P is external node, and marking variable IsOut assignment is IsOut=TURE, and this flow process terminates;
Step 7: take out N number of neighbor node successively, carries out PIT test; The number of times CountIn=0 of initialized target node P in region, initialized target node P at extra-regional number of times CountOut=0, and performs Alpha test;
Step 7.1:
Destination node P and neighbor node exchange message, and carry out PIT test, if there is a direction, along this direction destination node P can simultaneously away from or close to three anchor nodes A, B, C, then P is positioned at outside △ ABC; Otherwise P is positioned at △ ABC;
Step 7.2:
If destination node P meets the condition in △ ABC, 1. so continuation rule tests;
If still met, rule is 1. middle judges the condition in △ ABC, so just judges in △ ABC; If do not meet rule 1. judge the condition in △ ABC, then 2. test by rule again, if test result meets outside △ ABC, so just sentence outside △ ABC, otherwise just change the original sentence in △ ABC;
If destination node P meets the condition outside △ ABC, so continuation regular testing;
If still met, rule is 2. middle judges the condition outside △ ABC, so just judges outside △ ABC; If do not meet rule 2. judge the condition outside △ ABC, then 1. test by rule again, if test result meets in △ ABC, so just sentence in △ ABC, if test result meets outside △ ABC, so just sentence outside △ ABC;
Step 7.3:
If destination node P meets the condition in △ ABC, then CountIn=CountIn+1;
If destination node P meets the condition outside △ ABC, then CountOut=CountOut+1;
Step 7.4:
Take out next neighbor node, and the step 7.1 described in revolution execution, until all neighbor nodes take; Step 8: perform second stage test;
Step 8.1:
Do you judge that CountIn is greater than CountOut?
If so, then this destination node P is internal node, and marking variable IsOut assignment is IsOut=FALSE;
If not, then this destination node P is external node, and marking variable IsOut assignment is IsOut=TURE;
Step 8.2:
Do you judge that IsOut is TURE?
If so, then judge that destination node P is outside △ ABC region;
If not, then judge that destination node P is in △ ABC region;
Step 8.3: this flow process terminates;
Wherein:
1. rule is: cosine value decision rule;
If be a bit positioned at triangle interior, so it has following characteristic: the distance sum on this point and three summits is less than three limit sums; In the angle that this point and three summits form, obtuse angle number is no less than 2; Suppose that the distance between three anchor nodes A, B, C is respectively d aB, d bC, d aC; Destination node P is d to the distance of each anchor node aP, d bP, d cP; Use the cosine law can obtain the cosine value of angle between destination node P and three anchor node:
cos &angle; APB = d AP 2 + d BP 2 - d AB 2 2 d AP &times; d BP cos &angle; APC = d AP 2 + d CP 2 - d AC 2 2 d AP &times; d CP cos &angle; BPC = d BP 2 + d CP 2 - d BC 2 2 d BP &times; d CP - - - ( 1 ) ;
When having 2 obtuse angles at least in three angles of destination node P and three anchor node, so judge that P is inner at △ ABC; Otherwise, judge that P is outside at △ ABC;
2. rule is: edge effect rule;
When destination node P ecto-entad is when the sideline of △ ABC, also easily there are 2 obtuse angles, when appearance 2 obtuse angles, introduce constraint threshold k, if there is PA+PB-AB<K, namely the distance sum of destination node P to two anchor node A, B and the difference of two anchor node A, B spacings are less than threshold k, then change into and judge that P is outside at △ ABC; Otherwise just still judge that P is inner at △ ABC.
2. the wireless sensor network method for early warning of intrusion deathtrap according to claim 1, is characterized in that: the computing formula of the distance d of three described in cosine value decision rule between anchor node A, B, C is:
d = d 0 &times; 10 ( PL ( d 0 ) - PL ( dB ) - X &sigma; ) / 10 n - - - ( 2 ) ;
Wherein PL (dB)=PL (d 0)+10nlog 10(d/d 0)+X σ; PL (dB) unit is dBm, PL (d 0) for node is at reference distance d 0the signal strength values that place receives, d is the distance between transmitting-receiving node, and n is the path loss index under varying environment, X σthe normal random variable of to be standard deviation be σ.
3. the wireless sensor network method for early warning of intrusion deathtrap according to claim 1, it is characterized in that: the choosing method of the constraint threshold k described in edge effect rule is, according to the communication radius R of destination node P, test from 5%R, continuous increase, by testing different constraint threshold k to the impact of this method decision error rate, finally choose suitable numerical value; Described suitable criterion is the variation tendency depending on error rate in test process, and when retraining threshold value and being increased gradually by 5%R, error rate is declining thereupon, and this is rational variation tendency; Continuing in the process increased, error rate starts to stop declining, and then increase, this is between limited proportionality, also suitable just interval, and constraint threshold value corresponding when selecting error rate minimum is as suitable numerical value.
4. the wireless sensor network method for early warning of intrusion deathtrap according to claim 3, is characterized in that: described K value is 15%R.
CN201510106058.9A 2015-03-11 2015-03-11 A kind of wireless sensor network method for early warning for invading danger zone CN104618886B (en)

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